Lynn R. Goldman
Dr. Goldman reports no conflicts of interest related to the authorship of this chapter.
The mission of environmental public health extends well beyond remediating, cleaning up, or otherwise making up for past mistakes. It is to ensure conditions that enhance the health of humans and other species. This chapter examines the concept of prevention and its application in environmental public health. It explores the principles and frameworks that underlie prevention in environmental public health, and how prevention strategies in environmental public health fit within the general practice of public health.
The environment has a major impact on the risk of chronic diseases such as cancers, chronic lung disease, and birth defects and on the risk of acute illnesses such as viral gastroenteritis, respiratory infections, and such vector-borne diseases as malaria. Accordingly, environmental public health is concerned with the prevention of these conditions.
But the environment has far broader impacts on health. Some environmental conditions confer resilience to even the most harmful natural disasters, while others put people directly in harm's way (e.g., through building on flood plains and earthquake-prone faults.) Some environments promote health by providing nutritious food, adequate supplies of drinking water, opportunities for outdoor recreation, and the aesthetic and mental health benefits of nature contact. The state of knowledge about causation of communicable diseases is more advanced than that for chronic diseases and natural disasters, which are in turn better understood than environmental aspects of health promotion. However, prevention efforts in environmental health need to address all of these concerns.
From the outset it is important to emphasize that certain environmental health problems are much more serious in developing countries than in wealthy countries. In developing nations, for example, drinking water contaminated by microorganisms and toxic substances causes considerable morbidity and mortality (see Chapter 16), and burning coal, wood, and other biomass fuel sources for cooking and heating contributes to indoor and outdoor air pollution (see Chapter 13). Chemical releases are more common, and there are fewer means to protect workers, nearby communities, and passersby. Worldwide there are large numbers of deaths and injuries due to earthquakes, storms, and floods; many of these deaths are preventable with appropriate environmental measures such as construction standards for homes and buildings, which are less likely to be implemented in developing nations.
René Dubos, in 1965, noted that indices of environmental health are “expressions of the success or failure experienced by the (human) organism in its efforts to respond adaptively to environmental challenges.” Prevention in environmental health is at its core a continuous effort to adapt to environmental challenges, most of which are created by human activities. With rapid population growth, development, and technological change on a global scale, prevention efforts have become more and more complex.
Despite these challenges there is evidence of remarkable success in environmental health protection over the last two centuries. The sanitary movement of the 1800s resulted in enormous reductions in mortality from infectious diseases. This accounted for remarkable increases in life expectancy in much of the world—in the United States, from 47 years in 1900 to 80 in 2012. In the last forty-five years in the industrialized nations, stronger environmental laws have resulted in cleaner air, safer drinking water, and recovery of some rivers and lakes that in 1970 had unacceptable levels of pollution for fishing and recreation. In many parts of the world, to a great extent, the easiest problems have been addressed, leaving environmental threats that are much more difficult to control and require more participation from a broader range of society. Environmental health problems today often involve multiple small sources of pollutants rather than a few large and visible ones. Many of these small sources are from sectors such as agriculture and small business, where individual farmers and owners may be less familiar with environmental regulations and often resistant to change. Further, as countries confront climate change by reducing carbon emissions, new technologies will emerge and, with them, new challenges for prevention of health threats.
Global trends in environmental health are disturbing. Worldwide, cities are overcrowded, polluted, and provide too little open space and too few safe walking and cycling routes. Economic development and the rapid pace of urbanization have resulted in alarming increases in air and water pollution and in waste generation. Emissions of greenhouse gases, particulate air pollutants, and nitrous and sulfur dioxides from burning fuels are a major cause of morbidity and mortality globally. Drinking water is under pressure both from pollution and from overconsumption and aging drinking-water infrastructure. In many parts of the world there are serious shortages of potable water. Weather extremes associated with global warming are associated with increased risk of heat-related mortality, increased severity of weather events and the resultant impacts on human health and well-being, changes in the ranges of vector-borne diseases, altered agricultural productivity, and uncertain water supplies. Pollution and overfishing are threatening fish harvests. At the same time, efforts to produce more fish via fish farming have too often had other undesirable environmental consequences, such as water pollution. Globally, there is little control of chemicals and pesticides (Chapter 18) in commerce and in consumer goods and in how they are disposed of. Prevention of noncommunicable diseases is especially challenging for developing countries because these diseases are multifactorial, and because the scarcity of local data makes prevention efforts highly dependent on international practices instead of being rooted in local culture, lifestyles, and climate (McMichael, Woodruff, & Hales, 2006).
The DPSEEA (driving forces-pressures-state-exposure-effects-actions) model, presented in Chapter 1 (see Figure 1.4), is useful in understanding environmental health prevention efforts. Driving forces are factors such as population growth and technology development that motivate environmental processes. These result in the generation of environmental pressures, for example, increases in vehicle miles driven or in the number of coal-fired power plants. The state of the environment, such as the concentration of pollutants in air (and whether such concentrations are potentially hazardous), is modified by such pressures. Exposure occurs when people are present both at the place and at the time the hazard occurs, and when there is an intact pathway for exposure. Depending on the amount of exposure (dose) and timing of exposure, as well as other factors such as life stage and co-exposures, exposure may lead to health effects.
Actions to reduce or control the hazards (or to promote environmental health) can be taken at all points in this chain of events. In 1958, Leavell and Clark defined a model for prevention that remains relevant. In this three-level model, primary prevention involves interventions prior to the development of any signs of ill health. In the case of environmental health, strategies directed toward modifying driving forces, pressures, and state of the environment are primary prevention efforts. Such efforts are divided into two categories:
Secondary prevention is early detection of a health problem, prior to the onset of disease, for the purpose of intervening at an early stage to prevent the development of the disease. In environmental health this is usually a preventive effort targeting the phase when exposure has begun to occur but prior to the development of any health impacts. An example of such a prevention strategy is occupational lead screening, to identify workers at an early stage of exposure and to take steps to prevent further exposure. Tertiary prevention involves early identification and treatment of people with a disease, to prevent or forestall disability and/or death. An example of tertiary prevention is the effort to ensure that patients with asthma follow recommended guidelines for medical treatment and environmental remediation in order to reduce the frequency and severity of asthma attacks.
The case of childhood lead poisoning is a good illustration of the value of primary prevention. In the United States, early efforts to control childhood lead poisoning were focused on massive efforts to assess children's blood lead levels, via blood lead screening campaigns. This was tertiary prevention: these programs identified children with clinically elevated blood lead levels (initially, 60 μg/dL and above) so that they could be treated to avert the most severe consequences of lead poisoning. As a result of discoveries about lead toxicity the CDC's reference level for lead was lowered, in several steps, from 60 to (by 2012) 5 μg/dL. At the same time, government began to fund efforts to remediate lead contamination in households where there were children with elevated blood lead levels. This was secondary prevention, and it stopped lead-poisoned children from being reexposed when they returned home. By the 1990s in the United States, most children identified with elevated blood lead levels did not require specific medical therapy. The emphasis shifted to primary prevention efforts: control of lead in paint, pipe solder, and other plumbing materials and in numerous other consumer products and the phaseout of lead in gasoline in the 1980s. These measures lowered lead exposures across the entire population. Most recently, efforts to abate lead-based paint have focused on all housing that is likely to expose children to lead, not just homes with lead-poisoned children—often as part of broader “healthy housing” initiatives. This is a transition from an illness-based model, one predicated on identifying and treating clinically ill children, to a model of wellness promotion, one that seeks to prevent lead toxicity and to promote healthy residential settings. While physicians and other medical professionals continue to have a role to play, there is a much stronger role for environmental and housing experts and for community efforts to enforce housing codes (American Academy of Pediatrics, Committee on Environmental Health, 2005).
The practice of industrial hygiene is an approach to prevention in occupational health that hews to a prevention hierarchy that is similar in concept to primary and secondary prevention (see Chapter 8). From preferable to less preferable prevention approaches, the hierarchy is
Pollution prevention is an approach to environmental health prevention akin to the concept of primary prevention. It extends approaches used in industrial hygiene to the general environment. The principles of pollution prevention as defined by the 1990 Pollution Prevention Act are that
Pollution prevention aims for increased efficiency in the use of raw materials, energy, water, or other resources, or for protection of natural resources by conservation. Pollution prevention can be envisioned as a ladder of potential environmental health strategies, in order of most to least preferable:
Source reduction practices are varied and include equipment or technology modifications; process modifications; reformulation of materials; redesign of products; substitution of raw materials; and improvements in housekeeping, maintenance, training, or inventory control. When all costs are taken into account, reduction of pollution at the source is generally less expensive than end-of-pipe controls on emissions and/or environmental cleanup. Pollution prevention strategies can also be more effective than efforts to address pollution in one medium at a time. Multimedia approaches look at all impacts of decisions “from cradle to grave”; such an analysis, called a life cycle analysis, can result in the adoption of more effective preventive strategies (life cycle analysis is described in detail in Chapter 3).
In 1992, more than one hundred nations represented at the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro signed the Rio Declaration on Environment and Development, a document that formally adopted the goal of sustainable development and twenty-seven principles of sustainable development, many of which have a direct bearing on prevention. Chief among these is Principle 1, which states: “Human beings are at the center of concerns for sustainable development. They are entitled to a healthy and productive life in harmony with nature” (UNCED, 1992). Additional principles for sustainable development that are key to public health prevention are the precautionary principle and the principles of intergenerational equity, of access to information and the decision-making process, of integrated decision making, and of polluter pays.
The precautionary principle, as formally stated in 1992, says: “In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation”(UNCED, 1992). For example, the pesticide dichlorodiphenyltrichloroethane (DDT) was banned in the United States long before its precise mechanisms of action had been described by scientists (see Chapter 18). Another example concerns the introduction of tens of thousands of chemicals into commerce without requiring premarket testing or regulation of those chemicals, as described in Chapter 6. Adoption of the precautionary principle in this case would imply a duty to take “cost-effective” measures to reduce environmental degradation without the demand for “full scientific certainty” about the harm of toxic chemicals, greenhouse gases, and so forth prior to taking action to prevent damage to health and the environment from such hazards.
The principle of intergenerational equity states: “The right to development must be fulfilled so as to equitably meet developmental and environmental needs of present and future generations.” This principle emphasizes the responsibility of the present generation to take steps to prevent adverse circumstances for generations that follow. For example, persistent organic pollutants (POPs), such as DDT (discussed in Chapter 18), PCBs (see Tox Box 2.1, in Chapter 2), methylmercury (see Tox Box 13.2, in Chapter 13), and dioxins (see Tox Box 19.1, in Chapter 19), have left a legacy of pollution for future generations. Emissions of greenhouse gases have set into motion processes that will alter the earth's climate for generations to come. This principle can come into conflict with economic models that assume that actions need to be judged only against the expected economic return from other similar investments, an approach that can zero out benefits to future generations. In practice, decision makers need to include both economic analyses and consideration of the principle of intergenerational equity, particularly for outcomes such as climate change, for which the consequences (and therefore the economic costs) are very difficult to predict but likely to be large and irreversible (see Chapter 10).
The principle of access to information and the decision-making process states: “At the national level, each individual shall have appropriate access to information concerning the environment that is held by public authorities, including information on hazardous materials and activities in their communities, and the opportunity to participate in decision-making processes. States shall facilitate and encourage public awareness and participation by making information widely available.” This principle, often referred to as the right to know, can be found in U.S. law, including OSHA's right-to-know standard for workers, and the Emergency Planning and Community Right-to-Know Act (EPCRA) of 1986, a mainstay of preparedness for chemical and other disasters. Many different actors—environmental experts, farmers, industries, utilities, developers, government agencies at all levels, and individual consumers—are involved in environmental decision making and need environmental information to manage risk. Having shared information and input into decision-making processes is also a key element of any democratic process.
According to the principle of integrated decision making, “In order to achieve sustainable development, environmental protection shall constitute an integral part of the development process and cannot be considered in isolation from it.” This means that environmental considerations need to be incorporated into decision-making processes at all levels. This principle has been incorporated into the health in all policies movement in public health in the United States and globally. In the United States, the National Environmental Policy Act (NEPA) requires the preparation of environmental impact reports for all federally funded projects, and many states have such requirements as well. A related tool, the health impact assessment, focuses specifically on health consequences of decisions “upstream” from health. (HIAs are explored in detail in Text Box 15.5, in Chapter 15.) For example, a health impact assessment might assemble data comparing the health consequences of a highway expansion, a transit investment, and improved pedestrian infrastructure to help planners reach the most health-promoting decision on the use of transportation funds (Dannenberg et al., 2006).
The polluter pays principle embodies the notion that those who cause and profit from pollution should bear the burden of cleaning it up. In economic terms this is an effort to internalize the costs of externalities. More recently, this principle has also evolved into the concept of economic instruments such as pollutant trading systems that seek to shift the societal cost of pollution to the polluter, in order to reduce the overall levels of pollution. The ability to assign the cost of emissions and cleanups to polluters serves as a powerful incentive for pollution prevention.
In 1988, the U.S. Institute of Medicine published The Future of Public Health, a report that defined three core public health functions: assessment, policy development, and assurance (Institute of Medicine, 1988).
Exposure assessment—the science behind environmental public health assessment—is discussed extensively in Chapter 8; this chapter focuses only on aspects of public health assessment having to do with prevention. The DPSEEA framework (described earlier) helps to identify a number of potential targets for monitoring environmental conditions and associated health outcomes (also see Text Box 26.1). As a tool for prevention, monitoring can provide the data needed to
Research is also an important component of the assessment process. Information about mechanisms of environmental health risks, including gene-environment interactions, will assist researchers in developing more informed and targeted strategies for disease prevention. Additionally, we have considerable uncertainty about the value of ecosystem services to human health and welfare. There have been serious disruptions in fundamental planetary processes, as described in Chapters 2 and 3, most famously the carbon cycle with a multitude of potential health effects (see Chapter 12) but also the nitrogen and phosphorus cycles, which have implications for pollution of sensitive water bodies. Species extinctions, overfishing, overfarming, and overirrigation have been documented in dramatic terms, but we do not fully understand the impacts on health.
From the standpoint of prevention it is important to learn not only about the proximate causes of a problem but also the root causes. As an example, scientists have identified in utero exposure to methylmercury as a risk factor for neurodevelopmental delays in children (see Tox Box 13.2, in Chapter 13). This is an issue of intergenerational equity, and effort has been directed toward protection of the fetus by advising women who are or who may become pregnant to reduce their consumption of mercury-contaminated fish. Going upstream from the problem of mercury-laden fish, however, one can also identify major sources of mercury emissions, such as coal-fired power plants and require the installation of pollution control equipment to remove the mercury from these emissions. Examination of root causes might suggest a very different set of policy approaches than fish consumption advisories. In fact, because mercury releases have global impacts, the recently adopted Minamata Convention on Mercury has identified a range of causes of mercury pollution to be addressed, including phasing out nonmedical uses of mercury batteries, mercury switches and relays, some compact fluorescent lamps, mercury in soaps and cosmetics, and certain mercury-containing medical devices such as thermometers and blood pressure devices. Governments have also identified the need to reduce mercury emissions from small-scale gold mining and from coal-fired power plants as well as from large-scale industrial plants (United Nations Environment Programme, 2015).
Environmental health policy has undergone major transformations over the years. There are numerous examples of environmental health policy failures, most reflecting an inability to predict, prepare for, and prevent adverse effects of new technologies. This includes the massive food safety and consumer products problems in the early 1900s (well documented by author Upton Sinclair); the decision in the early part of the twentieth century to permit the use of lead in gasoline; the killer smog episodes in London in the mid-twentieth century caused by soot from coal burning; a very long term problem resulting from “playing catch-up” with the risks of industrial chemicals and pesticides (see Chapter 18), leading, for example, to epidemics of cancers from asbestos (see Tox Box 20.3, in Chapter 20) and the industrial chemical vinyl chloride; and today, the continued construction of polluting industrial and energy plants that burn fossil fuels even while the evidence of global warming is incontrovertible. In addition, nanotechnology-based industries in the United States and elsewhere have expanded at a much more rapid pace than the development of a policy framework to anticipate and mitigate the possible adverse consequences of this new technology.
At the same time, there are many examples of successful prevention strategies. The National Environmental Protection Act (NEPA) and similar laws in the United States and internationally have required environmental impact studies that have been effective tools for pollution prevention. The Toxics Release Inventory in the United States (known as a pollutant release and transfer registry elsewhere) is an example of a right-to-know approach to policy development that has promoted pollution prevention through informing industry and communities of toxic releases and driving pollution reduction and pollution prevention efforts; such efforts have been particularly effective in states such as Massachusetts that have toxic use reduction laws. In the United States the Clean Air Act for new sources and the Food Quality Protection Act have been effective in preventing risks. An ethic of pollution prevention has caught hold in a number of sectors. The American Chemical Society, chemists, and many in the chemical industry have advanced the science of green chemistry and green engineering to develop new materials and processes that are inherently safe from cradle to grave. Builders and architects are increasingly embracing the green building movement (discussed in Chapter 20) with voluntary certification programs, stimulating customer demand for buildings that are more sustainable. Movements such the initiative begun by the Health Care Without Harm coalition have captured the imagination of the medical community, which is in turn evolving more environmentally benign ways to build and operate hospitals and other medical facilities. Many companies, as well as governments at many levels, have undertaken environmental purchasing policies. All of these voluntary approaches have been driven by the availability of information about the potential hazards associated with various alternatives.
A fundamental issue in environmental health policy development is that there are often great uncertainties in every aspect of policy development. Risk characterizations often include large ranges of potential risks, but there can be large uncertainties in risk management decisions as well. It is when decisions must be made in the face of uncertainty that principles such as precaution may be invoked. Technology-based approaches, such as the Maximum Available Control Technology (MACT) standards developed for hazardous air pollutants under the Clean Air Act, can be a useful strategy for preventing risks (of magnitude unknown) in the face of uncertainty by applying available technologies. The hazardous air pollutant standards promulgated by the U.S. Environmental Protection Agency (U.S. EPA) have been extolled for resulting in a 90% reduction of hazardous air emissions during the decade after the passage of the 1990 Clean Air Act Amendments. While such approaches do achieve prevention goals to an extent, failure to analyze and understand risk across the life cycle can have adverse consequences. For example, in the case of the hazardous air pollutant standards, control of ambient air emissions could come at the cost of greater exposures within the workplace, in discharges to water or waste, or even in a final product (Goldstein, 2004). Without an effort to reduce uncertainties about the risk of a substance, such exposures could go unnoticed and uncontrolled, but the Clean Air Act does not drive the generation of such data. Conversely, excessive analysis can also have adverse and even paralyzing consequences; for example, the U.S. EPA's dioxin assessment took more than twenty years (see Tox Box 19.1, in Chapter 19).
A second limitation to our ability to prevent environmental health risks is that all too often there are trade-offs among risks. An example of a risk-risk trade-off is the disinfection of drinking water with chlorine. Chlorine not only kills most pathogens in source waters but also leaves a residual level that protects against pathogens that may be introduced within the water distribution system. Yet as described in Chapter 16, chlorination can form disinfection by-products, some of which have chronic, low-level toxicity. It is almost axiomatic that, as in the case of medicine, every environmental intervention that prevents one adverse effect is likely to have adverse side effects as well. A prevention strategy takes a careful look at all implications of alternative interventions.
Environmental public health assurance is complex because of the myriad parties who have a stake in environmental health issues and/or must take action in order to implement policies. Few of those parties are environmental health experts. In many cases, policymakers in the executive, legislative, and judicial branches of government must be persuaded that a particular policy can be implemented. Thus it is critical that the public be engaged at every stage of the process and that there be broad agreement with the assessment of the problem, as well as trust in the policymaking process. In other words, there needs to be a shared sense that there is a problem that needs to be addressed, a shared view of the magnitude of the problem and the uncertainties, and assurance that a reasonable effort was made to develop fair, effective policies and to engage all involved parties. Vested interests may opt to oppose implementation of a new policy, in which case it is particularly important to secure the agreement of other parties. Increasingly, in the case of pollutants with global transport, such as mercury, there are efforts to craft global agreements, such as the Minamata Convention on Mercury, adopted in 2013 and mentioned earlier. These international agreements are complex and difficult to negotiate, involving the entire cast of affected parties from multiple countries.
One particularly challenging aspect of implementing preventive policies is the difficulty of proving what would have happened in the absence of a given policy. As has recently been observed in the case of climate change, some parties disbelieve the results of models and predictions of future scenarios, and they may be reluctant to invest in preventive strategies on that basis. Furthermore, for those who think primarily in economic terms, preventive interventions may appear to be bad investments. As already noted above, because economists use a discount rate to calculate the future value of money that is invested in the present, economic analyses tend to downplay the value of measures that provide benefits in the remote future. Finally, the urgent may be the enemy of the important; more pressing and immediate issues may eclipse longer range concerns. Accordingly, it is crucial that preventive actions be accompanied by efforts to monitor the consequences of those actions, to link that information to policies that have been implemented, to modify actions based on this review, and to provide accurate and timely feedback to the public and policymakers about the successes and failures of such actions.
In the United States, public health organizations have defined a set of ten essential services of public health, all of which are necessary to support the three core functions of assessment, assurance, and policy development. More recently the CDC's National Center for Environmental Health (NCEH) has defined the ten essential services of environmental health, services relevant to the environmental health practice community. Both sets of services are shown in Table 26.1.
Each of these services is an important component of the overall public health infrastructure. For instance, the first essential service requires the creation of an environmental health surveillance system, which supports detection of environmental hazards and related illnesses and assessments of the need for additional services. Using data from this system, public health professionals can advocate for the necessary legal support and resources for programs to address community needs. In recent years the development of spatial data technology and its use in geographic information systems has allowed public health officials to map the occurrence of hazards and illnesses in their communities and then to use these maps in dialogues with citizens and elected officials to create awareness and the political will to address these concerns (see Chapter 5).
To reinforce, support, and standardize public health systems, the CDC developed a set of performance standards tools that can be used to assess the capacity of state and local agencies and local boards of health to provide the ten essential services of public health. These tools have been utilized by the NCEH to develop the Environmental Public Health Performance Standards (www.cdc.gov/NCEH/ehs/EnvPHPS/default.htm), a set of standards for environmental health agencies and other practitioners, based on the ten essential services of environmental health. Through voluntary use of these standards at the federal, tribal, state, and local levels, the NCEH aims to enhance the capacity, consistency, and accountability of the nation's environmental health services. A number of local and state agencies have used these standards to improve their environmental health services.
There also has been a need for assessments of the quality of local governments' environmental health services. In the United States an assessment protocol has been developed: Protocol for Assessing Community Excellence in Environmental Health: A Guidebook for Local Health Officials (PACE-EH) (National Association of County and City Health Officials [NACCHO], 2004). This multistep protocol (see Table 26.2) evaluates progress and supports planning for the future. (www.naccho.org/topics/environmental/PACE-EH/index.cfm). The NCEH strongly supports the use of community environmental health assessments as a means to improve community health, and makes a variety of resources and case studies available for this purpose (see, e.g., www.cdc.gov/nceh/ehs/ceha/default.htm). A number of other agencies, such as the U.S. Environmental Protection Agency, have developed tools for community involvement, centering around the core value of community empowerment and voice in the design of environmental health services and healthier communities. The EPA's CARE program (Community Action for a Renewed Environment) is one such example (www.epa.gov/care).
Table 26.2 The Protocol for Assessing Community Excellence in Environmental Health (PACE-EH) Process
| Task 1 | Determine community capacity. |
| Task 2 | Define and characterize the community. |
| Task 3 | Assemble a community-based environmental health assessment team. |
| Task 4 | Define the goals, objectives, and scope of the assessment. |
| Task 5 | Generate a list of community-specific environmental health issues. |
| Task 6 | Analyze the issues with a systems framework. |
| Task 7 | Develop locally appropriate indicators. |
| Task 8 | Select standards against which local status can be compared. |
| Task 9 | Create issue profiles. |
| Task 10 | Rank the issues. |
| Task 11 | Set priorities for action. |
| Task 12 | Develop an action plan. |
| Task 13 | Evaluate progress and plan for the future. |
Note: Detailed instructions for each of the thirteen tasks in the PACE EH process are outlined in Protocol for Assessing Community Excellence in Environmental Health: A Guidebook for Local Health Officials (NACCHO, 2004).
The need for environmental health practices has been recognized since ancient times. The biblical book Leviticus mentions food protection, housing quality, and quarantine. Engineers and public officials in ancient Rome planned for the water supply and waste disposal, and medieval England used quarantine to limit the spread of disease. Later, as recounted in Chapter 1, social reformers in England advocated for improved housing conditions and clean drinking water (as Edwin Chadwick did in his 1842 Sanitary Report, for example), and documented important environmental health protections (as in the 1871 Report of the Royal Sanitary Commission). Their counterparts in the United States published a similar report in Massachusetts and campaigned effectively for the establishment of a Massachusetts state board of health in 1869. By the end of the nineteenth century, forty of the forty-five states in the United States could claim health departments. The late years of the nineteenth century and the first six decades of the twentieth century saw the first of the modern eras of environmental health practice. During the first fifty years of the twentieth century, the United States and many industrialized nations passed public health laws that regulated water and sewage treatment and addressed protection of food, provision of safe housing and human and solid waste disposal, and reduction of insect- and rodent-borne diseases, resulting in a corresponding decrease in human morbidity and mortality and an increase in life expectancy (Duffy, 1990).
The rapid industrialization that had begun during the late nineteenth century continued with the economic expansion that followed World War II. Additional widespread pollution of land, water, and air and the creation of new pollutants such as synthetic organic compounds helped to usher in the second modern era of environmental health protection. That era saw the creation of increasingly complex national and local laws to regulate the production and certain uses of chemicals and pesticides and to control air and water pollution, as well as disposal of hazardous substances.
In the United States at the state level, legislatures created environmental agencies, adding responsibility for the enforcement of new environmental laws and regulations for air, water, and hazardous waste. In some cases, traditional environmental public health activities such as food protection and sanitary sewage disposal were also transferred to these new agencies. Although the increased visibility and funding were important in supporting necessary environmental health programs, the separation of these programs from health agencies over the last fifty years has resulted in the creation of separate data systems, uncoordinated planning, and the loss of a comprehensive picture of the community's health and environment. In addition, many environmental health specialists, and indeed their agencies, became increasingly isolated from their public health counterparts in the state and local departments of health, losing valuable affiliations that would later take years to reestablish.
Along with the new environmental laws and agencies came a new generation of environmental health specialists who devoted their careers to one specific area of the environment, such as solid waste, hazardous waste, air quality, or drinking water. Their training often did not include training in general public health concepts or in the use of public health tools such as epidemiology and effective public health campaigns. More recently, environmental health agencies have needed to learn how to address the environmental justice and equity concerns of their multicultural communities more effectively (Chapter 11) and to enhance community participation and communicate risk (Chapter 28). In the United States many laws have been written or amended to require public involvement in the development of policies, permits, and hazardous waste site remediation plans. Agencies have needed to expand their workforces, not only to include experts in environmental science, engineering, management, and law but also to bring in experts in communication who can support community engagement efforts (see Text Box 26.2).
In the United States, environmental health services are provided at federal, tribal, state, and local levels and in the medical, academic, nonprofit, and private sectors. The federal laws governing various aspects of the environment are enforced by numerous federal agencies, including the U.S. Environmental Protection Agency (EPA), the U.S. Department of Agriculture (USDA), the U.S. Food and Drug Administration (FDA), and others. Many federal laws contain provisions that supersede state laws in order to provide equal environmental health protection to all citizens. Some of the federal Acts, such as the Clean Air Act, permit delegation of authority to states and, under certain circumstances of local home rule, to local jurisdictions. State governments have the authority to enact further environmental legislation, as long as it does not conflict with federal law. Many of these state laws provide additional protections or address areas not covered by federal law. Within states, municipalities and counties usually have the authority, given by their state legislature, to enact local laws to protect health and environment for their citizens.
Who decides what agencies should provide environmental health services, how they should be organized, and what services should be included? Historically, environmental health agencies (or parts of agencies) have been created through a combination of public health leadership, citizen advocacy, and political will. Their creation begins with the perception of a need to protect the public from environmental hazards and with the desire for a government unit charged with the provision of those services that will be responsive to elected officials and the public. The specific services provided are built around a core set of environmental health services, such as food protection, water sanitation, and air quality protection, with further services added as determined by public health data and public interest. Ideally, the community-specific tailoring of these agencies becomes a method of ensuring that the highest priority services for that community are provided. Yet this necessary and desirable local political process has also resulted in a patchwork of services that are not coordinated and that leave large gaps in the core public health functions of assessment, assurance, and policy development.
Because the authority for these services has developed over many decades and in multiple locations, the organization and delivery of environmental health services is now complex and is not easily understood by professionals themselves, much less the general public. While federal environmental laws have driven the design and authority of state regulatory agencies in the United States, there has been no organizational standardization for enforcement of these laws. Many state regulatory agencies have become oriented toward specific media and often lack the public health support, such as capacity in epidemiology, public health evaluation, or applied research, that would allow a larger perspective on the environment and health (Burke, Shalauta, & Tran, 1995a). As a consequence, state regulatory enforcement efforts have often taken precedence over disease prevention and health promotion, as reflected by levels of funding and activities (Burke, Shalauta, & Tran, 1995b). However, over the last two decades in the United States a multitude of efforts have been undertaken to reconnect the practice of environmental health to prevention. These efforts have emphasized use of public health data to guide and assess environmental health policies and practices, the engagement of communities with disparate environmental and public health impacts, and an increased emphasis on measurement of indices of health whether via measurement of human exposures (e.g., biomonitoring) or tracking of health outcomes (e.g., asthma morbidity).
Prevention of illness, injury, premature death, and disability is a central mission of public health, and this is nowhere truer than in environmental public health. Prevention includes both the control of hazards—cleaning up a hazardous waste site or reducing air pollutants coming from a smokestack or tailpipe—and also health promotion through environmental strategies—providing parks, sidewalks, and bicycle paths. Prevention in environmental health extends upstream to such domains as energy, transportation, housing, and agriculture, whose practices have an impact on human health and well-being. Primary prevention, such as the replacement of a hazardous chemical by a safe one, is a trademark environmental health approach, but secondary prevention (such as blood lead screening) and tertiary prevention (such as maintenance treatment of childhood asthma) are also relevant in environmental health. The prevention hierarchy ranges from definitive approaches, such as completely removing a hazard, which are preferred, to administrative, behavioral, and end-of-pipe approaches, which are less preferred. The precautionary principle proposes that cost-effective preventive measures should proceed even in the face of scientific uncertainty. In environmental public health practice, all the core functions of public health—in the categories of assessment, policy development, and assurance—are used to pursue prevention.