Environmental Health: From Global to Local (Public Health/Environmental Health) [3 ed.] 1118984765, 9781118984765

Table of contents :
Title Page
Copyright
Dedication
Tables, Figures, Text Boxes, and Tox Boxes
The Editor
The Contributors
Acknowledgments
Potential Conflicts of Interest in Environmental Health: From Global to Local
References
Part 1: Methods and Paradigms
Chapter 1: Introduction to Environmental Health
What Is Environmental Health?
The Evolution of Environmental Health
Spatial Scales, from Global to Local
The Forces that Drive Environmental Health
Key Terms
Discussion Questions
References
For Further Information
Chapter 2: Ecology and Ecosystems as Foundational for Health
Environment as Ecology: Ecology as the Study of Our Home
Population Ecology
Community Ecology
Ecosystem Ecology
Systems Thinking: From Ecology to Human Health
Features of Our Home: Ecological Characteristics as Foundational for Health
Toward Ecological Approaches to Health and Home
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 3: Sustainability and Health
Historical Considerations of Sustainability
Sustainable Human Well-Being and the Three-Legged Stool
Drivers of Nonsustainability, Limits to Growth, and Collapse
What Should Concern Us More: Population Growth Or Consumerism?
Limits to Growth
Human Societal Collapse? Prevention Through Systems Thinking and Early Action
The Importance of Scale
The Way Forward
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 4: Environmental and Occupational Epidemiology
A Primer on Epidemiology
Environmental and Occupational Epidemiology
Epidemiology and Risk Assessment
Future Directions
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 5: Geospatial Data for Environmental Health
Components of Georeferenced Data
Basic GIS Operations
Mapping and Spatial Analysis of Exposure
Mapping and Spatial Analysis of Disease Risk
What Makes Good Maps of Good Data?
What Can We Do with GIS?
Are There Any Limitations?
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 6: Toxicology
Introduction to Toxicology
Toxicology and Environmental Public Health
Toxicant Classifications
Testing Compounds for Toxicity
From Regulatory Toxicology to Public Health Policy
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 7: Genes, Genomics, and Environmental Health
Fundamental Concepts of Genetics and Genomics
Approaches for Identifying Gene-Environment Interactions
Examples of Gene-Environment Interactions in the Real World
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 8: Exposure Science, Industrial Hygiene, and Exposure Assessment
Anticipation, Recognition, Evaluation, and Control
Exposure Science
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 9: Environmental Psychology
Environmental Psychology and Toxicology
Environmental Psychology Processes
So What? Interventions That Work
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 10: Environmental Health Ethics
Defining Ethics and Morals
The Modern Philosophical Background
Professionalism
Expanding Horizons and Challenges
Implications for Professional Ethics
Concluding Discussion
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 11: Environmental Justice and Vulnerable Populations
The Roots of Environmental Justice
Elements of Environmental Justice
From Research to Action on Environmental Justice
Social Inequality and Environmental Quality
Summary
Key Terms
Discussion Questions
References
For Further Information
Part 2: Environmental Health on the Global Scale
Chapter 12: Climate Change and Human Health
Greenhouse Gases
A Warming Earth: From Past to Future
Earth System Changes
Food and Malnutrition
Weather Extremes and Disasters
Air Pollution
Infectious Diseases
Mental Health Effects
The Public Health Response to Climate Change
Climate Change as a Public Issue
Summary
Key Terms
Discussion Questions
References
For Further Information
Part 3: Environmental Health on the Regional Scale
Chapter 13: Air Pollution
History of Air Pollution
Types of Ambient Air Pollution
Studies of Air Pollution and Health
Sources and Effects of Outdoor Pollutants
Air Pollution Prevention and Control
Larger Effects of Regional Air Pollution
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 14: Energy and Human Health
Household Energy
Fossil Fuels
Nuclear Energy
Renewable Sources of Energy
Energy Conservation and Efficiency
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 15: Healthy Communities
The History of Cities
Poverty and Industrialization in Cities
The Modern Metropolis: Consumption and Urban Sprawl
Community Design and Health
Cities as Healthy Human Habitats
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 16: Water and Health
The Role of Water in Life
Regulatory Framework
Risk Characterization for Water Contaminants
Emerging Issues
Summary
Key Terms
Discussion Questions
References
For Further Information
Part 4: Environmental Health on the Local Scale
Chapter 17: Solid and Hazardous Waste
Solid Waste
Solid Waste Management Strategies
Primary Prevention of Waste
Waste Treatment and Disposal
Health Concerns
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 18: Pest Control and Pesticides
Insect Pests
Vertebrate Pests
Pesticides
Integrated Pest Management
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 19: Food Systems, the Environment, and Public Health
What Is the Food System?
Food Production: Industrial Agriculture
Industrial Food Animal Production
Sustainable Agriculture
Food Consumption and Food Environments
Food Safety and Environmental Health: A Systems Perspective
Making Change: Food System Policy
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 20: Buildings and Health
The Range of Buildings
Key Elements of a Healthy Building
Toward Safe, Healthy Buildings
Architecture, Environment, and Human Health
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 21: Work, Health, and Well-Being
The Interaction of Work and Health
Protecting Safety and Health on the Job
Workers' Compensation
Sustainability
Globalization
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 22: Radiation
Nonionizing Radiations
Ionizing Radiation: The Basics
Sources of Ionizing Radiation Exposure
Cellular and Biological Effects of Ionizing Radiation
Human Health Effects of Ionizing Radiation
Radiation Protection
Assessing Radiation Risks
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 23: Injuries
Injury Prevention and Control
Policy for Injury Prevention and Control
Injury Prevention in Practice
Injury Control in Special Settings
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 24: Environmental Disasters
Scope of the Problem
The Public Health Consequences of Environmental Disasters
Disaster Risk and Its Determinants
Managing Disaster Risk
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 25: Nature Contact
The Links Between Nature and Human Health
Domains of Nature Contact
The Greening of Environmental Health
Summary
Key Terms
Discussion Questions
References
For Further Information
PART 5: The Practice of Environmental Health
Chapter 26: Environmental Public Health: From Theory to Practice
Concepts of Environmental Health Prevention
Principles of Prevention in Environmental Public Health
Core Functions of Environmental Public Health
Environmental Public Health Systems
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 27: Risk Assessment in Environmental Health
History
Risk Assessment
Risk Management and Communication
Summary
Key Terms
Discussion Questions
References
For Further Information
Chapter 28: Communicating Environmental Health
Communication, Social Marketing, and Environmental Health
Environmental Risk Communication
Summary
Key Terms
Discussion Questions
References
For Further Information
Index
End User License Agreement

Citation preview

Table of Contents Title Page Copyright Dedication Tables, Figures, Text Boxes, and Tox Boxes The Editor The Contributors Acknowledgments Potential Conflicts of Interest in Environmental Health: From Global to Local References Part 1: Methods and Paradigms Chapter 1: Introduction to Environmental Health What Is Environmental Health? The Evolution of Environmental Health Spatial Scales, from Global to Local The Forces that Drive Environmental Health Key Terms Discussion Questions References For Further Information Chapter 2: Ecology and Ecosystems as Foundational for Health Environment as Ecology: Ecology as the Study of Our Home Population Ecology Community Ecology Ecosystem Ecology Systems Thinking: From Ecology to Human Health Features of Our Home: Ecological Characteristics as Foundational for Health Toward Ecological Approaches to Health and Home Summary Key Terms Discussion Questions References For Further Information Chapter 3: Sustainability and Health Historical Considerations of Sustainability Sustainable Human Well-Being and the Three-Legged Stool Drivers of Nonsustainability, Limits to Growth, and Collapse What Should Concern Us More: Population Growth Or Consumerism? Limits to Growth Human Societal Collapse? Prevention Through Systems Thinking and Early Action The Importance of Scale The Way Forward Summary

Key Terms Discussion Questions References For Further Information Chapter 4: Environmental and Occupational Epidemiology A Primer on Epidemiology Environmental and Occupational Epidemiology Epidemiology and Risk Assessment Future Directions Summary Key Terms Discussion Questions References For Further Information Chapter 5: Geospatial Data for Environmental Health Components of Georeferenced Data Basic GIS Operations Mapping and Spatial Analysis of Exposure Mapping and Spatial Analysis of Disease Risk What Makes Good Maps of Good Data? What Can We Do with GIS? Are There Any Limitations? Summary Key Terms Discussion Questions References For Further Information Chapter 6: Toxicology Introduction to Toxicology Toxicology and Environmental Public Health Toxicant Classifications Testing Compounds for Toxicity From Regulatory Toxicology to Public Health Policy Summary Key Terms Discussion Questions References For Further Information Chapter 7: Genes, Genomics, and Environmental Health Fundamental Concepts of Genetics and Genomics Approaches for Identifying Gene-Environment Interactions Examples of Gene-Environment Interactions in the Real World Summary Key Terms

Discussion Questions References For Further Information Chapter 8: Exposure Science, Industrial Hygiene, and Exposure Assessment Anticipation, Recognition, Evaluation, and Control Exposure Science Summary Key Terms Discussion Questions References For Further Information Chapter 9: Environmental Psychology Environmental Psychology and Toxicology Environmental Psychology Processes So What? Interventions That Work Summary Key Terms Discussion Questions References For Further Information Chapter 10: Environmental Health Ethics Defining Ethics and Morals The Modern Philosophical Background Professionalism Expanding Horizons and Challenges Implications for Professional Ethics Concluding Discussion Summary Key Terms Discussion Questions References For Further Information Chapter 11: Environmental Justice and Vulnerable Populations The Roots of Environmental Justice Elements of Environmental Justice From Research to Action on Environmental Justice Social Inequality and Environmental Quality Summary Key Terms Discussion Questions References For Further Information Part 2: Environmental Health on the Global Scale Chapter 12: Climate Change and Human Health

Greenhouse Gases A Warming Earth: From Past to Future Earth System Changes Food and Malnutrition Weather Extremes and Disasters Air Pollution Infectious Diseases Mental Health Effects The Public Health Response to Climate Change Climate Change as a Public Issue Summary Key Terms Discussion Questions References For Further Information Part 3: Environmental Health on the Regional Scale Chapter 13: Air Pollution History of Air Pollution Types of Ambient Air Pollution Studies of Air Pollution and Health Sources and Effects of Outdoor Pollutants Air Pollution Prevention and Control Larger Effects of Regional Air Pollution Summary Key Terms Discussion Questions References For Further Information Chapter 14: Energy and Human Health Household Energy Fossil Fuels Nuclear Energy Renewable Sources of Energy Energy Conservation and Efficiency Summary Key Terms Discussion Questions References For Further Information Chapter 15: Healthy Communities The History of Cities Poverty and Industrialization in Cities The Modern Metropolis: Consumption and Urban Sprawl Community Design and Health

Cities as Healthy Human Habitats Summary Key Terms Discussion Questions References For Further Information Chapter 16: Water and Health The Role of Water in Life Regulatory Framework Risk Characterization for Water Contaminants Emerging Issues Summary Key Terms Discussion Questions References For Further Information Part 4: Environmental Health on the Local Scale Chapter 17: Solid and Hazardous Waste Solid Waste Solid Waste Management Strategies Primary Prevention of Waste Waste Treatment and Disposal Health Concerns Summary Key Terms Discussion Questions References For Further Information Chapter 18: Pest Control and Pesticides Insect Pests Vertebrate Pests Pesticides Integrated Pest Management Summary Key Terms Discussion Questions References For Further Information Chapter 19: Food Systems, the Environment, and Public Health What Is the Food System? Food Production: Industrial Agriculture Industrial Food Animal Production Sustainable Agriculture Food Consumption and Food Environments

Food Safety and Environmental Health: A Systems Perspective Making Change: Food System Policy Summary Key Terms Discussion Questions References For Further Information Chapter 20: Buildings and Health The Range of Buildings Key Elements of a Healthy Building Toward Safe, Healthy Buildings Architecture, Environment, and Human Health Summary Key Terms Discussion Questions References For Further Information Chapter 21: Work, Health, and Well-Being The Interaction of Work and Health Protecting Safety and Health on the Job Workers' Compensation Sustainability Globalization Summary Key Terms Discussion Questions References For Further Information Chapter 22: Radiation Nonionizing Radiations Ionizing Radiation: The Basics Sources of Ionizing Radiation Exposure Cellular and Biological Effects of Ionizing Radiation Human Health Effects of Ionizing Radiation Radiation Protection Assessing Radiation Risks Summary Key Terms Discussion Questions References For Further Information Chapter 23: Injuries Injury Prevention and Control Policy for Injury Prevention and Control

Injury Prevention in Practice Injury Control in Special Settings Summary Key Terms Discussion Questions References For Further Information Chapter 24: Environmental Disasters Scope of the Problem The Public Health Consequences of Environmental Disasters Disaster Risk and Its Determinants Managing Disaster Risk Summary Key Terms Discussion Questions References For Further Information Chapter 25: Nature Contact The Links Between Nature and Human Health Domains of Nature Contact The Greening of Environmental Health Summary Key Terms Discussion Questions References For Further Information PART 5: The Practice of Environmental Health Chapter 26: Environmental Public Health: From Theory to Practice Concepts of Environmental Health Prevention Principles of Prevention in Environmental Public Health Core Functions of Environmental Public Health Environmental Public Health Systems Summary Key Terms Discussion Questions References For Further Information Chapter 27: Risk Assessment in Environmental Health History Risk Assessment Risk Management and Communication Summary Key Terms Discussion Questions

References For Further Information Chapter 28: Communicating Environmental Health Communication, Social Marketing, and Environmental Health Environmental Risk Communication Summary Key Terms Discussion Questions References For Further Information Index End User License Agreement

List of Illustrations Chapter 1: Introduction to Environmental Health Figure 1.1 Title Page of Chadwick's Groundbreaking 1842 Report Figure 1.2 A Victim of Minamata Disease Being Bathed: Photograph by W. Eugene Smith Figure 1.3 The Need for Primary Prevention: An Early 20th-Century View Figure 1.4 The DPSEEA Model Chapter 2: Ecology and Ecosystems as Foundational for Health Figure 2.1 A Food Web in a North American Terrestrial Food Ecosystem Figure 2.2 Invasive Species and Their Impacts Figure 2.3 A Classical Model of Ecological Succession in a North American Forest Ecosystem Figure 2.4 The Phosphorus Cycle Figure 2.5 Transactions Between Atmosphere, Geosphere, and Hydrosphere Provide a Basis for the Earth's Capacity to Support Life Figure 2.8 Ecosystems as Settings for Human Health and Well-Being Figure 2.6 Linear Thinking Versus Systems Thinking Figure 2.7 A Systems Map of U.K. Land Use and the Domains That Influence It Figure 2.9 The Life Cycle and Transmission of Leptospira Bacteria Figure 2.10 The MA Conceptual Framework Figure 2.11 The Social Ecological Model Chapter 3: Sustainability and Health Figure 3.1 The Great Acceleration Figure 3.2 Nested Model of Sustainability Figure 3.3 A Safe Operating Space for Humanity Chapter 4: Environmental and Occupational Epidemiology Figure 4.1 Area of PFOA Contamination Chapter 5: Geospatial Data for Environmental Health Figure 5.1 Hypothetical Example of the Layering GIS Operation Figure 5.2 Examples of Buffers Around Point, Line, and Area Features

Figure 5.3 Map of Genesee County, Michigan, Block Groups (1990 Census) Showing Proportions of Respondents Self-Identifying Race as “Black” Chapter 6: Toxicology Figure 6.1 Toxicology: From Populations to Molecules Figure 6.2 Examples of Dose-Response Curves Figure 6.3 Metabolic Transformations of Benzo(a)pyrene Figure 6.4 Structures of Some Suspected Endocrine-Disrupting Chemicals Figure 6.5 Key Steps in Toxicokinetics Figure 6.6 The Metabolism of Acetaminophen Figure 6.7 Molecular Structure and LD50 for Eight Chemicals Chapter 7: Genes, Genomics, and Environmental Health Figure 7.1 The Human Genome Figure 7.2 The Basic Structural Elements of a Gene Figure 7.3 The Cystic Fibrosis Mutation Figure 7.4 Chromatin Dynamics in Response to Epigenetic Modification Figure 7.5 Schematic of the Agouti Gene and How Its Methylation Status Affects Phenotype in Mice Figure 7.6 Primary Biotransformation Pathway for Alcohol Chapter 8: Exposure Science, Industrial Hygiene, and Exposure Assessment Figure 8.1 An Air Pollution Monitoring Station for Ozone and Particulate Matter, in Atlanta Figure 8.2 Personal Protective Equipment Figure 8.3 Assessing Exposure in an Occupational Setting Chapter 9: Environmental Psychology Figure 9.1 Long Waits and Crowded Buses at a School in Singapore Figure 9.2 Effects of Noise Exposure on Reading Acquisition, Mediated by Poor Auditory Discrimination Figure 9.3 Illustration of Convenience, Attractiveness, and Normativeness in a School Cafeteria Figure 9.4 A Waste Setup That Provides a Physical Cue to Encourage Recycling Figure 9.5 The Five Oaks Neighborhood Following the Defensible Space Intervention Figure 9.6 Location of Hand Cleaner Dispenser in Patient Room: In Line of Sight (left) and Inside the Door (right) Figure 9.7 A Utility Bill Employing Social Norms to Encourage Energy Conservation Chapter 11: Environmental Justice and Vulnerable Populations Figure 11.1a Distribution of Major Industrial Facilities by Racial Composition of Census Tracts, Southern California Figure 11.1b Distribution of Major Industrial Facilities by Proportion of Census Tract Residents Living Below the Federal Poverty Line, Southern California Figure 11.2 The Four Elements of Cumulative Impacts Figure 11.3 Children in Los Angeles Playing Soccer Near an Oil Refinery Figure 11.4 Explanations for the Effect of Social Inequality on the Environment Figure 11.5 Members of Clean Up Green Up, an L.A. Environmental Justice Advocacy Group, Hold a Press Conference in Support of Their Goals

Chapter 12: Climate Change and Human Health Figure 12.1 Components of Radiative Forcing Figure 12.2 The Melting of Arctic Sea Ice Figure 12.3 Processes and Pathways Through Which Climate Change Influences Human Health Figure 12.4 Number of Days in June, July, and August When Daytime Maximum Temperatures Exceed a Given Threshold (indicated by a vertical line) Figure 12.5 Urban Heat Island Profile Figure 12.6 The Relationship Between Temperature and Ozone Levels in Santiago, Chile Figure 12.7 Satellite Photo of a Harmful Algal Bloom in Lake Erie in 2011 Figure 12.8 The Association Between Temperature and Childhood Diarrhea, Peru, 1993–1998 Figure 12.9a Alternative Emission Pathways Figure 12.9b Climate Stabilization Wedges Figure 12.10 The CDC's BRACE Framework Figure 12.11 No-Regrets Solutions Figure 12.12 Global Warming's Six Americas: Arraying the U.S. Population Along a Continuum of Belief, Concern, and Motivation Figure 12.13 A Comparison of Cumulative CO2 Emissions (1950–2000) (upper panel) with the Burden of Four Climate-Related Health Effects (Malaria, Malnutrition, Diarrhea, and Inland Flood-Related Fatalities (lower panel) Chapter 13: Air Pollution Figure 13.1 Children Wear Masks in the Thick Haze on Tiananmen Square in Beijing, China, January, 2013. Figure 13.2 The Distribution of PM2.5 Levels in Cities in India, China, Europe, and the United States Figure 13.3 Mortality and Air Pollution Levels During the 1952 London Fog Figure 13.4 The Respiratory System Figure 13.5 Particulate Matter Mass Distribution in an Urban Area Chapter 14: Energy and Human Health Figure 14.1 The Fuel Ladder Figure 14.2 Association Between Energy Use and Health, by Nation Figure 14.3 Pathways Linking Energy and Health Figure 14.4 World Energy Consumption Figure 14.5 Indoor Air Pollution from Traditional Cooking Figure 14.6 Products Made from a 42-Gallon Barrel of Crude Oil (in gallons) Figure 14.7 An Oil Refinery Figure 14.8 Renewable Energy Chapter 15: Healthy Communities Figure 15.1 World Population: Urban and Rural, 1950–2050 Figure 15.2 Nearly 1 Billion People Live in Urban Slums, Such as This One in Nairobi Figure 15.3 Heavy Traffic, as Shown Here in Delhi, Brings Pollution, Injury Risks, Noise, and Mental Stress, and Inhibits Physical Activity

Figure 15.4 Schematic Comparison of Street Networks and Land Use in a Traditional Neighborhood and in an Area of Sprawl Figure 15.5 Percentage of Self-Reported Obesity in Adults in the United States, by State, 2013 Figure 15.6 An Example of Complete Streets in Copenhagen, Where Many Streets Are Designed to Accommodate Pedestrians, Bicyclists, Transit, and Automobiles Figure 15.7 Access to Healthy Food Options Figure 15.8 Overlapping Frameworks for Healthy Community Design Figure 15.9 Relationship Between Growth of Bicycle Infrastructure and Amount of Cycling in Portland, Oregon Chapter 16: Water and Health Figure 16.1 The Hydrological Cycle Figure 16.2 Schematic of the Interconnections Between Water and Health Figure 16.3 Pesticide Movement in the Hydrological Cycle, Including Movement to and from Sediment and Aquatic Biota in a Stream Figure 16.4 Sanitation Options Figure 16.5 An Idealized Wastewater Treatment System, Based on Boston's Deer Island System Figure 16.6 Carrying Water Figure 16.7 Basic Drinking-Water Treatment Process Figure 16.8 A Multibarrier Approach to Maximize Microbiological Water Quality Chapter 17: Solid and Hazardous Waste Figure 17.1 Chemical Drums at Love Canal Figure 17.2 Composition of the 251 Million Tons of Municipal Solid Waste Produced in the United States (Before Recycling), 2012 Figure 17.3 Total Amount and Per Capita Generation Rate of Municipal Solid Waste Produced in the United States (Before Recycling), 1960–2012 Figure 17.4 Total Amount and Percentage of Municipal Solid Waste Recycled in the United States, 1960–2012 Figure 17.5 Glass and Paper Recycling in Industrial Nations Figure 17.6 Waste Tires Figure 17.7 Generalized Depiction of a State-of-the-Art Sanitary Landfill Figure 17.8 Generalized Diagram of Incineration Material and Process Flow Figure 17.9 Mine Tailings Pile: The Legacy of Sixty Years of Lead and Zinc Mining in Ottawa County, Oklahoma Chapter 18: Pest Control and Pesticides Figure 18.1 Application of Lead Arsenate in the Early 1900s Figure 18.2 Modern Pesticide Application Equipment Figure 18.3 A Corn Borer, an Example of an Insect Pest, Causing Damage in the Stalk of a Corn Plant Figure 18.4 Farmers Applying Organophosphate Insecticides in Thailand Chapter 19: Food Systems, the Environment, and Public Health Figure 19.1 Selected Components of the Food System Figure 19.2 Applying Herbicide to a North Carolina Cornfield

Figure 19.3 Potential Pathways for the Spread of Antibiotic-Resistant Bacteria from Animals to Humans Figure 19.4 Manure Cesspit Outside Hog CAFO in Duplin County, North Carolina Figure 19.5 Ducks in One of Takao Furuno's Rice Paddies in Japan Figure 19.6 The EPA Food Recovery Hierarchy Prioritizes Actions to Prevent and Divert Wasted Food Figure 19.7 Contribution of Different Food Categories to Estimated Domestically Acquired Illness and Death, United States, 1998–2008 Figure 19.8 A Health Inspector Tests the Temperature of Refrigerated Meat at a Restaurant Figure 19.9 A 1993 Outbreak Caused by E. Coli 0157 in Undercooked Beef at Jack in the Box Restaurants Sickened 732 People and Killed 4 Children Figure 19.10 An Example of Improper Grain Storage Figure 19.11 A U.S. Department of Agriculture Food Safety Inspection Service Inspector at a Poultry Processing Facility in Accomac, Virginia, Testing for Cleanliness and the Avian Influenza (AI) Virus Chapter 20: Buildings and Health Figure 20.1 Housing Can Take Many Forms and Vary Greatly in Desirability and Safety Figure 20.2 Trailer Provided by FEMA after Hurricane Katrina Figure 20.3 School Design Figure 20.4 Mold-Damaged Building in New Orleans Following Hurricane Katrina Figure 20.5 Concentrations of PBDE in Breast Milk, Stockholm, 1972–1997 Chapter 21: Work, Health, and Well-Being Figure 21.1 From July 1906 Through June 1907, 526 Workers Were Killed on the Job in Allegheny County, Pennsylvania Figure 21.2 Who Bears the Cost of Worker Injuries? Chapter 22: Radiation Figure 22.1 The Electromagnetic Spectrum Figure 22.2 Cell phones Are Virtually Ubiquitous, and Entail Exposure to Radiofrequency Radiation Figure 22.3 A Basal Cell Carcinoma of the Skin of Twenty Years, Duration in a Fifty-Eight-Year-Old Man Figure 22.4 Nuclear Transformation Mechanisms That Release Radioactivity Figure 22.5 Using X-Rays for Fitting Shoes Figure 22.6 The Chernobyl Disaster Chapter 23: Injuries Figure 23.1 The Injury Pyramid Figure 23.2 Typology of Violence Chapter 24: Environmental Disasters Figure 24.1 Annual Incidence of Natural and Technological Environmental Disasters—Worldwide, 1964–2013 Figure 24.2 Comparison of the Public Health Impacts of Natural and Technological Disaster Events, 1964–2013 Figure 24.3 Key Public Health Impacts for Natural and Technological Disasters, 1964–2013

Figure 24.4 Three Conceptual Frameworks for Disaster Risk Management Figure 24.5 The Four Elements of a Resilience Framework Chapter 25: Nature Contact Figure 25.1 John Muir ({–1914) Was a Naturalist and Conservationist Whose Writings Had a Profound Influence on American Attitudes Toward Nature Figure 25.2 The Human-Animal Bond Figure 25.3 A Community Garden Figure 25.4 Robert Taylor Homes, Chicago: An Aerial View, the Buildings Without Nearby Trees, and the Buildings with Nearby Trees Figure 25.5 A Sunday Afternoon on the Island of LaGrande Jatte, 1884–1886, by Georges Seurat Figure 25.6 Green Exercise Figure 25.7 Frank Lloyd Wright's Fallingwater Chapter 27: Risk Assessment in Environmental Health Figure 27.1 The Multitude of Factors Affecting Risk of Disease Figure 27.2 Timeline of Milestones in the History of Risk Assessment Figure 27.3 The Process of Using Environmental Health Risk Assessment to Protect Public Health Figure 27.4 Threshold Compared to Nonthreshold Dose-Response Models Figure 27.5 Approach to Carcinogen and Noncarcinogen Dose-Response Assessment Figure 27.6 Some Common Exposure Pathways Chapter 28: Communicating Environmental Health Figure 28.1 Social Amplification of Risk Framework

List of Tables Chapter 2: Ecology and Ecosystems as Foundational for Health Table 2.1 Scale in Ecology, and Some Disciplines That Contribute at Each Level Table 2.2 Type of Relationship Between Different Species Table 2.3 Links Between Ecology and Systems Thinking as a Basis for Health Chapter 3: Sustainability and Health Table 3.1 Metrics of Sustainability Chapter 6: Toxicology Table 6.1 Carcinogen Classification of Chemicals: IARC Results as of March 2015 Chapter 9: Environmental Psychology Table 9.1 Contrasting Toxicology and Environmental Psychology Table 9.2 Examples of Convenience, Attractiveness, and Normativeness Applied to a School Cafeteria Chapter 12: Climate Change and Human Health Table 12.1 The Main Greenhouse Gases Table 12.2 Temperature and Precipitation Effects on Selected Vectors and Vector-Borne Pathogens Table 12.3 Co-Benefits of Climate Mitigation and Adaptation Activities Chapter 13: Air Pollution

Table 13.1 Major Ambient Air Pollutants: Sources, Health Effects, and Regulations Chapter 14: Energy and Human Health Table 14.1 Energy Use in Selected Countries, 2005–2009 Chapter 15: Healthy Communities Table 15.1 Stages of Urban Evolution and Characteristic Environmental Conditions and Health Issues Table 15.2 Comparison of Sprawl and Smart Growth Chapter 16: Water and Health Table 16.1 Hot Spots of Current and/or Potential Water Conflicts Table 16.2 Examples of Large-Scale Human Impacts on Aquatic Systems Table 16.3 Classes of Chemical Contaminants in Water Table 16.4 Examples of Studies of Possible Links Between Exposure to Chemicals in Drinking Water and Increased Health Risk Table 16.5 Pathogens in or Related to Water, Diseases They Cause, and Approaches to Prevention and Treatment Table 16.6 Global Challenges in Water and Sanitation, Particularly in Low- and Middle-Income Countries Table 16.7 The Indicator Approach to Monitoring Water Quality Table 16.8 Simple, Low-Cost Water Treatment Options Table 16.9 Approaches to Disinfection Chapter 18: Pest Control and Pesticides Table 18.1 Pesticides Classified by Target or Mode of Action Chapter 19: Food Systems, the Environment, and Public Health Table 19.1 HACCP Principles Table 19.2 Jurisdiction over Food Safety in the United States Table 19.3 Some of the Many Policies Shaping the U.S. Food System Chapter 20: Buildings and Health Table 20.1 Average Exposure Concentrations of Formaldehyde and Contribution of Various Atmospheric Environments to Exposure to Formaldehyde Table 20.2 Hazardous Ingredients of Cleaners (Partial Listing) Table 20.3 Approaches to Protecting Health and Safety in Buildings Chapter 21: Work, Health, and Well-Being Table 21.1 The Public Health Impact of OSHA Regulations Chapter 22: Radiation Table 22.1 Units of Radiation Exposure and Dose Table 22.2 Average Amounts of Ionizing Radiation Received Annually by a U.S. Resident Table 22.3 Representative Radiation Doses in Select Medical Procedures Performed in the United States Table 22.4 Major Forms and Features of Acute Radiation Syndromes Table 22.5 Estimated Lifetime Risks of Fatal Cancer AttribuTable to 0.1 Sv Low-Dose-Rate WholeBody Irradiation

Chapter 23: Injuries Table 23.1 The Haddon Matrix Applied to Motor Vehicle Crashes Table 23.2 Options Analysis in Injury Control Table 23.3 Countermeasures for Intentional Injuries Table 23.4 Countermeasures for Burns Table 23.5 Countermeasures for Poisoning Table 23.6 Countermeasures for Falls Table 23.7 Countermeasures for Drowning Table 23.8 Countermeasures for Road Injuries Table 23.9 Countermeasures for Playground Injuries Table 23.10 Countermeasures for Home Injuries Chapter 24: Environmental Disasters Table 24.1 A Typology of Environmental Disasters Table 24.2 The Ten Deadliest Environmental Disasters—Worldwide, 1964–2013 Table 24.3 Major Causes of Death During Environmental Disasters Table 24.4 Public Health Consequences and Capabilities Associated with All Disasters Chapter 26: Environmental Public Health: From Theory to Practice Table 26.1 Essential Services of Environmental Public Health Table 26.2 The Protocol for Assessing Community Excellence in Environmental Health (PACE-EH) Process Chapter 28: Communicating Environmental Health Table 28.1 Factors Important in Risk Perception

Environmental Health From Global to Local Third Edition

Howard Frumkin, Editor

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Dedication I dedicate this book to my wife, Joanne, and to my children, Gabe and Amara. Joanne–lover of truth, of science, and of narrative, who walks the talk, who is incapable of pretense or malice, and whose love is an incalculable gift. Gabe and Amara–dedicated environmentalists, great lovers of the outdoors, hard-headed idealists, change agents, and two of the most wonderful people I know. They will make giant contributions to a safer, healthier, more sustainable, and more just world.

Tables, Figures, Text Boxes, and Tox Boxes Tables 2.1 2.2 2.3 3.1 6.1 9.1 9.2 12.1 12.2 12.3 13.1 14.1 15.1 15.2 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 18.1 19.1 19.2 19.3 20.1 20.2 20.3 21.1 22.1 22.2 22.3 22.4 22.5

Scale in Ecology, and Some Disciplines That Contribute at Each Level Type of Relationship Between Different Species Links Between Ecology and Systems Thinking as a Basis for Health Metrics of Sustainability Carcinogen Classification of Chemicals: IARC Results as of March 2015 Contrasting Toxicology and Environmental Psychology Examples of Convenience, Attractiveness, and Normativeness Applied to a School Cafeteria The Main Greenhouse Gases Temperature and Precipitation Effects on Selected Vectors and Vector-Borne Pathogens Co-Benefits of Climate Mitigation and Adaptation Activities Major Ambient Air Pollutants: Sources, Health Effects, and Regulations Energy Use Within Selected Countries, 2005–2009 Stages of Urban Evolution and Characteristic Environmental Conditions and Health Issues Comparison of Sprawl and Smart Growth Hot Spots of Current and/or Potential Water Conflicts Examples of Large-Scale Human Impacts on Aquatic Systems Classes of Chemical Contaminants in Water Examples of Studies of Possible Links Between Exposure to Chemicals in Drinking Water and Increased Health Risk Pathogens in or Related to Water, Diseases They Cause, and Approaches to Prevention and Treatment Global Challenges in Water and Sanitation, Particularly in Low- and Middle-Income Countries The Indicator Approach to Monitoring Water Quality Simple, Low-Cost Water Treatment Options Approaches to Disinfection Pesticides Classified by Target or Mode of Action HACCP Principles Jurisdiction over Food Safety in the United States Some of the Many Policies Shaping the U.S. Food System Average Exposure Concentrations of Formaldehyde and Contribution of Various Atmospheric Environments to Exposure to Formaldehyde Hazardous Ingredients of Cleaners (Partial Listing) Approaches to Protecting Health and Safety in Buildings The Public Health Impact of OSHA Regulations Units of Radiation Exposure and Dose Average Amounts of Ionizing Radiation Received Annually by a U.S. Resident Representative Radiation Doses in Select Medical Procedures Performed in the United States Major Forms and Features of Acute Radiation Syndromes Estimated Lifetime Risks of Fatal Cancer Attributable to 0.1 Sv Low-Dose-Rate Whole-Body Irradiation

23.1 23.2 23.3 23.4 23.5 23.6 23.7 23.8 23.9 23.10 24.1 24.2 24.3 24.4 26.1 26.2 28.1

The Haddon Matrix Applied to Motor Vehicle Crashes Options Analysis in Injury Control Countermeasures for Intentional Injuries Countermeasures for Burns Countermeasures for Poisoning Countermeasures for Falls Countermeasures for Drowning Countermeasures for Road Injuries Countermeasures for Playground Injuries Countermeasures for Home Injuries A Typology of Environmental Disasters The Ten Deadliest Environmental Disasters—Worldwide, 1964–2013 Major Causes of Death During Environmental Disasters Public Health Consequences and Capabilities Associated with All Disasters Essential Services of Environmental Public Health The Protocol for Assessing Community Excellence in Environmental Health (PACE-EH) Process Factors Important in Risk Perception

Figures 1.1 1.2

Title Page of Chadwick's Groundbreaking 1842 Report A Victim of Minamata Disease Being Bathed: Photograph by W. Eugene Smith

The Need for Primary Prevention: An Early 20th-Century View The DPSEEA Model A Food Web in a North American Terrestrial Food Ecosystem Invasive Species and Their Impacts A Classical Model of Ecological Succession in a North American Forest Ecosystem The Phosphorus Cycle Transactions Between Atmosphere, Geosphere, and Hydrosphere Provide a Basis for the Earth's Capacity to Support Life 2.6 Linear Thinking Versus Systems Thinking 2.7 A Systems Map of U.K. Land Use and the Domains That Influence It 2.8 Ecosystems as Settings for Human Health and Well-Being 2.9 The Life Cycle and Transmission of Leptospira Bacteria 2.10 The MA Conceptual Framework 2.11 The Social Ecological Model 3.1 The Great Acceleration 3.2 Nested Model of Sustainability 3.3 A Safe Operating Space for Humanity 4.1 Area of PFOA Contamination 5.1 Hypothetical Example of the Layering GIS Operation 5.2 Examples of Buffers Around Point, Line, and Area Features 5.3 Map of Genesee County, Michigan, Block Groups (1990 Census) Showing Proportions of Respondents Self-Identifying Race as ``Black'' 6.1 Toxicology: From Populations to Molecules 1.3 1.4 2.1 2.2 2.3 2.4 2.5

6.2 6.3 6.4 6.5 6.6 6.7 7.1 7.2 7.3 7.4 7.5 7.6 8.1 8.2 8.3 9.1 9.2 9.3 9.4 9.5 9.6 9.7 11.1a 11.1b 11.2 11.3 11.4 11.5 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9a 12.9b 12.10 12.11

Examples of Dose-Response Curves Metabolic Transformations of Benzo(a)pyrene Structures of Some Suspected Endocrine-Disrupting Chemicals Key Steps in Toxicokinetics The Metabolism of Acetaminophen Molecular Structure and LD$_{50}$ for Eight Chemicals The Human Genome The Basic Structural Elements of a Gene The Cystic Fibrosis Mutation Chromatin Dynamics in Response to Epigenetic Modification Schematic of the Agouti Gene and How Its Methylation Status Affects Phenotype in Mice Primary Biotransformation Pathway for Alcohol An Air Pollution Monitoring Station for Ozone and Particulate Matter, in Atlanta Personal Protective Equipment Assessing Exposure in an Occupational Setting Long Waits and Crowded Buses at a School in Singapore Effects of Noise Exposure on Reading Acquisition, Mediated by Poor Auditory Discrimination Illustration of Convenience, Attractiveness, and Normativeness in a School Cafeteria A Waste Setup That Provides a Physical Cue to Encourage Recycling The Five Oaks Neighborhood Following the Defensible Space Intervention Location of Hand Cleaner Dispenser in Patient Room: In Line of Sight (left) and Inside the Door (right) A Utility Bill Employing Social Norms to Encourage Energy Conservation Distribution of Major Industrial Facilities by Racial Composition of Census Tracts in Southern California Distribution of Major Industrial Facilities by Proportion of Census Tract Residents Living Below the Federal Poverty Line in Southern California The Four Elements of Cumulative Impacts Children in Los Angeles Playing Soccer Near an Oil Refinery Explanations for the Effect of Social Inequality on the Environment Members of Clean Up Green Up, an L.A. Environmental Justice Advocacy Group, Hold a Press Conference in Support of Their Goals Components of Radiative Forcing The Melting of Arctic Sea Ice Processes and Pathways Through Which Climate Change Influences Human Health Number of Days in June, July, and August When Daytime Maximum Temperatures Exceed a Given Threshold (indicated by a vertical line) Urban Heat Island Profile The Relationship Between Temperature and Ozone Levels in Santiago, Chile Satellite Photo of a Harmful Algal Bloom in Lake Erie in 2011 The Association Between Temperature and Childhood Diarrhea, Peru, 1993–1998 Climate Stabilization Wedges Climate Stabilization Wedges The CDC's BRACE Framework No-Regrets Solutions

12.12 Global Warming's Six Americas: Arraying the U.S. Population Along a Continuum of Belief, Concern, and Motivation 12.13 A Comparison of Cumulative CO$_{2}$ Emissions (1950–2000) (upper panel) with the Burden of Four Climate-Related Health Effects (Malaria, Malnutrition, Diarrhea, and Inland Flood-Related Fatalities (lower panel) 13.1 A Group of Children Wear the Masks on Tiananmen Square in Thick Haze in Beijing, China. 3-Jan2013 13.2 The Distribution of PM$_{2.5}$ Levels in Cities in India, China, Europe, and the United States 13.3 Mortality and Air Pollution Levels During the 1952 London Fog 13.4 The Respiratory System 13.5 Particulate Matter Mass Distribution 14.1 The Fuel Ladder 14.2 Association Between Energy Use and Health, by Nation 14.3 Pathways Linking Energy and Health 14.4 World Energy Consumption 14.5 Indoor Air Pollution from Traditional Cooking 14.6 Products Made from a 42-Gallon Barrel of Crude Oil (in gallons) 14.7 An Oil Refinery 14.8 Renewable Energy 15.1 World Population: Urban and Rural, 1950–2050 15.2 Nearly 1 Billion People Live in Urban Slums, Such as This One in Nairobi 15.3 Heavy Traffic, as Shown Here in Delhi, Brings Pollution, Injury Risks, and Mental~Stress, and Inhibits Physical Activity 15.4 Schematic Comparison of Street Networks and Land Use in a Traditional Neighborhood and in an Area of Sprawl 15.5 Percentage of Self-Reported Obesity in Adults in the United States, by State, 2013 15.6 An Example of Complete Streets in Copenhagen, Where Many Streets Are Designed to Accommodate Pedestrians, Bicyclists, Transit, and Automobiles 15.7 Access to Healthy Food Options 15.8 Overlapping Frameworks for Healthy Community Design 15.9 Relationship Between Growth of Bicycle Infrastructure and Amount of Cycling in Portland, Oregon 16.1 The Hydrological Cycle 16.2 Schematic of the Interconnections Between Water and Health 16.3 Pesticide Movement in the Hydrological Cycle, Including Movement to and from Sediment and Aquatic Biota in a Stream 16.4 Sanitation Options 16.5 An Idealized Wastewater Treatment System, Based on Boston's Deer Island System 16.6 Carrying Water 16.7 Basic Drinking-Water Treatment Process 16.8 A Multibarrier Approach to Maximize Microbiological Water Quality 17.1 Chemical Drums at Love Canal 17.2 Composition of the 251 Million Tons of Municipal Solid Waste Produced in the United States (Before Recycling), 2012 17.3 Total Amount and Per Capita Generation Rate of Municipal Solid Waste Produced in the United States (Before Recycling), 1960–2012 17.4 Total Amount and Percentage of Municipal Solid Waste Recycled in the United States, 1960–2012

17.5 Glass and Paper Recycling in Industrial Nations 17.6 Waste Tires 17.7 Generalized Depiction of a State-of-the-Art Sanitary Landfill 17.8 Generalized Diagram of Incineration Material and Process Flow 17.9 Mine Tailings Pile: The Legacy of Sixty Years of Lead and Zinc Mining in Ottawa~County, Oklahoma 18.1 Application of Lead Arsenate in the Early 1900s 18.2 Modern Pesticide Application Equipment 18.3 A Corn Borer, an Example of an Insect Pest, Causing Damage in the Stalk of a Corn Plant 18.4 Farmers Applying Organophosphate Insecticides in Thailand 19.1 Selected Components of the Food System 19.2 Applying Herbicide to a North Carolina Cornfield 19.3 Potential Pathways for the Spread of Antibiotic-Resistant Bacteria from Animals to Humans 19.4 Manure Cesspit Outside Hog CAFO in Duplin County, North Carolina 19.5 Ducks in One of Takao Furuno's Rice Paddies in Japan 19.6 The EPA Food Recovery Hierarchy Prioritizes Actions to Prevent and Divert Wasted Food 19.7 Contribution of Different Food Categories to Estimated Domestically Acquired Illness and Death, United States, 1998–2008 19.8 A Health Inspector Tests the Temperature of Refrigerated Meat at a Restaurant 19.9 A 1993 Outbreak Caused by E. Coli 0157 in Undercooked Beef at Jack in the Box Restaurants Sickened 732 People and Killed 4 Children 19.10 An Example of Improper Grain Storage 19.11 A U.S. Department of Agriculture Food Safety Inspection Service Inspector at a Poultry Processing Facility in Accomac, Virginia, Testing for Cleanliness and the Avian Influenza (AI) Virus 20.1 Housing Can Take Many Forms and Vary Greatly in Desirability and Safety 20.2 Trailer Provided by FEMA after Hurricane Katrina 20.3 School Design 20.4 Mold-Damaged Building in New Orleans Following Hurricane Katrina 21.1 From July 1906 Through June 1907, 526 Workers Were Killed on the Job in Allegheny County, Pennsylvania 21.2 Who Bears the Cost of Worker Injuries? 22.1 The Electromagnetic Spectrum 22.2 Cell Phones Are Virtually Ubiquitous, and Entail Exposure to Radiofrequency Radiation 22.3 A Basal Cell Carcinoma of the Skin of Twenty Years Duration in a Fifty-Eight-Year-Old Man 22.4 Nuclear Transformation Mechanisms That Release Radioactivity 22.5 Using X Rays for Fitting Shoes 22.6 The Chernobyl Disaster 23.1 The Injury Pyramid 23.2 Typology of Violence 24.1 Annual Incidence of Natural and Technological Environmental Disasters—Worldwide, 1964–2013 24.2 Comparison of the Public Health Impacts of Natural and Technological Disaster Events, 1964– 2013 24.3 Key Public Health Impacts for Natural and Technological Disasters, 1964–2013 24.4 Three Conceptual Frameworks for Disaster Risk Management 24.5 The Four Elements of a Resilience Framework 25.1 John Muir (1838–1914) Was a Naturalist and Conservationist Whose Writings Had a Profound

Influence on American Attitudes Toward Nature 25.2 The Human-Animal Bond 25.3 A Community Garden 25.4 Robert Taylor Homes, Chicago: An Aerial View, the Buildings Without Nearby Trees, and the Buildings with Nearby Trees 25.5 A Sunday Afternoon on the Island of La Grande Jatte, 1884–1886, by Georges~Seurat 25.6 Green Exercise 25.7 Frank Lloyd Wright's Fallingwater 27.1 The Multitude of Factors Affecting Risk of Disease 27.2 Timeline of Milestones in the History of Risk Assessment 27.3 The Process of Using Environmental Health Risk Assessment to Protect Public Health 27.4 Some Common Exposure Pathways 27.5 Threshold Compared to Nonthreshold Dose-Response Models 27.6 Carcinogen and Noncarcinogen Dose-Response Relationships 28.1 Social Amplification of Risk Framework

Text Boxes 1.1 1.2 1.3 2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 4.1 4.2 6.1 6.2 6.3 6.4 6.5 6.6

Definitions of Environmental Health Environmental Health: Common Good or Nanny State? A Prevention Poem: A Fence or an Ambulance Food Webs Biological Invasions Conservation Biology Ecosystem Services Restoration Ecology: The Practical Application of Ecological Literacy and Systems Thinking Infectious Disease as an Ecological and Social Process: The Example of Leptospirosis Planetary Health Sustainability in Health Care Example of a Community Cohort Study An Interview Study to Improve Sanitation Dose-Response Curve Transporting Vital, Yet Dangerous Chemicals Chemical Carcinogenesis Endocrine Disruptors The Microbiome and Toxicology LD50 for Various Compounds

6.7 7.1 7.2 8.1 8.2 8.3 10.1 10.2

Replace, Reduce, Refine: Laboratory Animals in Toxicology Liver Cancer from Moldy Corn and Peanuts: Aflatoxin and the Role of GSTM1 Polymorphism Genetic Susceptibility to Environmental Mercury Assessing an Electronics Manufacturing Facility: The Role of Anticipation Understanding Concentration, Exposure, and Dose Assessing Exposure to Carbon Monoxide Selected Ethics Approaches The Art of Ethics

10.3 10.4 10.5 10.6 11.1 11.2 11.3 12.1 12.2 13.1 13.2 13.3 14.1 14.2 14.3 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 16.1 16.2 16.3 16.4 16.5 16.6 16.7 17.1 17.2 17.3 17.4 17.5 18.1 18.2 18.3 19.1 19.2 19.3 19.4 19.5 20.1

Professionalism and Ethics Typical Elements in Professional Codes of Ethics Environmental Responsibility Principles in Ethics Codes Environmental Responsibility Roots of Environmental Justice in Warren County, North Carolina Children Are Not Small Adults Environmental Justice Meets Urban Forestry Some Effects of Weather and Climate on Vector- and Rodent-Borne Diseases The CDC's BRACE Framework Air Pollution in the World's Dirtiest Cities London 1952: One of the World's Worst Air Pollution Disasters The Clean Air Act: Environmental Regulation for Public Health Protections Health Impacts of the Dublin Coal Ban Peak Petroleum and Public Health Health Co-Benefits of Energy Conservation and Efficiency Urbanization Versus Urbanism Policies That Regulate Land Use Impacts of Community Design on Health Safe Walking and Cycling Health Impact Assessment: A Tool for Land-Use and Transportation Decision Making Smart Growth Principles to Promote Equitable, Healthy, and Sustainable Communities Principles of Universal Design LEED for Neighborhood Development Certification Program Water as a Nutrient A Gross Inequity Antibiotic Resistance Chronology of Events During the Walkerton, Ontario, E. coli O157 Outbreak in 2000 Risk Factors and the Changing Burden of Disease Water Treatment More Than a Century Ago (1881) The Contaminant Candidate List U.S. Solid and Hazardous Waste Laws and Policy The Challenge of Medical Waste e-Waste Tire Reuse and Recycling International Trafficking in Hazardous Wastes Insect Repellants Who Is Responsible for Applying Pesticides? Pesticide Toxicity Categories and Labeling Requirements Policy Approaches to Antibiotic Use in Animal Agriculture Organic Agriculture: What Does It Mean? The Environmental Impacts of Wasted Food Globalization, Seafood, and Food Safety Mycotoxins Manufactured Structures

20.2 20.3 20.4 20.5 21.1 21.2 21.3 22.1 22.2 22.3 23.1 23.2 23.3 23.4 24.1 24.2 24.3 25.1 25.2 25.3 25.4 25.5 25.6 25.7 26.1 26.2 27.1 27.2 27.3 27.4 27.5 28.1 28.2 28.3 28.4

Homelessness: An Environmental Health Problem? Chemical Safety in Buildings Sick Building Syndrome Building Design for the Elderly “Statistics Are People with the Tears Wiped Away” Mine Disasters, Miner Protections Core Elements of All Safety and Health Management Systems Is Cell Phone Use Linked to Cancer? What Are Isotopes? What Happens During Most Nuclear Power Plant Accidents? Fatal Occupational Injury at a Gun Range Texting and Driving Engineering the Driver Out of the Equation Firearm Policy Disaster Resilience The 11 E's of Public Health Preparedness A Case Study of Haiti's Troubled Recovery Getting Kids Outside: A Public Health Strategy? Community Gardens Nature Contact in the Inner City Parks and Public Health Green Exercise Nature Contact, Poverty, and Health: A Connection? Biophilic Design Keeping Track in Environmental Health Careers in Environmental Health Example of Problem Formulation: Assessing a New Incinerator Example of Hazard Identification: Evaluating Methylmercury Technical Terminology in Risk Assessment Risk Characterization for a Methylmercury Risk Assessment Risk Management for Methylmercury in Seafood Risk Communication: A Two-Way Process Elements of a Comprehensive Risk and Crisis Communication Plan Overcoming Psychological, Cultural, and Sociological Barriers to Risk Communication Questions Frequently Asked During an Emergency or Crisis

Tox Boxes 2.1 6.1 6.2 6.3 7.1 11.1 13.1

Polychlorinated Biphenyls (PCBs) Bisphenol A (BPA) Polycyclic Aromatic Hydrocarbons Phthalates Benzene Lead (Pb) Carbon Monoxide

13.2 16.1 16.2 18.1 18.2 19.1 20.1 20.2 20.3 20.4

Mercury (Hg) Arsenic Disinfection By-Products Organophosphates Organochlorine Pesticides Dioxins Volatile Organic Compounds (VOCs): The Case of Formaldehyde Radon Asbestos Polybrominated Diphenyl Ethers (PBDEs)

An instructor's supplement is available at www.wiley.com/go/frumkin3e. Additional materials such as videos, podcasts, and readings can be found at www.josseybasspublichealth.com. Comments about this book are invited and can be sent to [email protected].

The Editor Howard Frumkin has been dean, and professor of environmental and occupational health sciences, at the University of Washington School of Public Health since 2010. From 2005 to 2010, he held leadership roles at the U.S. Centers for Disease Control and Prevention, first as director of the National Center for Environmental Health and Agency for Toxic Substances and Disease Registry (NCEH/ATSDR), and later as special assistant to the CDC director for climate change and health. From 1990 to 2005, he was professor and chair of environmental and occupational health at Emory University's Rollins School of Public Health and professor of medicine at the Emory School of Medicine. Dr. Frumkin trained in internal medicine, epidemiology, and occupational and environmental medicine. His research interests include public health aspects of the built environment, climate change, energy policy, and nature contact; toxic effects of chemicals; and environmental health policy. He is the author or coauthor of over 200 scientific journal articles and chapters, and his books, in addition to this one, include Urban Sprawl and Public Health (Island Press, 2004, coauthored with Lawrence Frank and Richard Jackson), Emerging Illness and Society (Johns Hopkins University Press, 2004, co-edited with Randall Packard, Peter Brown, and Ruth Berkelman), Safe and Healthy School Environments (Oxford University Press, 2006, co-edited with Robert Geller, Leslie Rubin, and Janice Nodvin), Green Healthcare Institutions: Health, Environment, Economics (National Academies Press, 2007, co-edited with Christine Coussens), and Making Healthy Places: Designing and Building for Health, Well-Being, and Sustainability (Island Press, 2011, co-edited with Andrew Dannenberg and Richard Jackson). Dr. Frumkin has worked with many organizations active at the interface of human health and the environment. He has served on the boards of the Bullitt Foundation, the Children & Nature Network, the Seattle Parks Foundation, the Pacific Northwest Diabetes Research Institute, the U.S. Green Building Council, the Washington Global Health Alliance, Physicians for Social Responsibility, the Association of Occupational and Environmental Clinics, the American Public Health Association, and the National Environmental Education Foundation. He has served on the Executive Committee of the Regional Open Space Strategy for Central Puget Sound, on Procter & Gamble's Sustainability Expert Advisory Panel, on the National Toxicology Program Board of Scientific Counselors, on the National Research Council Committee on Sustainability Linkages in the Federal Government, on the Washington Department of Ecology Toxics Reduction Strategy Group, and on Seattle's Green Ribbon Commission. He has served on advisory boards for the Yale Climate and Energy Institute, the Wellcome Trust Sustaining Health initiative, the National Sustainable Communities Coalition, and the Center for Design and Health at the University of Virginia School of Architecture. As a member of the EPA's Children's Health Protection Advisory Committee, he chaired the Smart Growth and Climate Change work groups. A graduate of the Institute for Georgia Environmental Leadership, he was named 2004 Environmental Professional of the Year by the Georgia Environmental Council. Dr. Frumkin was born in Poughkeepsie, New York. He received his AB degree from Brown University, his MD degree from the University of Pennsylvania, his MPH and DrPH degrees from Harvard University, his internal medicine training at the Hospital of the University of Pennsylvania and Cambridge Hospital, and his environmental and occupational medicine training at Harvard. He is board certified in internal medicine and in environmental and occupational medicine, and is a Fellow of the American College of Physicians, the American College of Occupational and Environmental Medicine, Collegium Ramazzini, and the Royal College of Physicians of Ireland. He is an avid cyclist, paddler, and hiker. He is married to radio journalist Joanne Silberner, and has two children—Gabe, a political campaign worker, and Amara, a health worker.

The Contributors Michelle L. Bell, PhD Mary E. Pinchot Professor of Environmental Health School of Forestry & Environmental Studies Yale University New Haven, Connecticut Pamela Rhubart Berg, MPH Education Program Manager Center for a Livable Future Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Thomas A. Burke, PhD, MPH Jacob I. and Irene B. Fabrikant Professor and Chair in Health Risk and Society Director, Risk Sciences and Public Policy Institute Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Anthony G. Capon, MBBS, PhD, FAFPHM Professor and Director International Institute for Global Health United Nations University Kuala Lumpur, Malaysia Megan Cartwright, BS PhD Candidate, Environmental and Occupational Health Sciences School of Public Health University of Washington Seattle, Washington Kristin Aldred Cheek, BA, MS PhD Candidate, Department of Design and Environmental Analysis College of Human Ecology Cornell University Ithaca, New York Vincent T. Covello, PhD Founder and Director, Center for Risk Communication New York, New York Andrew L. Dannenberg, MD, MPH Affiliate Professor, Environmental and Occupational Health Sciences, and Urban Design and Planning School of Public Health and College of Built Environments

University of Washington Seattle, Washington David L. Eaton, PhD Dean, Graduate School and Professor, Environmental and Occupational Health Sciences School of Public Health University of Washington Seattle, Washington Anna Engstrom, BS PhD Candidate, Environmental and Occupational Health Sciences School of Public Health University of Washington Seattle, Washington Gary W. Evans, PhD Elizabeth Lee Vincent Professor of Human Ecology Departments of Design & Environmental Analysis and of Human Development College of Human Ecology Cornell University Ithaca, New York Henry Falk, MD, MPH Carter Consulting, Inc. Consultant to Office of Noncommunicable Disease, Injury and Environmental Health (ONDIEH) Centers for Disease Control and Prevention Atlanta, Georgia Timothy Ford, PhD Dean, School of Health Professions Shenandoah University Winchester, Virginia Lynn R. Goldman, MD, MS, MPH The Michael and Lori Milken Dean of Public Health and Professor of Environmental and Occupational Health Milken Institute School of Public Health The George Washington University Washington, DC George C. Hamilton, PhD Professor and Chair Department of Entomology Rutgers University New Brunswick, New Jersey Jeremy J. Hess, MD, MPH

Associate Professor of Medicine, Division of Emergency Medicine School of Medicine Associate Professor, Environmental and Occupational Health Sciences School of Public Health University of Washington Seattle, Washington Jason R. Holmes, MD Resident Physician, Emergency Medicine Emory University Atlanta, Georgia Leo Horrigan, MHS Food Systems Correspondent Center for a Livable Future Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Pierre Horwitz, PhD Professor of Environmental Science School of Natural Sciences Edith Cowan University Joondalup, Western Australia Andrew Jameton, PhD Professor Emeritus, Health Promotion, Social and Behavioral Health College of Public Health University of Nebraska Medical Center Omaha, Nebraska Mark E. Keim, MD, MBA Owner, DisasterDoc™, LLC Lawrenceville, Georgia Juleen Lam, PhD Assistant Research Scientist Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Dave Love, PhD, MSPH Assistant Scientist Center for a Livable Future Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Edward Maibach, MPH, PhD University Professor, Department of Communication

Director, Center for Climate Change Communication George Mason University College of Humanities and Social Sciences Fairfax, Virginia David Michaels, PhD, MPH Assistant Secretary of Labor for Occupational Safety and Health Washington, DC Professor of Environmental and Occupational Health Milken Institute School of Public Health The George Washington University Washington, DC Gary W. Miller, PhD Professor and Associate Dean for Research Department of Environmental Health Rollins School of Public Health Emory University Atlanta, Georgia Christine L. Moe, PhD Eugene J. Gangarosa Professor of Safe Water and Sanitation Director, Center for Global Safe Water, Sanitation, and Hygiene at Emory University Hubert Department of Global Health Rollins School of Public Health Emory University Atlanta, Georgia Rachel Morello-Frosch, PhD, MPH Professor, Department of Environmental Science, Policy & Management School of Public Health University of California, Berkeley Berkeley, California Matthew P. Moeller, MS, CHP Chief Executive Officer Dade Moeller & Associates Richland, Washington Keeve Nachman, PhD, MHS Assistant Professor and Program Director Food Production & Public Health Program Center for a Livable Future Johns Hopkins Bloomberg School of Public Health Baltimore, MD Roni Neff, PhD

Assistant Professor, Environmental Health Sciences Program Director, Food System Sustainability and Public Health Center for a Livable Future Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Cindy L. Parker, MD, MPH Assistant Professor, Departments of Environmental Health Sciences, and Krieger School of Arts and Sciences Associate Director, Environment, Energy, Sustainability & Health Institute Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Margot W. Parkes, MBChB, MAS, PhD Canada Research Chair in Health, Ecosystems and Society Associate Professor, School of Health Sciences, Cross Appointed, Northern Medical Program University of Northern British Columbia Prince George, British Columbia, Canada Manuel Pastor, PhD Professor, Departments of Sociology and of American Studies & Ethnicity Director, Program on Environmental and Regional Equity University of Southern California Los Angeles, California Jonathan A. Patz, MD, MPH Professor and John P. Holton Chair in Health and the Environment Director, Global Health Institute University of Wisconsin Madison, Wisconsin Héctor Luis Maldonado Pérez, BS Research Assistant and Graduate Student School of Public Health Rutgers University New Brunswick, New Jersey Junaid A. Razzak, MD, PhD Professor, Department of Emergency Medicine Johns Hopkins School of Medicine Department of International Health Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Jessica D. Rhodes, MD, MPH Family Medicine Resident

Sutter Santa Rosa Family Medicine Residency Santa Rosa, California Mark Gregory Robson, PhD, MPH, DrPH Distinguished Service Professor and Chair Department of Plant Biology and Pathology Rutgers University New Brunswick, New Jersey Sven E. Rodenbeck, ScD, PE, BCEE Rear Admiral (retired), U.S. Public Health Service Senior Service Fellow Agency for Toxic Substances and Disease Registry Centers for Disease Control and Prevention Atlanta, Georgia P. Barry Ryan, PhD Professor, Exposure Science and Environmental Chemistry Department of Environmental Health Director of Laboratories Rollins School of Public Health Emory University Atlanta, Georgia Jonathan Samet, MD, MS Director, USC Institute for Global Health Distinguished Professor and Flora L. Thornton Chair Department of Preventive Medicine Keck School of Medicine University of Southern California Los Angeles, California Christopher M. Schaupp, BS Graduate Student, Environmental and Occupational Health Sciences School of Public Health University of Washington Seattle, Washington Brian S. Schwartz, MD, MS Professor, Departments of Environmental Health Sciences and Epidemiology Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland Mary C. Sheehan, MALD, MPH, PhD Faculty Associate Johns Hopkins Bloomberg School of Public Health

Baltimore, Maryland Wattasit Siriwong, PhD Associate Professor and Deputy Dean College of Public Health Sciences Chulalongkorn University Bangkok, Thailand Marissa N. Smith, MS PhD Candidate, Environmental and Occupational Health Sciences School of Public Health University of Washington Seattle, Washington Kyle Steenland, PhD, MS Professor, Departments of Environmental Health and Epidemiology Rollins School of Public Health Emory University Atlanta, Georgia Gregory R. Wagner, MD Senior Advisor to the Director, National Institute for Occupational Safety and Health Centers for Disease Control and Prevention (CDC/NIOSH), Washington, DC Adjunct Professor, Harvard T. H. Chan School of Public Health Boston, Massachusetts Lance A. Waller, PhD Rollins Professor and Chair, Department of Biostatistics and Bioinformatics Rollins School of Public Health Emory University Atlanta, Georgia Nancy M. Wells, PhD Associate Professor, Department of Design and Environmental Analysis College of Human Ecology Cornell University Ithaca, New York James S. Woods, PhD, MPH, MS Research Professor Emeritus Department of Environmental and Occupational Health Sciences School of Public Health University of Washington Seattle, WA Anna Q. Yaffee, MD, MPH Resident Physician

Department of Emergency Medicine School of Medicine Emory University Atlanta, Georgia Michael G. Yost, PhD Chair and Professor, Department of Environmental Health and Occupational Health Sciences School of Public Health University of Washington Seattle, Washington

Acknowledgments In many religions and cultures teachers are revered. I honor that tradition, as well I should: I have been blessed with more superb teachers than I had any right to expect when I first marched off to school. They didn't know it, but they were all preparing me to envision this book and pull it together. One of the sweetest privileges of an editor—and there have been many—is the chance to thank them. I express my deep and lasting gratitude to my high school teacher Barbara Leventer, who taught me that writing a research paper means specifying a hypothesis, organizing an outline, finding the right sources, and writing clearly (yes, that was all possible before the Internet!); my college teachers the late Ed Beiser, who taught me that there is no excuse for muddled thinking and unclear expression, and Steve Lyons and the late Hunter Dupree, who taught me the majesty and endless relevance of history; my medical school teachers Paul Stolley, who taught me the power of epidemiological data and who set a standard for principled advocacy, and the late John Eisenberg, who modeled a formidable combination of clinical excellence, astute policy analysis, and great kindness; my residency chief Bob Lawrence, who taught me that primary care extends from the bedside to the global commons; and my graduate school teachers Richard Monson, the late John Peters, and David Wegman, who taught me the interface of public health and the environment. Dick Jackson has been a mentor, thought partner, and friend since he arrived at the CDC 20 years ago. I thank Dean Jim Curran and my colleagues and students at Emory University's Rollins School of Public Health, where I had the great good fortune to serve as a faculty member from 1990 to 2005, and where I edited the first edition of this textbook. I also thank my colleagues at the U.S. Centers for Disease Control and Prevention, where I directed the National Center for Environmental Health (NCEH) and the Agency for Toxic Substances and Disease Registry (ATSDR) from 2005 to 2010, and where I edited the second edition. And I thank my colleagues at the University of Washington School of Public Health, where I have served as dean since 2010. Two great universities and a great government agency have offered a wonderful career path, marked by intellectual stimulation, hard-working, dedicated colleagues, and dear friends. I thank my colleagues at other agencies, such as the Environmental Protection Agency and the National Institute of Environmental Health Sciences, and at organizations ranging from environmental and community groups to law firms to manufacturing companies, who have taught me more than I can say about the many facets of environmental health. Over the years I have especially appreciated my friends and colleagues at Physicians for Social Responsibility; the Institute of Medicine Roundtable on Environmental Health, Research, and Medicine; Atlanta's Clean Air Campaign; the EPA's Children's Health Protection Advisory Committee; the Association of Occupational and Environmental Clinics; the American Public Health Association; Sustainable Atlanta; the Children & Nature Network; the Bullitt Foundation; the Washington Global Health Alliance; the U.S. Green Building Council; the American Institute of Architects; and the Seattle Parks Foundation. Special gratitude to the members of my Green Reading Groups, first in Atlanta, and later in Seattle—perfect blends, both, of close friendship, intellectual curiosity, and environmental learning. Thank you to Karla Armenti, Kathlyn Barry, Darrell Norman Burrell, William Daniel, J. Aaron Hipp, Peter LaPuma, Susan West Marmagas, Camille Martina, Mary Kay O'Rourke, Anne Riederer, Lauren Savaglio, and Alfredo Vergara, who provided valuable feedback on the previous edition of this book, which helped greatly in designing changes for this edition. I thank the chapter authors of this book, all of them highly expert and exceedingly busy people. They willingly shared their expertise and time (and gracefully tolerated my prodding and editing) to help compile the kind of book that we would all want to use in our own teaching. I am especially pleased that the authors include several graduate students and trainees, whose skill and energy bode well for the future of our field. I thank my editors at Jossey-Bass. The late Andy Pasternack, who edited the first two editions, was a friend, supporter, and mentor; his premature loss leaves a hole in the universe. Seth Schwartz ably succeeded Andy, bringing the same belief in this project, generous tolerance of delays, and discipline. Melinda Noack and Justin Frahm rounded out an all-star team at Jossey-Bass. And I thank copyeditor Elspeth MacHattie, a consummate professional, a pleasure to work with, and an enormous asset to this book.

I thank the staff who supported the preparation of the first and second editions of this book: Hope Jackson, Robin Thompson, Adrienne Tison, Erica Weaver, Rachel Wilson, and Suzanne Mason at Emory, and Cheryl Everhart at NCEH/ATSDR. And special thanks to JeShawna Schmidt, who supported me at the University of Washington in preparing this third edition, with her extraordinary combination of organizational skills, work ethic, grace, dedication, kindness, and optimism. I had an unforgettable opportunity while preparing the third edition: a two-week academic residency at Villa Serbelloni, the Rockefeller Foundation's center in Bellagio, Italy. This sojourn exemplified the power of a physical setting—the indescribable beauty of Lake Como and of the facility itself—to inspire good work and to promote well-being. More importantly, it also exemplified the magic that occurs when people from diverse backgrounds and disciplines come together. My fellow residents hailed from South Africa, Kenya, India, and across the United States, and were working on housing, transportation, NGO governance, urban resiliency, literature, visual art, and dance—but all, in a real sense, were working on social change, dedicated to making the world a better place. I made lifelong friends, I learned from each of them, and they are all reflected in this book. I thank the Rockefeller Foundation for the privilege. Finally, I acknowledge my beloved wife, best friend, and trusted consultant, Joanne Silberner, who silently, eloquently raised her eyebrows when I told her I had committed to another edition of this book, then supported me unstintingly throughout. Without her, nothing.

Potential Conflicts of Interest in Environmental Health: From Global to Local In recent years, increasing attention has been focused on integrity in scientific publishing. Much of this concern has grown out of pharmaceutical research; in that arena, conflicts of interest are widespread (Friedman & Richter, 2004) and consequential; funding sources have been shown to predict research findings (Kjaergard & Als-Nielsen, 2002; Lexchin, Bero, Djulbegovic, & Clark, 2003; Smith, 2005; Lundh, Sismondo, Lexchin, Busuioc, & Bero, 2012). But pharmaceutical research is not the only vulnerable area; in environmental health, private interests may also collide with public good, so conflicts of interest must be recognized as a real concern in this field too (Michaels & Monforton, 2005; Sutton, Woodruff, Vogel, & Bero, 2011). In 2015, disclosures about an allegedly conflicted climate change researcher on the front page of the New York Times—nobody's ideal venue for such matters—reinforced this fact (Gillis, 2015; Gillis & Schwartz, 2015). Conflicts of interest have been defined as “conditions in which professional judgment concerning a primary interest (such as a patient's welfare or the validity of research) tends to be unduly influenced by a secondary interest (such as financial gain)” (Thompson, 1993). Conflicts of interest, real or perceived, can derail the quest for truth, have a corrosive effect on scientific data (Bekelman, Li, & Gross, 2003; Rennie, 2010), and undermine public faith in science (Friedman, 2002; Kennedy, 2004; Lo & Field, 2009). Importantly, the bias resulting from conflicts of interest may be subconscious, reflecting neither malfeasance nor even intent. Bias is a normal part of human cognition, and people are often unaware of their biases (Cain & Detsky, 2008; Young, 2009). Conflicts of interest may be financial or nonfinancial. The financial variety is intuitively clear; as former JAMA editor Drummond Rennie wrote, “numerous studies have confirmed what we all know: money talks” (Rennie, 2010). The nonfinancial variety is not always as clear. These conflicts may be personal, political, religious, ideological, or careerist (Levinsky, 2002). The editors of PLoS Medicine described two examples (The PLoS Medicine Editors, 2008): the peer reviewer who disapproves of a particular research method for religious reasons, and who obstructs the publication of research using that method; and the editor who remains close to her former advisor, and who tilts toward accepting the advisor's paper. Those who publish or report on science have increasingly tackled the challenge of conflicts of interest (Maurissen et al., 2005; Lo & Field, 2009). Transparency is a leading solution, recalling Justice Louis Brandeis's adage that “sunshine is the best disinfectant”—even if it is not always sufficient (Bero, Glantz, & Hong, 2005; Resnik & Elliott, 2013). The Committee on Publication Ethics (COPE, 2011), a forum for peer-reviewed journal editors and publishers, in its Code of Conduct, requires that “[r]eaders should be informed about who has funded research or other scholarly work and whether the funders had any role in the research and its publication and, if so, what this was.” Similarly, the International Committee of Medical Journal Editors (ICMJE, 2014) expects authors to disclose both “financial relationships with entities in the bio-medical arena that could be perceived to influence, or that give the appearance of potentially influencing,” and “other [nonfinancial] relationships or activities that readers could perceive to have influenced, or that give the appearance of potentially influencing” an author's work. Accordingly, most medical journals now require disclosures of potential conflicts of interest when publishing papers. Such disclosures serve a purpose; they inform readers' views of what they read (Chaudhry, Shroter, Smith, & Morris, 2002; Kesselheim et al., 2012). Disclosure has moved beyond the publication of research findings in journals. Many (but not enough) reports of scientific results in the popular media now mention funding sources (Cook, Boyd, Grossman, & Bero, 2007). Many universities require faculty to report potential conflicts of interest (Boyd & Bero, 2000). Disclosure is especially important in review papers (Michaels, 2009; Viswanathan et al., 2014). “Because analysis, interpretation, and synthesis, often of conflicting data, are important aspects of these papers,” wrote one journal editor, “they are particularly susceptible to suspicions of bias, subconscious or otherwise” (DeMaria, 2004). The same, of course, is true for textbook chapters. But it is rare for textbooks to disclose potential conflicts of interest. This omission is curious given the wide readership of textbooks, the tendency of textbook chapters to present broad conclusions, and the fact that student readers, at an

early stage of their training, may be more impressionable than discerning. This third edition of Environmental Health: From Global to Local, continuing a practice begun in the second edition, has addressed this concern by asking each chapter author to report both real and perceived conflicts of interest. Following guidelines from a Natural Resources Defense Council workshop (Sass, 2009) and from the ICMJE (2014), each author was asked to disclose relationships occurring during the last three years, currently active, or reasonably anticipated to occur in the foreseeable future “with companies that make or sell products or services discussed in the chapter, companies that make or sell related products or services, and other pertinent entities with an interest in the topic, specifying the type of relationship.” These relationships were defined as including (but not limited to) Grant support Employment (past, present, or firm offer of future) Stock ownership or options Payment for serving as an expert witness or giving testimony Personal financial interests on the part of the author, immediate family members, or institutional affiliations that might gain or lose financially through publication of the chapter Other forms of compensation, including travel funding, consultancies, honoraria, board positions, and patent or royalty arrangements Employment by a for-profit, nonprofit, foundation, or advocacy group If it is important for authors to offer these disclosures to readers, it is even more important for the editor —who selects and curates all material in the book—to do so. During the three years prior to starting work on this book, and while doing the editing, in addition to my work as dean at the University of Washington School of Public Health, I held the following positions: Board member of the U.S. Green Building Council, which promotes green, healthy buildings (uncompensated) Board member of the Bullitt Foundation, a regional environmental grantmaker in the Pacific Northwest (uncompensated) Board member of the Seattle Parks Foundation, which promotes parks and park access in Seattle (uncompensated) Member of the American Institute of Architects Design & Health Leadership Group, which promotes healthy building design (uncompensated) Member of the American Association for the Advancement of Science Climate Science Panel, which provides public information on climate science (uncompensated) Member of the Yale Climate and Energy Institute External Advisory Board (uncompensated) Member of the Procter & Gamble Sustainability Expert Advisory Panel (honorarium paid to University of Washington) Member of several editorial boards, all uncompensated (American Journal of Industrial Medicine, Salud Pública de México, Environmental Health Perspectives, American Journal of Preventive Medicine, ECOHEALTH, Annual Review of Public Health, and Ecopsychology) Each author's employment is shown in the author identification section, and disclosures of potential conflicts of interest appear at the bottom of the first text page of his or her chapter. I am not aware of another major textbook that has implemented such a policy. I hope this helps to ensure the integrity of every chapter in this book and becomes more common in scientific textbooks in coming years. Howard Frumkin Editor

References

Bekelman, J. E., Li, Y., & Gross, C. P. (2003). Scope and impact of financial conflicts of interest in biomedical research: A systematic review. JAMA, 289, 454–465. Bero, L. A., Glantz, S., & Hong, M. K. (2005). The limits of competing interest disclosures. Tobacco Control, 14(2), 118–126. Boyd, E., & Bero, L. (2000). Assessing faculty financial relationships with industry. JAMA, 284, 2209– 2214. Cain, D. M., & Detsky, A. S. (2008). Everyone's a little bit biased (even physicians). JAMA, 299(24), 2893–2895. Chaudhry, S., Shroter, S., Smith, R., & Morris, J. (2002). Does declaration of competing interests affect readers' perceptions? A randomized trial. BMJ, 325, 1391–1392. Committee on Publication Ethics. (2011). Code of conduct and best practice guidelines for journal editors. Retrieved from http://publicationethics.org/files/Code_of_conduct_for_journal_editors_Mar11.pdf Cook, D. M., Boyd, E. A., Grossman, C., & Bero, L. A. (2007). Reporting science and conflicts of interest in the lay press. PLoS ONE, 2(12), e1266. DeMaria, A. N. (2004). Authors, industry, and review articles. Journal of the American College of Cardiology, 43(6), 1130–1131. Friedman, L. S., & Richter, E. D. (2004). Relationship between conflicts of interest and research results. Journal of General Internal Medicine, 19(1), 51–56. Friedman, P. (2002). The impact of conflict of interest on trust in science. Science and Engineering Ethics, 8, 413–420. Gillis, J. (2015, March 3). Climate change researcher offers a defense of his practices. New York Times, p. A19. Retrieved from http://www.nytimes.com/2015/03/03/science/climate-change-researcher-weihock-soon-offers-a-defense-of-his-practices.html?_r=0 Gillis, J., & Schwartz, J. (2015). Deeper ties to corporate cash for doubtful climate researcher. New York Times, February 22, p. A1. Retrieved from http://www.nytimes.com/2015/02/22/us/ties-to-corporatecash-for-climate-change-researcher-Wei-Hock-Soon.html International Committee of Medical Journal Editors. (2014). Recommendations for the conduct, reporting, editing, and publication of scholarly work in medical journals. Retrieved from http://www.icmje.org/icmje-recommendations.pdf Kennedy, D. (2004). Disclosure and disinterest. Science, 303, 15. Kesselheim, A. S., Robertson, C. T., Myers, J. A., Rose, S. L., Gillet, V., Ross, K. M.,…Avorn, J. (2012). A randomized study of how physicians interpret research funding disclosures. New England Journal of Medicine, 367(12), 1119–1127. Kjaergard, L. L., & Als-Nielsen, B. (2002). Association between competing interests and authors' conclusions: Epidemiological study of randomised clinical trials published in the BMJ. BMJ, 325(7358), 249–249. Levinsky, N. G. (2002). Nonfinancial conflict of interest. New England Journal of Medicine, 347(10), 759–761. Lexchin, J., Bero, L. A., Djulbegovic, B., & Clark, O. (2003). Pharmaceutical industry sponsorship and research outcome and quality. BMJ, 326, 1167–1170. Lo, B., & Field, M. J. (2009). Institute of Medicine Committee on Conflict of Interest in Medical Research, Education, and Practice. Conflict of interest in medical research, education, and practice. Washington, DC: National Academies Press.

Lundh, A., Sismondo, S., Lexchin, J., Busuioc, O. A., & Bero, L. (2012). Industry sponsorship and research outcome. Cochrane Database of Systematic Reviews, 12, MR000033. doi:10.1002/14651858.MR000033.pub2 Maurissen, J. P., Gilbert, S. G., Sander, M., Beauchamp, T. L., Johnson, S., Schwetz, B. A.,…Barrow, C. S. (2005). Workshop proceedings: Managing conflict of interest in science: A little consensus and a lot of controversy. Toxicological Sciences, 87, 11–14. Michaels, D. (2009). Addressing conflict in strategic literature reviews: Disclosure is not enough. Journal of Epidemiology and Community Health, 63(8), 599–600. Michaels, D., & Monforton, C. (2005). Manufacturing uncertainty: Contested science and the protection of the public's health and environment. American Journal of Public Health, 95(Suppl. 1), S39–48. The PLoS Medicine Editors. (2008). Making sense of non-financial competing interests. PLoS Medicine, 5(9), e199. Rennie, D. (2010). Integrity in scientific publishing. Health Services Research Journal, 45(3), 885–896. Resnik, D. B., & Elliott, K. C. (2013). Taking financial relationships into account when assessing research. Accountability in Research, 20(3), 184–205. Sass, J. (2009). Effective and practical disclosure policies: NRDC paper on workshop to identify key elements of disclosure policies for health science journals. Natural Resources Defense Council. Retrieved from http://www.nrdc.org/health/disclosure Smith, R. (2005). Medical journals are an extension of the marketing arm of pharmaceutical companies. PLoS Medicine, 2, e138. doi:10.1371/journal.pmed.0020138 Sutton, P., Woodruff, T. J., Vogel, S., & Bero, L. A. (2011). Conrad and Becker's “10 Criteria” fall short of addressing conflicts of interest in chemical safety studies. Environmental Health Perspectives, 119(12), A506–507. Thompson, D. F. (1993). Understanding financial conflicts of interest. New England Journal of Medicine, 329, 573–576. Viswanathan, M., Carey, T. S., Belinson, S. E., Berliner, E., Chang, S. M., Graham, E.,…White, C. M. (2014). A proposed approach may help systematic reviews retain needed expertise while minimizing bias from nonfinancial conflicts of interest. Journal of Clinical Epidemiology, 67(11), 1229–1238. Young, S. N. (2009). Bias in the research literature and conflict of interest: An issue for publishers, editors, reviewers and authors, and it is not just about the money. Journal of Psychiatry and Neuroscience, 34(6), 412–417.

Part 1 Methods and Paradigms

Chapter 1 Introduction to Environmental Health Howard Frumkin Dr. Frumkin's disclosures appear in the front of this book, in the section titled “Potential Conflicts of Interest in Environmental Health: From Global to Local.”

Key Concepts Environmental health is the field of public health that addresses physical, chemical, biological, social, and psychosocial factors in the environment. It aims both to control and prevent environmental hazards and to promote health and well-being through environmental strategies. People have always been concerned with environmental health, but the nature of their concerns has evolved with the transition from prehistoric, to agricultural, to industrial, to postindustrial life. Many disciplines contribute to environmental health: epidemiology and toxicology, psychology and communications, urban planning and food science, law and ethics, and more. Environmental health utilizes the geographic concept of spatial scales, from the global (with issues such as climate change), to the regional (air quality), to the local (neighborhood design), to the hyperlocal (ergonomics). Environmental health thinking takes a systems approach, embracing complexity, and focusing on “upstream” factors as well as on “downstream” health impacts. Please stop reading. That's right. Close this book, just for a moment. Lift your eyes and look around. Where are you? What do you see? Perhaps you're in the campus library, surrounded by shelves of books, with carpeting underfoot and the heating or air-conditioning humming quietly in the background. Perhaps you're home—a dormitory room, a bedroom in a house, a suite in a garden apartment, maybe your kitchen. Perhaps you're outside, lying beneath a tree in the middle of campus, or perhaps you're on a subway or a bus or even an airplane. What is it like? How does it feel to be where you are? Is the light adequate for reading? Is the temperature comfortable? Is there fresh air to breathe? Are there contaminants in the air—say, solvents off-gassing from newly laid carpet or a recently painted wall? Does the chair fit your body comfortably? If you're inside, look outside. What do you see through the window? Are there trees? Buildings? Is the neighborhood noisy or tranquil? Are there other people? Are there busy streets, with passing trucks and busses snorting occasional clouds of diesel exhaust? Now imagine that you can see even farther, to a restaurant down the block, to the nearby river, to the highway network around your city or town, to the factories and assembly plants in industrial parks, to the power plant in the distance supplying electricity to the room you're in, to the agricultural lands and forests some miles away. What would you see in the restaurant? Is the kitchen clean? Is the food stored safely? Are there cockroaches or rats in the back room? What about the river? Is your municipal sewage system dumping raw wastes into the river, or is there a sewage plant discharging treated, clean effluent? Are there chemicals in the river water? What about fish? Could you eat the fish? Could you swim in the river? Do you drink the water from the river? As for the highways, factories, and power plant…are they polluting the air? Are the highways clogged with traffic? Are people routinely injured and killed on the roads? Are workers in the factories being exposed to hazardous chemicals or to noise or to machines that may injure them or to stress? Are trains pulling up to the power plant regularly, off-loading vast piles of coal? And what about the farms? Are they applying

pesticides, or are they controlling insects in other ways? Are you confident that you're safe eating the vegetables that grow there? Drinking the milk? Are the farmlands shrinking as residential development from the city sprawls outward? Finally, imagine that you have an even broader view. Floating miles above the Earth, you look down. Do you notice the hundreds of millions of people living in wildly differing circumstances? Do you see vast megacities with millions and millions of people, and do you see isolated rural villages three days' walk from the nearest road? Do you see forests being cleared in some places, rivers and lakes drying up in others? Do you notice that the Earth's surface temperature is slightly warmer than it was a century ago? Do you see cyclones forming in tropical regions, glaciers and icecaps melting near the poles? OK, back to the book. Everything you've just viewed, from the room you're in to the globe you're on, is part of your environment. And many, many aspects of that environment, from the air you breathe to the water you drink, from the roads you travel to the wastes you produce, may affect how you feel. They may determine your risk of being injured before today ends, your risk of coming down with diarrhea or shortness of breath or a sore back, your risk of developing a chronic disease in the next few decades, even the risk that your children or your grandchildren will suffer from developmental disabilities or asthma or cancer.

What Is Environmental Health? Merriam-Webster's Collegiate Dictionary first defines environment straightforwardly as “the circumstances, objects, or conditions by which one is surrounded.” The second definition it offers is more intriguing: “the complex of physical, chemical, and biotic factors (as climate, soil, and living things) that act upon an organism or an ecological community and ultimately determine its form and survival.” If our focus is on human health, we can consider the environment to be all the external (or nongenetic) factors— physical, nutritional, social, behavioral, and others—that act on humans. A widely accepted definition of health comes from the 1948 constitution of the World Health Organization: “A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.” This broad definition reaches well beyond blood pressure readings and X-ray results to include many dimensions of our lives: well-being, comfort, even happiness. Environmental health has been defined in many ways (see Text Box 1.1). Some definitions evoke the relationship between people and the environment—a systems-based, ecological approach—while others focus more narrowly on addressing particular environmental conditions. Some focus on controlling hazards, while others focus on promoting health-enhancing environments. Some focus on physical and chemical hazards, while others extend more broadly to aspects of the social and built environments. In the aggregate the definitions in Text Box 1.1 make it clear that environmental health is many things: an interdisciplinary academic field, an area of research, and an arena of applied public health practice.

Text Box 1.1 Definitions of Environmental Health “Environmental health comprises those aspects of human health, including quality of life, that are determined by physical, chemical, biological, social and psychosocial factors in the environment. It also refers to the theory and practice of assessing, correcting, controlling, and preventing those factors in the environment that can potentially affect adversely the health of present and future generations.” (World Health Organization) “Environmental health is the branch of public health that protects against the effects of environmental hazards that can adversely affect health or the ecological balances essential to human health and environmental quality.” (Agency for Toxic Substances and Disease Registry) “Environmental health includes both the direct pathological effects of chemicals, radiation and some biological agents, and the effects (often indirect) on health and well-being of the broad physical, psychological, social and aesthetic environment, which includes housing, urban development, land use, and transport.” (European Charter on Environment and Health)

“Environmental health focuses on the health interrelationships between people and their environment, promotes human health and well-being, and fosters a safe and healthful environment.” (National Association of City and County Health Officials) Source: U.S. Department of Health and Human Services, 1998.

The Evolution of Environmental Health Human concern for environmental health dates from ancient times, and it has evolved and expanded over the centuries.

Ancient Origins The notion that the environment could have an impact on comfort and well-being—the core idea of environmental health—must have been evident in the early days of human existence. The elements can be harsh, and we know that our ancestors sought respite in caves or under trees or in crude shelters they built. The elements can still be harsh, both on a daily basis and during extraordinary events; think of the Indian Ocean earthquake and tsunami of 2004, Hurricanes Katrina and Rita in 2005 and Sandy in 2012, the Sichuan earthquake of 2008, the Nepal earthquake of 2015, and the ongoing droughts in Australia and California. Our ancestors confronted other challenges that we would now identify with environmental health. One was food safety; there must have been procedures for preserving food, and people must have fallen ill and died from eating spoiled food. Dietary restrictions in ancient Jewish and Islamic law, such as bans on eating pork, presumably evolved from the recognition that certain foods could cause disease. Another challenge was clean water; we can assume that early peoples learned not to defecate near or otherwise soil their water sources. In the ruins of ancient civilizations from India to Rome, from Greece to Egypt to South America, archeologists have found the remains of water pipes, toilets, and sewage lines, some dating back more than 4,000 years (Rosen, 1958/1993). Still another environmental hazard was polluted air; there is evidence in the sinus cavities of ancient cave dwellers of high levels of smoke in their caves (Brimblecombe, 1988), foreshadowing modern indoor air concerns in homes that burn biomass fuels or coal. An intriguing passage in the biblical book of Leviticus (14:33–45) may refer to an environmental health problem well recognized today: mold in buildings. When a house has a “leprous disease” (as the Revised Standard Version translates this passage), …then he who owns the house shall come and tell the priest, “There seems to me to be some sort of disease in my house.” Then the priest shall command that they empty the house before the priest goes to examine the disease, lest all that is in the house be declared unclean; and afterward the priest shall go in to see the house. And he shall examine the disease; and if the disease is in the walls of the house with greenish or reddish spots, and if it appears to be deeper than the surface, then the priest shall go out of the house to the door of the house, and shut up the house seven days. And the priest shall come again on the seventh day, and look; and if the disease has spread in the walls of the house, then the priest shall command that they take out the stones in which is the disease and throw them into an unclean place outside the city; and he shall cause the inside of the house to be scraped round about, and the plaster that they scrape off they shall pour into an unclean place outside the city; then they shall take other stones and put them in the place of those stones, and he shall take other plaster and plaster the house. If the disease breaks out again in the house, after he has taken out the stones and scraped the house and plastered it, then the priest shall go and look; and if the disease has spread in the house, it is a malignant leprosy in the house; it is unclean. And he shall break down the house, its stones and timber and all the plaster of the house; and he shall carry them forth out of the city to an unclean place. Can we conclude that mold grew within warm, damp ancient dwellings? And what was that “unclean place outside the city”—an early hazardous waste site? Who hauled the wastes there, and did that work undermine their health? Still another ancient environmental health challenge, especially in cities, was rodents. European history

was changed forever when infestations of rats in fourteenth-century cities led to the Black Death (Zinsser, 1935; Herlihy and Cohn, 1997; Cantor, 2001; Kelly, 2005). Modern cities continue to struggle periodically with infestations of rats and other pests (Sullivan, 2004), whose control depends in large part on environmental modifications.

Industrial Awakenings Modern environmental health further took form during the age of industrialization. With the rapid growth of cities in the seventeenth and eighteenth centuries, sanitarian issues rose in importance. “The urban environment,” wrote one public health historian, “fostered the spread of diseases with crowded, dark, unventilated housing; unpaved streets mired in horse manure and littered with refuse; inadequate or nonexisting water supplies; privy vaults unemptied from one year to the next; stagnant pools of water; illfunctioning open sewers; stench beyond the twentieth-century imagination; and noises from clacking horse hooves, wooden wagon wheels, street railways, and unmuffled industrial machinery” (Leavitt, 1982, p. 22). The provision of clean water became an ever more pressing need, as greater concentrations of people increased both the probability of water contamination and the impact of disease outbreaks. Regular outbreaks of cholera and yellow fever in the eighteenth and nineteenth centuries (Rosenberg, 1962) highlighted the need for water systems, including clean source water, treatment including filtration, and distribution through pipes. Similarly, sewage management became a pressing need, especially after the provision of piped water and the use of toilets created large volumes of contaminated liquid waste (Duffy, 1990; Melosi, 2000; also see Chapter 16 and Text Box 4.2 in Chapter 4). The industrial workplace—a place of danger and even horror—gave additional impetus to early environmental health efforts. Technology advanced rapidly during the late eighteenth and nineteenth centuries, new and often dangerous machines were deployed in industry after industry, and mass production became common. In communities near industrial facilities, the air, water, and soil could become badly contaminated in ways that would be familiar to modern environmental professionals (Tarr, 1996, 2002), but the most abominable conditions were usually found within the mines, mills, and factories themselves. Workers became the proverbial canaries in the coal mines. Charles Turner Thackrah (1795–1833), a Yorkshire physician, became interested in the diseases he observed among the poor in the city of Leeds. In 1831, he catalogued many work-related hazards in a short book with a long title: The Effects of the Principal Arts, Trades and Professions, and of Civic States and Habits of Living, on Health and Longevity, with Suggestions for the Removal of Many of the Agents which Produce Disease and Shorten the Duration of Life. In it he proposed guidelines for preventing certain diseases, such as eliminating lead as a glaze in the pottery industry and using ventilation and respiratory protection to protect knife grinders. Public outcry and the efforts of early Victorian reformers such as Thackrah led to passage, in the U.K., of the Factory Act in 1833 and the Mines Act in 1842. Occupational health did not blossom in the United States until the early twentieth century, pioneered by the remarkable Alice Hamilton (1869–1970). A keen firsthand observer of industrial conditions, with a powerful social conscience, she documented links between toxic exposures and illness among miners, tradesmen, and factory workers, first in Illinois (where she directed that state's Occupational Disease Commission from 1910 to 1919) and later from an academic perch at Harvard (as that university's first female professor). Her books, including, in 1925, Industrial Poisons in the United States and, in 1934, Industrial Toxicology, helped to establish that workplaces could be dangerous environments for workers. A key development in the seventeenth through nineteenth centuries was the quantitative observation of population health—the beginnings of epidemiology. With the tools of epidemiology, observers could systematically attribute certain diseases to particular environmental exposures (as explored in Chapter 4). John Graunt (1620–1674), an English merchant and haberdasher, realized that London's weekly death records—the “bills of mortality”—were a treasure trove of information. He analyzed them, and published his findings in 1662 as Natural and Political Observations Upon the Bills of Mortality. Graunt's work was a pioneering example of demography. Almost two centuries later, when the British Parliament created the Registrar-General's Office (now the Office of Population Censuses and Surveys) and William Farr (1807– 1883) became its compiler of abstracts, the link between vital statistics and environmental health was forged. Farr made observations about fertility and mortality patterns, identifying rural-urban differences, variations between acute and chronic illnesses, and seasonal trends, and implicating certain

environmental conditions in illness and death. Farr's 1843 analysis of mortality in Liverpool led the British Parliament to pass the Liverpool Sanitary Act of 1846, which created a sanitary code for Liverpool and a public health infrastructure to enforce it. If Farr was a pioneer in applying demography to public health, his contemporary Edwin Chadwick (1800– 1890) was a pioneer in combining social epidemiology with environmental health. At the age of 32, Chadwick was appointed to the newly formed Royal Commission of Enquiry on the Poor Laws, and helped reform Britain's Poor Laws. Five years later, following epidemics of typhoid fever and influenza, he was asked by the British government to investigate sanitation. His classic 1842 report, Sanitary Conditions of the Labouring Population (Figure 1.1), drew a clear link between living conditions—in particular overcrowded, filthy homes, open cesspools and privies, impure water, and miasmas—and health, and made a strong case for public health reform. The resulting Public Health Act of 1848 created the Central Board of Health, with power to empanel local boards that would oversee street cleaning, trash collection, and water and sewer systems. As sanitation commissioner, Chadwick advocated such innovations as urban water systems, toilets in every house, and transfer of sewage to outlying farms where it could be used as fertilizer (Hamlin, 1998). Chadwick's work helped establish the role of public works—essentially sanitary engineering—in protecting public health.

Figure 1.1 Title Page of Chadwick's Groundbreaking 1842 Report Source: Wellcome Trust, Wellcome Images.

These achievements are profoundly important to public health. As eloquently pointed out by Thomas McKeown (1979) more than a century later, environmental health interventions were to do far more than medical care to improve public health and well-being during the industrial era. A recent economic analysis (Cutler & Miller, 2005) notes that from 1900 to 1940, infant mortality rates fell by 62%, total mortality fell by 40%, and life expectancy rose from 47 to 63 years—and that clean water alone accounted for three quarters of the decline in infant mortality, and over 40% of the decline in total mortality. Another analysis (Lee, 2007) attributes much of the decline in infant mortality during the same era to pasteurization of milk. These victories are well worth remembering at a time when some public health actions, including those in environmental health, are tinged with ideological controversy (see Text Box 1.2). The physician John Snow (1813–1858) was, like William Farr, a founding member of the London Epidemiological Society. Snow gained immortality in the history of public health for what was essentially an environmental epidemiology study. During an 1854 outbreak of cholera in London, he documented a far higher incidence of disease among people who lived near or drank from the Broad Street pump than among people with other sources of water. He persuaded local authorities to remove the pump handle, and the epidemic in that part of the city soon abated. (There is some evidence that it may have been ending anyway, but this does not diminish the soundness of Snow's approach.) Environmental epidemiology was to blossom during the twentieth century (see Chapter 4), supplemented by the development of geospatial information late in the century (see Chapter 5), and was to provide some of the most important evidence needed to support effective preventive measures. Finally, the industrial era led to a powerful reaction in the worlds of literature, art, and design. In the first half of the nineteenth century, Romantic painters, poets, and philosophers celebrated the divine and inspiring forms of nature. In Germany painters such as Caspar David Friedrich (1774–1840) created meticulous images of the trees, hills, misty valleys, and mercurial light of northern Germany, based on a close observation of nature, and in England Samuel Palmer (1805–1881) painted landscapes that combined straightforward representation of nature with religious vision. His countryman John Constable (1776–1837) worked in the open air, painting deeply evocative English landscapes. In the United States, Hudson River School painters, such as Thomas Cole (1801–1848), took their inspiration from the soaring peaks and crags, stately waterfalls, and primeval forests of the northeast. At the same time, the New England transcendentalists celebrated the wonders of nature. “Nature never wears a mean appearance,” wrote Ralph Waldo Emerson (1803–1882) in his 1836 paean, Nature. “Neither does the wisest man extort her secret, and lose his curiosity by finding out all her perfection. Nature never became a toy to a wise spirit. The flowers, the animals, the mountains, reflected the wisdom of his best hour, as much as they had delighted the simplicity of his childhood.” Henry David Thoreau (1817–1862), like Emerson a native of Concord, Massachusetts, rambled from Maine to Cape Cod and famously lived in a small cabin at Walden Pond for two years, experiences that cemented his belief in the “tonic of wildness.” And America's greatest landscape architect, Frederick Law Olmsted (1822–1903), championed bringing nature into cities. He designed parks that offered pastoral vistas and graceful tree-lined streets and paths, intending to offer tranquility to harried people and to promote feelings of community. These and other strands of cultural life reflected yet another sense of environmental health, arising in response to industrialization: the idea that pristine environments were wholesome, healthful, and restorative to the human spirit. This dimension is explored in Chapter 25.

Text Box 1.2 Environmental Health: Common Good or Nanny State? Political scientists, economists, and other scholars have long noted the tension between individualism and collectivism. Individualists emphasize personal independence, autonomy, and liberty, while collectivists emphasize the value of group norms and action—not only in promoting the common good but also in achieving social justice and in providing social support and identity. In recent years political discourse in the United States (dating from

the presidency of Ronald Reagan), Great Britain (dating from Margaret Thatcher's time as prime minister), and other countries, has tilted toward individualism, signaling a mistrust of collective action and especially of government action. President Reagan famously declared, in his first inaugural speech, “Government is not the solution to our problem; government is the problem.” In environmental health, as in many fields of public health, collective action is essential—so much so that public health has been defined as “collective action for sustained population-wide health improvement” (Beaglehole, Bonita, Horton, Adams, & McKee, 2004). Zoning for healthy neighborhoods, fuel efficiency and air quality regulations for clean air, and food inspections and standards for wholesome food are examples of concerted government action that protects public health. Critics regard some such government actions as paternalistic and restrictive of individual liberty. They warn of the nanny state (Calman, 2009; Wiley, Berman, & Blanke, 2013). There are strong moral and practical arguments for collective action in environmental health, not least the fact that preventing disease and promoting health often require action well beyond the scope of personal behavior (Minkler, 1999; Chokshi & Stine, 2013). Individuals cannot on their own achieve clean air, clean water, safe roads, walkable neighborhoods, or reduced carbon emissions. A rich legal tradition in the United States supports the role of government in promoting public health; examples include Jacobson v. Massachusetts (1905), in which the U.S. Supreme Court upheld a city's right to compel smallpox vaccination (Parmet, Goodman, & Farber, 2005), and Euclid v. Ambler (1926), in which the Supreme Court upheld a local zoning ordinance, based in part on protecting public health (Schilling & Linton, 2005). More generally, environmental health efforts are embedded in the larger concept of the common good—a concept with a lengthy history and a compelling contemporary role (Etzioni, 2004, 2015). Balancing the common good with individual rights remains a fascinating challenge in public health and public policy.

The Modern Era The modern field of environmental health dates from the mid-twentieth century, and no landmark better marks its launch than the 1962 publication of Rachel Carson's Silent Spring. Silent Spring focused on DDT, an organochlorine pesticide that had seen increasingly wide use since World War II. Carson had become alarmed at the ecosystem effects of DDT; she described how it entered the food chain and accumulated in the fatty tissues of animals, how it indiscriminately killed both target species and other creatures, and how its effects persisted for long periods after it was applied. She also made the link to human health, describing how DDT might increase the risk of cancer and birth defects (see Text Box 6.4 in Chapter 6). One of Carson's lasting contributions was to place human health in the context of larger environmental processes. “Man's attitude toward nature,” she declared in 1963, “is today critically important simply because we have now acquired a fateful power to alter and destroy nature. But man is a part of nature, and his war against nature is inevitably a war against himself… [We are] challenged as mankind has never been challenged before to prove our maturity and our mastery, not of nature, but of ourselves” (New York Times, 1964). The recognition of chemical hazards was perhaps the most direct legacy of Silent Spring. Beginning in the 1960s, Irving Selikoff (1915–1992) and his colleagues at the Mount Sinai School of Medicine intensively studied insulators and other worker populations and showed that asbestos could cause asbestosis (a fibrosing lung disease), lung cancer, mesothelioma, and other cancers. Outbreaks of cancer in industrial workplaces—lung cancer in a chemical plant near Philadelphia due to bis-chloromethyl ether (Figueroa, Raszkowski, & Weiss, 1973; Randall, 1977), hemangiosarcoma of the liver in a vinyl chloride polymerization plant in Louisville (Creech & Johnson, 1974), and others—underlined the risk of carcinogenic chemicals. With the enormous expansion of cancer research, and with effective advocacy by such groups as the American Cancer Society (Patterson, 1987), environmental and occupational carcinogens became a focus of public, scientific, and regulatory attention. But cancer was not the only health effect linked to chemical exposures. Herbert Needleman (1927–), studying children in Boston, Philadelphia, and Pittsburgh, showed that lead was toxic to the developing

nervous system, causing cognitive and behavioral deficits at levels far lower than had been appreciated. When this recognition finally helped to achieve the removal of lead from gasoline, population blood lead levels plummeted, an enduring public health victory—and one that may even have helped reduce crime levels twenty years later (Nevin, 2007). Research also suggested that chemical exposures could threaten reproductive function. Wildlife observations such as abnormal genitalia in alligators in Lake Apopka, Florida, following a pesticide spill (Guillette et al., 1994) and human observations such as an apparent decrease in sperm counts (Swan, Elkin, & Fenster,1997) suggested that certain persistent, bioaccumulative chemicals (persistent organic pollutants, or POPs) could affect reproduction, perhaps by interfering with hormonal function. Emerging evidence showed that chemicals could damage the kidneys, liver, and cardiovascular system and immune function and organ development. Some knowledge of chemical toxicity arose from toxicological research (see Chapter 6) and other insights resulted from epidemiological research (see Chapter 4). But catastrophes—reported first in newspaper headlines and only later in scientific journals—also galvanized public and scientific attention. The discovery of accumulations of hazardous wastes in communities across the nation—Love Canal in Niagara Falls, New York (Gibbs, 1998); Times Beach, Missouri, famous for its unprecedented dioxin levels; Toms River, New Jersey (Fagin, 2013); Woburn, Massachusetts (Harr, 1996), where municipal drinking water was contaminated with organic chemicals; “Mount Dioxin,” a defunct wood treatment plant in Pensacola, Florida; Anniston, Alabama, where residents (especially black residents) were exposed to intolerable levels of PCBs (Spears, 2014); and many others—raised concerns about many health problems, from learning disabilities to immune dysfunction to cancer to birth defects. Mercury contamination of Minamata Bay, Japan, and the resulting burden of neurological illness riveted world attention, spurred by the heart-wrenching photographs of Eugene Smith (Smith & Smith, 1975) (Figure 1.2). And acute disasters, such as the isocyanate release that killed hundreds and sickened thousands in Bhopal, India, in 1984, made it clear that industrialization posed real threats of chemical toxicity (Dhara & Dhara, 2002; Lapierre & Moro, 2002).

Figure 1.2 A Victim of Minamata Disease Being Bathed: Photograph by W. Eugene Smith In tandem with the growing awareness of chemical hazards, environmental health during the second half of the twentieth century was developing along another promising line: environmental psychology. As described in Chapter 9, this field arose as a subspecialty of psychology, building on advances in perceptual and cognitive psychology. Scholars such as Stephen Kaplan and Rachel Kaplan at the University of Michigan carried out careful studies of human perceptions and of reactions to various environments. An important contribution to environmental psychology was the theory of biophilia, first advanced by Harvard biologist E. O. Wilson in 1984. Wilson defined biophilia as “the innately emotional affiliation of human beings to other living organisms.” He pointed out that for most of human existence, people have lived in natural settings, interacting daily with plants, trees, and other animals. As a result, Wilson maintained, affiliation with these organisms has become an innate part of human nature (Wilson, 1984). Other scholars extended Wilson's concept beyond living organisms, postulating a connection with other features of the natural environment—rivers, lakes, and ocean shores; waterfalls; panoramic landscapes and mountain vistas (Kellert & Wilson, 1993; see Chapter 25). Environmental psychologists studied not

only natural features of human environments but also such factors as light, noise, and way-finding cues to assess the impact of these factors. They increasingly recognized that people responded to various environments, both natural and built, in predictable ways. Some environments were alienating, disorientating, or even sickening, whereas others were attractive, restorative, and even salubrious. A third development in modern environmental health was the continued integration of ecology with human health, giving rise to a field called ecohealth. Ancient wisdom in many cultures had recognized the relationships between the natural world and human health and well-being. But with the emergence of formal complex systems analysis and modern ecological science, the understanding of ecosystem function advanced greatly (see Chapter 2). As part of this advance the role of humans in the context of ecosystems was better and better delineated. On a global scale, for example, the concept of carrying capacity (Wackernagel & Rees, 1995) helped clarify the impact of human activity on ecosystems and permitted evaluation of the ways ecosystem changes, in turn, affected human health and well-being (Aron & Patz, 2001; McMichael, 2001; Alcamo et al., 2003; Waltner-Toews, 2004; Brown, Grootjans, Ritchie, & Townsend, 2005; Rayner & Lang, 2012). Ecological analysis was also applied to specific areas relevant to human health. For example, there were advances in medical botany (Lewis & Elvin-Lewis, 2003; van Wyk & Wink, 2004), in the understanding of biodiversity and its value to human health (Chivian & Bernstein, 2008), and in the application of ecology to clinical medicine (Aguirre, Ostfeld, Tabor, House, & Pearl, 2002; Ausubel, 2004). These developments, together, reflected a progressive synthesis of ecological and human health science, yielding a better understanding of the foundations of environmental health. A fourth feature of modern environmental health was the expansion of health care services related to environmental exposures. Occupational medicine and nursing had been specialties in their respective professions since the early twentieth century, with a traditional focus on returning injured and ill workers to work and, to some extent, on preventing hazardous workplace exposures. In the last few decades of the twentieth century, these professional specialties incorporated a public health paradigm, drawing on toxicological and epidemiological data, using industrial hygiene and other primary prevention approaches, and engaging in worker education (see Chapter 21). In addition, the occupational health clinical paradigm was broadened to include general environmental exposures. Clinicians began focusing on such community exposures as air pollutants, radon, asbestos, and hazardous wastes, emphasizing the importance of taking an environmental history, identifying at-risk groups, and providing both treatment and preventive advice to patients. Professional ethics expanded to recognize the interests of patients (both workers and community members) as well as those of employers, and in some cases even the interests of unborn generations and of other species (see Chapter 10). Finally, a wide range of alternative and complementary approaches—some well outside the mainstream—arose in occupational and environmental health care. For example, an approach known as clinical ecology postulated that overloads of environmental exposures could impair immune function, and offered treatments including “detoxification,” antifungal medications, and dietary changes purported to prevent or ameliorate the effects of environmental exposures (Rea, 1992–1998). Environmental health policy also emerged rapidly. With the promulgation of environmental laws beginning in the 1960s, federal and state officials created agencies and assigned them new regulatory responsibilities. These agencies issued rules that aimed to reduce emissions from smokestacks, drainpipes, and tailpipes; control hazardous wastes; and achieve clean air and water. Although many of these laws were oriented to environmental preservation, the protection of human health was often an explicit rationale as well. (Indeed, the mission of the U.S. Environmental Protection Agency, or EPA, is “to protect human health and the environment.”) Ironically, the new environmental regulations created a schism in the environmental health field. Responsibility for environmental health regulation had traditionally rested with health departments, but this was now transferred to newly created environmental agencies. At the federal level, the EPA assumed some of the traditional responsibilities of the Department of Health, Education, and Welfare (now Health and Human Services), and corresponding changes occurred at the state level. Environmental regulation and health protection became somewhat uncoupled from each other. Environmental regulatory agencies increasingly attempted to ground their rules in evidence, using quantitative risk assessment techniques (see Chapter 27). This signaled a sea change in regulatory policy. The traditional approach had been simpler; dangerous exposures were simply banned. For example, the 1958 Delaney clause, an amendment to the 1938 Federal Food, Drug, and Cosmetic Act, banned

carcinogens in food. In contrast, emerging regulations tended to set permissible exposure levels that took into account anticipated health burdens, compliance costs, and technological feasibility. Moreover, regulations tended to assign the burden of proof of toxicity to government regulators. As the scientific and practical difficulties of this approach became clear in the late twentieth century, an alternative approach emerged: assigning manufacturers the burden of proving the safety of a chemical. Based philosophically in the precautionary principle (see Chapter 26), this approach was legislated in Europe as part of the European Union's REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) initiative, which entered into force in 2007 (European Commission, 2009). It has not, for the most part, been implemented in U.S. toxics law (see Chapter 6). In the twenty-first century, then, while traditional sanitarian functions remain essential, the environmental health field has expanded well beyond its origins. Awareness of chemical toxicity has advanced rapidly, fueled by discoveries in toxicology and epidemiology. At the same time, the complex relationships inherent in environmental health—the effects of environmental conditions on human psychology, and the links between human health and ecosystem function—are better and better recognized. In practical terms, clinical services in environmental health have developed, and regulation has advanced through a combination of political action and scientific evidence.

Emerging Issues Environmental health is a dynamic, evolving field. Looking ahead, we can identify at least five trends that will further shape environmental health: environmental justice, a focus on susceptible groups, scientific advances, global change, and moves toward sustainability. Beginning around 1980, African American communities identified exposures to hazardous waste and industrial emissions as matters of racial and economic justice. Researchers documented that these exposures disproportionately affected poor and minority communities, a problem that was aggravated by disparities in the enforcement of environmental regulations. The modern environmental justice movement was born, a fusion of environmentalism, public health, and the civil rights movement (Bullard, 1994; Cole & Foster, 2000; see also Chapter 11). Historians have observed that environmental justice represents a profound shift in the history of environmentalism (Gottlieb, 1993; Shabecoff, 1993; Dowie, 1995). This history is commonly divided into waves. The first wave was the conservation movement of the early twentieth century, the second wave was the militant activism that blossomed in 1970 on the first Earth Day, and the third wave was the emergence of large, “inside-the-beltway” environmental organizations such as the Environmental Defense Fund, the League of Conservation Voters, and the Natural Resources Defense Council, which had gained considerable policy influence by the 1980s. Environmental justice, then, represents a fourth wave, one that is distinguished by its decentralized, grassroots leadership, its demographic diversity, and its emphasis on human rights and distributive justice. The vision of environmental justice—eliminating disparities in economic opportunity, environmental exposures, and health—is one that resonates with public health priorities. It emphasizes that environmental health extends well beyond the control of hazardous exposures to include human rights and equity as well. This vision will be an increasingly central part of environmental health in coming decades. Environmental justice is one example of a broader trend in environmental health—a focus on susceptible groups. For many reasons, specific groups may be especially vulnerable to the adverse health effects of environmental exposures. In the case of poor and minority populations, these reasons include disproportionate exposures, limited access to legal protection, limited access to health care, and in some cases compromised baseline health status. Children make up another susceptible population, for several reasons; they eat more food, drink more water, and breathe more air per unit of body weight than adults do and are therefore more heavily exposed to any contaminants in these media (Landrigan & Etzel, 2014). Children's behavior—crawling on floors, placing their hands in their mouths, and so on—further increases their risk of exposure. With developing organ systems and immature biological defenses, children are less able than adults to withstand some exposures. And with more years of life ahead of them, children have more time to manifest delayed toxic reactions. These facts have formed the basis for research and public health action on children's environmental health. Women bear some specific environmental exposure risks, both in the workplace and in the general environment, due both to disproportionate exposures (e.g., in health care jobs) and to unique

susceptibilities (e.g., to reproductive hazards). Elderly people also bear some specific risks, and as the population ages, this group will attract further environmental health attention. For example, urban environments will need to take into account the limited mobility of some elderly people and provide ample sidewalks, safe street crossings, and accessible gathering places to serve this population. People with disabilities, too, require specific environmental health attention to minimize the risks they face. In coming decades environmental health will increasingly take account of susceptible groups as the risks they face and their needs for safe, healthy environments become better recognized. A third set of emerging issues in environmental health grows out of scientific advances. In toxicology better detection techniques have already enabled us to recognize and quantify low levels of chemical exposure and have supported major advances in the understanding of chemical effects (see Chapter 6). Innovative toxicological approaches, including physiologically based pharmacokinetic modeling (PBPK) and high-throughput computational techniques, offer rapid insights into chemical toxicity. Advances in data collection and analysis techniques have supported innovative epidemiological analyses. In particular the use of geographic information systems (GISs) has yielded new insights on the spatial distribution of environmental exposures and diseases (see Chapter 5). The use of large databases—the “big data” revolution—has also enabled highly innovative analyses. Perhaps the most promising scientific advances are occurring at the molecular level, in the linked fields of genomics, toxicogenomics, epigenetics, and proteomics (see Chapter 7). New genomic tools such as microarrays (or gene chips) have enabled scientists to characterize the effects of chemical exposures on the expression of thousands of genes. Databases of genetic responses, and the resulting protein and metabolic pathways, will yield much information on the effects of chemicals and on the variability in responses among different people. Big data are also increasingly available from other data sources—smartphones that track travel patterns, social media, online searches, customer loyalty cards, charge card purchases, wearable devices that track activity and health parameters, and more. While these sources raise profound privacy concerns, reality mining can provide unprecedented insights into exposures, preferences, behaviors, and health outcomes across populations (Pentland, Lazer, Brewer, & Heibeck, 2009; Eagle & Greene, 2014). Scientific advances related to environmental health—from molecular biology to information science—will have profound effects on the field in coming decades. Moving from the molecular scale to the global scale, a fourth set of emerging environmental health issues relates to global change. This broad term encompasses many trends, including population growth, climate change, urbanization, changing patterns of energy use, and the increasing integration of the world economy (Friedman, 2008). These trends will shape environmental health in many ways. The global population now exceeds 7 billion and is expected to plateau at roughly 9 to 10 billion during the twenty-first century (see Chapter 3). Most of this population growth will occur in developing nations, and much of it will be in cities. Not only this population growth but also the increasing per capita demand for resources such as food, energy, and materials will strain the global environment (Heinberg, 2007; Brown, 2011), in turn affecting health in many ways. For example, environmental stress and resource scarcity may increasingly trigger armed conflict, an ominous example of the links between environment and health (Homer-Dixon, 1999; Klare, 2001). Global climate change, which results in large part from increasing energy use (see Chapter 14), will threaten health in many ways, from infectious disease risks to heat waves to severe weather events (see Chapter 12). As more of the world's population is concentrated in dense urban areas, features of the urban environment—noise, crowding, processed foods, vehicular and industrial pollution—will increasingly shape health (see also Chapter 15). And with integration of the global economy—through the complex changes known as globalization—hazards increasingly cross national boundaries, trade agreements and market forces challenge and possibly undermine national environmental and health policies (Gleeson & Friel, 2013; Walls, Smith, & Drahos, 2015), and global solutions to environmental health challenges will increasingly be needed (Labonté, Schrecker, Packer, & Runnels, 2009). Sustainability has been a part of the environmental health vernacular since the 1980s. In 1983, the United Nations formed the World Commission on Environment and Development to propose strategies for sustainable development. The commission, chaired by then Norwegian prime minister Gro Harlem Brundtland, issued its landmark report, Our Common Future, in 1987. The report included what has become a standard definition of sustainable development: “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” In 1992, several

years after the publication of Our Common Future, the United Nations Conference on Environment and Development (UNCED), commonly known as the Earth Summit, convened in Rio de Janeiro. This historic conference produced, among other documents, the Rio Declaration on Environment and Development, a blueprint for sustainable development. The first principle of the Rio declaration placed environmental health at the core of sustainable development: “Human beings are at the centre of concerns for sustainable development. They are entitled to a healthy and productive life in harmony with nature” (United Nations, 1992). Like environmental justice the concept of sustainable development blends environmental protection with notions of fairness and equity. As explained on the Web site of the Johannesburg Summit, held ten years after the Earth Summit: The Earth Summit thus made history by bringing global attention to the understanding, new at the time, that the planet's environmental problems were intimately linked to economic conditions and problems of social justice. It showed that social, environmental and economic needs must be met in balance with each other for sustainable outcomes in the long term. It showed that if people are poor, and national economies are weak, the environment suffers; if the environment is abused and resources are over consumed, people suffer and economies decline. The conference also pointed out that the smallest local actions or decisions, good or bad, have potential worldwide repercussions [United Nations Department of Economic and Social Affairs, 2006]. The concept of sustainability has emerged as a central theme, and challenge, not only for environmentalism but for environmental health as well. In the short term, sustainable development will improve the living conditions and therefore the health of people across the world, especially in the poor nations. In the long term, sustainable development will protect the health and well-being of future generations. As described in Chapter 3, some of the most compelling thinking in environmental health in recent years offers social and technical paths to sustainable development (Hawken, Lovins, & Lovins, 1999; Brown, 2001; McDonough & Braungart, 2002; Brown et al., 2005; Institute of Medicine, 2013). These approaches build on the fundamental links among health, environment, technological change, and social justice. Ultimately, they will provide the foundation for lasting environmental health.

Spatial Scales, from Global to Local The concept of spatial scale is central to many disciplines, from geography to ecology to urban planning. Some phenomena unfold on a highly local scale—ants making a nest, people digging a septic tank. Some phenomena spread across regions—the pollution of a watershed from an upstream factory, the sprawl of a city over a 100-mile diameter. And some phenomena, such as climate change, are truly global in scale. Al Gore, in describing environmental destruction in his 1992 book, Earth in the Balance, borrowed military categories to make this point, distinguishing among “local skirmishes,” “regional battles,” and “strategic conflicts.” Spatial scale is important not only in military and environmental analysis but also in environmental health. Some environmental factors that affect health operate locally, and the environmental health professionals who address these factors work on a local level; think of the restaurant and septic tank inspectors who work for the local health department or the health and safety officer at a manufacturing facility. Other environmental factors affect health at a regional level, and the professionals who address these problems work on a larger spatial scale; think of the state officials responsible for enforcement of air pollution or water pollution regulations. Global problems such as climate change require responses on the national and international scales. These responses are crafted by professionals in organizations such as the World Health Organization and the Intergovernmental Panel on Climate Change. So useful is the concept of spatial scales in environmental health that it provides the framework for this book. After introducing the methods and paradigms of environmental health in the first eleven chapters, this book addresses specific issues, beginning with global scale problems in Chapter 12, moving to regional scale problems in Chapters 13 to 16, and ending with local problems in Chapters 17 to 25. The final three chapters (Chapters 26 to 28) describe the practice of environmental health, focusing on such efforts as risk assessment and communication. It is clear that environmental health professionals work on different spatial scales, but it is not always so

clear who is an environmental health professional. Certainly, the environmental health director at a local health department; the director of environment, health, and safety at a manufacturing firm; an environmental epidemiology researcher at a university; or a physician working for an environmental advocacy group would self-identify and be recognized by others as an environmental health professional. But many other people work in fields that have an impact on the environment and human health. The engineer who designs power plants helps to protect the respiratory health of asthmatic children living downwind if she plans for effective emissions controls. The transportation planner who enables people to walk instead of drive also protects public health by helping to promote physical activity and clean up the air. The park superintendent who maintains urban green spaces may contribute greatly to the well-being of people in his city. In fact much of environmental health is determined by “upstream” forces that seem at first glance to have little to do with environment or health.

The Forces that Drive Environmental Health Public health professionals tell the emblematic story of a small village perched alongside a fast-flowing river. The people of the village had always lived near the river, they knew and respected its currents, and they were skilled at swimming, boating, and water rescue. One day they heard desperate cries from the river and noticed a stranger being swept downstream past their village. They sprang into action, grabbed their ropes and gear, and pulled the victim from the water. A few minutes later, as they rested, a second victim appeared, thrashing in the strong current and gasping for breath. The villagers once again performed a rescue. Just as they were remarking on the coincidence of two near drownings in one day, a third victim appeared, and they also rescued him. This went on for hours. Every available villager joined in the effort, and by mid-afternoon all were exhausted. Finally, the flow of victims stopped, and the villagers collapsed, exhausted, along the waterfront. Just at that moment another villager strode whistling into town, relaxed and dry. He had not been seen since the first victims were rescued and had not helped with any of the rescues. “Where were you?” his neighbors demanded of him. “We've been pulling people out of the river all day! Why didn't you help us?” “Ah,” he replied. “When I noticed all the people in the river, I thought there must be a problem upstream. I walked up to that old footbridge, and sure enough, some boards had broken and there was a big hole in the walkway. So I patched the hole, and people stopped falling through.” (See Text Box 1.3.)

Text Box 1.3 A Prevention Poem: A Fence or an Ambulance Like the story of the villagers who saved drowning victims, this poem emphasizes that prevention may lie with root causes. These root causes are often environmental, like the hole in the village's bridge or, in this case, an unguarded cliff edge (See Figure 1.3).

Figure 1.3 The Need for Primary Prevention: An Early 20th-Century View Source: Iowa Public Health Association, 1912.

'Twas a dangerous cliff, as they freely confessed, Though to walk near its crest was so pleasant; But over its terrible edge there had slipped A duke, and full many a peasant; So the people said something would have to be done, But their projects did not at all tally. Some said: “Put a fence round the edge of the cliff;” Some, “An ambulance down in the valley.” But the cry for the ambulance carried the day,

For it spread through the neighboring city. A fence may be useful or not, it is true, But each heart became brimful of pity For those who slipped over that dangerous cliff; And dwellers in highway and alley, Gave pounds or gave pence, not to put up a fence, But an ambulance down in the valley. “For the cliff is all right if you're careful,” they said, “And if folks ever slip and are dropping, It isn't the slipping that hurts them so much As the shock down below when they're stopping.” So day after day as those mishaps occurred, Quick forth would those rescuers sally, To pick up the victims who fell off the cliff With the ambulance down in the valley. Then an old sage remarked, “It's a marvel to me That people gave far more attention To repairing results than to stopping the cause, When they'd much better aim at prevention. Let us stop at its source all this mischief,” cried he; “Come, neighbors and friends, let us rally; If the cliff we will fence, we might also dispense With the ambulance down in the valley.” “Oh he's a fanatic,” the others rejoined; “Dispense with the ambulance? Never! He'd dispense with all charities too if he could. No, no! We'll support them forever! Aren't we picking up folks just as fast as they fall? And shall this man dictate to us? Shall he? Why should people of sense stop to put up a fence While their ambulance works in the valley?” But a sensible few who are practical too, Will not bear with such nonsense much longer. They believe that prevention is better than cure; And their party will soon be the stronger. Encourage them, then, with your purse, voice, and pen, And (while other philanthropists dally) They will scorn all pretense and put a stout fence On the cliff that hangs over the valley.

Better guide well the young than reclaim them when old, For the voice of true wisdom is calling; To rescue the fallen is good, but it's best To prevent other people from falling; Better close up the source of temptation and crime Than deliver from dungeon or galley; Better put a strong fence 'round the top of the cliff, Than an ambulance down in the valley. Joseph Malins (1895)

Upstream thinking has helped to identify the root causes of many public health problems, and this is nowhere more true than in environmental health. Environmental hazards sometimes originate far from the point of exposure. Imagine that you inhale a hazardous air pollutant. It may come from motor vehicle tailpipes, from power plants, from factories, or from any combination of these. As for the motor vehicle emissions, the amount of driving people do in your city or town reflects urban growth patterns and available transportation alternatives, and the pollutants generated by people's cars and trucks vary with available technology and prevailing regulations. As for the power plants, the amount of energy they produce reflects the demand for energy by households and businesses in the area they serve, and the pollution they emit is a function of how they produce energy (are they coal, nuclear, or wind powered?), the technology they use, and the regulations that govern their operations. Hence a full understanding of the air pollutants you breathe must take into account urban growth, transportation, energy, and regulatory policy, among other upstream determinants. This book contains chapters on many of the upstream forces that affect environmental health, including community design, transportation, and energy. These ideas are at the core of a useful model created by the World Health Organization (Briggs, 1999). The DPSEEA (driving forces-pressures-state-exposure-effects-actions) model was developed as a tool both for analyzing environmental health hazards and for designing indicators useful in decision making (Figure 1.4). The driving forces are the factors that motivate environmental health processes. In our air pollution example, these factors might include population growth; consumer preferences for energy-consuming homes, appliances, and vehicles; and sprawl that requires traveling over long distances. The driving forces result in pressures on the environment, such as the emission of oxides of nitrogen, hydrocarbons, particulate matter, and other air pollutants. These emissions, in turn, modify the state of the environment, accumulating in the air and combining to form additional pollutants such as ozone. However, this deterioration in the state of the environment does not invariably threaten health; human exposure must occur. In the case of air pollutants, exposure occurs when people are breathing when and where the air quality is low. (Some people, of course, sustain higher exposures than others; an outdoor worker, an exercising athlete, or a child at play receives relatively higher doses of air pollutants than a person in an air-conditioned office.) The hazardous exposure may lead to a variety of health effects, acute or chronic. In the case of air pollutants, these effects may include coughing and wheezing, asthma attacks, heart attacks, and even early death.

Figure 1.4 The DPSEEA Model Source: Briggs, 1999.

Finally, to eliminate or control environmental hazards and protect human health, society may undertake a wide range of actions, targeted at any of the upstream steps. For example, protecting the public from the effects of air pollution might include encouraging energy conservation to reduce energy demand and designing live-work-play communities to reduce travel demand (addressing driving forces), providing mass transit or bicycle lanes to reduce automobile use, requiring emissions controls on power plants or investing in wind turbines to reduce emissions from coal-fired power plants (addressing pressures), requiring low-sulfur fuel (addressing the state of the environment), warning people to stay inside when ozone levels are high (addressing exposures), and providing maintenance asthma medications (addressing health effects). However, as discussed in Chapter 26, the most effective long-term actions are those that are preventive, aimed at modifying the forces that drive the system. This theme is universal in public health, applying both to environmental hazards and to other health hazards, and it is the central message of this book.

Key Terms biophilia “The innately emotional affiliation of human beings to other living organisms,” as defined by E.O. Wilson. collectivism An approach emphasizing shared solutions, group norms and action, social justice, and social support and identity. common good The shared interests of an entire group or population, as distinct from the interests of individuals or special interests. DPSEEA

An acronym for a conceptual model, developed by the World Health Organization, that describes environmental factors relevant to health: driving forces-pressure-state-exposure-effects-actions. environment The complex of physical, chemical, biotic, and social factors that surround an organism. environmental health The field of public health that addresses physical, chemical, biological, social, and psychosocial factors in the environment. It aims both to control and prevent environmental hazards and to promote health and well-being through environmental strategies (see Text Box 1.1 for additional definitions). environmental justice Both equal protection for all communities from environmental hazards and equal access for all communities to environmental, social, and economic assets that promote health and well-being, such as clean air, safe drinking water, green space, public transit, and economic opportunity. health A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. individualism An approach emphasizing personal independence, autonomy, and liberty. nanny state Used as a derogatory term to describe government actions seen as overprotective or as undermining personal choice. precautionary principle The concept articulated in Principle 15 of the Rio Declaration, “Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponigng costeffective measures to prevent environmental degradation.” reality mining The collection and analysis of data, usually from electronic sources such as smartphones, social media posts, or credit card records, to identify patterns of behavior. sanitarian The field that emerged, and an individual with expertise in that field, food protection, hazardous substances, product safety, housing, institutional health and safety, radiation protection, recreational areas and waters, solid waste management, vector control, water quality, wastewater technology and management, hazardous waste management or industrial hygiene. sanitary issues The subset of environmental health concerns, dating from historical times, that includes provision of clean water, sewage management, and safe food. spatial scale A concept important in fields from geography to urban planning to public health; it refers to the physical extent of a process or place. A small spatial scale might be a room in a building; a large spatial scale might be an entire river system. sustainability The ability of a system to continue functioning without depleting or damaging the things it needs to function.

Discussion Questions 1. Name three ways in which your environment affects your health, three ways in which your environment affects your short-term mood, and three ways in which your environment affects your long-term well-being. 2. Imagine you were the health commissioner of your city or town in 1866, 150 years before this textbook was published. What would have been the most pressing environmental health concerns? Now imagine you are the health commissioner of your city or town today. What are the most pressing environmental health concerns?

3. The environment affects health in many ways, but most doctors and nurses receive very little training in environmental health. What environmental health topics do you think health care providers should learn about? 4. Environmental health relates to many upstream factors. Select any cabinet department of the U.S. government other than the Department of Health and Human Services, and describe how its work affects health.

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For Further Information There is a rich literature describing the history of environmental health. In fact much of this history is identical with the larger history of public health! While historical accounts of specific topics, such as chemical contaminants, appear at the end of later chapters in this book, some of the best general books include four that are listed in the References above—Duffy, 1990; Melosi, 2000; Rosen, 2015; and Tarr, 1996—and also D. Porter, Health, Civilization and the State: A History of Public Health from Ancient to Modern Times (New York: Routledge, 1999). Many agencies address environmental health issues. They include European Commission: http://ec.europa.eu/health/healthy_environments/policy/index_en.htm U.S. Centers for Disease Control and Prevention, National Center for Environmental Health and Agency for Toxic Substances and Disease Registry: http://www.cdc.gov/nceh and http://www.atsdr.cdc.gov U.S. Environmental Protection Agency: multiple EPA sites pertain to health; two good starting points are http://www2.epa.gov/communityhealth and http://www2.epa.gov/healthresearch U.S. National Institutes of Health, National Institute of Environmental Health Sciences: http://www.niehs.nih.gov World Health Organization: http://www.who.int/topics/environmental_health/en Similarly, many organizations address environmental health issues, some as a part of a larger public health agenda, and some because they are specifically focused on environmental health. Leading examples include American Public Health Association: https://www.apha.org/topics-and-issues/environmental-health Association of State and Territorial Health Officials: http://www.astho.org/programs/environmentalhealth International Society for Environmental Epidemiology: http://www.iseepi.org International Society of Exposure Science: http://www.isesweb.org National Association of City and County Health Officials: http://www.naccho.org/topics/environmental/index.cfm National Environmental Health Association: http://www.neha.org There are many academic programs of environmental health, at schools of public health, schools of medicine, and other institutions. Too numerous to list here, they are easily accessible through Web searches.

Chapter 2 Ecology and Ecosystems as Foundational for Health Margot W. Parkes and Pierre Horwitz The authors acknowledge Cindy L. Parker, Jessica Rhodes, and Brian S. Schwartz for their contributions to the systems section of this chapter, and Howard Frumkin for his editing assistance. Margot Parkes acknowledges support from her appointment as a Canada Research Chair in Health, Ecosystems, and Society (CRC 950-230463). During the preparation of this chapter Dr. Parkes received research funding from the Canadian Institutes for Health Research, the International Development Research Centre, and the Public Health Agency of Canada. Dr. Parkes has held (uncompensated) positions with the International Association for Ecology and Health (IAEH), the journal EcoHealth, the Canadian Public Health Association Working Group on Ecological Determinants of Health, the Canadian Community of Practice in Ecosystem Approaches to Health, and the Network for Ecosystem Sustainability and Health. During the preparation of this chapter Dr. Horwitz received research funding from the Wildlife Conservation Society, Rio Tinto, the Australian Government, and the State Government of Western Australia. He has held (uncompensated) positions with the International Association for Ecology and Health, the journals EcoHealth and BioScience, the Scientific and Technical Review Panel for the Ramsar Convention on Wetlands, and Bush Heritage Australia. Disclosures by Dr. Frumkin, who wrote Tox Box 2.1, appear in the front of this book, in the section titled “Potential Conflicts of Interest in Environmental Health: From Global to Local.”

Key Concepts Ecology is a scientific discipline that focuses on interactions of living things in relation to their environment, and encourages understanding of the environment as our home. An ecosystem is a complex system of organisms, their environment, and the interactions that connect them. Ecosystems provide a range of ecosystem services and constitute the life support systems that are foundational for human health. Ecological literacy helps us to interpret the consequences of our actions and the influence of the environment on our lives, and to make predictions about the future of life on this planet; it applies across spatial scales, from the subcellular, through the local and the regional, to the global. Subfields of ecology include population ecology, community ecology, and ecosystem ecology. Systems thinking is central to ecology and, indeed, to much of human health. An ecological approach to public health views humans as nested within ecosystems, calls for integrated consideration of environmental and social factors, and highlights system characteristics such as complexity, emergence, and feedback loops. The German physician and zoologist Ernst Haeckel coined the word ecology in the 1860s, but it would be almost a century—in the 1950s—before the science of ecology began to flourish. Ecology focuses on the interactions of living things in relation to their environment. This emerging science drew on critical strands of thought, including population dynamics, systems theory, and a strong environmental ethic. It was informed by, yet contrasted sharply with, a tendency of biology to deconstruct systems into component parts and to focus narrowly on these component parts. The word ecology (like the word economy) is derived from the Greek word oikos meaning household, home, or place to live. Thinking of the environment as our home expands the scope of environmental health science and practice well beyond simply controlling harmful exposures. An ecosystem is a complex system of organisms and their environment, including both living (biotic) and nonliving

(abiotic) components, and the interactions that connect them. These relationships support all of life and profoundly shape the health of the organisms within our shared home. The biological unit we recognize most readily is a species, which is a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding (known as the biological species concept). Species are held in assemblages (ecological communities); one or more ecological communities makes an ecosystem, and one or more ecosystems are found in a biome. Understanding our homes in ecological terms has become more important as societies have become more modern, urbanized, cosmopolitan, and technology-dependent—and in many cases more separated from exposure to the “elements” (air, soil, water, and weather). Together these trends shift our experiences away from the living systems around us and from what is local. They diminish our ability to read, interpret, and understand the system of which we are a part—to know what is likely to occur and to be appropriate locally, given the constraints and opportunities presented by human habitat—contributing to a loss of ecological literacy. The ecological concepts in this chapter provide a series of foundational principles to help us understand the links between environment and health, and their individual, community, and societal implications.

Environment as Ecology: Ecology as the Study of Our Home Ecology is attentive to the world around us, the world to which we belong. It is attentive to the parts that make up our surroundings—the abiotic components that are physical and chemical and the biotic components that live, reproduce, and grow. These parts influence one another, and have interrelationships and interdependencies that are so important that the whole that comes from these interactions is said to be more than the sum of its parts. In fact, some properties of ecosystems are emergent, meaning that they don't exist in isolation in individual parts of the system but arise when components interact (more about this later). Accordingly, ecology never deviates from the principle of holism, the all-encompassing approach of focusing on or investigating wholes rather than parts and seeking to see as many connections as possible, rather than eliminating some connections to see components parts more clearly. The corollary is that reducing an environment to its component parts only, and seeing the world as a machine, or as a series of linear cause-effect relationships (reductionism), is inconsistent with ecological understandings and approaches. Ecologists recognize the system—how it is organized (structure), what processes it uses (process), and what it does (function)—and on that basis seek to make sense of a complex and uncertain world. Accordingly, an ecologist is trained to observe and measure, and to do something that is somewhat intuitive for humans—to explore patterns across space (e.g., geographic distribution) and across time (e.g., aging, growth, and succession). A starting point in ecological thought is the question of scale; the analytical approach described above applies from the very smallest level of the living world (such as the tiniest microbes) to the very largest (the planet). A hierarchy is a way of organizing according to levels of scales. These organizational levels are central to ecology, and some of the corresponding disciplines are shown in Table 2.1. Other examples of hierarchies in ecology include food webs (organized according to trophic levels), systems (where all systems are made of smaller systems, and are part of larger systems), and the organizational units of ecology themselves. Table 2.1 Scale in Ecology, and Some Disciplines That Contribute at Each Level Level of scale Molecules

Disciplines

Molecular biology, genetics Cells Cell biology, biochemistry Tissues/organs Anatomy, physiology Organism/individual Embryology, morphology Populations (of single species) Population ecology

Focal studies Inheritance Infection Individual function Reproduction, behavior, and life history From demography and migration to speciation

and evolution Communities (assemblages of species) Ecosystems (and biomes) Planet

Community ecology

Landscapes

Ecosystem sciences Sustainability

Interdisciplinarity Transdisciplinarity

Some patterns repeat across scales. Taking the planet as an example, ecosystems can be thought of as the tissues of the planet and individuals as the cells; the powerful metaphor here is that each level, including the planet, can be considered living. Importantly, any ecological level (not just the ecosystem level) can function as a system, in which the whole is greater than the sum of the parts; one individual animal or plant can be the host “environment” to countless other individuals, even populations, of other species, and thereby function as a system of interacting life forms. With hundreds of species of archaea, bacteria, and fungi in the human gut, and hundreds more on the skin, in the mouth, and elsewhere on our bodies, each of us can be considered a walking ecosystem! Our language can become complicated around questions of scale too. When we humans talk of communities, we are often speaking about interactions among humans defined by location or special interest. To an ecologist such a community is technically a subpopulation. When we expand our notion of human communities to explicitly consider social and ecological interactions, the term community becomes more consistent with the ecologist's view—interactions among different species (the focus of community ecology, as described below)—and becomes more relevant for humans and their health. An even broader notion of the human community is the assemblage of life on Earth with which we live communally within a shared home, our planet. This notion lies at the heart of both an environmental ethic and the discipline of human ecology, the study of the reciprocal relationship between humans and their environments, including urban, rural, regional, and other habitats. Each level in Table 2.1 contributes to biodiversity. Biodiversity (or biological diversity) is the degree of variation of life, encompassing genetic variation, phenotypic variation, different life history stages (from spores to cells, or seeds to juveniles to adults, or eggs to larvae/pupae to adults), species, communities, and ecosystems. Biodiversity has become central to ecological thought and is increasingly recognized as a pillar of human health (see Bernstein, 2014, and also Discussion Question 1 later). Much of the effort in ecology is directed toward measuring and understanding the distribution, diversity, and abundance of life, and the factors that influence them. These factors are also considered at different levels, discussed here in relation to population ecology, community ecology, and ecosystem sciences. A special case of scale and hierarchy in ecology is the food web: the sequence, from tiny organisms to top predators, through which food is produced and consumed. Text Box 2.1 describes food webs, exploring an example from a North American terrestrial ecosystem (also see Discussion Question 2).

Text Box 2.1 Food Webs A food web consists of the pathways through which food energy and nutrients are captured, incorporated into living matter, consumed, and transmitted through the ecosystem. At the bottom of the food web, almost all food energy derives ultimately from the sun. Autotrophs (or primary producers)—for the most part plants, algae, and some bacteria—harness solar energy through photosynthesis, reducing inorganic carbon (in forms such as CO2) to organic carbon (such as carbohydrates) whose chemical bonds contain energy. These organisms are then consumed by heterotrophs (or consumers). In simple terms, the first level of heterotrophs consists of herbivores, which eat plants. Primary predators eat the herbivores, secondary predators eat the primary predators, and so on. For example, in many grassland ecosystems, grass is a primary producer, grasshoppers are primary consumers, rats that eat the grasshoppers are primary predators, and snakes that eat the rats are secondary predators. This predation sequence can continue; hawks that eat snakes are tertiary (or apex) predators. These trophic levels exemplify hierarchic scales, a recurring theme in ecology (and also illustrate the maxim of interrelatedness that “everybody is somebody else's lunch”). Throughout the process, when organisms die they are consumed by decomposers (or detritivores) such as

fungi or earthworms, which recycle energy and materials back into the food web. These relationships are depicted in Figure 2.1.

Figure 2.1 A Food Web in a North American Terrestrial Food Ecosystem Energy flow is a key feature of the food web. At each trophic level, energy is used for metabolic processes and is released back to the environment. Therefore energy transfer is incomplete, and the biomass of each trophic level is substantially less than that of the level below. Put differently, a consumer at any trophic level typically consumes far more than its own mass from the trophic level below. This is highly relevant to environmental health, since it explains why persistent pollutants such as mercury and polychlorinated biphenyls (PCBs; see Tox Box 2.1) undergo not only bioaccumulation but also biomagnification (or bioamplification) as they move up the food web. This helps explain why such pollutants can reach high concentrations in the tissues of animals high on the food web, such as raptors, killer whales, sea lions, salmon, and even humans.

Population Ecology Population ecology deals with the dynamics of species populations, how these populations interact with their surroundings, and how they change over time and space. All populations can be characterized by their age structure, sex ratio, reproductive strategies (such as how many offspring they produce, and how much parental care is needed), and migration rates (emigration and immigration). Demography is the study of these characteristics; they can be presented in life tables so that survival, breeding, and migration rates for any species can be explored to make predictions about the fate of a population. The size of a population, measured as the number of individuals, grows whenever the reproduction rate (plus immigration) exceeds the death rate (plus emigration). These periods of growth occur when resources—energy in such forms as food or light, needed nutrients, water, shelter, habitat (the physical space occupied by a species, including everything within it)—are sufficiently plentiful to enable individuals in the population to grow, mature, reproduce, and in some cases raise their young. Under hypothetical circumstances with no constraints, individuals will continue to reproduce, and a population will undergo exponential growth: that is, geometric growth, with the rate of growth proportional to population size

rather than linear or occurring at a fixed rate. But growth can continue only as long as resources are sufficient to sustain it. When a limit is reached the population is said to equilibrate at a certain size: the carrying capacity or the maximum population that can be sustained indefinitely by its supporting ecosystems. (For more on sustainability and carrying capacity and their relevance to human health, see Chapter 3.) Populations rarely achieve this carrying capacity because other important ecological processes intervene. As the numbers of a single species increase in a population so, soon after, will the numbers of their predators. In this sense predation (and also herbivory, where animals graze on a plant population) is said to regulate population growth, in other words, to keep it in check. A similar process occurs for parasitism, where a parasite makes the host less fit and less able to reproduce rapidly. In both cases the numbers of the prey and the host are regulated, and the numbers of the predators and the parasites are similarly limited by the availability of prey and hosts. Still another mechanism may regulate population numbers: competition. This occurs when similar species have overlapping distributions and depend on the same resources for their survival and growth. The closer species are in this regard, the more they are likely to compete for the same resources; they are said to have overlapping niches. A niche is the multidimensional ecosystem space in which a species exists (its habitat) and also what it does (its ecological role, both structurally and functionally). The resulting deprivation of resources for one or the other species diminishes its fitness or survival in the presence of the competitor.

Tox Box 2.1 Polychlorinated Biphenyls (PCBs)

What Are They? PCBs are a group of 209 isomers of a synthetic organic chemical. Each isomer of PCB consists of a pair of benzene rings, with various configurations of chlorine atoms attached. PCBs are generally liquids, and as the chlorine content increases, they become more oily and viscous. PCBs don't dissolve well in water but are very soluble in oils and fats. They are very stable and persist in the environment—an example of persistent organic pollutants.

How Are They Used? PCBs were manufactured in high quantities from the 1930s through the 1970s for use as insulating and dielectric fluids in electrical equipment such as capacitors and transformers. They were also used as coolants and lubricants and found many other industrial uses—as a component of carbon paper, in hydraulic oil, as plasticizers in paints, in adhesives, and more.

How Are People Exposed? At the time PCBs were being manufactured, people might have been exposed at work, while manufacturing PCBs or PCB-containing products, and also might have been exposed in the general environment, following leaks or spills or by exposure to PCB-containing wastes. Fires or leaks in transformers were a common means of exposure. Extensive PCB contamination occurred near industrial facilities, such as in Anniston, Alabama, the site of a major PCB manufacturing plant, or along the Hudson River, due to dumping at General Electric capacitor manufacturing facilities in the towns of Fort Edward and Hudson Falls, New York. When PCBs

enter the environment, they may remain in soil or river sediment for many years. In water, small organisms can absorb PCBs, which bioaccumulate as they move up the food web (Box 2.1), reaching very high levels in predator species. Fatty fish can contain substantial levels of PCBs, and fish consumption is now the leading route of human exposure—an illustration of the links between ecosystem function and human health. Other sources of exposure persist, even years after PCB manufacturing ended; these include old fluorescent light ballasts, old caulking, and other residual materials. In addition to ingestion, people can absorb PCBs by inhalation or through their skin. Ongoing population blood testing by the Centers for Disease Control and Prevention shows that many people carry a body burden of PCBs, although population PCB levels are declining over time.

What Are the Toxic Effects? High-level PCB exposure can cause a skin condition called chloracne and other acute symptoms. However, the far more common scenario is long-term, lower-dose exposure, say, from eating contaminated fish. The effects are far-reaching, if not fully understood. Toxicological data, and some epidemiological data, suggest that certain PCBs (a subset with dioxin-like activity) increase the risk of cancer, and the International Agency for Research on Cancer (IARC) in 2013 classified these PCBs as carcinogenic to humans. PCBs are also considered endocrine disrupters and developmental neurotoxins. They can interfere with hormone function, especially estrogens. Animal and human evidence suggests that maternal PCB exposure may lead to reduced conception rates, fertility, and birth weights. Children exposed to PCBs in utero and early in life may be at risk of behavioral, cognitive, and psychomotor abnormalities. PCB exposure is also associated with immune dysfunction.

How Are People Protected? PCB production was banned in the United States in 1979, and many other countries banned PCB production at about the same time. Residual PCBs in equipment and the general environment break down very slowly. People can reduce their exposure by reducing their consumption of fish that are high in PCBs, and by avoiding contact with such potential sources as old transformers.

Want to Learn More? The Agency for Toxic Substances and Disease Registry Toxicological Profile for PCBs dates from 2000, but a 2011 update provides more current information; these are available at www.atsdr.cdc.gov/toxprofiles. The most recent IARC review of PCBs may be found at monographs.iarc.fr/ENG/Monographs/vol107 and is summarized in B. Lauby-Secretan et al., “Carcinogenicity of Polychlorinated Biphenyls and Polybrominated Biphenyls,” Lancet Oncology, 2013, 14(4), 287–288. Another recent review focusing on carcinogenicity is C. Zani, G. Toninelli, B. Filisetti, and F. Donato, “Polychlorinated Biphenyls and Cancer: An Epidemiological Assessment,” Journal of Environmental Science and Health: Part C, Environmental Carcinogenesis & Ecotoxicology Reviews, 2013, 31(2), 99–144. A recent review focusing on developmental toxicity is N. El Majidi, M. Bouchard, and G. Carrier, “Systematic Analysis of the Relationship Between Standardized Prenatal Exposure to Polychlorinated Biphenyls and Mental and Motor Development During Follow-up of Nine Children Cohorts,” Regulatory Toxicology and Pharmacology, 2013, 66(1), 130–146. In addition to these technical sources, a book-length account of PCB exposure in Anniston, Alabama, with attention to health and social impacts and environmental justice, is Ellen Griffith Spears's Baptized in PCBs: Race, Pollution, and Justice in an All-American Town (Chapel Hill: University of North Carolina Press, 2014). Contributed by Howard Frumkin The principles of population ecology give us considerable insight into the roles that populations of a single species play with respect to other species and throughout ecosystems (see Table 2.1). Patterns emerge in

life history strategies across these levels, with two distinct patterns apparent. Some species, such as many weeds, are opportunists; they grow rapidly, mature quickly, and produce many progeny. These characteristics are associated with r-selected species. They are characteristically found in disrupted or unstable environments, such as after a fire, landslide, volcanic eruption, or similar disturbance. Other species, typically in more stable environments, grow to be larger individuals, take longer to reach maturity, live longer, produce fewer progeny, and invest considerably more parental energy. These species are referred to as K-selected species. A special case of population dynamics occurs when a species moves to a place where it has never occurred before, becoming an established and successful colonist. Biological invasions are explored further in Text Box 2.2.

Text Box 2.2 Biological Invasions The term biological invasions implies a large-scale movement of animals or plants into areas where they were previously absent or uncommon (in other words, beyond their historical or known geographic distribution). All living things have the potential to move into new areas, if environmental conditions are suitable and if the opportunity presents itself, which means that biological invasions are common occurrences. But human actions often facilitate such invasions, and the results can damage ecosystems, threaten human health, and be costly. One example is zebra mussels, (Figure 2.2, left side), which were discovered in the Great Lakes in the late twentieth century, probably having arrived via the ballast tanks of ships from Europe. These mussels have proliferated, clogging the intakes of municipal water supplies and power plants, contributing to the growth of harmful algal blooms, and displacing other food sources in the aquatic food web. Another example is the red imported fire ant, (Figure 2.2, right side), a species native to South America that has spread across much of the southeast United States since the mid-twentieth century. These ants attack humans and wild and domestic animals, inflicting painful stings, and because they are attracted to electromagnetic fields, can disrupt electrical machinery. Some invasive species, such as the gypsy moth and the emerald ash borer, can cause considerable damage to forests and crops. Still others can be vectors of human disease; examples include the Asian tiger mosquito, a vector of encephalitis and the West Nile virus that arrived in North America in imported tires in around 1985, and fresh water snails, intermediate hosts for schistosomiasis that have been introduced into many regions in Africa, the Middle East, Latin America, and the Caribbean. (See Figure 2.2.)

Figure 2.2 Invasive Species and Their Impacts The zebra mussel (upper left), and the inside of a pipe packed with zebra mussels (lower left), disrupting water flow. The red imported fire ant (upper right), and the hand of a victim of the ant's stings (lower right). Sources: TexasInvasives.org (upper left); TN Department of Agriculture Upper right); Science Photo Library (lower left); Photo by Bart Drees (lower right).

Ecosystem disturbances such as land clearing or too frequent or intense fires can pave the way for invasive species. Characteristics that enable an introduced species (sometimes known as an exotic or alien species) to establish itself in a new environment include a capacity to disperse into an area; suitable environmental conditions for its establishment, survival, and growth; the absence of predators and parasites that regulate its growth in other parts of its range; and the ability to grow, mature, and reproduce rapidly. These features together help it to outcompete other species with similar ecological requirements. Why worry about biological invasions? As the examples above suggest, invaders may compete with native species for space or food, by aggressiveness or by predation. Invasive species can also significantly alter the habitats for other species, and they can significantly restructure food webs. Invasive species may bring unwanted passengers—other symbionts, parasites, or pathogens. The action of moving and releasing species into an area has the potential to move and release other biotic material; moving soil with a plant will introduce soil organisms, transporting fish or other species in water will introduce waterborne microbes, plants, or animals. Many such examples of accidental introductions have occurred in all parts of the world. So far we have been concerned with population growth, and the factors that limit the apparently inexorable potential for populations to increase in size. But populations do not always grow. Population decline occurs when the death rate (plus emigration rate) exceeds the birthrate (plus immigration rate)— caused by such factors as habitat changes, lack of resources, disease, and predation. Unless these population pressures are removed, fewer and fewer individuals reach maturity and reproduce. At the extreme, breeding can eventually cease, and the last individuals die off. If all populations of one species suffer the same demise, the species is said to be extinct. At this point extinction is irreversible; the

unique assemblages of genes, and unique genes themselves, that make up the species are lost from ecosystems, and the planet, forever. Extinction, in geological time frames, is quite rare, although major episodes have occurred in the geological past (such as the mass extinction event that defines the end of the Cretaceous geological epoch and the beginning of the Tertiary, some 66 million years ago). The suggestion that the actions of humans, a single species, might be responsible for another extinction event of planetary magnitude with geological implications (Kolbert, 2014) is proving to be a source of profound concern. Conservation biology is one of the human responses to this prospect and is explored in Text Box 2.3.

Text Box 2.3 Conservation Biology Where human activity is implicated in the decline of a population and in the possibility of the extinction of a species, the field of conservation biology seeks to intervene to prevent this irreversible loss. Intervention is costly, so criteria for setting priorities are needed. These criteria are based on the size of the population, the rate of population loss, the distribution range (extent of occurrence of a species), and the area of the habitat that the species occupies in that range. A species or subspecies meeting the criteria can then be placed into a category of threat, according to the Red List scheme adopted by the International Union for Conservation of Nature (IUCN). Extinct (EX) Extinct in the wild (EW) Threatened, including

There is no reasonable doubt that the last individual has died. A species is known to survive only in cultivation, in captivity, or as a naturalized population (or populations) well outside its past range. Best available evidence indicates that a species faces a high to extremely high risk of extinction in the wild.

Critically endangered (CR) Endangered (EN) Vulnerable (VU) Near threatened (NT) Least concern (LC) Data deficient (DD)

A species has been evaluated and does not meet the criteria but is close to qualifying or likely to qualify for a threatened category in the near future. A species does not meet listing criteria under a higher category of threat (for widespread and abundant species). There is inadequate information to assess risk of extinction based on species distribution and/or population status.

In many countries laws have been established to protect endangered or threatened species and prevent extinctions. To gain legal protection under such laws, a species must be formally recognized by the government (by gazettal, or formal listing), often using the categories promoted by the IUCN. Once a species is listed, the government can ban or regulate the processes known to threaten the species.

Community Ecology A core focus in ecology is identifying characteristic assemblages of species. Populations of a number of species aggregate either because they have the same habitat requirements or because they are developing at the same rate and are affected by the same things at the same time. They can also evolve together over much longer periods of time, and even become dependent on one another. These assemblages are known

as ecological communities. Examples are everywhere: the highly idiosyncratic communities of insects, arachnids, and crustaceans found in caves; the plants and animals found in the riparian zone of a lake; and even the assemblage of species with which humans regularly find themselves living—pets (dogs and cats), rats and mice, cockroaches, seagulls, particular weeds, productive plants, and so on. Ecologists search for underlying reasons why these assemblages stay together and become so identifiable. They ask, What structures a community?, and ground their answers in biotic processes (predation, competition, disease, and parasite-host relationships, which are said to be density dependent) and in abiotic processes (disturbances such as fire, cyclones, drought, and flood, which are density independent). Succession (Figure 2.3) is the sequence by which ecological communities develop over time. According to classic ecological theory, disturbances enable colonizers to establish themselves. Over time they provide sustenance and improve the habitat for other species. Gradually communities shift from being dominated by r-selected species to being dominated by K-selected species. Climax communities eventually develop, and remain until disturbances occur and the process begins again. Local species diversity is maximized when ecological disturbances are neither too rare nor too frequent (the so-called intermediate disturbance hypothesis). When disturbances are too rare then only species associated with climax communities will persist; when they are too frequent then only colonizing opportunist species will be encouraged. Our understanding of ecological succession has been updated and informed by the experience of restoration ecology, which is explored in Text Box 2.5.

Figure 2.3 A Classical Model of Ecological Succession in a North American Forest Ecosystem Over time, a predictable sequence of species unfolds, with K-selected species replacing r-selected species.

Symbiosis is another key concept in community ecology—a particular set of long-term interactions between different biological species where at least one species in the relationship can receive benefit. Table 2.2 describes three types of symbiosis (parasitism, mutualism, and commensalism) as well as two other types of relationships between species: competition and predation. Table 2.2 Type of Relationship Between Different Species Relationship type Species Species B A

Example

Competition Predation Symbiosis: parasitism

Lion and hyena compete for same prey. Polar bear feeds on seal. Tapeworm lives in intestines of host, harming host.

Benefit Benefit Benefit

Harm Harm Harm

Symbiosis: mutualism Symbiosis: commensalism

Benefit Benefit

Benefit

Bee gains nectar from a flower and in the process pollinates flower. Neither benefit nor Cattle egrets live near cows, to eat insects found near harm the cows.

Ecosystem Ecology At the larger spatial scale of the ecosystem, ecologists study energy and matter cycles. In addition to energy, critical cycles are the hydrological (water) cycle, carbon cycle, nitrogen cycle, and phosphorus cycle (key nutrients required for life) and food webs. Elements cycle through different states and chemical configurations, through both biotic and abiotic pathways. Cycles of important or dominant elements (both energy and materials) demonstrate how ecosystems function, by illustrating how they change form. Parts of a cycle can be extremely slow and occur over very long geological time frames, while other parts can be brisk, seemingly occurring in the blink of an eye. The hydrologic cycle, pictured in Figure 16.1 (see Chapter 16), is a familiar part of our daily experience, through rainfall, evaporation, condensation, the flows of rivers and streams, and the retention of water in ice sheets, extensive wetland systems and ground water. Human land use and water use have a profound effect on the distribution of surface water and ground water and the ecosystems dependent on them. These ongoing disruptions to the hydrological cycle are also being influenced by climate change in new and, increasingly, unpredictable ways. On the one hand, when the atmosphere warms up it retains more water, along with more energy—the perfect ingredients for severe storms, with heavy rainfall and resulting floods that threaten people and property. On the other hand, in some regions climate change means far less rain. Prolonged droughts and fires in Australia, the American southwest, and other places have proven a huge challenge for farming communities and forest and park managers in terms of water resource management, as well as for other species living in affected ecosystems. Discussion Question 3 encourages consideration of how the hydrological cycle varies across regional and global scales. For more on how climate change affects the hydrological cycle, and through it human health and well-being, see Chapter 12. The phosphorus cycle (Figure 2.4), in contrast, is less evident to a casual observer. Phosphorus is an essential nutrient for cell growth and maintenance. Phosphorus occurs in rocks, and when the rocks weather and erode to form soils the phosphorus becomes available for uptake by microbes and plants. It can then be returned to the soil with dead and decaying material, where decomposition and soil formation processes make it available again. Or it can be consumed when herbivores graze on plants, becoming incorporated into the food chain and eventually excreted into water or soil. Eventually soils form sedimentary rocks and the cycle starts again. An interesting loop in the phosphorus cycle occurs when it is excreted in a concentrated form by bats (after they have been eating insects) and sea birds (after eating fish). Over long periods of time these concentrated deposits, called guano, build up, and people who discover them can mine them for the phosphorus they contain—an extremely valuable fertilizer (through which the phosphorus enters the soil and is incorporated into plants, and the cycle goes on!).

Figure 2.4 The Phosphorus Cycle Soil, formed by the interaction of biotic and abiotic environments, is a wonderful example of an ecological process. Soil is produced steadily over time, serving both as a setting for and a product of ecosystem interactions and energy and nutrient cycles. Fertile soil requires the presence of eroded rock substrate, nutrients, and organic matter; the latter two depend in turn on plant and animal life that flourished, died, and was decomposed by insects and microorganisms into organic and nutrient components. Soil formation is therefore a result of complex ecosystem transactions linking the geosphere, atmosphere, hydrosphere, and biosphere (Montgomery, 2007) and is foundational to the earth's capacity to support life (Figure 2.5).

Figure 2.5 Transactions Between Atmosphere, Geosphere, and Hydrosphere Provide a Basis for the Earth's Capacity to Support Life Source: Adapted from Parkes & Weinstein, 2004. Life occurs in the relatively thin “carpet” covering the surface of our large planet, where it is both a product of and contributes to the character of earth, air, and water (hence the double arrows).

Ecological cycles illustrate that ecosystems perform functions—from relatively simple ones, such as eroding, absorbing, and evaporating, to extraordinarily complex ones, such as decomposing. Ecosystem functions are made up of ecological processes and their component species, particularly microbes and invertebrates that “do most of the doing” in ecosystems. The richness of an ecological community reflects its level and complexity of ecosystem functions. Assuming that each species occupies a different niche, and is therefore capable of doing different things, then ecosystems that contain more species should be capable of fulfilling more functional roles. Increased diversity stabilizes the functioning of the total ecosystem by increasing its resilience to disturbances, thus providing “insurance” against potentially disruptive events (more about resilience later). Many of the processes, functions, and “products” discussed here—rainfall, soil, natural fertilizer—are enormously useful to people. In economic terms, what they provide has great value to people—including a role in promoting human health. This value is captured in the idea of ecosystem services (Text Box 2.4).

Text Box 2.4 Ecosystem Services Ecosystem services are defined simply as “the benefits people obtain from ecosystems” (Millennium Ecosystem Assessment, 2003, p. 49). But ecosystem services are often taken for granted and overlooked, with their value “externalized” from the market economy. Everyone recognizes that products and services such as a university course, a bicycle repair, or a pizza have value, as reflected in their market prices, but these prices exclude the “real” cost, because they all, in some way, depend on the services that ecosystems provide. Explicitly identifying the value of ecosystem services can lead to better decision making and more sustainable societies (see Chapter 3). The Millennium Ecosystem Assessment (2005b), one of the largest international initiatives seeking to understand ecosystems in relation to human well-being, has classified ecosystem services into four groups: Provisioning services provide or produce goods such as food, fiber, fuel, genetic resources,

biochemicals, natural medicines and pharmaceuticals, ornamental resources, and fresh water. Regulating services include the benefits gained from regulating such ecosystem features as air quality, climate, water quality, erosion, disease transmission, pest proliferation, pollination, and natural hazard occurrence. Cultural services include nonmaterial benefits such as cultural diversity, spiritual and religious values, knowledge systems, educational values, inspiration, aesthetic values, social relations, sense of space, cultural heritage values, and recreation and ecotourism. Supporting services are those that underpin the other services such as soil formation, photosynthesis, primary production, nutrient cycling, and water cycling. Ecosystem services are underpinned by, and utterly dependent upon, biodiversity (Sandifer et al., 2015). Attention to the benefits people obtain from ecosystems can directly inform decision making: for example, by communicating the implications of planning, implementation, and assessment efforts for integrated land and water management (UNU-IHDP, 2014). Ecological integrity is maintained when the structure, composition, and function of an ecosystem operate within natural or historic bounds—when human activity has not unduly stressed the ecosystem or undermined long-standing ecological processes. Ecological integrity is not just a feature of a sustainable ecosystem; it also indicates that the ecosystem can continue to provide human benefits, as depicted in Figure 2.8.

Figure 2.8 Ecosystems as Settings for Human Health and Well-Being A broad conceptual model showing the relationship between ecological integrity, ecosystem services, and the benefits that humans derive. The biodiversity of ecosystems, the structure of ecosystems, and the processes used and functions performed within ecosystems, all supply the foundational conditions under which ecosystem services are provided. Humans then derive and demand these ecosystem services for their well-being. Feedback loops show that there are consequences of humans deriving these services.

Systems Thinking: From Ecology to Human Health Systems thinking is a core feature of ecology. A systems thinker sees the world as a web of interrelated, interacting components, and not simply as an assembly of linear relationships. Systems have several features. They are composed of parts that are related to each other, in relationships that are often nonlinear and bidirectional. Systems have temporal and spatial boundaries, and can interact with the larger environment by receiving inputs and by generating outputs. Boundaries are the places where values are exposed and disagreements are highlighted. In complex systems, boundary setting is explicitly a social construct, an acknowledgment that a system is not “real.” Systems can be nested within larger systems, they can contain smaller subsystems (recall the issues of scale and hierarchy introduced in relation to Table 2.1), and they can overlap with other systems. Systems can be characterized by flows of energy, material, and information. They are dynamic, meaning that they undergo constant change, and while they often tend toward an equilibrium, they can change according to predictable patterns or in random, chaotic ways. Feedback loops, repeating chains or circuits of cause and effect, are a common and important feature of systems. These loops may be either positive (self-reinforcing) or negative (self-cancelling). Systems can be self-organizing, using numerous interactions or feedback loops among their components to establish a pattern or arrive at a state. They can also be adaptive in response to altered circumstances, leading to new equilibrium states. Sometimes

change can be abrupt, if the system passes a tipping point, or a system threshold. The simplest demonstration of this phenomenon might be a chemical titration. The Resilience Alliance describes a tipping point in social-ecological systems as a sequence of events in which eventually, through successional processes, all the resources become conserved and committed, competition for them is intense, and the system becomes tightly bound. At this tipping point, a critical event could trigger a release of the resources and allow reorganization and recolonization to occur (see Walker & Salt, 2006). At other times, systems can demonstrate resilience, defined as “the capacity…to absorb disturbance; to undergo change and still retain essentially the same function, structure, and feedbacks” (Walker & Salt, 2006, p. 32). Resilience is characterized by persistence, adaptiveness, variability, and unpredictability (evolutionary, developmental, and sustainable). Figure 2.6 shows a schematic comparison of systems thinking with linear thinking.

Figure 2.6 Linear Thinking Versus Systems Thinking The model on the left consists of simple, unidirectional relationships, while the model on the right demonstrates more complexity, with system boundaries, reciprocal relationships, and feedbacks.

There are countless examples of systems. Many of these come from the world of ecology—a colony of ants, a hurricane forming in the Caribbean and moving over North America, a patch of forest or desert, the microbiome in our intestines. Systems thinking is indispensable not only in ecology but in many other arenas, from engineering to information technology, from epigenetics to neuroscience, from politics to social structure. Not surprisingly, systems thinking is key in environmental health, because it helps us to understand the links between natural systems and human systems, and it underscores that all actions and decisions have consequences in a complex system. Application of systems thinking to humans' interactions with their environment is demonstrated by increasing attention to such concepts as social-ecological systems (Berkes, Colding, & Folke, 2003; Walker & Salt, 2006) and coupled human-natural systems (Liu et al., 2007). The concept of coupled humannatural systems offers an integrated approach to systems that does not seek to separate human or social systems from their environmental settings. (Some people prefer the term coupled humanenvironment system, because the word natural implies that humans are not part of natural systems and this implication undermines the point of integrated systemic thinking.) The social-ecological systems approach to systems thinking and analysis is explicit in its coupled human-environment view and does not seek to separate humans from ecological analysis. Social-ecological systems acknowledge the consequences of social actors and institutions, the biotic and abiotic responses of the ecosystem to human actions, whereby both social and ecological characteristics influence the trajectory of the system (in the way they co-evolve) and the degree of system resilience. An integrated understanding of both social and ecological dynamics helps elucidate people's interactions with such diverse settings as watersheds, fisheries, forests, and even urban areas. This is exemplified by the interactions depicted in Figure 2.7, which shows a systems map of land use in the United Kingdom. While land use may seem a simple issue, the systems map depicts just how many factors may influence, and be influenced by, the use of land and water for residential, agricultural, or commercial purposes as well as for non-use or indirect ecosystem services. The systems map also depicts well-being as being influenced by a range of these interactions, reflecting diverse relationships among biophysical and social processes, and the emergent characteristics of complex systems.

Figure 2.7 A Systems Map of U.K. Land Use and the Domains That Influence It Source: Foresight Land Use Futures Project, 2010.

Complexity is a feature of almost every system relevant to human health. What is complexity? Consider the differences between the simple and often replicable task of following a recipe, the complicated and highly technical task of sending a rocket ship to the moon, and the complex task of raising a child in a society, which is highly variable and not replicable and for which past experience of success does not necessarily translate to the next situation (Glouberman & Zimmerman, 2002). Complex systems are made up of a large number of heterogeneous elements, some simple and others complex and even chaotic. The elements of a complex system interact with each other through positive and negative feedbacks. These interactions can result in unpredictable and unexpected phenomena, a property known as emergence (Meadows, 2008)—the idea introduced earlier, that the whole becomes more than the sum of its parts. Emergence arises from the ways in which the parts of a system influence one another, expressing consequences and leading to outcomes that would not have occurred if the components had not been interacting. The effects of interactions persist over time and adapt to changing circumstances (Hammond, 2009; Meadows, 2008). Small changes in initial conditions can have large and unpredictable effects (Pearce & Merletti, 2006). Not surprisingly, emergent properties can result in surprises. A surprise in an ecological system would be an unexpected discrete event (e.g., a town records its highest daily rainfall); abrupt, nonlinear, discontinuous behavior (e.g., a sharp change is noted—from 1985 onward a town has received half the annual rainfall it received prior to that year); or genuine novelty (e.g., for the first time anywhere, silver nitrate was sprayed into the atmosphere to trigger a massive rainfall event). Surprises can prove challenging when trying to manage complex systems to further societal objectives such as sustainability. These ideas are developed further in Chapter 3. Many of the fundamentals of ecology can be understood in systems terms. Table 2.3 shows the wellknown laws of ecology proposed by ecologist Barry Commoner in 1971, and corresponding system attributes for each. Application of these “laws” and attributes reinforces recognition of social-ecological systems as complex adaptive systems, for which “understanding how their component parts function

doesn't mean you can predict their overall behavior” (Walker & Salt, 2006, p. 38). Table 2.3 Links Between Ecology and Systems Thinking as a Basis for Health Barry Commoner's laws of ecology

Corresponding systems attributes

Everything is connected to everything else. Interconnectedness and complexity. Emergence and emergent properties. There is no such thing as a free lunch. Interrelationships and reciprocity. Nature knows best. Integration. Knowing comes from the whole as much as the parts. Feedbacks and self-organization. Everything must go somewhere. Nestedness: nothing exists outside its ecology. Interdependence, cycling, nonlinearity, and uncertainty. Rethinking of waste as a part of ecological processes. Source: Adapted from Commoner, 1971; Parkes and Horwitz, 2009.

Features of Our Home: Ecological Characteristics as Foundational for Health Ecosystems are settings for human health (Figure 2.8). An understanding of ecology and some of its component perspectives—on populations, communities, and ecosystems—together with a systems perspective enables us to consider the role of ecological dynamics in maintaining the integrity of our home. In addition, ecological principles help us to identify pathways by which the ecosystems on which we depend set the context for health. The interrelationships depicted in Figures 2.7 and 2.8 remind us that ecosystems, as settings for human health and well-being, are best understood as a combination of ecological and social interactions. These include economic, cultural, political, and institutional components. This holistic systems orientation leads to perspectives on interconnectedness and reciprocity that have a long history among Indigenous knowledge systems around the planet, and have become increasingly central to such fields as restoration ecology (Text Box 2.5), human ecology, and sustainability science (Chapter 3).

Text Box 2.5 Restoration Ecology: The Practical Application of Ecological Literacy and Systems Thinking The field of restoration ecology is founded on the recognition that ecosystems can be seriously degraded or damaged, as signaled by diminished richness of species (local extinctions of populations) and reduced ecosystem functions, depriving recipients of the ecosystem services that were once available. This degradation might result from overexploitation, serious pollution events, or deconstructive land-use activities such as mining, forest removal, or land clearing for agriculture; or it might be a consequence of a serious disturbance like an intense fire or flood. The practice of restoration ecology builds on knowledge of the species assemblages that are local and endemic in order to reintroduce them, based on knowledge of the physical characteristics of the site. It must also seek to reverse or eliminate the disturbances that led to the ecosystem degradation in the first place, a task that is sometimes both ecologically and politically challenging. In restoration work considerable attention is devoted to invasive species and how to strategically control their proliferation. In theory, restoration ecology recognizes that ecosystems are nonequilibrial and that alternative stable states (alternative end points depending on an ecosystem's trajectory) are possible. Restoration goals must therefore be set, and the effort may be deemed to have failed unless the desired ecological functions and ecosystem services, including local biodiversity characteristics, have been recovered. Since ecosystems are dynamic, an adaptive approach is mandatory, including monitoring to determine the trajectory of the efforts and ensuring the resources to undertake interventions

where necessary. Restoration ecology is therefore an intentional, political process and an explicitly social-ecological endeavor (see Discussion Question 6). An ecological orientation emphasizes the environment as a dynamic, living system and as a context for health. Accordingly, the concept of environmental health expands its focus beyond the environment as a source of hazardous exposures (e.g., through soil, water, and air) to the environment as human habitat, nested within the landscapes, ecosystems, and social-ecological systems on which human survival, livelihood, and well-being depend. This requires an inclusive and interactive view of the environment, with features of the physical environment (such as water quality in a river) seen as embedded within larger features (such as the land, surface water, and groundwater interactions of watersheds). Indeed, an ecological perspective makes clear that all features of ecosystems reflect interactions among multiple living and nonliving components. Ecological relationships commonly demonstrate reciprocity, a principle that extends to the human relationship with the environment. Because of its importance for health and well-being, the Ottawa Charter for Health Promotion (World Health Organization [WHO], 1986) identified reciprocal maintenance as a fundamental component of creating supportive environments for health: The inextricable links between people and their environment constitutes the basis for a socioecological approach to health. The overall guiding principle for the world, nations, regions and communities alike, is the need to encourage reciprocal maintenance—to take care of each other, our communities and our natural environment. The conservation of natural resources throughout the world should be emphasized as a global responsibility [WHO, 1986]. The integrative, socioecological approach of the Ottawa Charter may not have been fully realized over recent decades, but it recalls long-held Indigenous approaches to health and well-being (Stephens, Parkes, & Chang, 2007), and it offers a compelling and practical approach to promoting human health (Hancock, 2011) (also see Discussion Question 5). An example from the ecology of infectious disease, leptospirosis, is presented in Text Box 2.6, with an emphasis on the interaction of ecological and social processes that influence health in an ecosystem setting.

Text Box 2.6 Infectious Disease as an Ecological and Social Process: The Example of Leptospirosis The disease ecology of leptospirosis demonstrates many of the concepts and approaches outlined in this chapter. Bacteria responsible for the disease (Leptospira) are very common in mammal hosts such as rats and other rodents, maintaining their numbers by multiplying in the host's kidneys, which provide the conditions for “breeding” of the bacteria (although we don't usually use this term in relation to bacteria). These maintenance or reservoir hosts are not necessarily, or are only mildly, debilitated by the “infection” because the host and the bacteria have evolved a type of commensalism (see Table 2.2). The bacteria are shed in the urine of the individual hosts, passing to the environment, where they encounter and infect new individual hosts, maintaining their populations in a population of mammals in the environment. This is a positive feedback cycle of infection: growth in the host, passage to the environment, infection in a new host, and so forth. Humans—and some other mammals, such as cattle and goats—become accidental hosts when they come in contact with bacteria-containing animal urine in the environment and are infected; several types of these bacteria (serovars) are pathogenic to humans, so here the relationship is more like parasitism, in which the parasite benefits and the host is harmed. In humans the infections can produce a wide range of clinical syndromes, including nonspecific fever, kidney and liver failure, and pulmonary hemorrhage. Infection of accidental hosts is obviously undesirable, lowering the host's reproductive fitness and possibly causing death. Some medical or veterinary attention is required in the form of antibiotics. This might control the infection in an individual, but addressing the disease more definitively requires attention to the environmental conditions in which the infection occurs. (See Figure 2.9.)

Figure 2.9 The Life Cycle and Transmission of Leptospira Bacteria An infected reservoir host such as a rat releases the bacteria to the environment through its urine. If the urine contaminates water or soil, livestock or domestic animals may ingest it and become secondary Leptospira hosts. People may be exposed by ingesting contaminated water or by bringing contaminated soil or water into contact with broken skin or their eyes. Leptospirosis may affect different organs and cause a range of symptoms.

Indeed there is a complex interaction between humans, animal reservoirs, Leptospira, and the environment in which they coexist. There are distinct epidemiological patterns of leptospirosis, depending on the ecosystem setting and closely associated with the hydrological cycle, where animal urine is passed directly into or runs off into surface waters. In rural areas transmission is usually associated with farming and livestock; risk of exposure rises during the warm and rainy months. In urban areas infection is associated with overcrowding, poor hygiene, inadequate sanitation, and poverty, all of which typically occur in urban slums in developing countries. In developed countries infection is now increasingly being associated with outdoor recreational exposure and international travel. A common explanation for outbreaks of leptospirosis is the ecological disturbance of land-use change. Deforestation in rural areas and impermeable surfaces (rooftops and roadways) in urban areas cause faster rainfall runoff into places where rodents may live, driving them toward greater human contact and resulting in infection. Upstream interventions include minimizing exposure during periods of risk, controlling rodent populations, restoring the ecological functions in watersheds, and addressing the social-economic circumstances that contribute to the changed hydrological conditions. Each of these interventions, antibiotics included, seeks to initiate negative feedback in the system. The example of leptospirosis illustrates that ecosystems and social systems interact, and that humans are part of the ecological community—one of an assemblage of species interacting within their environment. In addition to the host-agent-environment model of understanding infectious disease processes, the ecological concepts exemplified by leptospirosis demonstrate the importance of complex interactions, including positive and negative feedbacks loops, as core characteristics of relations between environment and health (Wilcox, Aguirre, & Horwitz, 2012). This ecological perspective is relevant not only to infectious diseases. The interacting spheres depicted in Figure 2.5 can, for example, provide extremely helpful guidance in understanding the source, fate, distribution, and impact of many environmental contaminants, noting especially the interactions between abiotic contaminants and biotic living systems. For more on the concept of ecotoxicology, see Chapter 3.

Toward Ecological Approaches to Health and Home

Public health and environmental health have not always succeeded in incorporating the ecologicallyoriented and systems-based perspective outlined in this chapter. This limits and constraints that include a preoccupation with proximate risk factors, a focus on individual-level versus ecosystem-level influences on health, a time-window (rather than life-course) view of how risks operate, and the unfamiliar challenge of scenario-based forecasting of health consequences of future, large-scale social and environmental changes (McMichael, 1999). Complexity can be overwhelming, so clear conceptual pathways from ecosystems to health are useful. A well-established example is provided by the Millennium Ecosystem Assessment (MA). The MA not only defined and classified ecosystem services (Text Box 2.4); it also identified how these services underpin well-being by providing a foundation for health, basic material for a good life, good social relations, security, and freedom of choice and action (MA, 2003, 2005a). These relationships are depicted within local, regional, and global contexts in the conceptual framework of the Millennium Ecosystem Assessment (Figure 2.10). This framework can be used to explore and demonstrate many of the ecological characteristics introduced in this chapter. The framework also encourages recognition that changes to ecosystems influence health through pathways that are direct (e.g., floods and heat waves), ecosystemmediated (e.g., altered infectious disease risks, reduced food yields), and also indirect, deferred and displaced (e.g., population displacement, livelihood loss) (MA, 2005a). All of these pathways may also be influenced by the other components of well-being depicted in Figure 2.10, and are affected by drivers of change operating over short- and long-term time frames.

Figure 2.10 The MA Conceptual Framework Source: MA, 2005b, Figure SDM1. Changes in drivers that indirectly affect ecosystems, such as population, technology, and lifestyle (upper right corner) can lead to changes in drivers that directly affect ecosystems, such as fisheries' catches or fertilizer applications to increase food production (lower right corner). The resulting changes in the ecosystem (lower left corner) cause ecosystem services to change and thereby affect human wellbeing. These interactions can take place at more than one scale and can cross scales. For example, a global timber market may lead to regional loss of forest cover, increasing flood magnitude along a local stretch of river. Similarly, interactions can take place across different time scales. Actions to respond to negative changes or to enhance positive changes can be taken at almost all points in this framework (crossbars).

The MA is just one example of applying ecological concepts to health and well-being. A range of related approaches encourage a systemic understanding of environmental impacts and health using ecological principles. The field of ecohealth adopts systems approaches to promote the health of people, animals, and ecosystems in the context of social and ecological interactions (Parkes, Horwitz, & Waltner-Toews, 2014). Related frameworks include ecosystem approaches to health (Charron, 2012; Webb et al., 2010), ecological public health (Rayner & Lang, 2012), and human-animal-ecosystem approaches including

conservation medicine and One Health (Wilcox et al., 2012; Zinsstag, Schelling, Waltner-Toews, & Tanner, 2011). By recognizing ecosystems as foundational for health and well-being, each of these approaches offer new insights for the field of environmental health, and present new opportunities to both understand and respond to contemporary health challenges.

Summary An ecologically oriented approach to public health views humans as nested within ecosystems, calls for integrative consideration of environmental and social factors, and highlights system characteristics such as complexity, emergence, and feedback loops. Recognizing ecology and ecosystems as foundational for health enhances our understanding of the determinants of health, and also our capacity to respond to evolving health challenges now and into the future. This chapter presents ecological literacy as an essential prerequisite for environmental health, creating an increased awareness of ecosystems as settings for health, in contexts ranging from cities to agricultural lands, from parks to wetlands to oceans, and on land, in water, or in air. Ecological approaches affirm the realization that the environment is our home.

Key Terms abiotic Physical or chemical; used of the properties of an ecosystem (cf. biotic). abundance Number of individuals in a species population. assemblage of species The characteristic collection of species that make up an ecological community. autotroph Autotrophs (literally, “self-feeders”) use inorganic molecules and an external energy source to manufacture their own organic molecules (biomass). bioaccumulation A process in which an organism takes up a chemical pollutant, such as DDT or mercury, and retains it in its tissues during its lifetime rather than expelling the pollutant as waste. biodiversity Degree of variation of life in all its forms (also known as biological diversity). biological invasion Large-scale movement of animals or plants into areas where they were previously absent or uncommon. biomagnification (bioamplification) A process in which a chemical pollutant occurring in an organism's tissues is retained and, when the organism is consumed by a predator, becomes more concentrated in the predator's tissues. This process continues at every level of consumption; so by the time the top predator consumes its prey, the pollutant is substantially more concentrated (and potentially more toxic). biotic Living; used of the biological features of an ecosystem (cf. abiotic). boundaries System boundaries differentiate between what is “in” and what is “out”: what is deemed relevant and what is irrelevant, important and unimportant, worthwhile and not worthwhile, and who benefits and who is disadvantaged. carrying capacity The maximum population that can be sustained indefinitely by its supporting ecosystems. climax community The assemblage of species that occurs once the effects of a disturbance have diminished, when colonizing and early successional species have been replaced by K-selected species able to persist in more stable conditions.

commensalism A symbiotic relationship in which one species derives a benefit from another without affecting the fitness or survival of the other species. community ecology The branch of ecology that considers assemblages of species and particularly the interactions among them. competition A relationship in which two or more species must share scarce or limited resources. complex system A system made up of a large number of heterogeneous elements, some simple and others complex and even chaotic. These elements interact with each other through positive and negative feedbacks. conservation biology The study of the biological characteristics of species that are important for their conservation. consumers Organisms, almost always animals, that eat other organisms; primary consumers are herbivores that eat producers (like plants) or detritivores; secondary consumers are predators or carnivores that eat primary consumers. coupled human-natural systems An integrated approach to systems that does not seek to separate human or social systems from their environmental settings. cycle A cycle (hydrological, carbon, nitrogen, phosphorus) is a sequence of events that repeats itself. decomposer (detritivore) An organism that derives its energy from consuming the dead or dying matter or products from other life. demography The study of the characteristics and structure of populations. distribution The geographic occurrence (in range and extent) of a species. disturbance Temporary physical, chemical, or biological disruptions to an ecosystem. Disturbances dictate the character of the ecosystem, and in this sense, under some circumstances, ecosystems need disturbances. dynamic A term applied to systems to convey the idea that they undergo constant change: constancy comes from the fixed rules that operate in a system and give it a recognizable state; change comes from feedback loops, self-organization, and emergence, with novelty generated by the system. ecological community See assemblage of species. ecological integrity The condition or quality of the whole of a successful ecosystem. This integrity has four attributes: (1) system “health” (continued successful functioning), (2) capacity to withstand stress, (3) undiminished optimum capacity for ongoing developmental options, and (4) continued capacity for change and development, unconstrained by human interruptions. ecological literacy A learned ability to read, interpret, and understand the environment. ecological processes The “how” of ecosystem functions; the cycling of water, nutrients, and energy. ecology A scientific discipline that focuses on interactions of living things in relation to their environment. ecosystem

A complex system of organisms and their environment, and the interactions that connect them. ecosystem functions What ecosystems are doing (embracing ecological processes). ecosystem services “The benefits people obtain from ecosystems” (MA, 2003, p. 49). This construct allows ecosystems, which provide the basis for life on Earth, to be more clearly and overtly included in economics and decision making. emergent Not existing in isolation in individual parts of the system but arising when components interact. Emergent properties characterize complex systems and uncertainty (see surprise). equilibrium A self-regulated stable state in which negative feedback will operate to bring a changing parameter back to its original condition so the ecosystem maintains its state. Contemporary ecological thinking considers ecosystems to be nonequilibrial, so that multiple states are possible rather than one stable state. exponential growth Geometric growth, with the rate of growth proportional to population size rather than linear or occurring at a fixed rate. extinction Extinction occurs when there are no living individuals of a species. feedback loop A repeating chain or circuit of cause and effect in which the events and parameters are of the system itself. flow Transfer of material or energy or information in an ecosystem. food web The pattern of relationships among ecosystem species as defined by who eats whom, who is feeding on what, and who is making their own food, usually arranged in trophic levels of producers, consumers, and decomposers. habitat The physical space occupied by a species, characterized by physical (rocks, soils, landforms, water depth, etc.), chemical (air and water quality), and biological (vegetation, animals, microbes, etc.) features. herbivores Plant eaters. heterotroph An organism that cannot make its own energy and must rely on organic molecules made by other organisms. hierarchy Something structured according to levels or scales. holism An all-encompassing approach of focusing on or investigating wholes rather than parts. human ecology The study of the reciprocal relationship between humans and their environments. Such study is necessarily interdisciplinary, drawing on social, natural, cultural, political, and technical disciplines and dimensions. introduced species (alien or exotic species) A species that moves to a place where it has never occurred before, becoming an established and successful colonist. K-selected species Species, typically found in stable environments, in which individuals grow to be larger, take longer to

reach maturity, live longer, produce fewer progeny (“expensive offspring”), and invest considerably more parental energy than r-selected species individuals do. Millennium Ecosystem Assessment The MA “assessed the consequences of ecosystem change for human well-being. From 2001 to 2005, the MA involved the work of more than 1,360 experts worldwide. Their findings provided a state-ofthe-art scientific appraisal of the condition and trends in the world's ecosystems and the services they provide, as well as the scientific basis for action to conserve and use them sustainably” (www.millenniumassessment.org). mutualism A form of symbiosis in which both species derive a benefit from each other. nested How complex systems are organized; they are composed of systems, and they themselves are found wholly within systems. niche The multidimensional ecosystem space where a species exists and also what it does. Arguably, no two species can have the same niche. This concept is paralleled in economics where a product is said to have a “niche” in the market. parasitism A relationship in which an individual of one species derives a benefit directly from an individual of another species, and in the process negatively affects the fitness and possibly even the survival of the (infected) individual. patterns Observable regularities repeated in space and or time. population decline Reduction in population size. occurring when the death rate (plus emigration) exceeds the reproduction rate (plus immigration). population ecology The study of populations of species, including their biology, demography, habitat, and specific interactions. population growth Increase in population size, occurring when the reproduction rate (plus immigration) exceeds the death rate (plus emigration). predator An animal that eats another animal (prey). Such predation is one way in which population numbers are regulated: when prey are abundant, predators can increase and vice versa. Constant rates of predation can suppress population growth among prey. primary producer See autotroph; primary producers are almost always photosynthesizing organisms. reciprocity (reciprocal maintenance) A state of mutual dependence or action or influence. Reciprocal maintenance—taking care of each other, our communities, and our natural environment so they will take care of us—is a guiding principle of the Ottawa Charter. regulation of population growth Constraint of population growth by resource availability, disease, predation, or some other factor that prevents a population from breeding to its maximum capacity. resilience The “capacity [of an ecosystem]…to absorb disturbance; to undergo change and still retain essentially the same function, structure, and feedbacks” (Walker & Salt, 2006). restoration ecology A field of practice that builds on knowledge of the species assemblages that are local and endemic in order to reintroduce them, based on knowledge of the physical characteristics of the site. richness

A measure of population numbers and of biodiversity, usually dependent on the size of the area sampled and the number of samples taken. r-selected species Species such as weeds that are opportunists, capitalizing on spare resources (such as extra light, space, or nutrients) to grow rapidly, mature quickly, and produce many progeny (“cheap offspring”) (cf. Kselected species). scale A spatial, temporal, quantitative, or analytical dimension (e.g., small to large or short-term to longterm) used to measure and study a phenomenon. self-organizing Able to establish a pattern or arrive at a state. In a system this ability is a product of numerous interactions among system components, often taking the form of feedback loops (positive or negative) that are entirely internal to the system. social-ecological systems An approach to systems thinking and analysis that does not separate humans from ecological analysis, whereby both social and ecological dynamics influence the trajectory of the system, and its degree of resilience. species A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. succession Following a disturbance, the gradual, orderly, and progressive replacement of one ecosystem community by another until a stable climax community is established. surprise Any of three properties of an ecological system: (1) an unexpected discrete event; (2) abrupt, nonlinear, discontinuous behavior; or (3) genuine novelty. Ecologist Lance Gunderson (2003) considers a crisis to be the consequence of surprises that leads to an unambiguous policy failure. symbiosis A term meaning “living together” that describes certain relationships between species; these relationships are often intimate and highly evolved. systems thinking An approach that assumes the issue under investigation is occurring in a complex and uncertain system, and cannot be seen in isolation from its context (cf. holism). tipping point A system threshold, the “straw that broke the camel's back.” Systems are “buffered” and can often absorb change and retain the same state. At some point, however, even a slight change is too much, and the system responds. trophic levels The levels that make up a food web. Classically, in terrestrial ecosystems, they form a pyramid of layers, with producers at the bottom, primary consumers in the next layer, secondary consumers next, and an apex predator at the top.

Discussion Questions 1. Recognition of the links between biodiversity and health is said to be increasing (Bernstein, 2014; MA, 2005a; Sandifer et al., 2015). What do you think has changed in our understanding of both health and biodiversity to create this new interest? Can you provide an example of a biodiversity and health connection that is relevant to your own life? Can you think of another example that might become more relevant two generations from now? 2. Figure 2.1 presents a food web in a North American ecosystem. What features of this figure make it possible to identify the geographic location this food web.? How might you depict a food web from a different part of the world or a different biome (e.g., sub-Saharan Africa or Australia or the Pacific

Ocean)? Consider the implications of swapping a species in Figure 2.1 with a species from another part of the world. How would the idea of biological invasion (Text Box 2.2) influence this? 3. The hydrological cycle is shown in Figure 16.1 (Chapter 16). Draw the hydrological cycle for the region of the planet in which you live, including in your diagram evaporation, evapotranspiration, cloud formation, rain/precipitation, infiltration, soil moisture, runoff, surface water flow (rivers), other surface water bodies on land (like lakes and swamps), aquifers, and then oceans and seas, glaciers, and ice caps (whichever are relevant to your region). Now draw the cycle again but at the global scale. Consider the ways the hydrological cycle may be different in the different regions of the planet. How different are these cycles? How similar are they? What are the points of connection between them? How is your understanding of the regional scale enhanced by understanding the global scale, and vice versa? What could you gain and lose by trying to understand the hydrological cycle at the scale of your neighborhood or the area where you spend most of your time? 4. Scales are important in ecology, and in environmental health. This can be illustrated by a “zoom in, zoom out” mental exercise. Think of your current home, and identify a small living thing there. Maybe a potted-plant? Maybe your cat? If you are not able to identify something else alive inside your home, use yourself as an example of a living creature. Now start to zoom out. Look down on this living thing with a view of the room it is in, and the house or building in which the room is situated. Do you notice more living (biotic) parts or more nonliving (abiotic) parts of the environment interacting with your living thing? Do you see any evidence of the living and nonliving things interacting? How do social dynamics influence this? Continue to zoom out farther to the street block and the neighborhood? Do you see more life yet? What other species do you see that make up this ecological community? What species do you not see? What things move and interact the most? Do you see cars, buses, and trucks? What are they carrying? Where are these things coming from and going to? Consider the kinds of energy being used and the ecological and social influences on these energy flows. Consider the same questions for water: where is it flowing from and flowing to? What are the ecological influences on how your living thing can access this water? Zoom out farther, more quickly now. Zoom out to the borders of the region in which you are currently located. Does what you are seeing look more or less alive? Do you visualize this view as a roadmap or as a satellite image? Which of these two views looks more alive? Why? Would you prefer to describe what you see as an environment or an ecosystem? Can you see evidence of ecological cycles from this vantage point? Stop! Once you have a large-scale (regional or even statewide) view in your mind's eye, consider three questions: How would this view have looked different 5 years ago? 50 years ago? 1,000 years ago? Identify two positive and three negative influences on health for each of these time frames at this scale. Give three examples of where you can see (imagine?) the atmosphere (air), geosphere (rock, land), and hydrosphere (water) interacting to support life within the view you see. Web sites that can help you experience these features of zooming in and out through social and ecological contexts include scaleofuniverse.com and www.ecologicalfootprint.com 5. The social ecological model (Figure 2.11) (also see Bronfenbrenner, 1977) is commonly invoked in public health to clarify the hierarchical role of social determinants of health, and the way health is grounded in the settings in which people live, work, learn, and play (WHO, 1986). While Figure 2.11 and ones like it are common depictions, they place little emphasis on ecosystems. Do you think this is an important omission? How would you redraw this figure to show the role of ecosystems? Could you adapt the figure to better reflect the “socioecological approach” proposed by the Ottawa Charter (WHO, 1986), which encourages reciprocal maintenance—taking care of each other, our communities,

and our natural environment? More recently, “social-ecological systems” have been described as another way to understand the links between humans and their environment, with an emphasis on the concept of resilience (Berkes et al., 2003). How does the idea of resilience influence how you view the social ecological model in Figure 2.11?

Figure 2.11 The Social Ecological Model Source: Bronfenbrenner, 1977.

6. Text Box 2.5 describes restoration ecology. Please give an example of a restoration ecology effort. In what ways does such an effort need to take account of similarities to, and differences from, the classical ecological succession model? Why is it important for restoration ecology to address the social and environmental determinants of health?

References Berkes, F., Colding, J., & Folke, C. (2003). Navigating social-ecological systems: Building resilience for complexity and change. New York: Cambridge University Press. Bernstein, A. S. (2014). Biological diversity and public health. Annual Review of Public Health, 35(1), 153–167. Bronfenbrenner, U. (1977). Toward an experimental ecology of human development. American Psychologist, 32(7), 513–531. Charron, D. F. (Ed.). (2012). Ecohealth research in practice: Innovative applications of an ecosystem approach to health. New York: Springer. Commoner, B. (1971). The closing circle: Confronting the environmental crisis. London: Cape. Glouberman, S., & Zimmerman, B. (2002). Complicated and complex systems: What would successful reform of Medicare look like? (Discussion Paper No. 8). Commission on the Future of Healthcare in Canada. Gunderson, L. (2003). Adaptive dancing: Interactions between social resilience and ecological crises. In F. Berkes, J. Colding, & C. Folke (Eds.), Navigating social-ecological systems: Building resilience for complexity and change (pp. 33–52). New York: Cambridge University Press. Hammond, R. A. (2009). Complex systems modeling for obesity research. Preventing Chronic Disease, 6(3), A97. Hancock, T. (2011). It's the environment, stupid! Declining ecosystem health is THE threat to health in the 21st century. Health Promotion International, 26(Suppl. 2), ii168–172.

Kolbert, E. (2014). The sixth extinction: An unnatural history. New York: Holt. Liu, J., Dietz, T., Carpenter, S. R., Alberti, M., Folke, C., Moran, E.,…Taylor, W. W. (2007). Complexity of coupled human and natural systems. Science, 317(5844), 1513–1516. McMichael, A. J. (1999). Prisoners of the proximate: Loosening the constraints on epidemiology in an age of change. American Journal of Epidemiology, 149(10), 887–897. Meadows, D. H. (2008). Thinking in systems: A primer. White River Junction, VT: Chelsea Green. Millennium Ecosystem Assessment. (2003). Ecosystems and human well-being: A framework for assessment. Washington, DC: Island Press. Summary available online at http://www.millenniumassessment.org Millennium Ecosystem Assessment. (2005a). Ecosystems and human well-being: Health synthesis. Geneva: World Health Organization. Retrieved from http://www.millenniumassessment.org/en/index.aspx Millennium Ecosystem Assessment. (2005b). Living beyond our means: Natural assets and human wellbeing. Statement from the board. Washington, DC: World Resources Institute. Full report available at http://www.millenniumassessment.org Montgomery, D. Dirt: The erosion of civilizations. Berkeley: University of California Press, 2007. Parkes, M. W., & Horwitz, P. (2009). Water, ecology and health: Ecosystems as settings for promoting health and sustainability. Health Promotion International, 24, 94–102. Parkes, M. W., Horwitz, P., & Waltner-Toews, D. (2014). Ecohealth. In A. C. Michalos (Ed.), Encyclopedia of quality of life and well-being research (pp. 1770–1775). Heidelberg: Springer-Verlag. Parkes, M. W., & Weinstein, P. (2004). An ecosystems approach to environmental health. In N. Cromar, S. Cameron, & H. Fallowfield (Eds.), Environmental health in Australia and New Zealand (pp. 45–65). Melbourne: Oxford University Press. Pearce, N., & Merletti, F. (2006). Complexity, simplicity, and epidemiology. International Journal of Epidemiology, 35(3), 515–519. Rayner, G., & Lang, T. (2012). Ecological public health: Reshaping the conditions for good health. London: Routledge. Sandifer, P. A., Sutton-Grier, A. E., & Ward, B. P. (2015). Exploring connections among nature, biodiversity, ecosystem services, and human health and well-being: Opportunities to enhance health and biodiversity conservation. Ecosystem Services, 12, 1–15. doi:10.1016/j.ecoser.2014.12.007 Stephens, C., Parkes, M., & Chang, H. (2007). Indigenous perspectives on ecosystem sustainability and health. EcoHealth, 4, 369–370. UNU-IHDP. (2014). Land, water, and people: From cascading effects to integrated flood and drought responses. Summary for decision-makers. Bonn: UNU-IHDP. Walker, B., & Salt, D. (2006). Resilience thinking: Sustaining ecosystems and people in a changing world. Washington, DC: Island Press. Webb, J., Mergler, D., Parkes, M. W., Saint-Charles, J., Spiegel, J., Waltner-Toews, D.,…Woollard, R. F., (2010). Tools for thoughtful action: The role of ecosystem approaches to health in enhancing public health. Canadian Journal of Public Health, 101, 439–441. Wilcox, B. A., Aguirre, A. A., & Horwitz, P. (2012). Connecting ecology, health, and sustainability. In A. A. Aguirre, R. S. Ostfeld, & P. Daszak (Eds.), New directions in conservation medicine: Applied cases of ecological health (pp. 17–32). New York: Oxford University Press. World Health Organization. (1986). Ottawa Charter for Health Promotion. First International Conference

on Health Promotion, Ottawa, Canada, 17–21 November 1986. Retrieved from http://www.who.int/healthpromotion/conferences/previous/ottawa/en Zinsstag, J., Schelling, E., Waltner-Toews, D., & Tanner, M. (2011). From “one medicine” to “one health” and systemic approaches to health and well-being. Preventive Veterinary Medicine, 101, 148–156.

For Further Information Books Aguirre, A. A., Ostfeld, R. S., & Daszak, P. (Eds.). (2002) New directions in conservation medicine: Applied cases of ecological health. New York: Oxford University Press. Aron, Joan L., & Patz, J. A. (2001). Ecosystem change and public health: A global perspective. Baltimore: Johns Hopkins University Press. Collinge, S. K., & Ray, C. (Eds.). (2006). Disease ecology: Community structure and pathogen dynamics. New York: Oxford University Press. Daily, G. C. (Ed.). (1997). Nature's services: Societal dependence on natural systems. Washington, DC: Island Press. Hallström, L. K., Guehlstorf, N. P., & Parkes, M. W. (2015). Ecosystems, society, and health: Pathways through diversity, convergence, and integration. Montreal: McGill Queens University Press. Hancock, T., Spady, D. W., & Soskolne, C. L. (Eds.). (2015). Global change and public health: Addressing the ecological determinants of health: The report in brief. Available at http://www.cpha.ca/uploads/policy/edh-brief.pdf Horwitz, P., Finlayson, C. M., & Weinstein, P. (2012). Healthy wetlands, healthy people: A review of wetlands and human health interactions (Ramsar Technical Report No. 6). Gland and Geneva: Ramsar and WHO. Available at http://www.ramsar.org/sites/default/files/documents/pdf/lib/rtr6-health.pdf Mayer, K. H., & Pizer, H. F. (Eds.). (2008). The social ecology of infectious diseases. Burlington, MA: Academic Press. Millennium Ecosystem Assessment. (2005). Ecosystems and human well-being: Biodiversity synthesis. Washington, DC: World Resources Institute. Full report available at http://www.millenniumassessment.org Parkes, M. W. (2011). Ecohealth and Aboriginal health: A review of common ground. Prince George, BC: National Collaborating Centre for Aboriginal Health. Available at http://www.nccahccnsa.ca/docs/Ecohealth_MargotParkes2011-EN.pdf Ostfeld, R. S., Keesing, F., & Eviner, V. T. (Eds.). (2008). Infectious disease ecology: Effects of ecosystems on disease and of disease on ecosystems. Princeton, NJ: Princeton University Press. Waltner-Toews, D. (2004). Ecosystem sustainability and health: A practical approach. New York: Cambridge University Press. Waltner-Toews, D., Kay, J. J., & Lister, N.-M. E. (2008). The ecosystem approach: Complexity, uncertainty, and managing for sustainability. New York: Columbia University Press. Wackernagel, M., & Rees, W. (1996). Our ecological footprint: Reducing human impact on the Earth. Gabriola Island, BC: New Society. Waldrop, M. M. (1993). Complexity: The emerging science at the edge of chaos. New York: Simon & Schuster. Zinsstag, J., Schelling, E., Whittaker, M., Tanner, M., & Waltner-Toews, D. (Eds.). (2015). One Health: The theory and practice of integrated health approaches. Wallingford, UK: CABI.

Programs, Organizations, Web Sites Future Earth: http://www.futureearth.org International Association for Ecology & Health, and its journal, EcoHealth: http://www.ecohealth.net Learning for Sustainability: http://learningforsustainability.net Millennium Ecosystem Assessment: http://www.millenniumassessment.org Resilience Alliance: http://www.resalliance.org The Rockefeller Foundation–Lancet Commission on Planetary Health: https://www.rockefellerfoundation.org/planetary-health

Chapter 3 Sustainability and Health Cindy L. Parker, Jessica D. Rhodes, and Brian S. Schwartz During the preparation of this chapter Dr. Parker served on the Boards of Physicians for Social Responsibility and the Chesapeake Climate Action Network, as a Fellow of the Post-Carbon Institute, and as co-chair of the Climate Communication Consortium of Maryland coordinating committee, all uncompensated positions. Dr. Rhodes and Dr. Schwartz report no conflicts of interest related to the authorship of this chapter.

Key Concepts Sustainability refers to the ability of a system to continue functioning without depleting or damaging the things it needs to function. The term has come to be used in many ways. Almost all are relevant to human health and well-being. Human activity over recent centuries—a growing population and growing energy and resource use—has altered many Earth systems in patterns that are not sustainable. Sustainability is a feature of complex systems, so systems thinking is required to address it. Sustainability has traditionally been considered to involve three domains—environmental, social (including health), and economic. Neo-sustainability refers to the ability of an activity to sustain a system by improving its quality and operating within its limits. This may imply innovative ideas of prosperity, growth, and quality of life. There are many approaches to measuring progress toward sustainability, on all levels, from global to local. Moving toward sustainability is necessary not only as a basis for long-term human health and equity but also as a basis for the continued viability of civilization as we know it. Did you know that you're living in an era called the Anthropocene? Geologists call the era in which modern civilization evolved the Holocene, an era characterized by relatively stable conditions on Earth. The Anthropocene represents a change. Popularized by atmospheric chemist Paul Crutzen at the dawn of the twenty-first century, this term identifies an era in which human influence has altered many fundamental Earth processes: the climate, the extent of photosynthesis (a key part of primary production, the basis of most food chains; see Chapter 2), land cover, river flows, ocean food webs, the cycling of materials such as nitrogen and phosphorus, and the likelihood of species extinctions, to name a few. The Anthropocene began during the industrial revolution when fossil fuel use rose dramatically. Carbon dioxide levels in the atmosphere climbed from preindustrial levels of around 270 parts per million (ppm) to 310 ppm by the mid-twentieth century, and with the Great Acceleration after World War II (Steffen, Grinevald, Crutzen, & McNeill, 2011)—with steeply increasing population, industrialization, fossil fuel extraction, agricultural activity (including mechanization, clearing of forests, and fertilizer use), and consumption of goods—these levels have risen to more than 400 ppm today. This has led to complex changes: accelerating rates of species extinction, increasing amounts of reactive nitrogen in the environment, and massive swaths of natural ecosystems being converted for human use. The most recent stage of the Anthropocene, the twenty-first century, is characterized by the rapid economic development of countries, including China, India, Brazil, and Indonesia, continuing the Great Acceleration. Figure 3.1 shows some indicators of this acceleration—more people, more economic activity, bigger impacts on the environment. These changes have occurred very quickly, which is cause for both pride and concern. But clearly this kind of geometric growth cannot go on for long in a finite world without serious consequences. The systems we have altered are in a very real sense life support systems, not only for our planet's plant and animal life but for humans as well. The air we breathe, the water we

drink, the materials we use, the crops we grow, all depend on them. Sustainability must be a matter of deep human concern.

Figure 3.1 The Great Acceleration Source: Steffen et al., 2004.

The twenty-first century has also seen an increasing awareness of the global scale of human impact on planet Earth. Attempts at global governance to manage and mitigate the damage have begun. What will it take for the Anthropocene to become an age of sustainability? What would a sustainable society look like? This chapter introduces some foundations of the concept of sustainability, discusses the core elements of sustainability, reviews ways to measure progress toward sustainability, and describes a path forward, including the concept of neo-sustainability.

Historical Considerations of Sustainability Many disciplines have used the term sustainability, often defined in different ways. We begin our

discussion with a simple definition: according to Merriam-Webster online, sustainable means “able to be used without being completely used up or destroyed,” “involving methods that do not completely use up or destroy natural resources,” and “able to last or continue for a long time.” In the twenty-first century, sustainability has become part of our modern lexicon but means widely different things to different people. Most agree it is a positive concept, and thus it is widely embraced. But where did the term sustainability originate? Why is it important? What does it have to do with the Great Acceleration? And what does it have to do with health? Many Indigenous peoples have lived by the philosophy of sustainability for generations (Sveiby, 2009), but modern uses of the term date to the environmental movement of the 1960s and 1970s. People began to realize that industrialization and economic development—vehicles for improving living conditions for people worldwide—were seriously damaging the environment. Initially, sustainability was a concept grounded in conservation. In 1970, an International Union for Conservation of Nature (IUCN) report emphasized the importance of conservation, defined as “management of the resources of the environment —air, water, soil, minerals and living species including man—so as to achieve the highest sustainable quality of human life.” Notably, human well-being was at the center of this framework. At the United Nations Conference on the Human Environment in 1972 in Stockholm, a declaration was issued acknowledging how economic and social development had improved quality of life throughout the world but also noting that this development had simultaneously damaged the Earth's ecosystems—calling into question the staying power of the benefits. The declaration called on society to protect the Earth's natural resources for the benefit of present and future generations. Shortly after, in 1980, the IUCN released its World Conservation Strategy, which challenged human society on its “quest for economic development and enjoyment of the riches of nature” to recognize “resource limitation and carrying capacities of ecosystems” and take into account “the needs of future generations” (IUCN, 1980). The report also argued that economic growth and development are compatible with conservation, and that conservation must be integrated with them to make development sustainable (IUCN, 1980), without clearly explaining how necessary trade-offs might be achieved. Sustainability became popularized with the United Nations' 1987 Brundtland Report, Our Common Future. However, the Brundtland Report focused not on sustainability but on sustainable development, defined as economic development that “meets the needs of the present without compromising the ability of future generations to meet their own needs” (World Commission on Environment and Development, 1987). The report is written at a high level; it does not specify how current development that does not affect future generations is to be measured and tracked. While the report acknowledges that sustainable development implies limits, it declares that these are “not absolute limits but limitations imposed by the present state of technology and social organization on environmental resources and by the ability of the biosphere to absorb the effects of human activities” (World Commission on Environment and Development, 1987). By suggesting that technology and innovation could overcome limits to growth (which in practical terms meant economic growth), the Brundtland Report avoided the vexing problem of limits. Even though virtually every environmental impact could also affect human health, health did not formally enter the sustainable development discussion until 1989, when then World Health Organization (WHO) director Dr. Hiroshi Nakajima prioritized the linkages among health, economic development, and the environment (Institute of Medicine [IOM], 2013). The WHO Commission on Health and the Environment was soon launched, and issued reports on the arenas of food and agriculture, energy, industry, and urbanization (IOM, 2013). These reports influenced discussions at the landmark 1992 United Nations (UN) Conference on Environment and Development in Rio de Janeiro, Brazil (the Rio Conference). Principle 1 of the Rio Declaration on Environment and Development states, “Human beings are at the centre of concerns for sustainable development. They are entitled to a healthy and productive life in harmony with nature” (United Nations, 1992a), while Agenda 21, the action plan that arose from the Rio Conference, devotes a chapter to “protecting and promoting human health” (United Nations, 1992b). Through both the Rio Declaration and Agenda 21, the international community endorsed the idea of sustainable development, with human health an integral consideration. Even though health is certainly a fundamental need, some argue a right, of human society, sustainability is not about the health of individuals, although that result flows from it. Rather it is about the health of the global population—all of us. This idea is developed in Text Box 3.1, which examines planetary health.

Text Box 3.1 Planetary Health Unsustainable practices are threatening health on an unprecedented scale. In 2014, a team from the Lancet, the University of Auckland, the Auckland University of Technology, Umeå University, and the London School of Hygiene and Tropical Medicine proposed a broad framework for addressing this challenge, calling their concept planetary health. They argued powerfully for the need to act, based on the same sustainability considerations introduced in this chapter: Our patterns of overconsumption are unsustainable and will ultimately cause the collapse of our civilization. The harms we continue to inflict on our planetary systems are a threat to our very existence as a species. The gains made in health and wellbeing over recent centuries, including through public health actions, are not irreversible; they can easily be lost, a lesson we have failed to learn from previous civilizations. We have created an unjust global economic system that favors a small, wealthy elite over the many who have so little [Horton et al., 2014]. Planetary health, according to these authors, aims “to protect and promote health and wellbeing, to prevent disease and disability, to eliminate conditions that harm health and wellbeing, and to foster resilience and adaptation.” They propose “a new principle of planetism and wellbeing for every person on this earth—a principle that asserts that we must conserve, sustain, and make resilient the planetary and human systems on which health depends by giving priority to the wellbeing of all.” This is more than a public health agenda; it is “an attitude toward life and a philosophy for living,” requiring “urgent transformation…in our values and our practices.” In this transformation, health professionals would serve as an “independent conscience,” deploying traditional public health values of social justice and fairness for all, and working through “collective actions of interdependent and empowered peoples and their communities” (Horton et al., 2014).

Sustainable Human Well-Being and the Three-Legged Stool In the decades since, the idea of sustainable development has continued to evolve and recognition of the importance of health has grown. The UN's Millennium Development Goals, adopted by all UN member states in 2000, all incorporated health, either explicitly (through setting targets for reducing child mortality, improving maternal health, and combating infectious diseases, etc.) or implicitly (through setting targets for eradicating extreme poverty and hunger, achieving universal primary education, promoting gender equality, and ensuring environmental sustainability, etc.). The 2002 UN World Summit on Sustainable Development in Johannesburg introduced the idea that sustainable development rests on three interdependent and mutually reinforcing pillars—economic development, social development, and environmental protection—a three-legged stool that requires all legs to be of equal importance and thus the same length (United Nations, 2002). Critics, however, have argued that the three pillars are not equivalent because the environment underpins both economy and society (Adams, 2006), and they have proposed a nested model of sustainability (see Figure 3.2). In this view the environment represents an outer bound to human activity, implying the existence of limits, and furthering thinking about the underlying complex relationships (Adams, 2006).

Figure 3.2 Nested Model of Sustainability Source: Adapted from Adams, 2006.

Where does health fit in? Health—defined by the WHO (1948) as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity”—is at the core of the social dimension, so much so that some have argued that achieving well-being in a sustainable manner ought to guide sustainability efforts (Holdren, 2008). The dependence of health on the larger environmental context is captured in the concept of ecosystem services, such as purification of air and water, protection from some natural disasters, and pollination of crops (Millennium Ecosystem Assessment, 2005). As described in Chapter 2, many of these services are essential for human well-being, although they are typically undervalued by conventional economic reckoning (Summers, Smith, Case, & Linthurst, 2012). When ecosystem damage compromises these services, disease and suffering can follow, in both predictable and unpredictable ways (Myers et al., 2013). In fact, while failure in any of the three domains —economic, social, or environmental—can trigger human suffering on a large scale, and all are interrelated, Diamond (2005) and others have argued that in human history, serious environmental problems are a recurring primary cause of societal collapse. A closely related core component of the social dimension is equity. Since the Rio conference, there has been broad agreement that deep inequities—between rich nations and poor nations and also within nations—are not only unfair, they are a barrier to sustainability (Ehrlich, Kareiva, & Daily, 2012). Equity considerations also extend across time, which is no surprise given that sustainability intrinsically considers long-term outcomes. The concept of intergenerational equity posits that we have a moral requirement to leave a livable world to future generations (Padilla, 2002). These concepts correspond closely to the idea of environmental justice (see Chapter 11). The Brundtland Report's definition of sustainable development can thus be seen, in retrospect, as both holistic and vague. This may have served a useful purpose in 1987 to appeal to a broad audience and garner acceptance of the general concept, but such vagueness has allowed governments, environmentalists, policymakers, and businesses to act in the name of sustainability and sustainable development in widely different ways that conveniently suited their needs (Adams, 2006). Recent decades have seen an explosion of interest in sustainability. Sustainable is now a catchword in green business, and many corporations, universities, and cities have offices of sustainability. Ironically, despite such interest and action, human destruction of the environment continues at an accelerated pace. This failure may be in part due to the way each entity has defined sustainability. If sustainability can mean anything to anyone, it is no longer a useful term (Farley & Smith, 2014).

Drivers of Nonsustainability, Limits to Growth, and Collapse Humans place demands on the environment through our numbers (population size), but also by how we use, produce, and/or distribute land, food, water, consumer goods, and energy. Many of these activities use finite natural resources (e.g., ores to make metals; petroleum to make plastics; ancient groundwater aquifers, which are not rechargeable on human time scales, to irrigate crops), while others rely on renewable resources (e.g., wind, sun, rechargeable aquifers). These drivers are captured in the equation I = PAT where I is society's impact on the Earth's systems (and therefore, as we have seen, on human health and well-being), P is population, A is affluence (a measure of per capita consumption), and T is a

technology factor reflecting the efficiency of production and consumption (Ehrlich & Holdren, 1971). This is a reminder that both population and the intensity of how people live are drivers of sustainability. The remarkable growth of the P and T parts of the equation is evident in Figure 3.1. Consumerism encourages, and relies on, the acquisition of goods and services in ever-greater amounts; it has been estimated that 70% of the U.S. economy and 20% of the world economy is based on the purchasing decisions of the U.S. consumer (United Nations Environment Programme, 2012). The P part of the equation, population, has been the subject of robust debate since the eighteenth century. In his Essay on the Principle of Population, Thomas Malthus argued that the human population could not continue to grow exponentially because the natural resources that provided human subsistence, namely the products of agriculture, were limited and could grow only arithmetically. When the population exceeded the ability of the Earth's resources to provide subsistence, he argued, war, pestilence, famine, and death would inevitably result to restore the population into balance with natural resource limits (Malthus, 1798). Some contemporary scholars, such as Jean-Jacques Rousseau, disagreed with Malthus and thought human ingenuity would provide for unlimited social improvement and endless growth (Farley & Smith, 2014). The global exploitation of fossil fuels and technological improvements leading to the agricultural revolution of the twentieth century seemed, for a time, to have proven Malthus wrong. Dramatically increased agricultural productivity fed a growing population. But in the decades since, with continued population growth and concomitant environmental degradation, Malthus's basic premise that there are limits to ecosystem services has emerged as relevant to any discussion of sustainability.

What Should Concern Us More: Population Growth Or Consumerism? In the 1960s, as the world awoke to the environmental impacts of industrialization and economic growth, the concept of limits was reexplored. In 1968, in Tragedy of the Commons, Garrett Hardin posited limits to human consumption through the concept of carrying capacity. In population biology, as noted in Chapter 2, carrying capacity refers to the maximum species population that an ecosystem can continuously support, and Hardin effectively applied the concept to the human population. He argued that when there are resources shared in common, individual users benefit directly from their use but share only indirectly in the cost of overuse. This encourages individuals to exploit the resource for private gain at the expense of the common good, and ultimately leads to degradation of the resource (Hardin, 1968). Hardin's example was a shared pasture, on which each herder has an incentive to maximize the number of his or her own livestock grazing. But if all herders acted on that incentive, overgrazing would result. For the pasture, as for other common pool resources, exceeding the limit or carrying capacity would result in ecosystem degradation and collapse. In the same year, Paul Ehrlich revived the Malthusian debates with his book Population Bomb (1968), in which he predicted that population growth would continue to outpace agricultural growth, leading to global famine and starvation as early as the 1970s. While his predictions certainly did not pan out in the time frame suggested, he made an important contribution to the discussion of whether there is a limit to the human population the Earth can sustain. And given current population projections of almost 10 billion people by 2050 (United Nations Department of Economic and Social Affairs, Population Division, 2015), and the mounting threat of climate change to agricultural production, Malthus and his neo-Malthusian counterparts may, in the end, turn out to be correct. There has been a longstanding tension between those who view population as the primary driver of environmental degradation and those who point instead to consumerism. While population can be directly measured, and has been for a long time, progress toward measuring the environmental impact of technology and consumption has only more recently developed. The concept of the ecological footprint emerged in the early 1990s from the attempt to measure these impacts while moving beyond a focus on economic indicators and looking through the lens of ecosystem services (Rees, 2013). The ecological footprint of a population is defined as “the total area of land and water ecosystems required to produce the resources that the population consumes, and to assimilate the wastes that the population generates, wherever on earth the land/water are located” (Rees, 2013). Thus the ecological footprint approximates the area of earth needed to sustain the consumption and absorb the waste of a society. Another component of the footprint is biodiversity loss, which inevitably accelerates as a society's ecological footprint grows.

Today's global ecological footprint is 2.6 global hectares (gha) per person—substantially higher than what is available—just 1.8 gha per person (Borucke et al., 2013). Wealthy consumers, on average, use 4 to 10 gha per person of productive ecosystems to support their lifestyles, up to five times their fair share of global biocapacity. Even at current average levels of economic production and consumption, we are already exceeding the long-term carrying capacity of the Earth. To support the current global population of 7 billion at the average standard of living of a North American would require in excess of four more planet Earths. The global population is living and developing in part by “depleting essential natural capital and overcharging vital waste sinks” (Rees, 2013). This stark finding allows us to grasp the concept that our present lifestyles and resource use are unsustainable and inequitable.

Limits to Growth In 1972, an international scientific think tank convened to analyze the impacts of human population growth on the environment by using computer systems models to explore the question of whether the Earth has finite limits. In its report, Limits to Growth, the Club of Rome predicted that if human population and consumption continued to grow unabated, human carrying capacity on Earth would be exceeded, resulting in widespread ecosystem collapse (Meadows, Meadows, Randers, & Behrens, 1972). The report firmly claimed that there are limits to human economic and population growth. It attracted plenty of detractors. Some, such as economist Julian Simon, rejected the neo-Malthusian view of limits to growth, and challenged the model used in the Club of Rome report. He argued that human population growth is itself a source of human ingenuity and intellectual capital that can yield solutions to environmental problems and overcome resource scarcity (Simon, 1981). In 2004, the Club of Rome's Limits to Growth: 30-Year Update was released. This report discussed the degraded state of the global environment, from which resources are being extracted and exploited faster than they can be restored and into which pollutants and wastes are being released faster than they can be absorbed. It warned that humanity is in a dangerous state of overshoot: that is, of exceeding carrying capacity (Meadows, Meadows, & Randers, 2004). In retrospect, the 1972 “business as usual” scenario turned out to have projected accurately the consumption, population growth, and greenhouse gas emissions over the subsequent four decades, validating the think tank's original model and conclusions (Farley & Smith, 2014). However, the growing evidence of overshoot and its associated risks has not yet spurred fundamental changes in how we live. In the words of sustainability experts, “the predominant paradigm of social and economic development remains largely oblivious to the risk of human-induced environmental disasters at continental to planetary scales” (Rockström et al., 2009a). Recent work has also addressed signals of limits to growth (Rockström et al., 2009a, 2009b). A team based at the Stockholm Resilience Centre and the Stockholm Environment Institute has proposed a safe operating space for humanity within nine key planetary boundaries (Rockström et al., 2009b) (Figure 3.3). For seven of these nine, they proposed quantitative limits that, if exceeded, could trigger abrupt, nonlinear environmental change, with potentially catastrophic consequences for human civilization (Table 3.1). This approach offers insights into humanity's predicaments (Rockström et al., 2009b).

Figure 3.3 A Safe Operating Space for Humanity Source: Rockström et al., 2009b. There are nine planetary limits, represented by the green inner circle. Each limit, surpassed, takes humanity into potentially unsafe territory. The diagram suggests that this has occurred with respect to climate change, biodiversity loss, and the nitrogen cycle.

Table 3.1 Metrics of Sustainability Ecological footprint (Borucke et al., 2013) Living Planet Index (Loh et al., 1998) City Development Index (United Nations Commission on Human Settlements, 2001) Human Development Index (United Nations Development Programme, 1990) Environmental Sustainability Index (Esty, Levy, Srebotnjak, & de Sherbinin, 2005) Environmental Performance Index (Esty et al., 2006) Environmental Variability Index (South Pacific Applied Geoscience Commission, 2005) Index of Sustainable Economic Welfare (Cobb, 1989) Environmental adjusted domestic product (Hanley, 2000) Genuine progress indicator (Cobb, Halstead, & Rowe, 1995) Unfortunately, three of these nine boundaries have already been crossed. First, we have already surpassed the boundary of 350 ppm of carbon dioxide (1 watt/m2 of radiative forcing above preindustrial levels) and

now risk irreversible climate change, such as the melting of ice sheets and major sea level rise (Rockström et al., 2009b) (see Chapter 12). Second, the rate of biodiversity loss is now 100 to 1,000 times the natural background rate, well beyond the boundary of 10 times, and equivalent to the rates of the last major extinction (Rockström et al., 2009b). Biodiversity is the cornerstone of stable ecosystems (see Chapter 2), and even though little is known about the exact rate of species loss that would lead to ecosystem collapse, we are pushing the edge. Third, we have surpassed the safe boundaries of the nitrogen and phosphorus cycles. Mainly through fertilizer production and legume cultivation, humans convert over 120 million tons per year of atmospheric nitrogen to its reactive forms, well beyond the estimated safe limit of 35 million tons per year, and more than all of Earth's natural nitrogen fixation systems combined. Humans mine vast amounts of phosphorus from rock and 8.5 to 9.5 million tons flows into the oceans annually, more than eight times the natural background rate. High concentrations of nitrogen and phosphorus cause largescale algae blooms that grow quickly and then die and sink to the ocean's bottom. The decay process depletes the available oxygen from the water, resulting in oxygen levels too low to support life (eutrophication), and killing any marine life unable to exit the area (Rockström et al., 2009b). The fact that we have crossed three of nine planetary boundaries means we are clearly not in a safe operating space for humanity and a sustainable future is not in sight. To make matters worse, the Earth's dynamic system means that the boundaries may interact, and transgression of one boundary may fundamentally lower the safe thresholds for others (Rockström et al., 2009a). Although there have been some global efforts to curb human impact on the environment, such as the Convention on Biological Diversity and the United Nations Framework Convention on Climate Change, progress has been minimal, as increasing rates of biodiversity loss and carbon dioxide emissions continue unabated.

Human Societal Collapse? Prevention Through Systems Thinking and Early Action The idea of environmental limits and the possibility that we have exceeded them has spurred contemplation about the fate of modern human society. Some believe surpassing environmental limits will lead to the collapse of modern society, as it has contributed to the decline of past civilizations. In his book Collapse (2005), evolutionary biologist Jared Diamond identified major environmental problems facing humanity today, and noted that many of them—deforestation; soil erosion, salinization, and fertility loss; water management problems; overhunting; overfishing; invasive species; population growth; and populations' increased per capita impact—have contributed to the collapse of past societies. Additional problems, including anthropogenic climate change, environmental toxicants, and energy scarcity, threaten modern society (Diamond, 2005). Others writers, such as Thomas Homer-Dixon (2001), have argued that resource scarcity (another way of thinking about humans surpassing environmental limits) will contribute to a future of violence and conflict. Still others have taken an economic approach to environmental limits. Both Richard Heinberg (2011) and Jeff Rubin (2012) have discussed a plateauing of economic growth, imposed by environmental limits and our overuse of some of Earth's most important natural resources, namely fossil fuels. If humans are now facing environmental limits to growth, and collapse is one possible outcome of these environmental limits, perhaps our previous discussion of the three pillars of sustainable human wellbeing needs revision, designating the environmental pillar as the most important one after all. This idea of the primacy of the environment is gaining increasing attention (Farley & Smith, 2014). Humanity's basic needs derive from healthy ecosystems and planetary systems (e.g., the climate system), therefore human health and well-being depend on the sustainability of healthy environments and ecosystems. The limits to growth are limits to the well-being of healthy environments and ecosystems. Human society, the climate, ecosystems, the economy, food production and distribution, and other such components form an interconnected, dynamic, complex system. Such systems can be difficult to understand and characterize. If health depends on sustainability, and if sustainability is a function of complex dynamic systems, then achieving sustainability depends on systems thinking. (Systems thinking is described in Chapter 2.) Viewing the world as a complex, dynamic, interconnected system yields several lessons with regard to achieving sustainability and avoiding collapse. First, managing a complex system—involving in this case matching resource use to limits, across spatial scales, under diverse government jurisdictions and cultural traditions, under changing circumstances, and without full

information, while working toward fair and equitable social arrangements—is enormously challenging: a classic example of a wicked problem. A wicked problem is one that has no clear solution, in large part owing to complexity compounded by organizational, political, and cognitive barriers (Rittel & Webber, 1973). While originally described in the context of social policy, wicked problems confront us in many aspects of environment, health, and sustainability, from setting energy policy to managing fisheries to tackling climate change. Second, and relatedly, complex systems are policy resistant because the features of complexity can overwhelm our ability to understand and respond (Hammond, 2009). The more complex the system, the more daunting the challenge. Effective sustainability efforts under such circumstances require structured analysis of problems, embracing and harnessing complexity rather than oversimplifying (Ostrom, 2009), taking innovative and flexible approaches, working across organizational and disciplinary boundaries, constantly incorporating new information and adapting to it, and effectively engaging stakeholders (Folke, Hahn, Olsson, & Norberg, 2005; Plummer & Armitage, 2007; Waltner-Toews, 2008). Lastly, systems thinking helps anticipate some of the challenges inherent in moving toward sustainability. In complex systems, small changes can lead to large and unexpected results; abrupt changes may occur if tipping points are reached; and systems can self-organize and reach new equilibrium states, some of which may be far less hospitable to humans than the Holocene has been. Environmental scientist and pioneering systems thinker Donella Meadows (2008) has pointed out that “because of feedback delays within complex systems, by the time a problem becomes apparent it may be unnecessarily difficult to solve” (p. 3). To address the challenge of managing complex systems, the idea of adaptive management arose in ecology in reference to natural resource management. This is a structured, iterative approach to decision making in the face of uncertainty and complexity, in which observations over time feed learning and become the basis of ongoing course corrections. Adaptive management is pertinent not just to natural resources; for example, as described in Chapter 12, climate change adaptation relies on very similar principles. In public health more generally, and in sustainability efforts, systems science is widely applicable, and tools such as systems dynamics models, network analysis, and agent-based modeling (Luke & Stamatakis, 2012) help address complex challenges. These observations suggest that early action is preferable to delayed action, that resiliency of systems is a critical goal, and that critical thresholds define priorities for action—with special urgency when we are approaching or exceeding them.

The Importance of Scale A major challenge to date in moving toward sustainability has been that many drivers are global in scale; greenhouse gas emissions on the other side of the globe contribute to climate change regardless of what we do to reduce our own emissions. In contrast, climate change, energy scarcity, water scarcity, food production, land use, and the connections among them require local responses. This has implications for community resilience; as energy gets more expensive, the production of food and clean water will be impacted (Neff, Parker, Kirschenmann, Tinch, & Lawrence, 2011), the transportation of food and other goods over great distances will be curtailed, and more generally, the idea that localities can overcome local ecological and environmental limits by using cheap and plentiful fossil energy will be constrained. It is a paradox that a set of profoundly global problems—climate change, ecological degradation, energy scarcity, water scarcity, species and biodiversity losses—must be addressed with local responses. Consideration of scale is thus critical to any discussion of sustainability. Policy responses must be developed at all scales, from local to regional, national, and global. These responses can build on the observation that grassroots efforts at the local level can be very effective not only in engaging the local populace but also in motivating change at larger scales (e.g., local food production efforts may create momentum toward changes in the national Farm Bill). The issue of scale has also been inherent in the Intergovernmental Panel on Climate Change's thinking about responses to climate change. Mitigation efforts to reduce greenhouse gas emissions generally require effort at larger scales, whereas adaptation efforts, to reduce the impacts of climate change that are already built in and oncoming, generally require effort at smaller scales. Building community resilience in many ways is just a comprehensive and forward-

looking set of adaptation responses.

The Way Forward Health in All Policies and Sustainability in All Policies During the recent decades many public health practitioners have come to realize that intersectoral action is needed to protect the public's health—a practical application of systems thinking. Policies promulgated in other sectors, such as agriculture, housing, urban planning, or environmental protection, have public health implications, both positive and negative. In 1972, the Finnish government, in an effort to reduce high rates of cardiovascular mortality, adopted the concept of healthy policies in working with meat and dairy producers, schools, and the media. The program was so successful that Finland became a model for intersectoral action to improve the public's health. The idea of health in all policies (HiAP) gained popularity in 2006, during the Finnish presidency of the European Union. Other countries, recognizing that a healthy population is central to most other societal activities, are adopting HiAP as a core principle in all public policy making. While this has been a welcome development, the focus may still be too narrow to ensure that human wellbeing can be sustained into the future. The inability of society or an economy to exist without a healthy environment providing our most basic needs suggests that the sustainability of healthy environments may need to be an essential component of all policy considerations; that is, we need sustainability in all policies (SiAP). Accordingly, the Sustainable Development Goals (sustainabledevelopment.un.org), successors to the Millennium Development Goals, embed health progress in the framework of sustainability.

A New Definition of Sustainability For the word sustainability to be as meaningful and useful as possible, a precise and measurable definition is essential. As we have discussed, sustainability was initially oriented toward development in less developed countries, but it now must apply to everyone, everywhere on the planet. One approach is the concept of neo-sustainability, defined as “the ability of an activity to sustain a system by improving its quality and operating within its limits.” This definition is built on three premises, or rules, of sustainability, that link our prior discussions: 1. There are natural limits to growth, as dictated by the carrying capacity of the environment. 2. Environmental concerns must be given primacy, because without healthy ecosystems societal wellbeing will not be sustainable. 3. A systems approach must be used, because the economy, society, and the environment are nested systems and decisions made in one arena impact all others (Farley & Smith, 2014). Although neo-sustainability makes concrete the decades of thinking on and experience with our environmental challenges, there are still major questions that local and global societies must tackle. We still have to consider: What are our individual and collective needs? How much is enough? What factors and resources are under our control? How much control do we actually have and how best can we exercise it? What is the best way to allocate resources? How do we balance the needs of the present against the needs of future generations? What is it exactly that we want to sustain? Various methods have been recommended to motivate action with these sustainability principles in mind. One is to seek equity, including intergenerational equity, international equity, and equity across communities. Another is to set limits, meaning requiring that resources be used more sparingly and more fairly. Another is to minimize environmental harms, and if they are unavoidable, to ensure they are

equitably distributed. If society decides it cannot do without wind turbines or incinerators, these cannot be located only in poor areas. Neo-sustainability principles, systems thinking, and considerations of scale would lead to the conclusion that actions must not exceed environmental limits at any scale: local, regional, or global. We cannot shift environmental harms from one region to another (e.g., through use of consumer electronics in the United States that leads to exposure to toxic by-products of recycling in West Africa, or through deep well injection from across state lines—where environmental regulations may be more lax—of the flowback of contaminated water from hydraulic fracturing). Only if we considered our stewardship of the environment in unconnected pieces rather than in reference to scale and systems thinking could we conclude that shifting environmental harms from one location to another is a reasonable policy option (Farley & Smith, 2014). What is to be sustained? After an extensive literature review the Board on Sustainable Development of the U.S. National Academy of Sciences offered a three-part answer (U.S. National Research Council, Policy Division, Board on Sustainable Development, 1999): Nature, including the Earth, biodiversity, and ecosystems Life support, including ecosystem services, resources, and environment Community, including cultures, groups, and places Using the nested approach of describing the relationships of economy, society, and environment, each of these realms would require metrics to gauge progress toward sustainability.

Measuring Progress Toward Sustainability So that responsible parties, including governments, non-governmental organizations, and the private sector, can know whether sustainability by any definition is being achieved, sustainability metrics must be tracked over time. Optimal metrics have a number of attributes: they are credible; specific; actionable; relevant; consistent and comparable over time and space; scalable from the local to the global; robust to minor changes in methodology, scale, or data; accurate; unbiased; explicit; understandable; cost effective; helpful for prioritizing key issues in need of action; and available in a timely manner (Hambling, Weinstein, & Slaney, 2011). Perhaps the most widely influential set of sustainability metrics comes from the UN Commission on Sustainable Development (CSD) (United Nations Department of Economic and Social Affairs, 2007). CSD issued indicators to track progress in sustainable development following the adoption of Agenda 21 in Rio in 1992, and has subsequently refined them, most recently in 2007. The CSD indicators are distributed across fourteen theme areas (poverty, governance, health, education, demographics, natural hazards, atmosphere, land, oceans/seas/coasts, freshwater, biodiversity, economic development, global economic partnership, and consumption and production patterns) with multiple subthemes for each, leading to a total of ninety-six indicators, of which fifty are “core” indicators. The health indicators include mortality (both childhood mortality and life expectancy), health care delivery (access, and penetration of specific services), nutritional status, and health status (morbidity from certain diseases, tobacco use prevalence, and suicide rate). Many cities and regions have identified their own sustainability metrics. Measuring the state of ecosystems is key for sustainability indicators. Extensive data regarding the health of ecosystems around the world and their continued ability to meet human needs were gathered in 2005, in an initiative called the Millennium Ecosystem Assessment (www.millenniumassessment.org/en/index.html). These findings provide a useful baseline for subsequent measures of sustainability. The most widely used measure of economic performance is the gross domestic product (GDP), but economists have discussed alternative metrics more suited to measuring sustainability. Although the GDP is widely used (including in the CSD metrics discussed above) and standardized across countries, it is a poor measure of sustainability for at least two major reasons. First, it assumes that more economic activity is invariably better. However, there is a very high correlation between GDP and energy inputs into economies—and energy inputs account in large part for the environmental limits we are now facing (Warr & Ayres, 2010). Second, GDP calculations are indifferent to the type of economic activity counted; they do not subtract for economic activity that impedes societal and environmental sustainability, such as coal mining, or for the results from such activity, such as treating disease resulting from air pollution (Daly,

2013). The ecological footprint has many advantages as a metric, including its widespread familiarity and use; the availability of online “quizzes” that enable people to assess their own ecological footprints and compare themselves to others near and far; and its ability to be used at different scales to help with decision making about priorities and to track progress (Borucke et al., 2013). Many other metrics for sustainability and societal progress exist (see Table 3.1). No metrics are perfect; many do not incorporate dynamic changes over time, systems thinking, feedbacks, scale, or interconnections among the various domains of sustainability. More accurate metrics of sustainability will require the use of complex systems models.

Can Sustainability Be Achieved? What Might It Look Like? Several authors have written about what sustainability might look like if we could achieve it. Heinberg (2011) has written that our concept of growth must transition from economic expansion to human development. Both Heinberg (2011) and Rubin (2012) have argued that we are about to experience not only limits to growth but the end of growth. One framework, contraction and convergence, promotes an overall reduction of resource use (and greenhouse gas emissions), together with sharing of the contraction across nations and subpopulations, to promote equity (Stott, 2012). Scholars have variously imagined futures that are highly local (Heinberg, 2011) and highly urban, with smaller homes, less “stuff,” less driving, and greatly reduced per capita carbon footprints (Owen, 2009), perhaps as eco-cities incorporating urban agriculture and other forms of nature (Wong & Yuen, 2011). Some have argued that we won't achieve sustainability by simply replacing our current consumer culture with a new consumer culture based on solar panels, electric cars, and vegetable-based plastics (Heinberg, 2011). Others have focused on the role of the food system, our approach to providing food, and our dietary habits. Pollan's proposed solution to the obesity epidemic and other food challenges—“eat food, not too much, mostly plants”—would also yield sustainability benefits (Pollan, 2008). Climate and food system connections have also been made explicit in solutions; for example, contraction and convergence on meat is similar to what must be done across countries on greenhouse gas emissions (Friel et al., 2009). The health sector has a broad and varied role to play in achieving sustainability. Health professionals can use the health co-benefits from reduced resource use, healthier ecosystems, cleaner air from reduced greenhouse gas emissions, and a sense of community that derives from sustainable community design principles to motivate these transitions. Opportunities for sustainability within the health care delivery system are described in Text Box 3.2. Including health professionals in policymaking could encourage full recognition of the health co-benefits of sustainability efforts.

Text Box 3.2 Sustainability in Health Care Where should sustainability happen? For the most part the sustainability focus has been anywhere energy and resources are created and used—in energy generation, in manufacturing, in transportation, in agriculture, and in the design and operation of cities and buildings. Health professionals may feel that sustainability initiatives have little relevance to their work. But the health care sector is an important setting in which to encourage sustainability efforts, for at least four reasons. First, health facilities are highly energy intensive (second only to the food industry in energy use per square foot) (Energy Information Administration, 2009). In fact the health care sector accounts for 8% of all U.S. greenhouse gas emissions (Chung & Meltzer, 2009). Second, reducing the use of energy and resources can yield substantial economic benefits—an important consideration in an industry whose costs have been rising rapidly. Third, sustainable practices are often also healthy practices, advancing the central mission of health care facilities. Finally, many health care organizations strive to be leaders in their communities, and sustainability offers an opportunity to play this role. In response to such thinking, a set of efforts known collectively as green health care (or sustainable health care) has emerged in recent years and is slowly spreading. Green health care advances sustainability by

Reducing energy use in health care facilities through energy conservation and the use of renewable energy sources Reducing materials use through efficiency efforts Reducing the health-related transportation footprint by encouraging walking, cycling, and transit use by employees, patients, and visitors, and by encouraging telecommuting and teleconferencing when feasible Reducing water use through conservation Reducing the waste stream through efficiency, reuse, and recycling Supporting local agriculture through preferential purchasing Leading community resilience efforts by preparing for emergencies such as heat waves Reducing the use of persistent, bioaccumulative, and/or toxic chemicals by preferentially purchasing safer materials Efforts across the health care sector are being led by such organizations as Health Care Without Harm (noharm.org), Practice Greenhealth (practicegreenhealth.org), and the Healthier Hospitals Initiative (healthierhospitals.org). Health care organizations such as Kaiser Permanente have set a high standard of practice and serve as a model for the industry (share.kaiserpermanente.org/article/environmental-stewardship-overview). The signs of unsustainability are all around us. Having already crossed three of nine planetary boundaries is an ominous indication that the time to change course is short if we want a sustainable future for humanity and other life on planet Earth. Scholars have provided some specific instructions for how to get started, and there is already much we can do, while additional research may continue to provide new ideas and means to achieve our goals. There is much work to do; the future may be bright with possibilities, but we must get to work now.

Summary Sustainability refers to the ability of a system to continue functioning without depleting or damaging the things it needs to function. In the context of environmental health, sustainability applies to three interdependent aspects of human existence: the environment, society, and the economy (including equity). Population growth and patterns of resource use have created threats to both sustainability and human health: alterations of earth systems, excessive use of materials and energy, and production of waste faster than ecosystems can absorb it. Measures such as the ecological footprint help quantify these pressures. Trends in climate, biodiversity loss, and nitrogen cycling may indicate that humanity is exceeding planetary limits; this poses large-scale public health risk. Sustainable practices maintain, or better yet improve, the systems upon which human well-being depends, and therefore promote human health. Emerging conceptual frameworks, such as contraction and convergence, and emerging implementation approaches and metrics, are driving action toward long-term sustainability.

Key Terms adaptive management A process of structured, iterative decision making in the setting of complexity and uncertainty. Information is continually gathered, supporting frequent and iterative course corrections. The goal is to reduce uncertainty over time, continually improve decision making, and yield better outcomes. Anthropocene The current era, in which humans have altered many fundamental Earth processes, such as the chemistry of the soil, water, and atmosphere, with substantial, largely negative consequences for ecosystems and biodiversity; in short, the era in which humans control the climate. Brundtland Report The 1987 report of the UN's World Commission on Environment and Development (chaired by Gro

Harlem Brundtland, former prime minister of Norway), titled Our Common Future. carrying capacity The maximum number of organisms that an ecosystem can support and sustain without degrading the ability of that ecosystem to maintain that abundance in the future. co-benefits Collateral outcomes of policies or programs that offer benefits beyond those primarily intended. For example, shifting from single-occupancy vehicle use to walking, cycling, and transit use, in an effort to reduce energy use, also yields cleaner air and more physical activity and reduces road traffic injuries. collapse Throughout history and prehistory, once thriving human civilizations have experienced gradual or at times rapid declines, eventually ending in failure, as, for example, the Mayan, Anasazi, and Easter Island civilizations did. consumerism A culture of valuing the ever-increasing acquisition and consumption of goods and services. (Not to be confused with the ecological term consumer, referring to heterotrophs.) contraction and convergence A suggested framework for achieving sustainability. It promotes an overall reduction of resource use— thus reducing waste production, including greenhouse gas emissions—shared across nations and all populations equitably. ecological footprint “The total area of land and water ecosystems required to produce the resources that the population consumes, and to assimilate the wastes that the population generates, wherever on earth the land/water are located” (Rees, 2013, p. 701). ecosystem services Essential benefits to humans provided by ecosystems, such as pollination of food crops, purification of air and water, and protection against some natural disasters. Great Acceleration A period of time following World War II when population, industrialization, and resource use increased exponentially. green health care Health care delivery that achieves better environmental performance, including reduced energy and resource use, reduced waste generation, local sourcing of food and supplies, and related activities. Health in all policies A model for intersectoral action to improve the public's health by thoughtfully developing all policies so as to minimize negative public health consequences. intergenerational equity The concept that future generations are no less important or valuable than present generations and therefore future generations have a right to a livable world. limits to growth A concept popularized by the 1972 book of the same name (Meadows et al., 1972), which described the consequences of various computer-simulated population and economic growth scenarios in the face of finite resources. Malthusian Referring to the theory proposed by Thomas Malthus in 1798 that population growth would always eventually outstrip available food resources, condemning the growing population to starvation and disease, and thereby reducing the population. Millennium Development Goals Eight international development goals that emerged from the United Nations Millennium Summit in 2000 to focus efforts to improve people's well-being, especially in developing countries. neo-sustainability A new concept of sustainability built on the three critical premises of limits to growth, environmental primacy, and the need to employ a systems approach.

overshoot Exceed the carrying capacity of the environment in relation to population size. population growth In this chapter, a reference to the ever-increasing human population. primacy of the environment The concept that without a healthy environment, there can be no human society or functional economic system, and therefore protecting the environment is the first priority. resilience The “capacity of a system to absorb disturbance; to undergo change and still retain essentially the same function, structure, and feedbacks” (Walker & Salt, 2006, p. 32). Rio Declaration A product of the United Nations Conference on Environment and Development that took place in Rio de Janeiro in 1992, meant to direct future sustainable global development. safe operating space for humanity A framework of planetary boundaries within which, humanity can develop without causing environmental change that would unacceptably jeopardize future life on the planet. scale Geographic size or level, as in local, regional, national, or global. sustainability The ability of a system to continue functioning without depleting or damaging the things it needs to function. sustainability metrics (or indicators) Standards or statistics for measurement of sustainability. With these metrics a baseline of the sustainability of practices or activities can be ascertained and progress toward sustainability goals can be measured and tracked. sustainable development Economic development that “meets the needs of the present without compromising the ability of future generations to meet their own needs” (World Commission on Environment and Development, 1987). Sustainable Development Goals A new set of development goals, created to replace the Millennium Development Goals when they sunset in 2015, addressing similar concerns of health, poverty, education, and equity but in a sustainability framework. systems thinking An approach to considering a coupled human-natural system that recognizes the interlinkages among the many parts of the system and their ability to change, adapt, and evolve. tipping point The point at which an object or system is displaced from its state of equilibrium. Often used to describe a climate threshold that, when surpassed, will push the Earth's climate irreversibly out of a stable state.

Discussion Questions 1. Was the early thinking of Thomas Malthus at all relevant to humanity's current predicament? Why or why not? 2. What are the key drivers of our nonsustainability? How are they connected to one another? 3. What happened during the Great Acceleration? 4. Does your city have sustainability metrics? If so, what do you think of them? If not, find a city that does, and comment on whether these metrics would be applicable to your city. 5. Can human intellectual development, ingenuity, and technology overcome limits to growth and concerns about societal collapse?

6. What is systems thinking, and how can it allow us to come to a better understanding of our sustainability challenges? 7. Consider your own lifestyle—where you live, how you travel, what you eat, and so on. Is your lifestyle sustainable? Is it healthy? Could you make changes that would promote both sustainability and health? 8. How do you think public health should incorporate sustainability into its mission?

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United Nations Environment Programme. (2012). GEO 5: Global environment outlook: Environment for the future we want. Nairobi: Author. U.S. National Research Council, Policy Division, Board on Sustainable Development. (1999). Our common journey: A transition toward sustainability. Washington, DC: National Academies Press. Walker, B., & Salt, D. (2006). Resilience thinking: Sustaining ecosystems and people in a changing world. Washington, DC: Island Press. Waltner-Toews, D. (2008). The ecosystem approach: Complexity, uncertainty, and managing for sustainability. New York: Columbia University Press. Warr, B. S., & Ayres, R. U. (2010). Evidence of causality between the quantity and quality of energy consumption and economic growth. Energy, 35(4), 1688–1693. Wong, T., & Yuen, B. (Eds.). (2011). Eco-city planning: Policies, practice and design. New York: Springer. World Commission on Environment and Development. (1987). Report of the World Commission on Environment and Development: Our common future. New York: United Nations. World Health Organization. (1948). Preamble to the Constitution of the World Health Organization. Geneva: Author.

For Further Information Books and Articles Brown, L. R. (2011). World on the edge: How to prevent environmental and economic collapse. New York: Norton. Heinberg, R., & Lerch, D. (Eds.). (2010). The post carbon reader: Managing the 21st century's sustainability crisis. Healdsburg, CA: Watershed Media. Hopkins, R. (2008). The transition handbook: From oil dependency to local resilience. White River Junction, VT: Chelsea Green. Nelson, D. R. (2011). Adaptation and resilience: Responding to a changing climate. Wiley Interdisciplinary Reviews. Climate Change, 2(1), 113–120.

Organizations International Institute for Environment and Development (IIED): www.iied.org. Promotes sustainable patterns of world development through collaborative research, policy studies, networking, and knowledge dissemination. International Institute for Sustainable Development (IISD): www.iisd.ca. Publishes the Earth Negotiations Bulletin: http://www.iisd.ca/enbvol/enb-background.htm Sustainable Communities Online (formerly Sustainable Communities Network): http://www.sustainable.org. An online clearinghouse for information on sustainability. Transition Network: https://www.transitionnetwork.org. Promotes the “transition model,” creating initiatives that rebuild resilience and reduce CO2 emissions. Worldwatch Institute: www.worldwatch.org. Dedicated to fostering the evolution of an environmentally sustainable society—one in which human needs are met in ways that do not threaten the health of the natural environment or the prospects of future generations.

Chapter 4 Environmental and Occupational Epidemiology Kyle Steenland and Christine L. Moe Dr. Steenland and Dr. Moe report no conflicts of interest related to the authorship of this chapter.

Key Concepts Epidemiology is the study of the distribution and determinants of health and disease in human populations. Environmental epidemiology and occupational epidemiology study the role of exposures in the general environment and in the workplace, respectively. They employ many similar methods. In environmental and occupational health, epidemiological data complement other kinds of data, such as toxicological data. There are many kinds of epidemiological study designs. The optimal study design depends on the features of the population being studied, the exposure of interest, the disease of interest, and other factors. The strongest epidemiological conclusions come from studies that use large populations and accurate and precise measurements of exposure and disease. Epidemiologists work to achieve results that are free of bias (confounding, selection bias, and information bias). Epidemiological data can both identify a harmful exposure and quantify the amount of harm due to the exposure. Hence they are invaluable in risk assessment, standard setting and other policymaking, and dispute resolution in environmental and occupational health. Epidemiological data can also determine the degree to which an intervention to change exposure, and improve health outcomes, is effective.

A Primer on Epidemiology Epidemiology is the study of the distribution and determinants of health and disease in human populations. Epidemiologists seek to determine whether a given exposure, or set of exposures, causes a certain disease. Obviously, if we can show that an exposure causes disease, we have a chance to intervene and prevent disease occurrence, which is our ultimate goal. Epidemiology can give us the tools, the techniques of study design and analysis, to determine whether a given exposure is associated with a given disease, and sometimes to determine whether an intervention to change exposure, and improve health outcomes, is effective. How do we judge that an association is causal (a process sometimes called causal inference)? A general philosophical framework for judging causality, accepted by most epidemiologists, stems from the writings of the philosopher Karl Popper (for a good discussion of causal inference, see Rothman & Greenland, 2008). This framework posits that observations (especially repeated observations) that one event (A) is followed by another (B) enable the epidemiologist to form a hypothesis; that is, a proposition that A causes B. The key to Popperian philosophy is that all hypotheses (or theories of causation) are tentative and may be disproved by further testing. Hypotheses that are tested many times and hold up tend to become accepted as scientific facts (e.g., we now accept that cigarettes cause lung cancer), but over the course of time many accepted hypotheses are overthrown by new scientific insights (e.g., we now know that miasma, or foul air, does not cause cholera). On the practical level a famous set of criteria set out by Austin Bradford Hill (1965) is commonly used by epidemiologists to judge whether a particular causal hypothesis is plausible, that is, whether the observed

association between A and B supports the conclusion that in fact A causes B. Hill set out nine criteria. Only one—the proper temporal relationship—is absolutely required: the exposure must precede the disease. Although it seems this should always be easy to know, sometimes it is not clear; in cross-sectional studies, for example, one generally does not know this. Other commonly used Hill criteria that favor causality are consistency (the association is repeated in many studies), a large effect size (the exposed have much more disease than the nonexposed), a positive dose-response relationship (more exposure causes more disease), and biological plausibility (some biological explanation makes it reasonable that A causes B). Regulators and risk assessors must conclude from the weight of the epidemiological evidence, applying criteria such as these, whether an association is likely to be causal. A number of agencies, such as the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), the Institute of Medicine (IOM) (a part of the National Academies of Sciences, Engineering, and Medicine), and the U.S. Environmental Protection Agency (EPA), regularly review epidemiological evidence and publish summaries in which they evaluate whether associations are likely to be causal. Epidemiology has provided evidence judged as causal for many exposures and diseases, including evidence associating lead with cognitive impairment in children, trihalomethanes (in water) with bladder cancer, particulate air pollution with cardiorespiratory disease, radon gas with cancer, and ergonomic stress with low back pain, to name just a few.

Kinds of Epidemiological Studies Epidemiological studies can be divided into categories that reflect their design. Descriptive Studies At the simplest level are the descriptive studies, which characterize a disease by factors such as age, sex, time, and geographic region. These studies do not formally test a hypothesis that a specific exposure (or risk factor) is associated with a disease but rather describe patterns in disease occurrence in terms of broad demographic and other variables. These studies are often first steps and may provide clues about factors that cause disease. For example, the fact that malaria occurs mainly in tropical areas provides a clue that a warm climate may play a role in its transmission. The fact that heart disease occurs at a later age in women than men may provide a clue that endogenous estrogen plays a protective role. Descriptive studies can sometimes perform an important role in public policy by determining which diseases are responsible for the greatest burden in different countries. One of the most important efforts in this regard in recent years is the Global Burden of Disease Study (Lim et al., 2012), a large international effort based on using existing data from a variety of sources, to estimate which diseases in different countries were responsible for the most death and disability. This is done with a measure called disabilityadjusted life years (DALYs), a sum of years lived with disability and years lost due to premature death. Going further, Lim et al. used existing estimates of the effects of major known risk factors for disease to estimate the relative importance of major known risk factors in causing disability and premature death, using DALYs. The major environmental exposures causing the most burden of disease were indoor and outdoor air pollution, ranked third and ninth, respectively, among all major risk factors. The high number of DALYs from indoor air pollution is due to the common use of biofuel (e.g., wood, dung) for cooking and heating in large parts of the world, as discussed in Chapters 14 and 20, causing not only chronic disease among adults (lung cancer, heart disease) but also pneumonia in children. Correlational, or Ecological, Studies Descriptive studies are a close cousin to correlational studies, or ecological studies, which examine the correlation between some specific exposure and disease rates, at the level of groups rather than individuals. For example, one can correlate breast cancer rates in countries around the world with degree of socioeconomic development; breast cancer incidence is higher in richer, more urbanized countries. Like descriptive studies, ecological studies often provide clues about possible risk factors for disease, factors that can then be examined further in studies of individuals. Generally, ecological studies are viewed as weaker than studies of individuals, because across a population, individuals with the risk factors are not necessarily the same individuals who contract the disease. As a result, ecological studies are often called hypothesis-generating studies. However, in some instances an ecological design is the design of choice.

One example is time series studies of air pollution, in which pollution levels are correlated with disease rates on a day-to-day basis. Such studies have the advantage of looking at a population that is presumably stable over time (eliminating most confounding). The only variables changing on a daily basis are the exposure variable of interest (air pollution levels) and the outcome of interest (daily disease rates), although seasonal variation in temperature also needs to be taken into account. Etiologic, or Analytical, Studies Etiologic studies, or analytical studies, are generally studies of individuals in which the investigators seek to test a specific hypothesis about exposure and disease: for example, whether pesticide exposure is associated with Parkinson's disease. These studies are often undertaken after descriptive and correlational studies have indicated that they are worth doing: that is, after a plausible hypothesis has emerged that needs to be tested. Analytical studies can in turn be divided into two types, clinical trials and observational studies. Clinical Trials Clinical trials, usually called randomized clinical trials, are in a sense the model for rigorous epidemiological studies. They are often done to compare one medication or treatment to another. They are controlled experiments, because they assign treatment (or exposure) randomly to one group and not another. The treated and untreated groups are therefore likely to be comparable with regard to other variables (such age, weight, sex, and education) that might affect the disease outcome; therefore any difference in subsequent disease rates can be assumed to be due to exposure. Both treated and untreated groups are followed prospectively over time. Randomized clinical trials in medicine are usually used to compare a treatment hypothesized to be beneficial to a conventional treatment or to no treatment. In environmental/occupational epidemiology the “treatment” is the exposure of interest. Clinical trials are generally impractical in this setting for ethical reasons. One cannot ethically expose half of a population to a toxin, such as inhaled silica, and not expose the other half in order to evaluate the effect of exposure. Therefore the epidemiologist interested in studying suspected occupational and environmental toxins often needs to conduct observational studies. However, randomized intervention trials can used to measure the effect of lowering exposures. For example, it is common to use randomized trials to determine whether improving water quality or sanitation can reduce childhood diarrhea (as discussed in Text Box 4.2). Another possibility could be determining whether a new keyboard could reduce carpal tunnel syndrome resulting from typing at a computer (O'Connor, Page, Marshall, & Massy-Westropp, 2012). Observational Studies Observational studies are uncontrolled studies, or natural experiments, of which the epidemiologist takes advantage. For example, the epidemiologist wants to study the effect of lead on cancer risk, so he or she observes a cohort of lead-exposed workers over time and compares their cancer rates to those of the general population. However, the workers and the general population may differ in some important respects, such as smoking habits or diet, that may in turn affect cancer rates (such variables are called confounders). The epidemiologist may be able to adjust or control for the effects of such confounders, but if he or she cannot, these effects may distort the findings about the effect of exposure on disease. For this reason observational studies are viewed as less definitive than clinical trials. The three principal designs for observational studies are cohort, case-control, and cross-sectional. Cohort studies start with an exposed group and a nonexposed group, both disease free, and follow them forward in time to observe disease incidence or mortality rates. Disease rates in the exposed and nonexposed groups can be then compared using a rate ratio or a rate difference. The observation period in cohort studies may start in the past and move forward to the present (retrospective studies), or start in the present and move into the future (prospective studies). The former is quicker and usually less expensive. For example, to study lung cancer among welders and nonwelders one can identify a cohort as of 1950 and trace its members' lung cancer mortality until the present. The disadvantage of the retrospective approach is having to depend on historical information about exposure levels and about potential confounders (e.g., smoking habits). Although prospective studies take a long time and are often expensive, they are more appropriate when one wants to measure exposure levels and confounding

variables at baseline, or when biological samples such as blood tests are required. Prospective studies may also be needed to study diseases that are difficult to ascertain in retrospect, such as spontaneous abortions (whose occurrence and date of occurrence may be difficult to remember accurately). Cohort studies can consider disease events per person (cumulative incidence, or risk) or disease events per person-time (rates, such as incidence rate or mortality rate). The former are appropriate for short follow-up periods and fixed cohorts, in which everyone can be followed for the whole follow-up period. The latter are appropriate for long follow-up periods and dynamic cohorts, in which individuals may enter follow-up at different times and be lost to follow-up at any time and are therefore followed for different periods of time. Cohort studies are good for rare exposures and common diseases, because one begins with assembling an exposed group and hence can readily assemble an adequate number of exposed subjects (e.g., welders); conversely, when the disease is rare, a very large number of subjects may need to be assembled to yield an appreciable number of cases. (Text Box 4.1 presents an example of a cohort study.)

Text Box 4.1 Example of a Community Cohort Study Perfluorooctanoic acid (PFOA, also known as C8), a synthetic chemical created during World War II, is an 8-carbon fluorocarbon useful for the polymerization of longer chain fluorocarbons. It is present at background levels of about 4 ng/ml in the blood of virtually everyone in the U.S. population, as well as everyone in other industrialized countries, although the exact route of exposure is not clearly known. PFOA has been used in making commercial products such as Teflon, Scotchgard, and Gore-Tex, although such use has been cut back or eliminated since the mid-2000s. PFOA causes tumors in animals (liver, testicular, and pancreatic) and causes neonatal death in mice. PFOA biopersists indefinitely and has a half-life in humans of about 3.5 years, so it is likely to be an environmental contaminant for a long time to come. Operations at a Dupont plant making Teflon in Parkersburg, West Virginia, resulted in PFOA contamination of drinking water in nearby parts of West Virginia and Ohio (Figure 4.1). Approximately 70,000 residents living in six water districts near the plant had their blood levels measured in 2005 and 2006 as part of the settlement of a class action lawsuit against Dupont; blood levels averaged 80 ng/ml (with a very wide range for which the median was 28 ng/ml). In addition, approximately 1,000 workers at the chemical plant had been measured in 2004 and had displayed blood levels on the order of 500 ng/ml at that time.

Figure 4.1 Area of PFOA Contamination As part of the class action settlement, the C8 Science Panel was created. The three-person panel was charged with determining whether PFOA was “probably linked” to any disease in the midOhio valley. The C8 Science Panel was guaranteed independence from either side in the lawsuit. A finding of a probable link would trigger court-ordered surveillance for the diseases implicated. Note that the probable link standard is a lower bar than epidemiologists usually use to determine causality; the panel simply had to decide whether PFOA was more probably than not associated with a given disease. The panel was made up of three persons so that there would be no possibility of a tie vote. The panel embarked on a six-year epidemiological effort consisting of eleven studies with a cost of $35 million, far more than is available in typical federal grant funding by the U.S. National Institutes of Health; this funding was supplied by Dupont but was administered by the West Virginia court. One of these studies was a cohort study of 32,000 adults, a subset of the 70,000 people tested in 2005 and 2006. Among these 32,000 were approximately 3,000 workers who had worked at the Dupont plant. This cohort had many advantages for an epidemiological study. It was a very large cohort, enabling study of relatively rare diseases. Most of these subjects had been tested in the mid2000s and their PFOA blood levels at that time were known. Some cohort members lived far from the plant and had low PFOA levels, whereas those close to the plant had very high levels. This large exposure contrast was ideal for an epidemiological approach, enabling a determination of whether higher exposure was associated with higher disease. The cohort was

relatively homogeneous, living within a confined region, with limited potential for the confounding that can occur when studying diverse widespread populations. Furthermore, data were available to study the cohort members' exposure back in time, critical for estimating the effect of exposure on chronic disease, which might occur many years after exposure. Interviews with the cohort were likely to be possible, enabling study of disease incidence, a stronger end point than mortality, as many serious diseases are not necessarily fatal. (However, the C8 Science Panel also assessed mortality in the cohort, using the National Death Index.) Data on plant emissions of PFOA over time were available. The C8 Science Panel used a fatetransport model to estimate the spread of PFOA into the groundwater system, which was the source of the contaminated public drinking water. The fate-transport model estimated how far the PFOA traveled in the air before settling to the ground, and how much went into the Ohio River directly. Then the model estimated how long it took the PFOA to get into the groundwater and estimated groundwater levels over time. Finally, a second model estimated how much PFOA a study participant might have absorbed from drinking water, and what his or her likely serum levels were in any given year. These models were linked with residential history so that the C8 Science Panel was able to estimate the PFOA serum levels of all study participants for each year from 1950 through 2011. The additional exposure of workers was also modeled, using over 2,000 serum PFOA estimates available from Dupont from the 1970s to 2004. Overall the model performed well. The correlation between modeled exposures and PFOA serum levels measured in 2005 and 2006 was 0.71 (Winquist, Lally, Shin, & Steenland, 2013). The C8 Science Panel conducted interviews with the 32,000-person cohort (representing 80% of the target adult population) from 2008 to 2011, in which residential and medical history was collected. Self-reported medical history for serious chronic disease was then verified by medical histories from doctors and hospitals. Approximately 60% of participants reported a chronic disease for which medical records were sought. Approximately 75% of these people consented to medical record review; among those who consented, at least one record was obtained for 92% of them, and about 77% of these records validated the self-report. The C8 Science Panel then conducted a cohort analysis of verified medical disease for fifty-five different diseases. The cohort study consisted of a retrospective cohort incidence follow-up, internal to the cohort, in which incidence rates of disease were calculated for different levels of cumulative serum levels (summed across all years since birth). This study was unusual in having an internal estimate of dose rather than an external estimate of exposure. Of the fifty-five diseases studied, the C8 Science Panel concluded that six were “probably linked” to PFOA (kidney cancer, testicular cancer, ulcerative colitis, thyroid disease, high cholesterol, and pregnancy-induced hypertension). Of these, only one (testicular cancer) had been implicated in animal studies. Ulcerative colitis, an autoimmune disease, had perhaps the strongest evidence. Based on 151 observed cases, rate ratios increased steadily by quartile of cumulative PFOA serum level, from 1.00 (the lowest quartile referent group), to 1.76 (1.04, 2.99), 2.63 (1.56, 4.43), and 2.86 (1.65, 4.96), with a p value for a positive trend of 200 cm. (This is called a tail risk—the extreme end of the distribution

of probabilities for a particular outcome.) One expected effect of sea level rise is an increase in flooding and coastal erosion in low-lying coastal areas. This will endanger large numbers of people; fourteen of the world's nineteen current megacities are situated at sea level. Coastal regions at risk of storm surges will expand and the population at risk will increase from the current 75 million to 200 million (McCarthy, Canziani, Leary, Dokken, & White, 2001). For Bangladesh, a 1.5 meter rise is projected to have even more catastrophic consequences. Countries such as Egypt, Vietnam, Bangladesh, and small island nations are especially vulnerable, for several reasons. Coastal Egypt is already subsiding due to extensive groundwater withdrawal, and Vietnam and Bangladesh have heavily populated, low-lying deltas along their coasts. Rising sea levels may affect human health and well-being indirectly, in addition to direct effects through inundation or heightened storm surges. Rising seas, in concert with withdrawal of freshwater from coastal aquifers, could result in saltwater intruding into those aquifers and could also disrupt stormwater drainage and sewage disposal.

Particularly Vulnerable Regions Certain regions and populations are more vulnerable than others to the health impacts of climate change (Hess, Malilay, & Parkinson, 2008). These vulnerable areas include Areas or populations within or bordering regions with a high endemicity of climate-sensitive diseases (such as malaria) Areas with an observed association between epidemic disease and weather extremes (e.g., El Niño– linked epidemics) Areas at risk from combined climate impacts relevant to health (e.g., stress on food and water supplies or risk of coastal flooding) Areas at risk from concurrent environmental or socioeconomic stresses (e.g., local stresses from landuse practices or an impoverished or undeveloped health infrastructure) and with little capacity to adapt These Earth system changes have complex direct and indirect implications for human health, as illustrated in Figure 12.3. This figure, crafted by Dr. Tony McMichael, a seminal thinker regarding the health impacts of global change, reflects the ecological approach presented in Chapter 2. It depicts the interacting physical, social, and economic processes that determine health. The following sections of this chapter address major categories of anticipated health effects of climate change. These include malnutrition (possibly the largest problem); risks from weather extremes and disasters such as heat and cold, storms and flooding, and drought and wildfires; air pollution and aeroallergens; infectious diseases, including those that are waterborne, foodborne, and vector-borne; mental health effects; and the effects of armed conflict and dislocation. The last section of the chapter addresses the public health response to climate change, from preparedness to greenhouse gas mitigation. Co-benefits of mitigation are considered, as well as the ethical dimensions of climate change and health.

Figure 12.3 Processes and Pathways Through Which Climate Change Influences Human Health Source: McMichael, 2013.

Food and Malnutrition Malnutrition is one of the most pressing health concerns in the context of the changing climate. Three mechanisms affect food security: reduced crop yields, increased crop losses, and decreased nutrient content. On average, climate change is projected to reduce global food production by up to 2% per decade, even as demand increases by 14% (Porter et al., 2014). More than 800 million people currently experience chronic hunger, concentrated in areas where productivity could likely be most affected (Food and Agriculture Organization of the United Nations [FAO], 2013; Wheeler & von Braun, 2013). Major contributors to reduced yields will be water shortages (especially for glacial melt–dependent regions in Asia, Europe, and

South America) and hotter temperatures (because most cultivars are already growing close to their thermal optimum). Wheat, maize, sorghum, and millet yields are estimated to decline by approximately 8% across Africa and South Asia by 2050 (Porter et al., 2014). By 2050, around 25 million more children might be undernourished as the result of climate change, and rates of growth stunting could increase substantially (Nelson et al., 2009; Lloyd, Sari Kovats, & Chalabi, 2011). Climate change-related price shocks (rapid rises in food prices), especially for staples such as corn and rice, could more than double by mid-century, placing impoverished populations at further risk (Bailey, 2011). Plant diseases caused by fungi, bacteria, viruses, and oomycetes, already responsible for a 16% global crop loss, may substantially increase with climate change (Chakraborty & Newton, 2011). In addition, climate change favors the growth of many weeds, which compete with crops (Ziska & McConnell, 2015). Also, the nutrient value of some crops may diminish. CO2 “fertilization” can reduce the protein content in wheat and rice, and the iron and zinc content in crops such as rice, soybeans, wheat, and peas (S. S. Myers et al., 2014). Adaptive measures range from drought- or salt-resistant crops to improved technology such as drip irrigation and hoop houses (inexpensive greenhouses). Other potential adaptation strategies include changing planting dates, increasing crop diversity, reducing waste, increasing cropping efficiency, and changing diets. An indirect pathway by which climate change may affect crops is biofuel production. Some crops and cropland will be diverted from food to fuel. While the impacts are controversial, this diversion may have unintended consequences, contributing to food shortfalls and rising food prices (Tirado, Cohen, Aberman, Meerman, & Thompson, 2010; Harvey & Pilgrim, 2011; HLPE, 2013). In addition to reducing crop production, climate change will affect food availability in another way: through its effects on fisheries and aquaculture. According to the FAO (2013), 540 million people globally depend on wild fisheries and aquaculture as sources of protein and income. For the poorest 80% of these, fish represents at least half of their animal protein and dietary minerals. Climate change will affect river and marine ecosystems and threaten fish availability, through many pathways. A key issue is ocean acidification; oceans have absorbed about 30% of anthropogenic CO2, their surface pH has become 0.1 units more acidic since the beginning of the industrial era, and IPCC scenarios predict a further drop in global surface ocean pH of between 0.14 and 0.35 units over the twenty-first century (IPCC, 2013). Ocean acidification threatens marine shell-forming organisms (such as corals) and their dependent species. Other challenges to fisheries include altered river flows, destructive coastal storms, and the spread of pathogens (Cochrane, De Young, Soto, & Bahri, 2009; Porter et al., 2014).

Weather Extremes and Disasters Extreme temperatures, severe storms, rising sea levels, and floods, droughts, and wildfires are all threats to public health. Although slight changes in the average blood pressure or cholesterol level across a population can represent a health risk, in the case of climate it is the extremes of temperature and in the water cycle that threaten human health.

Heat Waves Extremes of both hot and cold temperatures are associated with higher morbidity and mortality compared to the intermediate, or comfortable, temperature range (Kilbourne, 2008). The relationship between temperature and morbidity and mortality is J-shaped, with a steeper slope at higher temperatures. The body's thermoregulatory mechanisms can cope with a certain amount of temperature rise through control of perspiration and vasodilation of cutaneous vessels. The ability to respond to heat stress is thus limited by the capacity to increase cardiac output as required for greater cutaneous blood flow. Over time, people can adapt to high temperatures by increasing their ability to dissipate heat through these mechanisms. Heat-related illnesses range from heat exhaustion to kidney stones (which increase with dehydration). Epidemiologists quantify heat-related mortality in two ways: tabulating death certificates that cite heat as a cause, and tracking mortality increases across populations during heat waves—periods of unusually

hot weather, defined by the World Meteorological Organization as more than five consecutive days with temperatures at least 5°C above the average maximum temperature during the 1961 to 1990 baseline period. The first approach typically leads to underestimates, because heat-related deaths are routinely attributed to cardiovascular and other causes without citing heat as the underlying factor. In the United States, an average of 658 deaths are certified as heat-related each year, representing more fatalities than all other weather events combined (Luber & McGeehin, 2008; Centers for Disease Control and Prevention [CDC], 2013). More accurate risk estimates compare observed versus expected mortality during heat events; for example, 70,000 excess deaths were estimated for the 2003 European heat wave and 15,000 for the 2010 Russian heat wave (Robine et al., 2008; Matsueda, 2011). Heat waves have been growing more frequent, more intense, and longer in duration over recent decades (Habeeb, Vargo, & Stone, 2015), and this trend is expected to continue, especially in the high latitudes of North America and Europe (Goodess, 2013). “Mega” heat waves (as have occurred in Europe and Russia) are projected to increase in frequency by five- to tenfold within the next forty years (Barriopedro, Fischer, Luterbacher, Trigo, & García-Herrera, 2011). Figure 12.4 shows the projected number of extremely hot days each year in Milwaukee, Atlanta, New York City, and Dallas (defined as above 32°C [90°F] in the first three cities, and above 38°C [100°F] in Dallas). Each city will confront a marked increase in hot days—for example, a tripling in New York (Patz, Frumkin, Holloway, Vimont, & Haines, 2014). These trends will have serious public health consequences. While air conditioning and preparedness have reduced heatrelated deaths and illness in the United States (Kalkstein, Greene, Mills, & Samenow, 2011), climatic and demographic trends (such as the aging population) suggest that risks may persist. One estimate, focusing on a set of twelve U.S. cities, projected over 200,000 excess heat-related deaths during the twenty-first century (Petkova et al., 2014). While the reduction of extremely cold days will avoid some cold-related deaths, this reduction is not expected to balance the increase in heat-related deaths (Luber et al., 2014).

Figure 12.4 Number of Days in June, July, and August When Daytime Maximum Temperatures Exceed a Given Threshold (indicated by a vertical line)

Source: Patz et al., 2014. The solid-line curves show observations from 1960–1999, and the dotted-line curves, shifted to the right, show projected distributions for 2046–2065 under a business-as -usual emissions scenario. A relatively small shift can lead to a substantial change in the area under the steep portion of the curve.

The epidemiology of heat waves has been well studied, and vulnerability and protection factors are well known. People who are most vulnerable include the poor, the elderly, those who are socially isolated, those who lack air conditioning, and those with certain medical conditions that impair the ability to dissipate heat. A particular risk factor is living in cities, especially in hot parts of cities, because of the heat island effect. An urban heat island is an urban area that generates and retains heat as a result of buildings, human and industrial activities, and other factors (Figure 12.5). Black asphalt and other dark surfaces (on roads, parking lots, and roofs) have a low albedo (reflectivity); they absorb and retain heat, reradiating it at night, when the area would otherwise cool down. In addition, urban areas are relatively lacking in trees, so they lose the cooling effect associated with evapotranspiration.

Figure 12.5 Urban Heat Island Profile Source: WikiMedia Commons, 2011. The urban heat island results from dark surfaces, loss of tree canopy, and concentrated generation of heat. Some neighborhoods in a city are far warmer than others, due to local factors such as topography and building types.

An interesting aspect of heat, and one with both health and economic consequences, is its impact on people at work. Outdoor workers such as farmworkers and construction workers, and those in facilities without air conditioning, such as garment factories in poor nations, are most directly affected by heat. The reduction in their work capacity can be substantial, with serious economic consequences. One study estimates that ambient heat stress has reduced global labor capacity by 10% at summer's peak over the past few decades (Dunne, Stouffer, & John, 2013), and by mid-century, workdays lost due to heat could reach 15% to 18% in Southeast Asia, West and Central Africa, and Central America (Kjellstrom, Holmer, & Lemke, 2009). These regions contain some fragile economies, which could be particularly susceptible to reduced labor capacity.

Climate-Related Disasters Floods, droughts, and extreme storms have claimed millions of lives during recent years and have adversely affected the lives of many more millions of people and caused billions of dollars in property damage. According to the International Federation of Red Cross and Red Crescent Societies (IFRC), an average of 114,992 people died each year due to natural disasters during the period from 2003 to 2012 (Vinck, 2013). (The IFRC's World Disasters Report draws from the EM-DAT International Disaster Database at the Centre for Research on the Epidemiology of Disasters [CRED] at the University of Louvain, which is cited extensively in Chapter 24.) The number of people affected by natural disasters is two orders of magnitude greater than the number killed (CRED, 2015). In addition to causing acute deaths and injuries, disruption of health care, and lasting health impacts such as mental health disorders,

disasters can halt or reverse economic growth and profoundly disrupt social structures. Floods and Heavy Rain Floods are the most common type of natural disaster worldwide, with between 150 and 200 major floods occurring annually (Vinck, 2013). Increased severe rainstorms are one contributor. In the United States, the amount of precipitation falling in the heaviest 1% of rain events increased by 20% during the past century, and total precipitation increased by 7%. Over the last century the upper Midwest experienced a 50% increase in the frequency of days with precipitation of over four inches (Kunkel, Easterling, Redmond, & Hubbard, 2003). Other regions, notably the South, have also seen marked increases in heavy downpours, with most of these events coming in the warm season and almost all of the increase coming in the last few decades. Heavy rains can increase the risk of waterborne diseases, a risk discussed below in the section on infectious diseases. They can also result in flooding that kills, injures, and displaces people. Population concentrations in high-risk areas such as floodplains and coastal zones increase vulnerability to floods. Degradation of the local environment can also contribute significantly to vulnerability. For example, Hurricane Mitch, the most deadly hurricane to strike the Western Hemisphere in the last two centuries, caused 11,000 deaths in Central America, with thousands more people recorded as missing. Many fatalities occurred during mudslides in deforested areas (National Climatic Data Center, 1999). Wildfires The incidence of extensive wildfires (those burning over 400 hectares each) in the Western United States rose fourfold between the period from 1970 to 1986 and the period from 1987 to 2003 (Westerling, Hidalgo, Cayan, & Swetnam, 2006). Several climate-related factors may have played a role in this increase: droughts that dried out forests; higher springtime temperatures that hastened spring snowmelt and thereby lowered soil moisture; and the rise of some tree pest species (Running, 2006; Westerling et al., 2006). Forecasts call for an increased risk of wildfires in many (but not all) areas over the course of the twenty-first century (Moritz et al., 2012). Wildfires threaten health both directly and through reduced air quality. Fire smoke carries a large amount of fine particulate matter that exacerbates cardiac and respiratory problems such as asthma and chronic obstructive pulmonary disease (COPD). A study on worldwide mortality estimated 339,000 premature deaths per year (with a possible range of 260,000–600,000 deaths) attributable to pollution from forest fires, especially particulates (Johnston et al., 2012).

Air Pollution Climate change may affect exposure to air pollutants in many ways because it can influence both the levels of pollutants that are formed and the ways in which these pollutants are dispersed. Air quality is likely to suffer with a warmer, more variable climate (Bernard, Samet, Grambsch, Ebi, & Romieu, 2001).

Ozone Ozone is an example of a pollutant whose concentration may increase with a warmer climate. As explained in Chapter 13, higher temperatures increase ozone formation from precursors—a relationship demonstrated in many cities, and shown graphically in Figure 12.6. Accordingly, the ozone season in affected cities occurs during the summer, when warmer temperatures promote ozone formation. (Particulate matter formation can also increase at higher temperatures, due to increased gas-phase reaction rates.) This suggests that hotter summers will worsen air quality. However, air pollution chemistry is complex, and other factors—from changing vegetation to policies that reduce methane emissions—will also play a role, leading to variability from place to place (Fiore, Naik, & Leibensperger, 2015).

Figure 12.6 The Relationship Between Temperature and Ozone Levels in Santiago, Chile Source: Rubio & Lissi, 2014. This graph shows the association between measured maximum temperature, and the average eight-hour ozone level, measured in Santiago's O'Higgins Park. In studies in cities around the world, hot days feature higher ozone levels.

The role of vegetation is especially interesting. As explained in Chapter 13, many species of trees emit volatile organic compounds (VOCs) such as isoprenes, which are precursors of ozone. Isoprene production is highly responsive to leaf temperature and light. Under the right circumstances, higher levels of isoprenes result in higher levels of ozone (Squire et al., 2015). The relationship between climate change and air pollution is complex. Many feedback loops operate, some helpful and others harmful. On the one hand, some particles in the air reflect radiant energy and can help to cool the atmosphere; the best-known example is the cooling that follows major volcanic eruptions. On the other hand, a warmer climate will mean more demand for energy to power air conditioners, resulting in more air pollution (if fossil fuel plants supply the power). Overall, for air pollution, as for many other aspects of climate change, the impacts are not fully understood, but potential threats to public health deserve careful attention.

Aeroallergens Pollen is another air contaminant that may increase with climate change. Higher levels of carbon dioxide promote growth and reproduction by some plants, including many that produce allergens. Ragweed plants experimentally exposed to high levels of carbon dioxide can increase their pollen production several-fold. Over half the U.S. population (55%) tests positive for allergens, and over 34 million have asthma (Allergy USA, 2014). In recent decades the allergy season has lengthened with earlier flowering of some species, such as oaks, and levels of allergens such as ragweed (Ambrosia) pollen have risen, a predictable effect of higher temperatures and CO2 levels (Zhang et al., 2015). Ragweed season has been lengthening since the mid-1990s, particularly at higher latitudes along a 1,600-mile north-south sampling of monitoring stations through mid-North America (Ziska et al., 2011). Aeroallergens are not the only allergens to become more troublesome with climate change. With higher levels of carbon dioxide, poison ivy grows more exuberantly, and its allergen, urushiol, becomes more allergenic. Unhappily, poison ivy seems to enjoy a special advantage compared to other plants; its vines grow twice as much per year in air with doubled preindustrial carbon dioxide levels as in unaltered air, a fivefold greater increase than reported for other plant species (Mohan et al., 2006). Emerging evidence

suggests that other allergenic species respond to climate change by becoming more harmful; researchers have observed enhanced growth of weeds such as stinging nettle and leafy spurge, which cause rashes following skin contact (Ziska, 2003), greater allergenicity of Aspergillus (Lang-Yona et al., 2013), and extended ranges and active seasons for some stinging insects.

Infectious Diseases A range of infectious diseases can be influenced by climate conditions. The diseases most sensitive to influence by ambient climate conditions are those spread not by person-to-person pathways but directly from the source: the waterborne and foodborne diseases as well as vector-borne diseases (which involve insects and/or rodents in the pathogen's life cycle). For each of these infectious diseases, climate factors interact with a range of other factors: land-use patterns (deforestation, road construction, urbanization, dam construction), disease control programs, and others. Accordingly, these diseases, and the ways in which climate change affects them, are best considered through the lens of ecological thinking (see Chapter 2).

Waterborne Diseases Waterborne diseases are likely to become a greater problem as climate change continues and affects both freshwater and marine ecosystems. In freshwater systems, both water quantity and water quality can be affected by climate change. In marine waters, changes in temperature, ph, and salinity will affect coastal ecosystems in ways that may increase the risk of certain diseases. Freshwater Ecosystems Waterborne diseases are particularly sensitive to changes in the hydrological cycle. Many community water systems are already overwhelmed by extreme rainfall events. Flooding can contaminate drinking water with runoff from sewage lines, containment lagoons (such as those used in animal feeding operations), or nonpoint source pollution (such as agricultural fields) across watersheds. Runoff can exceed the capacity of the sewer system or treatment plants, which then discharge the excess wastewater directly into surface water bodies. Urban watersheds sustain more than 60% of their annual contaminant loads during storm events (Fisher & Katz, 1988). Thus it is no surprise that outbreaks of such diseases as cryptosporidiosis and giardiasis are associated with prior heavy rainstorms (Curriero, Patz, Rose, & Lele, 2001; Cann, Thomas, Salmon, Wyn-Jones, & Kay, 2013). Childhood gastrointestinal illness in the United States (Uejio et al., 2014) and India (Bush et al., 2014) has been linked to heavy rainfall. A Dutch study showed a 33% increase in gastrointestinal illness associated with sewage overflow following heavy rain; flood waters contained Campylobacter, Giardia, Cryptosporidium, noroviruses, and enteroviruses (De Man et al., 2014). An infamous example of heavy rain contributing to an outbreak was the 1993 Milwaukee cryptosporidiosis outbreak (Rose, 1997), which sickened over 400,000 and killed over 100. With climate change projected to result in more severe and frequent precipitation events, the risk of waterborne diseases is expected to rise (Patz & Hahn, 2013). Using 2.5 inches (6.4 cm) of daily precipitation as the threshold for initiating a combined sewer overflow (CSO) event, the frequency of such events in Chicago is expected to rise by 50% to 120% by the end of this century (Patz Vavrus, Uejio, & McLellan, 2008), posing increased risks to drinking and recreational water quality. Intense rainfall can also contaminate recreational waters and increase the risk of human illness (Schuster et al., 2005). For example, heavy runoff leads to higher bacterial counts in rivers in coastal areas and at coastal beaches, especially at the beaches near river outflows (Dwight, Semenza, Baker, & Olson, 2002). This suggests that the risk of swimming at some beaches increases with heavy rainfall, a predicted consequence of climate change. Marine Ecosystems Warm water and nutrient loading (primarily with nitrogen and phosphorus) favor blooms of marine algae, including two groups, dinoflagellates and diatoms, that can release toxins into the marine environment. These harmful algal blooms (HABs)—previously called red tides—can cause acute

paralytic, diarrheic, and amnesic poisoning in humans, as well as extensive die-offs of fish, shellfish, and marine mammals and birds that depend on the marine food web. Over recent decades the frequency and global distribution of harmful algal blooms appear to have increased, along with more human intoxication from algal sources (Anderson, Cembella, & Hallegraeff, 2012). These have occurred both in marine settings and in freshwater lakes, such as Lake Erie (Figure 12.7). For example, in the summer of 2012, a group of seven vacationers on the Washington coast harvested mussels, prepared them in a soup, and ate them; within hours they experienced paresthesias, a “floating” sensation, nausea, vomiting, ataxia, and other symptoms. They were diagnosed with paralytic shellfish poisoning, a condition caused by eating fish or shellfish contaminated by saxitoxin, an algal product more toxic than sodium cyanide (Hurley, Wolterstorff, MacDonald, & Schultz, 2014). Of note, the number of cases reported in 2012 was substantially higher than in previous years; this was attributed to an unusually warm, sunny summer. Climate change is predicted to increase the frequency of such episodes, and in addition, ocean acidification may increase the toxicity of some algal species (Fu, Tatters, & Hutchins, 2012; Glibert et al., 2014). Ciguatera, a form of poisoning caused by ingesting fish that contains toxins from any of several dinoflagellate species, could also expand its range. This condition has been linked to sea surface temperatures, and as these warm, according to one projection, ciguatera fish poisoning could increase by two- to fourfold over the coming century (Gingold, Strickland, & Hess, 2014).

Figure 12.7 Satellite Photo of a Harmful Algal Bloom in Lake Erie in 2011 Source: National Oceanic and Atmospheric Administration, 2014. This was the worst bloom in recent history, impacting over half the lake shore.

Some bacteria, especially Vibrio species, also proliferate in warm marine waters (Pascual, Rodó, Ellner, Colwell, & Bouma, 2000). Copepods (or zooplankton), which feed on algae, can serve as reservoirs for V. cholerae and other enteric pathogens. For example, in Bangladesh, cholera follows seasonal warming of sea surface temperatures, which can enhance plankton blooms (Colwell, 1996). Other Vibrio species have expanded in northern Atlantic waters in association with warm water (Thompson et al., 2004). For example, in 2004 an outbreak of V. parahaemolyticus shellfish poisoning was reported from Prince William Sound in Alaska. This pathogenic species of Vibrio had not been isolated from Alaskan shellfish previously due to the coldness of the Alaskan waters. What could have caused the species' expanded range? Water temperatures during in the 2004 shellfish harvest remained above 15°C, and mean water temperatures were significantly higher than they had been during the previous six years (McLaughlin et al., 2005). Such evidence suggests the potential for warming sea surface temperatures to increase the geographic range of shellfish poisoning and Vibrio infections into temperate and even arctic zones. The incidence of diarrhea from other pathogens also shows temperature sensitivity, which may in turn signal sensitivity to changing climate. During the 1997 and 1998 El Niño event, winter temperatures in Lima, Peru, increased more than 5°C above normal, and the daily hospital admission rates for diarrhea more than doubled compared to rates over the prior five years (Checkley et al., 2000) (Figure 12.8)—a pattern that has been confirmed in multiple settings (Vezzulli, Colwell, & Pruzzo, 2013). Long-term studies of the El Niño–Southern Oscillation, or ENSO, have confirmed this pattern. ENSO refers to natural year-to-year variations in sea surface temperatures, surface air pressure, rainfall, and atmospheric circulation across the equatorial Pacific Ocean. This cycle provides a model for observing climate-related

changes in many ecosystems. Sea surface temperature has had an increasing role in explaining cholera outbreaks in recent years (Vezzulli et al., 2013), as has ENSO, perhaps because of concurrent climate change (Rodó, Pascual, Fuchs, & Faruque, 2002). Overall there is growing evidence that climate change can contribute to the risk of waterborne diseases in both marine and freshwater ecosystems.

Figure 12.8 The Association Between Temperature and Childhood Diarrhea, Peru, 1993–1998 Source: Checkley et al., 2000. Daily time series between January 1, 1993, and November 15, 1998, for admissions for diarrhea and for mean ambient temperature in Lima, Peru. Shaded area represents the 1997–1998 El Niño event.

Foodborne Diseases More frequent warm days, greater humidity, and other climate-related factors can affect the persistence and dispersal of foodborne pathogens in many ways, and can increase the risk of foodborne infectious diseases (Hellberg & Chu, 2015). (As described in Chapter 16, waterborne and foodborne diseases can be hard to distinguish from each other, because contaminated water often contaminates food.) Data from many parts of the world show a strong association between temperature and the incidence of food poisoning with various pathogens—Campylobacter, Salmonella, Cryptosporidium, Shigella, and Giardia —showing different time lags between peak temperature and the peak in infections, and with the effect

most pronounced at especially high temperatures (Kovats et al., 2004; Naumova et al., 2007). Not surprisingly, modeling suggests a sharp increase in foodborne illness with continued climate change. For example, one study, focusing on Beirut, projected a 16% to 28% increase by mid-century, and an increase of up to 42% by 2100 (El-Fadel, Ghanimeh, Maroun, & Alameddine, 2012). Improved food-handling practices, which play a major part in prevention, are therefore an important aspect of climate change adaptation (Lake et al., 2009).

Vector-Borne Diseases Vector-borne diseases are infectious diseases, caused by protozoa, bacteria, and viruses, that are spread by organisms such as mosquitoes and ticks. The life cycle of these pathogens involves much time outside the human host and therefore much exposure to and influence by environmental conditions. The term tropical diseases is a reminder that each pathogen or vector species thrives in a limited range of climatic conditions. The incubation time of a vector-borne infectious agent within its vector organism is typically very sensitive to changes in temperature and humidity (Patz et al., 2003). Many other mechanisms govern the impact of climate change on vector-borne diseases, as shown in Text Box 12.1 geographic shifts of vectors or reservoirs; changes in rates of development, survival, and reproduction of vectors, reservoirs, and pathogens; and increased biting by vectors and prevalence of infection in reservoirs or vectors (Medlock & Leach, 2015). All affect transmission to humans, such that exposure to vector-borne disease will likely worsen in a warmer world (Mills, Gage, & Khan, 2010; Patz & Hahn, 2013).

Text Box 12.1 Some Effects of Weather and Climate on Vectorand Rodent-Borne Diseases Vector-borne pathogens spend part of their life cycle in cold-blooded arthropods that are subject to many environmental factors. Changes in weather and climate that can affect transmission of vector-borne diseases include variations in temperature, rainfall, wind, extreme flooding or drought, and sea level rise. Rodent-borne pathogens can be affected indirectly by ecological determinants of food sources, affecting rodent population size, and floods can displace them and lead them to seek food and refuge. These effects are summarized in Table 12.2. Table 12.2 Temperature and Precipitation Effects on Selected Vectors and Vector-Borne Pathogens Temperature effects Vector

Survival can decrease or increase depending on the species. Some vectors have higher survival at higher latitudes and altitudes with higher temperatures. Changes in susceptibility of vectors to some pathogens (e.g., higher temperatures reduce the size of some vectors but reduce the activity of others). Changes in the rate of vector population growth. Changes in feeding rate and host contact (which may alter the survival rate). Changes in the seasonality of populations.

Pathogen

Decreased extrinsic incubation period in vector at higher temperatures. Changes in the transmission season. Changes in distribution. Changes in viral replication.

Precipitation effects Vector

Increased rain may increase larval habitat and vector population size by creating a new habitat. Excess rain or snowpack can eliminate habitat by flooding, thus decreasing the vector population size. Low rainfall can create habitat by causing rivers to dry into pools (dry season malaria). Decreased rain can increase container-breeding mosquitoes by forcing increased water storage. Epic rainfall events can synchronize vector host seeking and virus transmission. Increased humidity increases vector survival; decreased humidity decreases vector survival.

Pathogen

Few direct effects but some data on humidity effects on malarial parasite development in the anopheline mosquito host.

Vertebrate host

Increased rain can increase vegetation, food availability, and population size. Increased rain can also cause flooding and decrease population size but increase contact with humans. Decreased rain can eliminate food and force rodents into housing areas, increasing human contact, but it can also decrease population size.

Increased sea level

Can alter estuary flow and change existing salt marshes and associated mosquito species, decreasing or eliminating selected mosquito breeding sites (e.g., reduced habitat for Culiseta melanura).

Source: Adapted from Gubler et al., 2001.

Mosquito-Borne Diseases Malaria and arboviruses are transmitted to humans by mosquitoes. Because insects are cold-blooded, climate change can shift the distribution of mosquito populations, affect mosquito biting rates and survival, and shorten or lengthen pathogen development time inside the mosquito, factors that ultimately determine infectivity. Malaria remains a scourge in many parts of the world. Despite considerable progress in fighting this disease in recent decades, it still accounts for over a million deaths each year, about 90% of these in Africa (Murray et al., 2012). Malaria risk is complex, and varies with demographic shifts, control measures, and other factors (Parham et al., 2015). However, malarial mosquito populations can be exquisitely sensitive to warming; an increase in temperature of just half a degree centigrade can translate into a 30% to 100% increase in mosquito abundance, an example of biological amplification by temperature effect (Pascual, Ahumada, Chaves, Rodó, & Bouma, 2006). Accordingly, most models forecast global increases in malaria risk over the next century, especially in highland regions of Africa, Asia, and Latin America (with some reduction of risk in tropical regions) (Caminade et al., 2014), emphasizing the importance of malaria control measures as a part of climate adaptation. Arboviruses include the causative agents of dengue fever, West Nile virus, chikungunya, and Rift Valley fever. Dengue and chikungunya are transmitted by Aedes mosquitoes, West Nile virus by Culex mosquitoes, and Rift Valley fever usually through contact with the blood or organs of infected animals but also by Aedes mosquitoes. The four diseases differ clinically and epidemiologically, and have distinct geographic ranges. For example, Rift Valley fever has generally been confined to east Africa, although it has recently spread to other parts of Africa and to the Arabian peninsula, while dengue fever is widespread across south Asia, Africa, and Latin America. However, the four diseases also share important

features, all relevant to climate change. First, there is evidence that climatic conditions, such as temperature and rainfall, can affect their spread. Second, the geographic range of all four diseases has expanded in recent decades. Third, modeling projects the potential for further spread with continued climate change. Finally, for each disease, infection reflects complex interplays of behavior, land use, mosquito control strategies, and other factors, so controlling these diseases in the face of climate change will be a complex challenge (Martin et al., 2008; Dhiman, Pahwa, Dhillon, & Dash, 2010; Weaver & Reisen, 2010; Morin et al., 2013; Campbell et al., 2015; Paz, 2015). Tick-Borne Disease Lyme disease is a tick-borne disease that was first described in the 1970s and has since become prevalent in North America, Europe, and Asia. The ecology and infectivity of this disease are related to many factors, such as habitat fragmentation and increased human contact with the mammals (deer, mice, and others) that carry the vector, the Ixodes tick. However, the tick life cycle is strongly influenced by temperature and other weather factors; for example, cold weather is limiting (Ostfeld & Brunner, 2015). The tick range has been expanding, and warming temperatures are projected to shift the range limit for this tick northward by 200 km by the 2020s and 1,000 km by the 2080s (Ogden et al., 2006). Rodent-Borne Diseases Rodent populations can be affected by weather, raising the potential for the diseases they transmit to be climate responsive. Examples of these diseases include hantavirus infection, leptospirosis, and plague. Hantavirus infections are transmitted largely by exposure to infectious excreta from rodents and may cause serious disease and a high fatality rate in humans. Hantavirus pulmonary syndrome emerged in the southwestern United States in 1993, after an El Niño brought heavy rains, which in turn led to a growth in rodent populations (Glass et al., 2000). Leptospirosis, a bacterial disease that can feature pulmonary hemorrhage, meningitis, and kidney failure, is transmitted through the urine of infected rodents and other mammals. Events that increase exposure to rodents, such as extreme flooding, can greatly increase the risk of contracting this disease (Lau, Smythe, Craig, & Weinstein, 2010). Finally, plague is caused by the bacteria Yersinia pestis, which is transmitted by fleas, whose primary reservoir host is rodents. Plague also varies with weather and across seasons (Ben Ari et al., 2011). In fact, historical tree-ring data suggest that during the major plague epidemics of the Black Death period (1280 to 1350), climate conditions were becoming both warmer and wetter (Stenseth et al., 2006).

Mental Health Effects Mental health disorders such as depression and anxiety cause major morbidity worldwide (Whiteford et al., 2013). Climate change may threaten mental health in several ways (Fritze, Blashki, Burke, & Wiseman, 2008; Berry, Bowen, & Kjellstrom, 2010; Doherty & Clayton, 2011).

Mental Health Impacts of Climate-Related Disasters Following disasters such as floods and wildfires, mental health consequences such as post-traumatic stress, depression, and anxiety are common, and may represent a major part of the resulting health burden (North & Pfefferbaum, 2013; Goldmann & Galea, 2014). Several months after Hurricane Katrina, 49.1% of those surveyed in New Orleans, and 26.4% in other affected areas, had developed anxiety-mood disorder, as defined in the DSM-IV, and one in six had post-traumatic stress disorder (PTSD) (with considerable overlap between the two) (Galea et al., 2007). Researchers have documented similar patterns after floods, dam collapses, heat waves, droughts, and wildfires—all disasters likely to increase with climate change. Mental health typically improves over time following disasters, but distress may persist for years, especially among vulnerable groups (Norris, Tracy, & Galea, 2009). Risk factors for mental disorders following disasters include low social capital or support, physical injury, property loss, witnessing others with illness or injury or in pain or dying during the disaster, loss of family, displacement, and a preexisting history of psychiatric illness. Children may be at special risk. These risk factors suggest a variety of protective strategies, including strengthening social support both before and after disasters, providing postdisaster mental health services, and prompt insurance compensation for loss.

Slow-moving climate disasters may also threaten mental health. In Australia during the recent decadelong drought, increases were found in anxiety, depression, and possibly suicidality among rural populations (Berry, Hogan, Owen, Rickwood, & Fragar, 2011). Strategies to reduce this burden included raising mental health literacy, building community resilience through social events, and disseminating drought-related information (Oldham, 2013).

Mental Health Impacts of Displacement Climate change may degrade familiar environments, causing a sense of loss, stress, and mental distress. In Arctic settings, where climate change has led to rapid environmental degradation and where indigenous peoples place high cultural value on place attachment, this phenomenon has been documented (Brubaker, Berner, Chavan, & Warren, 2011). In addition, climate change may force populations to relocate, either after an acute disaster or because needed resources (such as fresh water) become increasingly scarce (United Nations High Commissioner for Refugees, 2009). This relocation may create a considerable mental health burden (Loughry, 2010). An important protective strategy is keeping families, even entire communities, united (Jacob, Mawson, Payton, & Guignard, 2008).

Anxiety and Despair Related to Climate Change Climate change may exacerbate feelings of despair, anxiety, and hopelessness (Fritze et al., 2008; Doherty & Clayton, 2011). As discussed later in this chapter, effective communication and empowering people to take constructive actions may be useful strategies.

Heat and Mental Illness Hot weather may pose special hazards for people with underlying mental illness (Bulbena, Sperry, & Cunillera, 2006; Bouchama et al., 2007). Four categories of ailments are relevant: depression and suicide, dementia, psychotic illness, and substance abuse. Suicide has long been observed to vary in seasonal patterns, with increases in the spring and early summer in northern latitudes, and to increase with hot weather. A study of suicides in the United Kingdom between 1993 and 2003 (Page, Hajat, & Kovats, 2007) showed a 3.8% increase in suicide for each degree Celsius of temperature rise above 18 degrees. Could a warming climate increase the risk of suicide? Dementia is an established risk factor for hospitalization and death during heat waves (Basu & Samet, 2002). Contributing factors may include impaired cognitive ability to recognize risk and to respond appropriately, and the effects of medications and age. For patients with psychotic illness such as schizophrenia, extremely hot weather has been associated with increased risk of disease exacerbation, as measured by increased hospital admissions (Sung, Chen, Lin, Lung, & Su, 2011). Three reasons may operate: illness-associated defects in thermoregulation, medicationrelated defects in thermoregulation, and impaired cognitive ability to recognize risk and to respond appropriately. Substance abuse may increase risk during severe heat because of the dehydration associated with alcohol and opioid use, and the elevation of body temperature induced by sympathomimetic drugs, such as amphetamine, cocaine, and MDMA (Martinez, Devenport, Saussy, & Martinez, 2002). Adaptation measures include increased special attention to people with mental illness in heat wave preparedness planning, increased monitoring of such patients during heat waves, and training of health care providers (Cusack, de Crespigny, & Athanasos, 2011).

War, Refugees, and Population Dislocation Climate-related disasters may trigger broad population dislocations, often to places ill prepared for the quantity and needs of refugees overwhelmed by undernutrition and stress. Even with baseline refugee support, displaced groups commonly experience a range of public health threats, including violence, sexual abuse, and mental illness (McMichael, McMichael, Berry, & Bowen, 2010). A growing body of evidence links climate change and violence, from self-inflicted and interpersonal harm

to armed conflict (Levy & Sidel, 2014). A meta-analysis by Hsiang, Burke, and Miguel (2013) found that each standard deviation of increased rainfall or warmer temperature increases the likelihood of intergroup conflict by 14% on average. Strategic analyses by military authorities—both the Center for Naval Analysis Military Advisory Board, a group of retired generals (CNA Military Advisory Board, 2014), and the U.S. Department of Defense (2014)—have warned that climate change could catalyze instability and conflict.

The Public Health Response to Climate Change The links between human health and climate change are complex, diverse, and not always discernible, especially over short time spans. Understanding and addressing these links requires systems thinking, with consideration of many factors, ranging beyond health to such sectors as energy, transportation, agriculture, and development policy (Frumkin & McMichael, 2008). Interdisciplinary collaboration is critical. A wide range of tools is needed, including innovative public health surveillance methods, geographically based data systems, classical and scenario-based risk assessment, and integrated modeling.

Mitigation and Adaptation Two kinds of strategies, both familiar to public health professionals, are relevant in responding to climate change. The first, known as mitigation, corresponds to primary prevention, and the second, known as adaptation, corresponds to secondary prevention (or preparedness). Mitigation aims to stabilize or reduce the production of greenhouse gases (and perhaps to sequester those greenhouse gases that are produced). Key mitigation strategies include more efficient energy production and reduced energy demand. For example, sustainable energy sources, such as wind and solar energy, do not contribute to greenhouse gas emissions (see Chapter 14). Similarly, transportation policies that rely on walking, bicycling, mass transit, and fuel-efficient automobiles result in fewer greenhouse gas emissions than are produced by the current U.S. reliance on large, fuel-inefficient automobiles (see Chapter 15). Much energy use occurs in buildings, and green buildings that emphasize energy efficiency, together with electrical appliances that conserve energy, also play a role in reducing greenhouse gas emissions (see Chapter 20). Some mitigation strategies aim not to reduce the production of greenhouse gases but to accelerate their removal from the atmosphere. Carbon dioxide sinks such as forests are effective in this regard, so land-use policies that preserve and expand forests are an important tool in mitigating global climate change. An important concept in mitigation is stabilization wedges. This concept is explained in Figure 12.9. Figure 12.9 graphs annual carbon emissions over time. It shows two possible pathways during the twentyfirst century: the current path, which is a steep continued rise in emissions, and a flat path, which represents stabilization of current emissions. (Of course, this is a simplified schematic; other paths are possible, such as stabilization at some different emission level, or a downward path representing reduced emissions.) The triangle between the current path and the flat path is called the stabilization triangle, and it represents the reductions needed to reach stabilization. Figure 12.10 divides that triangle into wedges, each corresponding to a strategy that reduces carbon emissions by 1 billion tons per year. These strategies include energy efficiency, waste reduction, replacing coal with natural gas, increasing reliance on nuclear energy, switching to renewable energy sources, and land-use and agricultural changes. In 2004, when this concept was introduced, seven wedges were needed to achieve stabilization; at present, because emissions have continued to rise since then, eight or nine wedges would be required. To surpass stabilization, and reduce carbon emissions enough to avoid dangerous climate change, as many as nineteen wedges could be needed (Davis, Cao, Caldeira, & Hoffert, 2013). Most of these strategies are technically feasible and currently available (Pacala & Socolow, 2004; Socolow, 2011, September 27).

Figure 12.9a Alternative Emission Pathways Source: Princeton Environmental Institute, Carbon Mitigation Initiative, 2015.

Figure 12.9b Climate Stabilization Wedges Source: Princeton Environmental Institute, Carbon Mitigation Initiative, 2015.

Adaptation aims to reduce the public health impact of climate change. For example, if we anticipate severe weather events such as hurricanes, then preparation by emergency management authorities and medical facilities can minimize morbidity and mortality. This presupposes rigorous vulnerability assessment efforts, to identify likely events, at-risk populations, and opportunities to reduce harm (Ebi, Smith, & Burton, 2005; Kirch, Menne, & Bertollini, 2005; Menne & Ebi, 2006; Schipper & Burton, 2009). Improving essential infrastructure could help communities adapt to climate change. For example, vegetation, building placement, white roofs, and architectural design can reduce the urban heat island effect and therefore electricity demands for air conditioning. These efforts can involve complicated tradeoffs. For example, a recent study found that waste heat from air conditioning can warm outdoor air more than 1°C, so an important adaptation to urban heat islands—the use of air conditioning—can actually contribute to urban heat islands (Salamanca, Georgescu, Mahalov, Moustaoui, & Wang, 2014)! Other examples of adaptation measures include heat wave early warning systems (Lowe, Ebi, & Forsberg, 2011) and switching from surface water to groundwater sources to reduce the risk of contamination (Ebi, Lindgren, Suk, & Semenza, 2013). Optimal adaptation strategies achieve multiple objectives in tandem,

taking advantage of co-benefits, as discussed on the next page. A holistic, ecological approach to climate change adaptation, rather than engineering single solutions, may better build resiliency and secure the multiple potential benefits and cost savings associated with these improvements. As sea level rises, seawalls have frequently served to stabilize shorelines. But planting mangroves for storm surge protection incurs a fraction of the cost of building and maintaining seawalls or dikes for this purpose, while also preserving wetlands and marine food chains that support local fisheries (Arkema et al., 2013).

Public Health Action Public health action related to climate change is based on many of the core public health functions, and utilizes many of the standard tools in the public health toolbox (Frumkin, Hess, Luber, Malilay, & McGeehin, 2008). For instance, public health surveillance is needed to detect the emergence or range expansion of infectious diseases, and public health communication helps people recognize hazards and take appropriate precautionary actions. Forecasting and modeling, which are relatively new to public health, are also central to tackling climate change. In this endeavor, public health professionals collaborate with climate scientists, demographers, and others to build scenarios predicting how climate change will affect human health. Because the effects of climate change vary from place to place, scenarios are developed for specific locations (Moss et al., 2010; Ebi et al., 2014). This in turn enables planning and implementing strategies to protect the public. Several frameworks for public health action on climate change have been proposed. A leading example is Building Resistance Against Climate Affects, or BRACE, described in Text Box 12.2.

Text Box 12.2 The CDC's BRACE Framework The Building Resilience Against Climate Effects (BRACE) framework, developed at the U.S. Centers for Disease Control and Prevention (CDC), is an approach to anticipating and managing the health effects of climate change (Marinucci, 2014). Designed to be used by state and local public health officials, it is implemented through the CDC's Climate-Ready States & Cities Initiative (www.cdc.gov/climateandhealth/climate_ready.htm). The BRACE framework consists of five steps, as shown in Figure 12.10.

Figure 12.10 The CDC's BRACE Framework

Source: CDC, 2015.

Several aspects of the BRACE framework are notable. First, it embodies adaptive management—an iterative, learning-based approach to the design, implementation, and evaluation of interventions in complex, changing systems, as expressed by the cyclical structure of Figure 12.10. Second, the framework requires integrating climate data and health data, which in turn requires collaboration across disciplines. Third, priority setting is built into the framework, as agencies move sequentially through the steps. This is an important aspect when public health agencies face scarce resources and competing demands, and need to focus on the most important challenges.

Co-Benefits An important theme in both mitigation and adaptation is co-benefits. Although the steps needed to address climate change may appear formidable, some of them—reducing greenhouse gas emissions, shifting to renewable energy sources, shifting transportation patterns, shifting diets toward less meat, and others—yield many benefits (Jack & Kinney, 2010; Cheng & Berry, 2013; Thurston, 2013; West et al., 2013; Balbus, Greenblatt, Chari, Millstein, & Ebi, 2014), making them especially attractive, cost effective, and politically feasible. Examples of such co-benefits are shown in Table 12.3. Many of these co-benefits have been carefully investigated and quantified. For example, the production of meat is highly carbon intensive, accounting for as much as 18% of global greenhouse gas emissions (FAO, 2006). A British study found that lowering the consumption of red and processed meat in that country could reduce its greenhouse gas emissions by 3%, while cutting risks of coronary heart disease, diabetes, and colorectal cancer by fractions ranging up to 12% (Aston, Smith, & Powles, 2012). Similarly, a study in the Midwestern United States found that replacing short automobile trips by bicycling could reduce regional PM2.5 and ozone levels, and increase physical activity, enough to avoid 1,295 deaths per year in a region of 31.3 million people, and save approximately $3.8 billion a year from avoided mortality and reduced health care costs (Grabow et al., 2012). Such opportunities are referred to as no-regrets solutions, as suggested in Figure 12.11. Table 12.3 Co-Benefits of Climate Mitigation and Adaptation Activities

Benefits Direct

↑ Physical activity

Indirect

↓ Cardiovascular disease, cancer, depression, etc.

↑ Air quality ↓ Cardiovascular & respiratory disease Healthier diets

↓ Cardiovascular

Climate strategies Mitigation Shift From Shift Diets SingleToward Occupancy Less Meat, Vehicles More Toward Fruits and Cycling, Vegetables Walking, Transit

Shift Energy Sources From Fossil Fuels to Renewable Energy Sources

Adaptation Reduced Green Urban Energy Building Trees, Demand Parks, Through and Conservation Green Space

disease, stroke ↑ Nature contact

↑ Mental health, ↑ physical activity, ↑ property values

↑ Social capital

↑ Overall health and well-being

↓ Urban heat ↓ Heat-related island morbidity Improved ↓ Flooding stormwater management Economic benefits

Figure 12.11 No-Regrets Solutions Source: Pett, 2009. Joel Pett Editorial Cartoon used with the permission of Joel Pett and the Cartoonist Group. All rights reserved.

Climate Change as a Public Issue Public Belief in Climate Change Perspectives on and responses to climate change vary widely. Two decades of polling suggest that about two thirds of Americans believe that climate change is occurring; of these about two thirds (or about 40% of the total) believe humans cause it, and about half (or about one in three overall) believe it will pose a serious threat in their lifetimes (Jones, 2014; Pew Research, 2014; Leiserowitz et al., 2015). Americans tend to view climate change as remote in time and space—a problem for the next generation or people in faraway countries—and rank it as a low priority, well behind concerns such as jobs, health care, or even other environmental issues (Pew Research, 2014). In other wealthy nations, climate change tends to elicit greater public concern (Pugliese & Ray, 2009; Lee, Markowitz, Howe, Ko, & Leiserowitz, 2015). The U.S. population may be segmented along a spectrum from “alarmed” (≈16%) to “dismissive” (≈10%), according to climate change beliefs, concerns, and motivations (Roser-Renouf et al., 2014) (Figure 12.12). Many factors shape views of climate change (Brulle, Carmichael, & Jenkins, 2012): economic trends, cultural norms, the beliefs of family and friends, and values and political ideology. People often form and

reinforce their beliefs using cognitive shortcuts called heuristics, which bypass evidence (Pidgeon & Fischoff, 2011). Media coverage matters (Boykoff, 2011). Deliberate, well-funded attempts to deceive the public and sow confusion have succeeded (Oreskes & Conway, 2010; Brulle, 2014); despite robust scientific consensus on climate change, there is widespread perception that scientists disagree, which in turn fuels public disbelief (Lewandowsky, Gignac, & Vaughan, 2013). Many people also are unduly influenced by personal experience, such as short-term weather perturbations. A heat wave may strengthen belief in climate change, and a snowy winter may undermine it. Interpretation of weather rests heavily on prior beliefs and social cues (T. A. Myers, Maibach, Roser-Renouf, Akerlof, & Leiserowitz, 2013; Zaval, Keenan, Johnson, & Weber, 2014).

Figure 12.12 Global Warming's Six Americas: Arraying the U.S. Population Along a Continuum of Belief, Concern, and Motivation Source: Roser-Renouf et al., 2014.

As discussed in Chapter 28, effective communication may shift knowledge, attitudes, and behavior toward reducing risks and promoting health. This is as true for climate change as it is for other health-relevant exposures (Maibach, Roser-Renouf, & Leiserowitz, 2008), and climate communication has become a focus of research and practice in both public health and other fields (Moser & Lisa, 2007; Moser, 2010; Whitmarsh, O'Neill, & Lorenzoni, 2011; Bostrom, Böhm, & O'Connor, 2013). The salient principles are those used in environmental health communication more generally: two-way communication, gearing messages to the audience, limiting use of fear-based messages (Feinberg & Willer, 2011), frequently repeating simple, clear messages from trusted sources, and making health-promoting choices easy and appealing. For communicating climate change, health may be a compelling frame (Maibach, Nisbet, Baldwin, Akerlof, & Diao, 2010; Myers, Nisbet, Maibach, & Leiserowitz, 2012), reflecting the fact that substantial numbers of people believe that climate change threatens health (Akerlof et al., 2010). Although further research is needed to define the role of health in climate communication, practical communication resources are becoming available (Maibach, Nisbet, & Weathers, 2011). Moreover, health care providers are a highly trusted source, ranking significantly higher than mainstream media (Leiserowitz et al., 2015), implying an important role for health professionals in climate communication.

Climate Change Policy International efforts to address climate change are carried out under the United Nations Framework Convention on Climate Change (UNFCCC). Adopted in 1992, the UNFCCC sets out a framework that aimed to stabilize atmospheric concentrations of greenhouse gases at a level that would prevent dangerous interference with the climate system. The UNFCCC has carried out its business through regular meetings called the Conferences of Parties (COP). Perhaps the best known was the third meeting, in 1997 in Kyoto. This resulted in the Kyoto Protocol, which committed developed countries and emerging market economies to reduce their overall emissions of six greenhouse gases by at least 5% below 1990 levels over the period between 2008 and 2012, with specific targets varying from country to country. However, the United States, at the time the largest greenhouse gas emitter (China has since surpassed it), did not sign the Kyoto Protocol. By 2007, it was clear that many signatory nations were not on track to achieve their anticipated emission reductions, even though the protocol required relatively modest emissions reductions, far below those required to stabilize greenhouse gases at any level below 700 ppm. Barriers to robust international

agreements have included the unwillingness of some wealthy countries (including the United States) to accept binding limits, and tension between wealthy countries (which have caused most greenhouse gas emissions) and low- and middle-income countries (which are eager for economic development, and believe that wealthy countries should shoulder much of the responsibility). Market mechanisms could play a powerful role in reducing carbon emissions. This involves putting a price on carbon, to correct a market failure that contributes to ongoing emissions: the fact that the costs of these emissions are not borne by the individuals and firms that benefit but instead are externalized. There are two major approaches to increasing the price of carbon, both designed to guide decision making, reduce high-carbon practices, and incentivize the development and use of low-carbon technologies. In the first, cap and trade, government sets a ceiling (or cap) on total greenhouse gas emissions and distributes emissions permits (say, through an auction) among companies that emit. Companies then buy and sell these permits at prevailing market prices, as government progressively lowers the cap to reach stated goals. The United States successfully used a cap-and-trade system to reduce sulfur dioxide and nitrous oxide emissions beginning in the 1980s, and greenhouse gas cap-and-trade systems are in place in the European Union, California, Tokyo, and other jurisdictions. The second mechanism is a carbon tax, in which government places a tax on carbon emissions. Carbon taxes are in use in Sweden and Ireland, in the Canadian provinces of British Columbia and Quebec, in Boulder, Colorado, and other jurisdictions. Economists and policy experts debate the relative merits of these two approaches (Aldy & Stavins, 2012; Goulder & Schein, 2013). While the debate may sound far removed from public health, the role of carbon pricing in preventing illness and injury makes the subject very much a matter of health policy (HowdenChapman, Chapman, Capon, & Wilson, 2011). However, both approaches require legislative action, and both meet stiff political opposition from such interests as fossil fuel companies (Jenkins, 2014). This political reality has prevented action at the federal level in the United States, and in Australia led to the repeal of a carbon tax in 2014, just two years after it was adopted. The alternative, then, is executive action. In the United States, this means regulation by the U.S. Environmental Protection Agency (EPA). Regulation of greenhouse gases dates to the Massachusetts v. EPA Supreme Court ruling in 2007, which found that greenhouse gases met the definition of air pollutants under the Clean Air Act. The EPA was then required to make a scientific determination—an endangerment finding—that greenhouse gas emissions were “reasonably anticipated to endanger public health or welfare.” The EPA made this determination in 2009—a striking example of climate regulation being grounded in public health. This finding, in turn, required the EPA to regulate motor vehicle greenhouse gas emissions. Since then, the EPA has initiated a series of regulatory actions, both for mobile sources and for stationery sources, designed to reduce greenhouse gas emissions, as well as to yield other benefits. These include stricter vehicle emission standards for both light-duty vehicles (called Corporate Average Fuel Efficiency, or CAFE, standards) and trucks, and stricter emissions standards for power plants and factories. In November, 2014, U.S. President Barack Obama and Chinese President Xi Jinping, whose nations together account for more than a third of the world's greenhouse gas emissions, announced a joint commitment on climate change. President Obama agreed to cut US CO2 emissions 28% below 2005 levels by the year 2025, and President Xi pledged that by 2030, China's CO2 emissions would peak and its share of renewable energy would rise by 20 percent. These commitments set the stage for the twenty-first COP, in Paris, in December, 2015. At that convening, nearly 200 nations agreed on the goal of limiting global warming to two degrees Centigrade, each nation agreed to set Nationally Determined Contributions toward that goal, wealthy nations agreed to help fund climate adaptation actions by poor nations, and provisions for transparency and verification were adopted. While critics noted that these steps would not suffice to avoid serious risks, most observers celebrated COP21 as a turning point and a major step forward.

Ethical Considerations Climate change raises ethical concerns in several ways. First, on the global scale, the nations responsible for the lion's share of carbon emissions to date account for a small proportion of the world's population and are relatively resilient to the effects of climate change. In contrast, the large population of the global south—the poor countries—accounts for a relatively small share of cumulative carbon emissions, and a

very low per capita emission rate (although total emissions from developing nations are growing rapidly, with China surpassing the United States in 2006). The United States, with 5% of the global population, produces 25% of total annual greenhouse gas emissions. This discrepancy exemplifies the ethical implications posed by climate change on a global scale, shown graphically in Figure 12.13. Poor populations in the developing world have little by way of industry, transportation, or intensive agriculture; they contribute only a fraction of the greenhouse gases per capita that the developed countries produce, and their capacity to protect themselves against the adverse consequences of what are mostly others' greenhouse gases is quite limited (Shue, 2014). Of course, if developing nations do not choose energyefficient development pathways, global climate change trends will intensify even as the imbalance of equity decreases (Patz & Kovats, 2002).

Figure 12.13 A Comparison of Cumulative CO2 Emissions (1950–2000) (upper panel) with the Burden of Four Climate-Related Health Effects (Malaria, Malnutrition, Diarrhea, and Inland Flood-Related Fatalities (lower panel) Source: Patz, Gibbs, Foley, Rogers, & Smith, 2007. Note the mismatch between the countries that have contributed most to climate change, and the countries that are suffering its consequences the most.

Within the United States, and within many other nations, a similar disparity exists. Poor and disadvantaged people in many cases bear the brunt of climate change impacts, including health impacts—

a pattern reflecting broader inequities in environmental health, as discussed in Chapter 11. This was graphically demonstrated in the aftermath of Hurricane Katrina, a disaster typical of those expected to increase with climate change. The poor populations of New Orleans and the nearby Gulf region were disproportionately likely to fail to evacuate, to suffer catastrophic disruption following the storm, and to be unable to recover (Pastor et al., 2006; Dyson, 2007). The realization of inequities in risk and recovery resources has given rise to the concept of climate justice, a subset of environmental justice (Schlosberg & Collins, 2014). Finally, an ethical issue arises with respect to intergenerational justice. Climate change has enormous potential impacts on the health and well-being of future generations (Page, 2007; Gardiner, 2011). As discussed in Chapter 10, ethical and religious thinkers have argued that we in the present owe a moral obligation to those who will follow to reverse climate change. For economists, the discount rate is a means of expressing value with regard to future generations. For example, the Stern report, a prominent economic analysis of climate change, used a 1.4% discount rate (Stern, 2006), whereas other economists have applied a several-fold higher discount rate (Broome, 2008). The higher discount rate implies to policymakers that the current generation should spend less on mitigating climate change, whereas the lower discount rate suggests more spending on mitigating climate change now, to avoid future harm. Policy decisions on how much the current generation should spend to mitigate climate change for the benefit of yet unborn people involve both an ethical issue and an economic issue.

Summary Climatologists now state with high certainty that global climate change is real, occurring more rapidly than expected, and caused by human activities, especially through fossil fuel combustion and deforestation. Environmental public health researchers assessing future projections for global climate have concluded that, on balance, adverse health outcomes will dominate under these changed climatic conditions. The number of pathways through which climate change can affect the health of populations makes this environmental health threat one of the largest and most formidable of the new century. Conversely, the potential health co-benefits from moving beyond our current fossil fuel–based economy may offer some of the greatest health opportunities in recent history.

Key Terms adaptation Adjustments in ecological, social, or economic systems in response to observed or expected climate impacts. More particularly, changes in processes, practices, and structures to reduce potential harm or to exploit beneficial opportunities associated with climate change. adaptive management An iterative, learning-based approach to the design, implementation, and evaluation of interventions in complex, changing systems. albedo Reflectivity; the fraction of incident energy (such as light) reflected by a surface without being absorbed. cap and trade An environmental policy tool designed to limit emissions of a pollutant such as carbon dioxide or sulfur dioxide. The cap is a limit on emissions set by a regulatory authority; the limit is lowered over time to reduce emissions. The trade is a market for permits to emit. Using this trading, emitters able to reduce their emissions can sell their allocated permits to other emitters. This approach creates incentives to innovate to reduce emissions (cf. carbon tax). carbon tax An environmental policy tool designed to reduce carbon emissions by placing a tax on carbon emissions, generally upstream (say, at the point of fossil fuel production). By increasing the price of carbon-based fuels, a carbon tax would reduce demand (cf. cap and trade). climate change Global-scale changes resulting from higher concentrations of greenhouse gases, land-use changes such

as deforestation, and other drivers. Features Earth system changes such as changes in rainfall patterns, greater ocean acidification, and more frequent heat waves. These effects vary from place to place. climate justice The concept of fairness and equity in bearing the risks of climate change and benefiting from protection against that change. A form of environmental justice. climate variability Fluctuations of climate over seasons and years relative to long-term average patterns. co-benefits Benefits that flow from an action in addition to the primary benefits that motivated the action (also called collateral benefits). For example, shifting travel from automobiles to walking, cycling, and transit is a climate mitigation strategy that also yields benefits through improved air quality, increased physical activity, and reduced road traffic fatalities. dangerous interference “Dangerous anthropogenic interference with the climate system” is the term of art used by the UNFCCC to characterize human actions that have driven earth system changes beyond a threshold of safety and stability. El Niño–Southern Oscillation (ENSO) Natural year-to-year variations in sea surface temperatures, surface air pressure, rainfall, and atmospheric circulation across the equatorial Pacific Ocean. endangerment finding The EPA's 2009 determination, under the Clean Air Act, that greenhouse gas emissions were “reasonably anticipated to endanger public health or welfare.” This finding triggered EPA regulation of greenhouse gases. global warming The increase in average surface temperature on a global scale. Climate change is a preferred term because, while warming refers only to one parameter (temperature) and one direction of change (hotter), climate change takes in the complex changes in many earth systems. greenhouse gases Atmospheric gases that increase radiative forcing: carbon dioxide, water vapor, methane, and others. harmful algal blooms Overgrowths of algae in bodies of water, usually following excess loading of nutrients into the water, and often harming aquatic ecosystems and posing health risks to people. heat wave A period of extremely hot days, defined by the World Meteorological Organization as more than five consecutive days with temperatures 5°C above the average maximum during the 1961–1990 baseline period. Kyoto Protocol A 1997 international treaty, negotiated under the UNFCCC, that committed nations to reduce greenhouse gas emissions. mitigation Actions that aim to stabilize or reduce the production of greenhouse gases (and perhaps to sequester those greenhouse gases that are produced), corresponding to the public health concept of primary prevention. ocean acidification The ongoing trend toward lower pH in the oceans, resulting from absorbing carbon dioxide. radiative forcing The difference between solar energy absorbed by the Earth and energy radiated from it. stabilization wedges Mitigation strategies that contribute to reducing greenhouse gas emissions, and that—in aggregate— achieve a designated goal. tail risk

The extreme end of a distribution of probabilities for a particular outcome. In the context of climate change, tail risk corresponds to low-probability, high-consequence events such as extreme sea level rise. United Nations Framework Convention on Climate Change (UNFCCC) A framework adopted internationally in 1992 that aimed to stabilize greenhouse gases at a level that would prevent “dangerous interference” with the climate system. urban heat island An urban area that is routinely hotter than surrounding areas. vulnerability assessment Systematic, place-based evaluation of degree of exposure to hazards (susceptibility) and capacity to cope with or recover from consequences of disasters (resilience).

Discussion Questions 1. Climate change has been called the major environmental health challenge of the twenty-first century. Do you agree or disagree? Explain your reasoning. 2. Identify three current environmental health problems likely to be exacerbated by climate change. How might existing public health practices be altered to anticipate these effects of climate change? What other key sectors (beyond health) should be engaged? 3. What are some of the major driving forces behind both the risks of climate change and our vulnerabilities to that change? Which scientific experts would be best able to assemble a comprehensive assessment of climate change risks? What types of policymakers should be involved, and at what levels (local, regional, international)? 4. What are three potential co-benefits and three potential unintended consequences of mitigating greenhouse gas emissions? 5. How large is your carbon footprint? Online calculators are available at these sites: www.carbonfootprint.com/calculator.aspx; www3.epa.gov/carbon-footprint-calculator; www.nature.org/greenliving/carboncalculator; and www.terrapass.com/carbon-footprint-calculator 6. A substantial minority of Americans do not believe that climate change is occurring or that humans play a role. Why do you think these beliefs persist despite scientific evidence to the contrary? 7. Suppose your local health department hired you to oversee climate change planning and preparedness. What steps would you take in your first sixty days on the job? In your first year?

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For Further Information Review Articles McMichael, A. J. (2013). Globalization, climate change, and human health. New England Journal of Medicine, 368(14), 1335–1343. Patz, J. A., Frumkin, H., Holloway, T., Vimont, D. J., & Haines, A. (2014). Climate change: Challenges and opportunities for global health. JAMA, 312(15), 1565–1580.

Reports Intergovernmental Panel on Climate Change (IPCC): http://www.ipcc.ch. IPCC reports represent some of the most authoritative and exhaustive synthesis assessments. Its fifth assessment report was published in 2014. Full and summary reports and downloadable graphs and figures are available from the IPCC Web site. U.S. Centers for Disease Control and Prevention: http://www.cdc.gov/climateandhealth. This site focuses specifically on health aspects of climate change, including public health actions in response. U.S. Environmental Protection Agency (EPA): http://www.epa.gov/climatechange/effects/health.html. This informative EPA site covers the many sectors affected by climate change. U.S. Global Change Research Program: This initiative publishes periodic National Climate Assessments under the title Climate Change Impacts in the United States. The most recent assessment was published in 2014. It is available at http://nca2014.globalchange.gov World Health Organization (WHO): http://www.who.int/globalchange/climate/en. The WHO has been assessing the health risks of climate change for nearly two decades, and this Web site contains links to WHO reports and ongoing projects.

Books Butler, C. D. (Ed.). (2014). Climate change and global health. Boston: CABI. Epstein, P., & Ferber, D. (2011). Changing planet, changing health: How the climate crisis threatens our health and what we can do about it. Berkeley: University of California Press. Griffiths, J., Rao, M., Adshead, F., & Thorpe, A. (Eds.). (2009). The health practitioner's guide to climate change: Diagnosis and cure. London: Earthscan. Levy, B. S., & Patz, J. A. (Eds.). (2015). Climate change and public health. New York: Oxford University Press. Luber, G., & Lemery, J. (Eds.). (2015). Global Climate change and human health: From Science to Practice. San Francisco: Jossey-Bass.

Blogs Dot Earth: http://dotearth.blogs.nytimes.com. An interactive blog that explores trends and ideas with readers and experts. World-renowned reporter Andrew C. Revkin carefully follows and reports on climate change science and policy. RealClimate: http://www.realclimate.org. A blog containing commentaries by climate scientists that sort out the often polarizing or conflicting stories in the mainstream press. Discussions are restricted to climate science topics (and not political or economic implications). Postings are signed by the author(s) so you know exactly from where the information comes.

Materials for Teachers EcoHealth: http://ecohealth101.org. A source of useful information and student exercises for middle and high school teachers and students. Topics (and lesson plans) include human health effects of climate change, ozone depletion, biodiversity and land-use change, mechanized intensive agriculture, and globalization. GRID-Arendal: http://www.grida.no. A collaborating center of UNEP. The mission of this site (established in 1989 by the government of Norway) is to communicate environmental information to policymakers and facilitate environmental decision making for change.

Part 3 Environmental Health on the Regional Scale

Chapter 13 Air Pollution Michelle L. Bell and Jonathan Samet Dr. Bell and Dr. Samet report no conflicts of interest related to the authorship of this chapter. Anna Engstrom and Marissa Smith report no conflicts of interest related to the authorship of the tox boxes.

Key Concepts Air pollution is a major contributor to adverse human health conditions, from asthma to cardiovascular disease to premature death. Air pollution is not just a modern phenomenon; it has been recognized as a problem for thousands of years. Air pollution is a growing concern for developing areas of the world with expanding transportation and industry. Air pollution is not a single entity; it consists of distinct, identifiable components (such as ozone and particulate matter), each with its own sources, chemistry, and toxic effects. Air pollution emissions come from many sources; these can be natural sources or human activities. The ambient concentration of an air pollutant in a particular location depends on many factors, including emissions sources, weather, and land patterns. Air quality management strategies include controlling emissions at the source, reducing emissions, and decreasing population exposure. This chapter discusses the relationship between outdoor (ambient) air pollutants and human health. These environmental contaminants differ from many others in that exposure is unavoidable and affects all segments of the population. For example, when point source water contamination occurs, the natural resource needed (water) can be retrieved from another location or treated, but outdoor air pollution affects everyone. Indoor air pollution is also a health concern; this is discussed in Chapter 20. The discussion begins with a brief history of air pollution, which has been recognized to some extent as a health problem for centuries. Various study designs used to assess the health effects of air pollution are discussed, as each has key strengths and weaknesses. Our understanding of how air pollution affects health is based on a synthesis of research over multiple disciplines and research designs. This chapter reviews the general sources and health effects of major outdoor air pollutants. It concludes with a discussion of the links between air pollution and other environmental health concerns.

History of Air Pollution Air pollution has long been a contributor to ill health. With the discovery of fire, humans began to pollute air in the places they lived and the outside air. As urban areas developed, pollution sources, such as chimneys and industrial processes, were concentrated, leading to visible and damaging pollution dominated by smoke. Nearly 2,500 years ago, Hippocrates noted that health could be affected by the air we breathe and that the quality of the air differed by area (Hippocrates, 1849). In thirteenth-century London air pollution was so severe that abatement strategies were developed (Brimblecombe, 1986). At that time, air pollution was generally a local issue, generated from kilns, hearths, and furnaces. Since then, the nature of air pollution has changed along with growing populations, industrialization, and fossil fuel–based transportation. High-volume production and transport of pollution across large distances mean that the effects of air pollution can occur far from sources. Air pollution problems now range from the local to the global scale.

Modern-day recognition of the dangers of air pollution can be traced to several extreme episodes during the last century. In 1930, in the Meuse Valley in Belgium, more than sixty people died during such an episode, over ten times the underlying mortality rate (Firket, 1936; Nemery, Hoet, & Nemmar, 2001). The original investigators warned that should such an air pollution episode occur in a city with a larger population, such as London, thousands would die. In October 1948, industrial pollution settled on Donora, a small town in southwestern Pennsylvania (Schrenk, Heimann, Clayton, Gafafer, & Wexler, 1949; Davis, 2002). Twenty people died, about six times the typical mortality rate. Perhaps the most severe such event took place in London in December 1952 (see Text Box 13.2 and Figure 13.3 later in the chapter). In these and similar episodes, pollution levels and subsequent health effects were so severe that the connection between air pollution and health was readily apparent. In response to severe air pollution episodes such as those in Donora and London, many governments, particularly those of the United States and the United Kingdom, enacted legislation to improve air quality and initiated research on air pollution and health. Despite control measures that have lowered concentrations, air pollution continues to harm health in developed areas and is a growing concern in regions of the world with rapidly developing industry and transportation systems (see Text Box 13.1). The Global Burden of Disease initiative estimated that ambient particulate matter, one type of air pollution, alone caused over 3.2 million premature deaths in 2010 (Lim et al., 2012).

Text Box 13.1 Air Pollution in the World's Dirtiest Cities Air pollution levels in the fast-growing cities of low- and middle-income countries can be extreme. The combination of vehicular traffic and industry—with ineffective regulation and uncontrolled emissions—has led to some of the highest pollution levels on the Earth. In China, where air quality can be poor (Chan & Yao, 2008), urban air pollution levels routinely exceed World Health Organization (WHO) standards by an order of magnitude (Figure 13.1). The Chinese government launched a “war on pollution” in 2013, and in 2014, the Chinese Environmental Protection Ministry announced that only eight of the nation's seventy-four large cities had met official air quality standards (up from three the previous year). There were also 471 “environmental emergencies” in 2014, due to especially high air pollution levels (“Air in 90% of China's cities…,” 2015). As shown in Figure 13.2, Indian cities have even higher particulate matter levels than do Chinese cities. Many other cities of Asia, Africa, and Latin America are similarly afflicted, and air pollution continues to rise in many regions of the world.

Figure 13.1 Children Wear Masks in the Thick Haze on Tiananmen Square in Beijing, China, January, 2013. Source: Xinhua News Agency, 2014. Lou Linwei / Alamy Stock Photo.

Figure 13.2 The Distribution of PM2.5 Levels in Cities in India, China, Europe, and the United States Source: Greenstone et al., 2015. In each panel, the vertical dotted line corresponds to the WHO standard, and the vertical solid line corresponds to the relevant nation's standard.

The health impacts of this pollution are severe. The 2010 Global Burden of Disease Study attributed over 3.2 million deaths, 3.1% of global disability-adjusted life years (DALYs), and 22% of ischemic heart disease DALYs to particulate matter (Lim et al., 2012); most of these occurred in the cities of developing nations. By one calculation the average Indian in a polluted city would gain 3.2 years of life if urban pollution were reduced to legal standards (Greenstone et al., 2015). A study of Mexico City, Santiago, and São Paulo estimated that air pollution control would avert over 156,000 deaths, 4 million asthma attacks, 300,000 children's medical visits, and almost 48,000 cases of chronic bronchitis in those cities over a twenty-year period (Bell, Davis, Gouveia, Borja-Aburto, & Cifuentes, 2006). Some notable progress has been achieved. For example, Mexico City was the most polluted city on the planet in 1992, according to the United Nations, due to a combination of a large population, vehicular and industrial sources, practices such as trash burning, and challenging geographic and meteorological conditions. (The city lies in the high-altitude crater of an extinct volcano, where low atmospheric oxygen levels cause incomplete fuel combustion, intense sunlight drives ozone formation, and the topography helps form inversion layers that trap pollutants.) Months would go by without a single day of acceptable air quality. In the 1990s, the city initiated its PROAIRE program, combining regulatory, economic, technological, and

behavioral approaches. Air quality has improved dramatically, and health benefits are expected to follow (Riojas-Rodríguez, Álamo-Hernández, Texcalac-Sangrador, & Romieu, 2014).

Types of Ambient Air Pollution The concentration of an air pollutant depends on many factors, including emissions, weather, and land patterns. During conditions of stagnant winds and a temperature inversion, pollution does not disperse, leading to higher pollutant concentrations. Pollution in a given area can vary by season or day depending on weather and sources, such as traffic and wood burning. Some pollutants, such as ozone and small particles with long residence times in the atmosphere, can travel large distances, causing damaging effects far from the pollution sources. Air pollutants can be categorized by source or by physical and chemical characteristics. Table 13.1 summarizes the characteristics of several major air pollutants, their sources and health effects, and their pertaining regulations and guidelines, including the National Ambient Air Quality Standards (NAAQS) established under the U.S. Clean Air Act and the guidelines of the World Health Organization (2006). An air pollutant may be directly emitted (a primary pollutant) or formed in the atmosphere through physical and chemical conversion of precursors (a secondary pollutant). For example, carbon monoxide (CO) emitted from a car tailpipe is a primary pollutant; however, ozone, a secondary pollutant, is formed in the atmosphere when sunlight chemically converts other pollutants into ozone and other oxidant species. Table 13.1 Major Ambient Air Pollutants: Sources, Health Effects, and Regulations

Lead

Sulfur dioxide

Source types and major Health effects sources

Regulations and guidelines

Primary Anthropogenic Leaded fuel (phased out in some locations such as the United States), lead batteries, metal processing

Accumulates in organs and tissues. Learning disabilities, cancer, damage to the nervous system.

U.S. NAAQS Quarterly average: 0.15 µg/m3

Primary Anthropogenic Combustion of fossil fuel (power plants), industrial boilers, household coal use, oil refineries Biogenic Decomposition of organic matter, sea spray, volcanic eruptions

Lung impairment, respiratory symptoms. Precursor to PM. Contributes to acid precipitation.

WHO guidelines Annual: 0.50 mg/m3 U.S. NAAQS 1-hour average: 75 ppb (196 µg/m3) 3-hour average: 0.5 ppm (1300 µg/m3)

Interferes with delivery of oxygen. Fatigue, headache, neurological damage, dizziness.

WHO guidelines 10-minute average: 500 µg/m3 Annual: 20 µg/m3 U.S. NAAQS 1-hour average: 35 ppm (40 mg/m3) 8-hour average: 9 ppm (10 mg/m3)

Carbon monoxide Primary Anthropogenic Combustion of fossil fuels (motor vehicles, boilers, furnaces) Biogenic Forest fires

WHO guidelines 15-minute average: 100 mg/m3 30-minute average: 60 mg/m3 1-hour average: 30 mg/m3

Particulate matter Primary and secondary Anthropogenic Burning of fossil fuel, wood burning, natural sources (e.g., pollen), conversion of precursors (NOx, SOx, VOCs) Biogenic Dust storms, forest fires, dirt roads

Respiratory symptoms, decline in lung function, exacerbation of respiratory and cardiovascular disease (e.g., asthma), mortality. Effects can vary by particle size and composition.

Nitrogen oxides

Decreased lung function, increased respiratory infection. Precursor to ozone. Contributes to PM and acid precipitation.

Tropospheric ozone

Primary and secondary Anthropogenic Fossil fuel combustion (vehicles, electric utilities, industry), kerosene heaters Biogenic Biological processes in soil, lightning

Secondary Formed through chemical reactions of anthropogenic and biogenic precursors (VOCs and NOx) in the presence of sunlight

Decreased lung function, increased respiratory symptoms, eye irritation, bronchoconstriction.

U.S. NAAQS PM10: 24-hour average 150 µg/m3: PM2.5: Annual arithmetic mean: 12 µg/m3: 24-hour average: 35 µg/m3 WHO guidelines PM10: Annual: 20 µg/m3 24-hour average: 50 µg/m3 PM2.5: Annual: 10 µg/m3 24-hour average: 25 µg/m3 U.S. NAAQS (NO2) Annual arithmetic mean: 53 ppb (100 µg/m3) 1-hour average: 100 ppb (188 µg/m3) Related to compliance with NAAQS for ozone WHO guidelines (NO2) 1-hour average: 200 µg/m3 Annual: 40 µg/m3 U.S. NAAQS 8-hour average: 0.075 ppm (147 µg/m3)

WHO guidelines 8-hour average: 100 µg/m3 Toxic pollutants Primary and secondary Cancer, reproductive effects, EPA rules on emissions for (hazardous Anthropogenic neurological damage, more than 80 industrial pollutants) (e.g., Industrial processes, respiratory effects. source categories (e.g., dry asbestos, mercury, solvents, paint thinners, cleaners, oil refineries, dioxin, some fuel chemical plants) VOCs) EPA and state rules on vehicle emissions Volatile organic Primary and secondary Range of effects, depending EPA limits on emissions compounds (e.g., Anthropogenic on the compound: irritation EPA toxic air pollutant benzene, terpenes, Solvents, glues, smoking, of respiratory tract, nausea, rules toluene) fuel combustion cancer. Related to compliance Biogenic Precursor to ozone. with NAAQS for ozone Vegetation, forest fires Contributes to particulate matter. Biological Primary Allergic reactions, pollutants (e.g., Anthropogenic respiratory symptoms, pollen, mold, Systems, such as central air fatigue, asthma. mildew) conditioning, that create

conditions that encourage production of biological pollutants Biogenic Trees, grasses, ragweed, animals, debris Note: This table lists only a sample of the sources and health effects associated with each pollutant. Additionally, health effects may be the result of characteristics of a pollutant mixture rather than of a single pollutant. Additional legal requirements often apply, such as state regulations.

Another important feature of air pollution is whether the emissions are natural (biogenic) or from human activity (anthropogenic). Naturally occurring pollutants include volatile organic compounds (VOCs) from vegetation, pollens, volcanic gases, and dust from deserts.

Text Box 13.2 London 1952: One of the World's Worst Air Pollution Disasters By the 1950s, high air pollution levels in London were common. In fact London's characteristic fogs had long been noted by tourists, authors such as Charles Dickens, and painters such as Claude Monet. However from December 5 to 9, 1952, an unprecedented air pollution event took place. Several factors contributed to the episode: the use of coal as a primary method of home heating; a particularly cold winter, meaning even more coal burning; and stagnant atmospheric conditions preventing pollution from dispersing. Pollution became so thick that visibility was reduced to near zero. Traffic came to a virtual standstill. The sharp increase in air pollution was immediately followed by a sharp increase in sickness and death, with mortality rates three times normal levels. Mortuaries did not have enough room and undertakers ran out of coffins. Indicators of morbidity, such as hospital admissions, rose with air pollution concentrations. Later analysis of archived autopsy lung tissue found soot and an excess of other particles (Hunt, Abraham, Judson, & Berry, 2003). Mortality rates did not return to normal levels until several months after the fog. The initial government report (U.K. Ministry of Health, 1954) hypothesized that influenza accounted for the extra deaths during these months. However, more recent analysis has shown that the true death toll from the episode was 10,000 to 12,000 deaths, rather than the 3,000 to 4,000 typically reported, and that only a fraction of those could be attributed to influenza (Bell & Davis, 2001; Bell, Davis, & Fletcher, 2004) (Figure 13.3).

Figure 13.3 Mortality and Air Pollution Levels During the 1952 London Fog Source: Adapted from Bell & Davis, 2001.

In physical form, air pollutants can be gases or particles. Pollutants that are aerosols consist of small, solid or liquid particles suspended in air. A pollutant's physical form and chemical composition and characteristics (e.g., its solubility if it is a gas) affect the pollutant's ability to penetrate the respiratory system. Other factors that affect respiratory penetration are the pollutant's ambient concentration and the exposed individual's ventilation rate (that is, rate of inhalation of air). For example, exercise increases the breathing rate, and oral breathing enables pollutants to bypass the nasal passages, where they might be prevented from entering the lungs. Gaseous pollutants that are highly soluble in water, such as sulfur dioxide (SO2), are largely removed by the upper airway, whereas less water-soluble gases, such as ozone, penetrate deeper into the lungs (Figure 13.4).

Figure 13.4 The Respiratory System This figure shows the lung structure as well as the fraction of particles of different sizes deposited in the various parts of the lung. Very large particles are stopped at the nose, while very small particles reach the alveoli and deposit there. Source: Oberdörster, Oberdörster, & Oberdörster, 2005. Reproduced with permission from Environmental Health Perspectives. Drawing courtesy of J. Harkema.

Finally, air pollutants can also be classified by the way they are legally regulated. A commonly used term in the United States is criteria pollutants, a group of key outdoor air pollutants defined by the Clean Air Act (CO, lead, nitrogen dioxide, ozone, particulates, and SO2) and for which the U.S. Environmental Protection Agency (EPA) promulgates NAAQS to protect human health and welfare. (Welfare in this context includes such public goods as crops and livestock, air and ground transportation, and visibility.) Another regulatory category, hazardous air pollutants (HAPs), established by the Clean Air Act Amendments of 1990, includes a number of volatile organic chemicals, pesticides, herbicides, and radionuclides. This category does not include all known hazardous air pollutants and does include some pollutants for which the hazard level is unknown.

Studies of Air Pollution and Health The health effects of air pollution have been extensively studied through diverse research methods, including epidemiological, human exposure, and animal and other toxicological studies. Each approach has strengths and weakness, and results from complementary research designs are needed to paint a complete picture of the many ways air pollution affects health.

Epidemiological studies investigate air pollution and health outcomes in the real world, typically in large populations. Air monitoring data are often used as surrogates for individual exposure. That is, one or more monitors placed in a city are assumed to represent citywide exposures. In reality, people's activity patterns (the ways they spend their time in different environments, such as work and home) also determine their individual exposures. Adverse health outcomes can be assessed through public health databases, questionnaires, or tests of pulmonary function. For example, a landmark study of air pollution and mortality in six U.S. cities used outdoor monitors in each city to estimate exposure. People in the city with the highest air pollution levels had a 26% higher mortality rate than those in the least polluted city (Dockery et al., 1993). Another epidemiological study, the American Cancer Society's Cancer Prevention Study II (CPSII), tracked about 500,000 adults in 151 U.S. metropolitan areas, and used aggregate exposure data based on monitor measurements) and individual-level health information. The investigators found that participants in the most polluted areas had a 17% higher mortality rate than those in the least polluted areas (Pope et al., 1995, 2002; Krewski et al., 2009). A key advantage of epidemiological studies is the investigation of real-world populations and air pollution conditions. However, potential weaknesses of epidemiological studies are the often limited ability to control for other factors—referred to as confounding factors, such as population characteristics and pollutants other than those being investigated—and the difficulty of accurately estimating personal exposure (see Chapter 8). Controlled human studies involve exposure of volunteers to a specified concentration of a pollutant or pollutant mixture in a laboratory setting and measurements of health responses (Sandstrom, 1995). Exposure studies can control for many potential confounding factors, carefully characterize exposure, and incorporate detailed outcome assessment. To protect participants' safety, such research examines health effects that are mild, acute, and reversible. For example, human exposure studies can investigate heart rate variability, lung function changes and the fraction of particles deposited in the lung. Exposures are typically of short duration and at low concentrations. Human exposure studies are particularly useful for characterizing mechanisms of injury and assessing threshold concentrations for short-term effects. Animal studies involve exposures on a short- or long-term basis to a pollutant or pollutant mixture under well-characterized conditions. Animals are sometimes even placed at sites of particular interest, such as along roadways. Generally rodents are used, but dogs and primates have also been studied. For example, animal exposure studies of air pollution have been used to research respiratory and heart rates in rats, DNA damage in mice, brain damage in dogs, and myocardial ischemia in dogs. Animal studies sometimes incorporate invasive assessment procedures, such as lung biopsies. Biological samples can be collected for detailed studies of mechanisms of injury. Various animal models are used that mimic human diseases, such as asthma, coronary heart disease, and congestive heart failure. However, evidence from animal studies may not apply to people, and responses to a particular pollutant sometimes vary even among animal species. Cellular and molecular studies are increasingly important, particularly for investigating mechanisms of disease. Elegant mechanistic studies may assess gene expression in response to air pollution exposure. Emerging technologies (so-called omics approaches, as discussed in Chapter 7) are expected to deepen mechanistic understanding and to provide useful biomarkers of exposure.

Sources and Effects of Outdoor Pollutants The health consequences of air pollution are wide-ranging, extending from effects on comfort and wellbeing to respiratory symptoms and premature death. This section reviews the sources and health impacts of several common outdoor air pollutants; they are summarized in Table 13.1. Much human health research aims to investigate a particular pollutant, while controlling for potential confounding by other pollutants. Indeed, some pollutants, such as CO, appear to have individual, specific health effects. However, air pollution is actually a complex mixture of multiple pollutants. Damage from air pollution may result from the combined effects (interaction) of several pollutants. Programs for air pollution control generally provide individual standards for each pollutant, although the adverse health effects of different pollutants may be related and a number of pollutants have common sources. Some key ambient air pollutants are discussed in Tox Boxes in other chapters: benzene

in Chapter 7, lead in Chapter 11 and VOCs in Chapter 20.

Particulate Matter Particulate matter (PM) refers to a class of pollution rather than an individual pollutant with a specified chemical structure, such as SO2. PM consists of solid or liquid particles suspended in air, regardless of their chemical composition. PM can be either primary (directly emitted) or secondary (formed in the atmosphere through gaseous precursors such as nitrogen oxides [NOx], sulfur oxides [SOx], and VOCs). PM results from the burning of fuel (e.g., emissions from power plants), driving on unpaved roads, industrial activity, and wood-burning stoves, and from natural sources such as pollen, dust, salt spray, erosion, and mold. PM concentrations can vary within a region or even a city (e.g., concentrations can be higher near major highways). The composition of PM can differ by location, season, source, and meteorology (Bell, Dominici, Ebisu, Zeger, & Samet, 2007). In the eastern United States, PM often has a substantial sulfate component, reflecting the contributions of emissions from power plants. In the western United States, transportation emissions contribute a larger fraction of PM, creating a substantial nitrate component. Variation can also exist at the subregional level. Particles are generally categorized by size, using a measure called aerodynamic diameter, which is determined by a particle's shape and density and permits comparison of particles having irregular shapes and different sizes and densities. PM10 refers to particles with an aerodynamic diameter of 10 µm or less, whereas PM2.5, or fine PM, has an aerodynamic diameter up to 2.5 µm, and ultrafine PM particles have an aerodynamic diameter up to 0.1 µm. Coarse PM (PM10–2.5) refers to particles with an aerodynamic diameter between 2.5 and 10 µm. Total suspended particles (TSP) refers to almost all particles in the air and is typically measured as particles up to about 45 µm in aerodynamic diameter. Figure 13.5 depicts the typical mass distribution of particles in an urban area, showing two modes, one of fine particles, which tend to be of secondary origin, and the other of coarse particles, which are more likely to be primary. There is often a third mode of very small particles in the nano size range (below 0.1 µm), which have been generated freshly by combustion.

Figure 13.5 Particulate Matter Mass Distribution in an Urban Area

A particle's size is related to its source and determines how it is transported in the atmosphere and where it is deposited in the environment and in the respiratory system. Smaller particles penetrate more deeply into the lung. Such particles are typically generated through combustion processes. Diesel exhaust, a combination of gases and particles, is of particular concern because the particles are extremely small (40%. Trench fatalities reduced by 35%. HIV and hepatitis B infections in health care workers reduced by >90%.

The hierarchy of controls (described more fully in Chapter 8, and corresponding to the prevention hierarchy discussed in Chapter 26) embodies the principle that the most effective way to control a hazard is to address it at its source. U.S. occupational health and safety regulations implement this principle by requiring or encouraging employers to use the most effective way to address the hazard, such as reducing exposure to toxic substances through substitution, putting barriers between workers and electrical hazards, using sound-dampening enclosures to reduce noise exposures, creating closed systems to avoid toxic exposures, or installing ventilation systems. Lowest priority is given to personal protective equipment, such as respirators, which are dependent on human behavior, often uncomfortable to wear, and inherently less reliable.

Control of Chemical Hazards With few exceptions, workers are the group with the highest exposures to chemical substances. In those workplaces where chemicals are produced or used, exposure levels are often many times higher than are found in the general environment. For example, children living near lead smelters have been found to be overexposed to that metal, although their exposures were only a fraction of the worker exposure levels in the smelter itself. Similarly, the cancer-causing chemical benzene is emitted by oil refineries, where worker exposure levels are several times higher than the exposure of the general public. The U.S. legal structure allows workplace exposures to be far higher than exposures to the general public. In theory, EPA chemical regulations attempt to reduce the lifetime risk of illness from exposure to less than one in a million (see Chapter 6). The EPA also has specific mandates and authority to protect the most vulnerable—the very young and chronically ill—from airborne toxics. OSHA and MSHA standards are intended to protect people who are healthy enough to work, even if they are exposed throughout their

working lifetime. While the goals of both the EPA and the worker protection agencies are often unmet, the EPA's standards are far stricter than those of OSHA and MSHA for the same substance. These regulatory differences have implications for scientific research. Because workers sustain higher exposures than members of the general public, they are the proverbial “canaries in the coal mine.” It is for this reason that much of the epidemiological research on toxic chemicals is performed on workers; measuring the effects on less exposed nonworkers is more difficult. For example, chemical workers in China who were exposed to bisphenol A (BPA), a chemical used to make plastic products such as water bottles, were found to have low sperm counts (Li et al., 2011). These kinds of findings provide some of the strongest evidence supporting concerns about exposure to BPA in consumer products and in the general environment, (see Tox Box 6.1). OSHA has been successful in limiting exposure to some of the best-known and most dangerous workplace chemicals, chemicals that were virtually unregulated before OSHA. For example, asbestos was widely present in commercial construction, shipyards, and the manufacture of certain friction products like brakes. OSHA tightly regulates current use, and few workers remain exposed to the substance (see Tox Box 20.3). However, OSHA's standards regulating workplace exposure to chemicals are for the most part out of date and inadequately protective. When Congress passed the OSH Act, it gave OSHA two years to adopt any then-existing national consensus or established federal standards. During that two year period, the agency adopted about 500 legally enforceable permissible exposure limits (PELs). Since then, OSHA has updated or issued new standards for only thirty or so chemicals—the remaining PELs are based on evidence from the late 1960s or earlier. For most workplace chemicals, OSHA has no standard at all. OSHA does not have standards for many of the other hazards encountered by inspectors in the course of their work. In situations in which no standard exists, OSHA may issue citations under the General Duty Clause of the OSH Act, which states that the employer is required to provide a workplace “free from recognized hazards.”

OSHA Inspections and Penalties With its limited number of inspectors, OSHA will generally visit a worksite for one of the following reasons: because of a worker complaint, a fatality, or a serious injury or because the site is in a highhazard industry and therefore subject to random visits. In theory, the threat of a monetary penalty encourages employers to comply with OSHA's requirements. OSHA penalties, however, have only been increased once in the agency's forty-five-year history. As of December 2015, the maximum penalties were $7,000 for a serious violation and $70,000 for a repeat or willful violation. At that time, the median OSHA penalty was issued at around $4,400 per inspection, and the median penalty issued resulting from an inspection following a worker fatality was just $9,800. Even with these significant limitations, progress has been made in preventing work-related injury. In 1970, an estimated 14,000 workers were killed on the job, an annual rate of 18 per 100,000, or about 38 workers killed on the job every day. Today, with a far larger workforce, that rate has fallen to 3.3 per 100,000, or about 13 every day (BLS, 2015).

Fix the Workplace, Not the Worker Just as the obligation to control workplace hazards has generated controversy, our understanding of the root causes of workplace injuries and illnesses, and the means to prevent them from occurring, is contested terrain. For decades, many safety professionals were influenced by the work done in the 1930s by a safety expert named Herbert Heinrich. Heinrich claimed, based on his review of thousands of reports of injuries compiled by the insurance industry and employers, that 88% of work “accidents” were caused by “unsafe acts.” Although his assertion that the actions of workers were responsible for most workplace injuries was widely accepted, Heinrich was badly misguided on several levels. His most basic mistake was attributing the incident in which the worker was injured to a single cause, the act of a generally careless worker. By doing so, he gave license to employers to blame the victims (the workers) rather than look for the root causes. A more accurate and useful understanding of workplace incident causation involves recognition that there are many factors that contribute to the occurrence of an event and that the work environment—both physical and organizational—is critically important. Successful interventions to prevent and reduce occupational injury and illness require particular attention to modifiable risk factors

such as hazardous exposures and also factors embedded in work policies and practices.

Workers' Compensation In the first two decades of the twentieth century, most U.S. states established social insurance systems —workers' compensation plans—intended to provide medical care and partial wage replacement for injured workers until they had recovered sufficiently from their injuries to return to work. Over time, these systems evolved to cover (and exclude) various injuries and began to cover some illnesses as well. Each state system has its own rules and regulations as well as different benefit levels and durations for injured workers. There is no national (federal) system that applies to all workers with occupational diseases and injuries, although certain specific working groups, such as railroad workers and federal employees, are covered by national plans.

System Limitations The workers' compensation system was originally designed so that employer-provided insurance would reimburse workers for lost wages while providing medical coverage and rehabilitation associated with work-related injuries. Under this “no-fault” system, workers no longer have the right to sue their employer for an injury they suffered at work but, in theory, have relatively certain access to medical care and wages lost while they recuperate. Injured workers, however, face numerous barriers to filing and receiving compensation for their injuries (Azaroff, Levenstein, & Wegman, 2002), and only a fraction of injured workers receive any benefits through the state workers' compensation programs (Shannon & Loew, 2012). For example, in an enumeration of all recordable work-related amputations in Massachusetts, less than 50% of the cases received any workers' compensation benefits (Davis et al., 2014). A similar study in California found that one third of employer-recorded amputation and carpal tunnel syndrome cases had not received workers' compensation benefits (Joe et al., 2014). The workers' compensation system performs even more poorly for low-wage workers. Many injured lowwage workers face additional barriers to filing, including greater job insecurity, lack of knowledge about their rights, or a limited command of English. In particular, immigrant workers may fear wrongful termination or retaliation for filing or even reporting an injury. These barriers are documented in numerous surveys of low-wage and immigrant workers who report being injured on the job and not filing a workers' compensation claim (Smith, 2012). The challenges facing individuals with occupational illnesses are even greater, and it is the rare worker with an occupational illness who receives any benefits from the compensation system. Most cases of workrelated chronic disease are rarely diagnosed as work related. When that linkage is made, the diagnosis generally comes long after employment ends. Even when the proper diagnosis is made, a worker who is eligible for benefits under Medicare, Medicaid, the Veterans Health Administration, or a private insurer is more likely to take that route, and avoid the challenges of obtaining benefits through the workers' compensation system (Leigh, 2011; Leigh & Robbins, 2004).

Who Pays for Work-Related Injuries and Illnesses? The workers' compensation system was originally designed so that employers would bear the costs of workplace injury and illness. In theory, bearing these costs provides an incentive to employers to eliminate hazards and therefore prevent injuries and illnesses from occurring. However, in the United States currently, the costs of workplace injury and illness are borne primarily by injured workers, their families, and taxpayer-supported safety net programs. Workers' compensation payments cover only about 21% of lost wages and medical costs due to work injuries and illnesses, and private health insurance handles only 13%. Workers and their families pay for 50% of these costs, with taxpayers shouldering the remaining 16% (Leigh & Marcin, 2012) (also see Figure 21.2).

Figure 21.2 Who Bears the Cost of Worker Injuries? Source: Leigh & Marcin, 2012.

For working families struggling to meet basic necessities and set aside some savings, a work injury to a breadwinner can be especially devastating. A recent study of the impact on earnings, for instance, found that workers in New Mexico who receive workers' compensation benefits for wage loss caused by workplace injuries lose an average of 15% of predicted earnings over the ten years following the injury. Even with workers' compensation benefits, an injured worker's income is, on average, almost $36,000 less over ten years than if the injury had not occurred (Scherer, Seabury, O'Leary, & Ozonoff, 2014). Workplace injuries can also cause loss of self-esteem and self-confidence, stress in relationships between spouses and with children, and strained relations with colleagues and supervisors. These indirect costs can translate into tangible economic costs, including lower wages (Keogh, Nuwayhid, Gordon, & Gucer, 2000; Strunin & Boden, 2004). It is likely that the proportion of the costs of work injuries and illnesses covered by working families and taxpayers has risen in recent years, as many state legislatures have enacted changes in their workers' compensation systems that have made it more difficult for injured workers to obtain benefits. Indeed, during the first decade of this century, reductions in workers' compensation benefits have correlated with expansions in the Social Security Disability Insurance program, the federal program that provides benefits to disabled workers below the age of 66.

Sustainability The health and safety of the workforce is an important but often neglected component in sustainable economic development. In the fossil fuel industries—coal mining and oil and gas drilling and refining— workers suffer high levels of injuries, illnesses, and fatalities (in addition to the better-known environmental issues linked with the use of these fuels, as discussed in Chapters 12 and 14). The transition from carbon dependence to sustainable energy provides hope for improving overall worker health and safety. More generally, according to the ILO, “Economic growth is not sustainable when it is based on poor and unsafe working conditions, suppressed wages and rising working poverty and inequalities.” Developing and emerging economies that invest in quality jobs experience greater improvement in living standards than nations that do not make quality jobs a priority (ILO, 2014). However, a shift to sustainability—for example, to renewable energy and recycled or “green” products— does not necessarily guarantee improved workplace health and safety. For example, workers involved with wind turbines are at high risk of injury from falls and welding arc flashes. New techniques developed to construct green buildings, such as skylights and wastewater recovery, have resulted in worker fatalities. Workers at recycling facilities are exposed to arsenic, cadmium, other heavy metals, and organic dusts, as well as fire hazards and the risk of injury from repetitive motion. Insulating homes to be more energy efficient can expose the applicators to foams containing isocyanates, which can lead to adult-onset asthma. Thus even though emerging technologies are creating new green jobs and products, old safety hazards still exist in these workplaces. A key aspect of sustainability is life cycle analysis—a reckoning of the health and environmental costs of

products, from raw material harvesting, to manufacturing, to use, to disposal. Understanding the connections between workers' exposures during production and community and consumer exposures during use and disposal provides an important opportunity for cross-cutting public health interventions. Life cycle analysis also entails understanding the global supply chains that convey goods from place to place and expose workers, their families, and communities along the way. Worker safety and health is more than a labor issue or a factor in an economics discussion; it is an issue with broad implications for public health and global human rights. Worker safety is also becoming a component of various measures of sustainability, especially as investors are looking to invest in sustainable firms. This investor interest in worker safety stems from the growing recognition that well-managed firms are safe firms, and that high injury rates are signs of a poorly managed firms. Public reporting of a firm's worker safety performance is therefore useful to investors who want to invest in well-managed firms. To support this interest, worker injury and illness rates are being incorporated into voluntary corporate reporting efforts, efforts supported by such organizations as the Global Reporting Initiative and, in the United States, the Sustainability Accounting Standards Board. The close relationship between safety and sustainable management can be seen in the transformation of the aluminum producer Alcoa under the leadership of CEO Paul O'Neil. When O'Neil (who was later appointed Secretary of the Treasury by President George W. Bush) became CEO of Alcoa, he focused the entire corporation on the goal of zero injuries. As the company took tight control of production processes to drive down injury rates, Alcoa workers were able to produce higher quality products in a more efficient manner. Under O'Neil's leadership, Alcoa's net annual income increased fivefold, and its market capitalization grew by $27 billion. At the same time, the injury rate among Alcoa workers dropped dramatically, and it continues to be one of the safest manufacturing firms in the world (Duhigg, 2012).

Globalization As a result of our drive toward globalization, work and its hazards no longer respect national boundaries. Many goods are assembled in one country from parts manufactured in multiple other places, and then the finished goods are distributed both nationally and internationally. Occasionally a large multinational employer takes responsibility for ensuring the health and safety of workers all along these complex supply chains, but more often hazards are confronted and addressed (or ignored) at the local level. In all countries the hazards confronting workers and the means of addressing them reflect evolving economic and political priorities and realities, social norms, legal structures, labor availability, and experience with prior approaches. Many low- and middle-income countries have limited means to ensure workforce protections. Many countries rely in whole or in part on standards or conventions developed by international organizations such as the International Labour Organization, a United Nations agency, to identify and describe the goals of their health and safety efforts. The ILO does not have enforcement powers, so the implementation of any conventions or standards that are adopted depends on local resources, legal powers, and commitment. The ILO aggregates and makes available extensive data relevant to work and working conditions, including occupational injuries (www.ilo.org/global/statisticsand-databases/lang-en/index.htm). The ILO and the World Health Organization (WHO) have also provided leadership for international efforts to reduce or eliminate certain work hazards through technical assistance, training, and education. For example, the ILO has developed the Global Programme for Elimination of Silicosis, and has assisted a number of countries in developing national programs tailored to local conditions. The ILO and WHO have worked together to provide the technical support and training that enables countries to develop and implement these programs. Both organizations have focused on reducing or eliminating the use of asbestos as well, because of the risk it poses to both workers and others who inhale asbestos fibers in the general environment. They have also highlighted the plight of the most vulnerable workers, particularly children. National and international nongovernmental organizations, including labor unions and human rights organizations, actively promote worker protections. Some investigate, monitor, and report on working conditions and advocate for improved protections. Others are active in promoting specific legislation or control of particularly hazardous work. All have important roles to play in the recognition and mitigation of workplace risk and the prevention of injury and disease from workplace exposures.

In some instances, international pressure has led to improvements in working conditions in developing countries. For example, a series of catastrophic events in Bangladesh, culminating with the death of more than 1,100 workers in the 2013 Rana Plaza factory collapse, triggered international outrage at some of the well-known U.S. and European clothing brands that had contracted for the work being performed in those unsafe factories. In response, some Western clothing brands have formed organizations whose aim is to help identify and eliminate the most significant hazards in Bangladesh clothing factories. While it appears that these programs have had some impact on conditions in this one country's clothing factories, the success of any program that aims at a single country will be limited. This limitation stems from the propensity of industries will move to locations where costs, including worker wages and safety requirements, are lower. This raises important questions for citizens of all countries, but especially the developed ones: What is our responsibility to the worker in a developing country or an emerging industrial power, laboring in unsafe conditions to produce consumer products for Europe or the United States? As consumers of the products of her labor, do we share an obligation to ensure that she is able to work without putting her health and safety at risk? If we believe that all workers should be able to come home safely to their families at the end of their shifts, then worker safety and health is more than a labor issue or a factor in an economics discussion; it is an issue of global human rights.

Summary Work is a primary human activity and a key determinant of health. Accordingly, understanding the workplace—both physical circumstances, such as chemical exposures and injury risks, and social constructs, such as work organization—is essential to a full understanding of environmental health. Occupational injuries and illnesses occur in predictable patterns, related to particular industries, work practices, and levels of economic development; are often undercounted; and can impose a substantial burden on workers and their families. Among vulnerable populations such as low-wage workers, immigrants, and members of minority groups, this burden is especially high. Workers have the right to safe workplaces, and employers are responsible for providing workplaces free from serious hazards. Application of the hierarchy of controls and the systematic implementation of safety and health management systems by employers can greatly reduce risk of injury and illness; these practices are reinforced by government regulation. Compensation systems exist to pay for medical care and lost wages of workers who are injured or sickened on the job, and to assist them in rehabilitation and a return to functioning and employment, but these systems have serious limitations and often fail to provide the benefits to which these workers are entitled. Both globalization and the transition to sustainable economic activity will continue to shape occupational safety and health risks, and public health strategies, in coming years.

Key Terms employment Paid work. ergonomic hazards Hazards that stem from work activities that are poorly designed, so that accomplishing them is associated with increased risk of injury or illness. globalization The international integration of economic systems, featuring the increased movement of goods, people, and capital across the globe. hazards Substances or situations that pose a risk to health, safety, or well-being. hierarchy of controls An ordered set of priorities for the implementation of strategies (from most effective to least effective) to protect health and safety. Controls that protect all workers from the hazard without their active

involvement (such as elimination of the hazard altogether or substitution of less hazardous materials and processes) are at the top of the hierarchy. Engineering controls (such as enclosing and ventilation) are the next level. Administrative controls (such as setting limits on the duration of work in high heat and humidity) are next. Finally, personal protective equipment (such as protective clothing or properly fitted and cleaned respirators) can be used in an emergency and to supplement higher levels of protection. injury and illness prevention programs See safety and health management systems. International Labour Organization (ILO) A specialized agency of the United Nations with a self-described mission “to promote rights at work, encourage decent employment opportunities, enhance social protection and strengthen dialogue on work-related issues.” life cycle analysis A technique for assessing the environmental and social (including health) impacts associated with all the stages of a product's life, from cradle to grave, and for designing and producing products that minimize waste and pollution at the end of their useful life. Mine Safety and Health Administration (MSHA) The U.S. government agency, located in the Department of Labor, focused on prevention of death, disease, and injury from mining and promotion of safe and healthful workplaces for U.S. miners. MSHA inspects all working mines at least annually in order to ensure compliance with existing regulations and identify new problems. MSHA develops and promulgates regulations, disseminates information, and supports and oversees training of miners. musculoskeletal disorders (MSDs) Disorders of the muscles, joints, tendons, ligaments, bones, and nerves, often caused by work and commonly because of exposure to ergonomic hazards. National Institute for Occupational Safety and Health (NIOSH) The U.S. federal government agency that conducts research, supports research, and makes recommendations to prevent worker injury and illness. NIOSH also supports health professional training, investigates unusual outbreaks of disease or injury in workplaces, and disseminates information to assist those in a position to prevent or reduce safety and health risks for people who work. Occupational Safety and Health Administration (OSHA) Created by the Occupational Safety and Health Act of 1970, OSHA is located in the Department of Labor. Employers in the US are required by the OSH Act to provide safe and healthful workplaces, and OSHA is the U.S. government agency charged with making that happen. To accomplish this, the agency sets and enforces standards and provides training, outreach, education, and assistance. OSHA's jurisdiction includes most private sector workplaces in the United States other than mines, which are within the jurisdiction of MSHA. permissible exposure limits (PELs) Legally enforceable limits to exposure to workplace hazards issued by OSHA. safety and health management system A systematic approach taken by employers to managing safety and health activities by integrating occupational safety and health programs, policies, and objectives into organizational policies and procedures. It is a set of safety and health program components that interact in an organized way. sustainability The ability of a system to continue functioning without depleting or damaging the things it needs to function, thereby fulfilling the social, economic, and other requirements of present and future generations. temporary worker A worker who is hired for a limited period of time, with no employer commitment for future employment. Many temporary workers are hired by labor staffing agencies and assigned to work at places of employment not owned or controlled by the staffing agency. unemployment

A state of not having paid work but desiring or seeking it. vulnerable workers Workers at increased risk of injury or illness because of their language, lack of ability to read, legal status, or other characteristics. workers' compensation Social insurance programs intended to provide partial or complete wage replacement and resources for health care and rehabilitation for workers who have been injured or made sick by exposure to hazards at work. The specific requirements and structures of the programs (e.g., what is and is not covered and how much is paid for what duration of disability) vary substantially by state and by country.

Discussion Questions 1. What are some of the ways that work and health interact? How do these differ for workers in different industries? 2. What are the characteristics of workers who are at greatest risk for workplace injury? 3. What are some of the reasons employers have when they choose to invest in workplace safety? What are the reasons why they may choose not to invest? 4. What factors play a role in the underreporting of workplace injuries and illnesses? 5. In the United States the Occupational Safety and Health Administration (OSHA) and the Mine Safety and Health Administration (MSHA) have the job of encouraging employers to follow the law and provide safe workplaces. What tools do these agencies have? In what situations are these tools more or less effective? 6. Even though it been disproved conclusively, why do some safety professionals still believe that worker carelessness is the primary cause of work injuries? What are the potential consequences of the widespread prevalence of this mistaken belief? 7. Please look at each item of clothing you are now wearing. In what countries were your clothes manufactured? If you wanted to assess the working conditions of the people who made your clothes, how would you collect that information?

References AFL-CIO. (2015). Death on the job, the toll of neglect: A national and state-by-state profile of worker safety and health in the United States (24th ed.). Retrieved from http://www.aflcio.org/content/download/154671/3868441/DOTJ2015Finalnobug.pdf American Diabetes Association. (2013). Economic costs of diabetes in the U.S. in 2012. Diabetes Care, 36, 1033–1046. Azaroff, L. S., Levenstein, C., & Wegman, D. H. (2002). Occupational injury and illness surveillance: Conceptual filters explain underreporting. American Journal of Public Health, 92, 1421–1429. Bureau of Labor Statistics. (2014a). Employer-reported workplace injuries and illnesses 2013 (News release). Retrieved from http://www.bls.gov/news.release/osh2.nr0.htm Bureau of Labor Statistics. (2014b). Nonfatal occupational injuries and illnesses requiring days away from work, 2013 (News release). Retrieved from http://www.bls.gov/news.release/osh2.nr0.htm Bureau of Labor Statistics. (2015). Census of Fatal Occupational Injuries Summary, 2014. Retrieved from http://www.bls.gov/news.release/cfoi.nr0.htm Byler, C. G. (2013). Hispanic/Latino fatal occupational injury rates. Monthly Labor Review, 136(2), 14– 23. Centers for Disease Control and Prevention. (1999). Improvements in workplace safety—United States,

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Scherer, E., Seabury, S. A., O'Leary, P., Ozonoff, A., & Boden, L. (2014). Using linked federal and state data to study the adequacy of workers' compensation benefits. American Journal of Industrial Medicine, 57, 1165–1173. Schulte, P. (2005). Characterizing the burden of occupational injury and disease. Journal of Occupational and Environmental Medicine, 47, 607–622. Shannon, H. S., & Lowe, G. S. (2002). How many injured workers do not file claims for workers' compensation benefits? American Journal of Industrial Medicine, 42, 467–473. Smith, J.D.R. (2012). Immigrant workers and workers' compensation: The need for reform. American Journal of Industrial Medicine, 55, 537–544. Spieler, E. A., & Wagner, G. R. (2014). Counting matters: Implications of undercounting in the BLS Survey of Occupational Injuries and Illnesses. American Journal of Industrial Medicine, 57, 1077–1084. Steege, A. L., Baron, S. L., Marsh, S. M., & Menendez, C. C. (2014). Examining occupational health and safety disparities using national data: A cause for continuing concern. American Journal of Industrial Medicine, 57, 527–538. Steenland, K., Burnett, C., Lalich, N., Ward, E., & Hurrell, J. (2003). Dying for work: The magnitude of U.S. mortality from selected causes of death associated with occupation. American Journal of Industrial Medicine, 43, 461–482. Strunin, L., & Boden, L. I. (2004). Family consequences of chronic back pain. Social Science & Medicine, 58, 1385–1393.

For Further Information Useful Web Sites Bureau of Labor Statistics; Injuries, Illnesses, and Fatalities program: http://www.bls.gov/iif Center for Construction Research and Training: http://www.cpwr.com National Council for Occupational Safety and Health: http://www.coshnetwork.org National Institute for Occupational Safety and Health: http://www.cdc.gov/NIOSH Occupational Safety and Health Administration: http://www.osha.gov OSHWiki of the European Agency for Safety and Health at Work: http://oshwiki.eu/wiki/Main_Page

Books The following three books, written across a forty-year period, explore general trends in U.S. workplaces, focusing on the social dimensions of work and how these affect workers. Ehrenreich, B. (2001). Nickel and dimed: On (not) getting by in America. New York: Metropolitan Books. Terkel, S. (1974). Working: People talk about what they do all day and how they feel about what they do. New York: Pantheon Books. Weil, D. (2014). The fissured workplace: Why work became so bad for so many and what can be done to improve it. Cambridge, MA: Harvard University Press. The next book is a standard text of occupational health, with detailed information on a variety of industries and health conditions. Levy, B. S., Wegman, D. H., Baron, S. L., & Sokas, R. K. (2011). Occupational and environmental health: Recognizing and preventing disease and injury (6th ed.). New York: Oxford University Press. The following five books provide historical accounts of occupational health and safety disasters, beginning with the 1911 Triangle Shirtwaist Factory fire and continuing with accounts of occupational cancer and

lung diseases during the twentieth century. Great reads for those interested in history. Brodeur, P. (1985). Outrageous misconduct: The asbestos industry on trial. New York: Pantheon Books. Cherniack, M. (1986). The Hawk's Nest incident: America's worst industrial disaster. New Haven, CT: Yale University Press. Levenstein, C., & Delaurier, G. F. (2002). The cotton dust papers: Science, politics, and power in the “discovery” of byssinosis in the U.S. Amityville, NY: Baywood. Randall, W. S., & Solomon, S. D. (1977). Building 6: The tragedy at Bridesburg. Boston: Little, Brown. von Drehle, D. (2004). Triangle: The fire that changed America. New York: Atlantic Monthly Press. This final book explores how science has been used, and abused, in occupational and environmental health policy. Michaels, D. (2008). Doubt is their product: How industry's war on science threatens your health. New York: Oxford University Press.

Chapter 22 Radiation Matthew P. Moeller This chapter is an update to the chapter on radiation in the second edition prepared by Arthur C. Upton. The author also acknowledges the contributions to this chapter by Steven E. Merwin, CHP, who, as a founder of Dade Moeller & Associates, has always advanced science, demanded thoughtful reasoning, and supported this colleague as both peer and friend. This revision is dedicated to my father, Dade W. Moeller, PhD, CHP, who was an extraordinary health physicist, environmentalist, scientist, and educator. Matthew P. Moeller, CHP, is CEO of Dade Moeller & Associates, a consulting company with roots in radiation protection that specializes in the occupational and environmental sciences by providing professional and technical services to federal, state, and commercial clients in support of nuclear, radiological, and environmental operations. Major company projects include those for the U.S. Department of Energy, National Institute for Occupational Safety and Health, and National Oceanic and Atmospheric Administration.

Key Concepts There are several forms of radiation, with both common features and important differences. Each may interact with living cells, and each presents potential public health concerns. The risk of each type of radiation-induced injury varies with the dose of radiation. Exposure to each form of radiation occurs from specific sources and via specific pathways, and there are public health policies designed to limit undue exposures. These policies balance benefits (e.g., from diagnostic procedures) with risks. Radiation is all around us. It comes from a fundamental event: an atom that has excess energy in an excited state rids itself of energy to move to a more stable state. Radiation is energy in an electromagnetic form. In all its forms, radiation is one of the most common environmental exposures, from both naturally occurring sources, radioactive materials, and radiationgenerating devices. We are exposed to radiation during airline flights, in our homes, during medical procedures, and on the beach. Radiation is integral in numerous industrial and professional settings, including medicine, dentistry, scientific research, nuclear electric power generation, and oil and gas exploration. When radiation interacts with matter, energy is deposited—and when that matter happens to be living tissue, adverse changes at the cellular level may result. Radiation is therefore a core topic in environmental health. Modern knowledge of radiation is just over a century old. The discovery of radiation and radioactive materials correlates directly with experiments designed to understand the atomic structure. While the ancient Greek philosopher Democritus, in the fifth century b.c., postulated that all matter is made up of a set of particles called atoms, it was not until 1895 that X-rays were discovered (by Roentgen), followed in short order by Becquerel's discovery of radioactivity in 1896 (although the term radioactivity was coined by Marie Curie two years later), and the electron by J. J. Thomson in 1897. A veritable Golden Age of theoretical and empirical advances followed. In 1911, Rutherford deduced the atom was composed of a tiny central core, or nucleus, containing all the positive charge and almost all the mass of the atom, and a nearly empty surrounding cloud region containing the light, negatively charged electrons in sufficient number to balance the inner positive charge. In 1932, Chadwick proved the existence of neutrons, establishing that all nuclei are composed of closely packed protons and neutrons. This insight was critical to understanding the atom and radioactivity: certain combinations of protons and neutrons are stable and remain intact unless disrupted by nuclear collisions, while other combinations are unstable. These unstable nuclei undergo transformations—spontaneous disintegration processes—that alter the proton to neutron ratio to achieve a stable state. Further developments in nuclear research came in rapid succession. In 1939, researchers discovered

uranium fission in the laboratory. On December 2, 1942, at the University of Chicago, the first selfsustaining nuclear fission chain reaction was started, making atomic energy a practical possibility—one that was realized in 1951, when a nuclear reactor first produced electricity. On July 16, 1945, the Trinity test in Alamogordo, New Mexico, marked the detonation of the first atomic weapon; the use of atomic weapons in Hiroshima and Nagasaki followed within months. Radiation is propagated through space in energy packets called photons. Each photon has an associated wavelength and frequency. A wave motion consists of a series of crests and troughs; the distance between successive crests, or successive troughs, is wavelength. Given that all photons travel at the speed of light (3 × 1010 cm/s), the number of individual waves, or cycles, passing through a certain point of a medium over the course of a second is frequency. The energy of a photon is inversely proportional to its wavelength and directly proportional to its frequency; it is expressed in terms of electron volts (eV). The energy ranges for the various types of radiation have not been precisely defined and overlaps in these energy ranges are common. All electromagnetic radiations are fundamentally the same—all traveling at the same velocity (speed of light), and differing only in wavelength, frequency, and energy. Figure 22.1 shows the electromagnetic spectrum, arrayed along these factors. These factors are key in determining the characteristics of the radiation and the amount of harm it may cause. As the wavelength shortens and frequency increases, more energy is released at close range, potentially harming living things.

Figure 22.1 The Electromagnetic Spectrum One characteristic essential to understanding the mechanism of harm is ionization potential; that is, whether the radiation contains sufficient energy to ionize atoms. When sufficient energy is present, the radiation interacts with one or more orbiting electrons of an atom and strips them away. The removed electron exhibits a unit negative charge while the residual atom exhibits a unit positive charge; these are known as an ion pair. The accompanying transfer of energy can result in chemical and biological changes that are harmful to health.

This chapter begins by describing nonionizing radiation types with longer wavelengths and lower frequencies—the lower part of Figure 22.1—and progresses up the spectrum, toward shorter wavelengths and greater frequencies, to ionizing radiations. Following this progression, the health effects of exposure to radiation increase in hazard.

Nonionizing Radiations Extremely Low Frequency Electromagnetic Fields Electric and magnetic fields are usually coupled, hence the term electromagnetic fields (EMFs), but at extremely low frequencies they may exist separately. An electric field can be produced by transferring electrons from one object to another, creating an imbalance of charged particles. A familiar example is the attraction between a comb and a person's hair. A magnetic field can be produced by sending electrical charges (electricity) through a wire. Any home appliance that has a motor can be a source of a magnetic field; examples are a refrigerator, a blender, and a vacuum cleaner. These EMFs do not carry enough energy to ionize matter, and are therefore called nonionizing radiation. Extremely low frequency (ELF) EMFs, time-varying magnetic fields with wavelengths greater than 108 cm and frequencies less than 300 Hz (Figure 22.1), are widely present throughout the environment. They arise with solar activity and thunderstorms, generally intermittently, and with low intensity. Stronger ELF EMFs are the localized 50 to 60 Hz fields generated by electric power lines, transformers, motors, household appliances, video display tubes (VDTs), and various medical devices, notably magnetic resonance imaging (MRI) systems. Some occupations, such as power line workers, welders, railway engine drivers, and sewing machine operators, have especially high exposures. Types and Mechanisms of Injury The induction of electric fields and currents results in energy being absorbed in the human body. The most common effects of ELF field exposure are awareness and annoyance, as with the “shock” of discharging an electrical charge. Some people report a sensitivity to EMFs, but scientific studies have not substantiated this condition. ELF EMFs may interfere with pacemakers. Some epidemiological data suggest an association between ELF magnetic field exposure and childhood leukemia, leading the International Agency for Research on Cancer (IARC) to classify ELF magnetic fields as “possibly carcinogenic to humans” (IARC, 2012); however, this claim is controversial as no experimental and mechanistic data exist to support this association. In fact no accepted mechanism has been identified to link ELF EMFs and significant adverse human health effects (World Health Organization, 2007; Foster & Moulder, 2013). Radiation Protection and Prevention Areas containing EMFs stronger than 0.5 mT (such as exist around transformers, accelerators, MRI systems, and other electrical devices) should be posted with warning signs and should be avoided by persons wearing pacemakers. Organizations such as the American Conference of Governmental Industrial Hygienists and the International Commission on Non-Ionizing Radiation Protection recommend exposure limits for workers, members of the general public, and people wearing medical devices such as pacemakers.

Radio and Microwave Radiations Microwave and radiofrequency radiation (MW/RFR), the second category of nonionizing radiation, has wavelengths from 107 cm to 0.1 cm with frequencies from about 3 × 103 Hz to 3 × 1011 Hz (Figure 22.1). MW/RFR sources are common and include radars, televisions, radios, cellular phones (Text Box 22.1), cell phone towers, and other telecommunications systems; industrial operations such as metalworking; household appliances such as microwave ovens; and medical applications such as diathermy and hyperthermia (Sliney & Colville, 2000). The human body is largely transparent to the longer wavelength radiations of microwaves. As the wavelength shortens and the frequency increases, energy is increasingly absorbed, peaking at the ultra

high frequency (UHF) television range (about 3 × 108 Hz). At frequencies above 109 Hz, less energy is absorbed and above 1010 Hz, the energy is reflected by the skin. For this reason, microwaves in the range between 109 Hz and 1010 Hz are potentially the most hazardous, as there is heating of the skin without thermal receptors being stimulated; in effect, a person does not recognize energy is being absorbed.

Text Box 22.1 Is Cell Phone Use Linked to Cancer? As cellular telephones have become commonplace across the world, concern about potential health risks has grown (Figure 22.2). Fears of increased risks of cancer from radiofrequency radiation have prompted public objections to the siting of television, radio, and cell phone transmission towers. As cell phone use expands, it will become the leading source of RFR exposure globally.

Figure 22.2 Cell phones Are Virtually Ubiquitous, and Entail Exposure to Radiofrequency Radiation Source: Wood, 2013.

Evidence to date is not definitive. Early epidemiological studies were generally negative. However, they were conducted when cell phones produced higher field strength than modern phones, when cell phone use was lower, and when long-term follow-up was not yet possible, limiting the conclusions that could be drawn. The largest study to date, the INTERPHONE study, enrolled over 5,000 glioma and meningioma cases, along with matched controls, and found suggestive results: an increased risk of gliomas in the very highest category of phone users, and a possible increased risk on the side of the head where the phone was used (INTERPHONE Study Group, 2010). However, subsequent studies have not consistently replicated these results (e.g., Hardell, Carlberg, & Hansson Mild, 2011), and other findings that would be corroborative, such as a dose-response relationship, increasing risk with increasing latency and/or lower age at first exposure, and increased risk in the temporal lobe (the part of the brain nearest the phone), have not consistently emerged. Almost all (but not all) animal studies have been negative. It is perhaps no surprise that reviewers and official bodies have reached inconsistent conclusions, with the International Agency for Research on Cancer (IARC) designating radiofrequency EMFs as “possibly carcinogenic to humans” (Group 2B) (Baan et al., 2011), while the German Commission on Radiological Protection (SSK), found “lack of, or insufficient evidence of, causality” (Leitgeb, 2012). The major health impacts of cell phones may not relate to EMFs at all, but rather to the (likely far higher) risks of distraction while using cell phones (Collet, Guillot, & Petit, 2010; Klauer et al., 2014). Cell phones also offer health benefits, such as their utility in calling for help in emergencies and in delivering health care. No comprehensive assessment, weighing risks and

benefits, has yet been performed. Types and Mechanisms of Injury The biological effects of MW/RFR appear to be primarily thermal. MW/RFR can penetrate deeply enough to burn dermal and subcutaneous tissues, burns that are slow to heal. Cataracts of the lens of the eye also can result from high-intensity exposures (1.5 kW/m2) (Lipman, Tripathi, & Tripathi, 1988), and death from hyperthermia has occurred in the industrial use of MW/RFR sources (Roberts & Michaelson, 1985). MW/RFR can also interfere with cardiac pacemakers and other medical devices. Although the biological effects of MW/RFR are attributed primarily to thermal mechanisms, some evidence suggests that nonthermal mechanisms may operate as well. These may include damage to DNA (Blank, 2008; Mazor et al., 2008), impairment of fertility, developmental disturbances, neurobehavioral abnormalities, depression of immunity, stimulation of cell proliferation, and carcinogenic effects (Tenforde, 1998; International Commission on Non-Ionizing Radiation Protection [ICNIRP], 2004: Hardell et al., 2007; Sadetski et al., 2008). Concern about cancer risk from radiofrequency radiation has gained significant attention due to the widespread use of cell phones. Radiation Protection and Prevention Prevention of injury from MW/RFR requires proper design and shielding of MW/RFR sources, along with appropriate training and supervision of potentially exposed people (especially those wearing pacemakers or other sensitive devices). To prevent detectable heating of tissue, exposures to MW/RFR of different frequencies should be kept below the relevant threshold limit values, which are based on the amount of radiofrequency energy absorbed in tissue, or the specific absorption rate (SAR) (ICNIRP, 1998; Sliney & Colville, 2000). The current SAR limit for cell phones, set by the Federal Communications Commission (FCC), is 1.6 watts per kilogram (FCC, 2015).

Infrared Radiation Infrared radiation (IR), electromagnetic waves with frequencies from about 3 × 1011 Hz to 4.3 × 1014 Hz (Figure 22.1), is commonly experienced as heat. Examples are the heat from the sun, a burning log fire, hot blacktop on a sunny day, and such industrial sources as furnaces, welding arcs, and heating lamps. The hazard from IR is excessive heat. Types and Mechanisms of Injury The injuries caused by IR are mainly burns of the skin and cataracts of the lens of the eye. Human skin contains heat sensors, which usually prompt aversion in time or distance to prevent injuries from a significant heat source. In contrast, the lens of the eye lacks heat sensors and the ability to dissipate heat received. For this reason it is particularly vulnerable. Consequently, glassblowers, blacksmiths, oven operators, and those working around heating and drying lamps are at risk of IR-induced cataracts (Lydahl, 1984). Radiation Protection and Prevention Control of IR hazards and avoidance of IR-related injuries requires limiting the duration of exposures and shielding sources, as may be achieved with proper training, adequate supervision of potentially exposed people, and the use of physical barriers and other engineered controls as well as personal protective devices such as specialized clothing and goggles. It is recommended that people not be exposed to intensities of IR exceeding 10 mW/cm2.

Visible Light Visible light consists of electromagnetic waves ranging in wavelength from approximately 7.6 × 10−5 cm (red) to 3.8 × 10−5 cm (violet), which corresponds to 760 and 380 nm, with frequencies from 3.9 × 1014 Hz to 7.9 × 1014 Hz (Figure 22.1). Sources of visible light in the environment vary widely in the intensity of their emissions. Common high-intensity sources other than the sun include lasers, electric welding or carbon arcs, and tungsten filament lamps.

Types and Mechanisms of Injury A light that is too bright can injure the eye through photochemical reactions in the retina. Sustained exposure to intensities exceeding 0.1 mW/cm2, such as can result from gazing at a bright source of light, can produce photochemical blue-light injury, and brief exposure of the retina to intensities exceeding 10 mW/cm2, depending on image size, may cause a retinal burn, resulting in a scotoma (blind spot), which can be permanent. The lens, iris, cornea, and skin are also vulnerable to injury from the thermal effects of laser radiation. Conversely, too little illumination can also be harmful, causing eyestrain and aggravating seasonal affective disorder (SAD). Radiation Protection and Prevention Industrial applications involving potential exposure are carbon arcs, lasers, or other high-intensity sources. Protection against injuries requires avoiding exposures. Strategies include engineering controls such as shielding materials, proper training, effective procedures, adequate supervision of potentially exposed people, and personal protective devices such as protective eye shields.

Ultraviolet Radiation Ultraviolet radiation (UVR) consists of electromagnetic waves, subdivided for convenience into three bands of the spectrum (Figure 22.1): UVA, 315 to 440 nm (or black light); UVB, 280 to 315 nm; and UVC, 100 to 280 nm (which is germicidal). UVR is nonionizing at lower frequencies and ionizing at higher frequencies. The chief source of population exposure to UVR is sunlight, which varies in intensity with latitude, elevation, and season. Important man-made sources of high-intensity exposure include sunlamps and tanning lamps, welding arcs, plasma torches, germicidal and black light lamps, electric arc furnaces, hot-metal operations, mercury-vapor lamps, and lasers. Common low-intensity sources include fluorescent lamps and certain laboratory equipment. While UVR may damage health, it is also essential in vitamin D synthesis. Types and Mechanisms of Injury Because UVR does not penetrate deeply into human tissues, the injuries it causes are confined chiefly to the skin and eyes. Dermal reactions to UVR, common among fair-skinned people, include sunburn, pigmentation, skin cancers (basal cell and squamous cell carcinomas and possibly, to a lesser extent, melanomas), aging of the skin, telangiectasia, solar elastoses, and solar keratoses (Figure 22.3). Injuries of the eye include photokeratitis and photoconjunctivitis, which may result from brief exposure to a highintensity UVR source (welder's flash) or from more prolonged exposure to intense sunlight (snow blindness); prolonged exposure may also cause cataracts, macular degeneration (evidence is equivocal), and other conditions (Yam & Kwok, 2014).

Figure 22.3 A Basal Cell Carcinoma of the Skin of Twenty Years, Duration in a Fifty-Eight-Year-Old Man

Source: Warren, 1953. Reprinted with permission from Elsevier. Such tumors are the commonest of cancers and occur primarily in sun-exposed areas of the skin.

The effects of UVR result both from its immunosuppressive effects and from its absorption by DNA, leading to pyrimidine dimer formation and mutational changes in exposed cells (Halliday, Byrne, & Damian, 2011; Pfeifer & Besaratinia, 2012). Sensitivity to UVR can therefore be increased by DNA repair defects (e.g., xeroderma pigmentosum), by agents (such as caffeine) that inhibit the repair enzymes, and by photosensitizing agents (such as tetracyclines and some other medications) that produce UVRabsorbing DNA photoproducts. UVB, although far less intense than UVA in sunlight, plays a more important role in sunburn and skin carcinogenesis. UVA contributes to these outcomes, as well as to tanning, some photosensitivity reactions, aging of the skin, photokeratitis, and cortical lens opacities. Radiation Protection and Prevention Exposure to sunlight or other sources of UVR should be limited in exposure in intensity and duration, especially for fair-skinned people. Even at higher frequencies, UVR is shielded by an ordinary window. Protection afforded by clothing depends on its color and composition; for example, cream-colored and bright pink cotton cloth provide sun protection factors (SPFs) of 10 and >30, respectively (Gies, 2007). Most topical sunscreens protect against UVB, and broad-spectrum sunscreens also protect against UVA. UVR-blocking sunglasses are useful for eye protection. In the workplace, methods of protection may include engineering and administrative controls. The Earth's protective layer of stratospheric ozone has been depleted by chlorofluorocarbons and other air pollutants, increasing the UVR reaching the Earth, and raising the risk of nonmelanotic skin cancer, especially at high latitudes. The Montreal Protocol is expected to avert further thinning of the ozone layer, and to allow it to be restored over coming decades. This success is credited with avoiding as many as 2 million cases of skin cancer globally each year by the year 2030 (van Dijk et al., 2013).

Ionizing Radiation: The Basics The X-ray, gamma ray, and cosmic ray radiations comprise the remainder of the electromagnetic spectrum. They are of progressively shorter wavelengths and greater frequencies (see Figure 22.1). All are ionizing radiations, which means they can deposit enough localized energy in a living cell to break chemical bonds and give rise to ion pairs and free radicals. Radiation may cause ionization either directly or indirectly. Electrically charged particles with sufficient kinetic energy to produce ionization by collision are called directly ionizing particles; these include protons, alpha particles, and beta particles. Electrons may also be directly ionizing. In contrast, uncharged neutrons, gamma rays, and neutral mesons may impart only enough energy to liberate directly ionizing particles; these are called indirectly ionizing radiations. Radioactivity may be defined as spontaneous nuclear transformations that result in the formation of new elements (Cember & Johnson, 2008). A starting point for understanding this process is understanding the various transformation mechanisms; these are shown in Figure 22.4.

Figure 22.4 Nuclear Transformation Mechanisms That Release Radioactivity

Through these transformation mechanisms, unstable nuclei assume more stable forms. Which mechanism occurs depends upon the nature of the instability, and the mass-energy relationship among the parent nucleus, resulting progeny nucleus, and emitted particle.

In several of the transformation mechanisms shown in Figure 22.4, gamma ray emission and X-ray emission serve to dissipate excess energy. Gamma rays are photons originating in the nucleus while Xrays are photons originating from the inner orbits of the atom. The two kinds of radiation are indistinguishable, although gamma radiation usually carries more energy. Gamma rays lose energy through chance encounters that result in the ejection of electrons from atoms. Both X-rays and gamma rays are sparsely ionizing in comparison with charged particles; that is, their energy deposition is less concentrated as their energy is deposited over a greater distance. A radionuclide (see Text Box 22.2) can be quantified by its transformation kinetics, including its halflife and activity. Each radionuclide is transformed at a different, unique rate. These transformation rates range from nanoseconds to billions of years. Half-life is the time required for any given radionuclide to decrease to one-half of its original quantity by nuclear transformations. Radionuclides with very long halflives, such as some components of nuclear waste, pose challenges to safe storage, as discussed in Chapter 14. Activity, the rate of transformations per unit time, is a measure of radioactivity. The becquerel (Bq), a unit of activity, is defined as that quantity of material in which one atom is transformed per second. Of historical importance, the original unit of activity was named for Marie and Pierre Curie; this measure is still used in some settings, such as in assessing home to radon exposure. (The U.S. Environmental Protection Agency [U.S. EPA] recommends abatement of a home if the measured air concentration exceeds 4 picocuries per liter of air, or pCi/L.) The concentration of radioactivity, or the relationship between the mass of radioactive material and the activity, is called specific activity. The specific activity is the number of becquerels per unit mass or volume.

Text Box 22.2 What Are Isotopes? For any particular element, the number of neutrons within the nucleus may vary. The element oxygen, which always contains eight protons, consists of three naturally occurring and stable (nonradioactive) nuclear species: ones with a nucleus containing eight, nine, and ten neutrons, resulting in atomic mass numbers of 16, 17, and 18. These three nuclear species of the same element are called isotopes of oxygen. Isotopes cannot be distinguished chemically as they have the same extranuclear electronic structure and therefore undergo the same chemical reactions. Nuclear species of different elements are called nuclides and radioactive species of different elements are called radionuclides. One of the challenges to understanding the measurement and effect of radiation is an abundance of terms for units of exposure and dose. The units presented in Table 22.1 are those of the International System, introduced in the 1970s to standardize usage throughout the world. They have largely supplanted earlier units, such as the curie. Table 22.1 Units of Radiation Exposure and Dose Parameter

Units

Description

Absorbed dose Gray (Gy), in units of joule/kg Energy imparted to tissue. Equivalent dose Sievert (Sv), in units of joule/kg Absorbed dose corrected for the LET (linear energy transfer) deposition density. Effective dose Sievert (Sv), in units of joule/kg Equivalent dose corrected for the sensitivity of the exposed tissue (or organ). Committed Sievert (Sv), in units of joule/kg Cumulative effective dose to be received over time effective dose from an intake of radioactivity. Collective Person-sieverts (person-Sv), in Effective dose applied to a population. effective dose units of joule/kg Radiation exposures are divided into external and internal doses. An external dose is received from

sources outside the body; the energy is imparted immediately upon exposure. An internal dose occurs when radioactive material enters the body through inhalation, ingestion, absorption through the skin or via a wound. An internal dose may be received over an extended period of time because the radioactive material inside the body continues to deposit energy within the body as it decays, unless it is removed by some other biological, therapeutic, or physical mechanism.

Sources of Ionizing Radiation Exposure People are exposed to radiation from a wide variety of natural and anthropogenic sources. Natural sources include cosmic rays from outer space and gamma-emitting photons emitted from naturally occurring radioactive minerals in the Earth, especially radon. The major anthropogenic exposures occur in medical diagnosis and treatment, although other exposures, ranging from consumer products to industrial uses to nuclear waste, may be important. Table 22.2 shows the average radiation doses received by a U.S. resident. Importantly, these are only averages; a person who frequently flies across the country or who needs frequent diagnostic X-rays may have a substantially different exposure profile. Table 22.2 Average Amounts of Ionizing Radiation Received Annually by a U.S. Resident Source

Dose (mSv)a Percentage of total

Natural Cosmic Terrestrial

0.27 0.28

4 4

1.9 0.39 2.84

31 7 46

2.4 0.8 3.2 0.10