3
Research

As discussed in Chapter 2, there is substantial evidence that communities of concern bear disproportionate burdens of exposure to environmental hazards and the subsequent adverse health effects. Although environmental justice has many facets (e.g., legal, economic, and political), it may be approached appropriately in a variety of ways by the public and private sectors, and the health community should naturally focus on the health aspect of environmental justice. This aspect is most appropriately viewed as a public health issue—one for which pubic health perspectives and methodologies can contribute constructively to the clarification and resolution of the environmental health issues raised by the communities of concern about environmental justice. The committee recognizes that the diagnosis, treatment, and prevention of adverse health outcomes caused by environmental health hazards require a good understanding of the biological and physiologic mechanisms by which such hazards cause disease and that these mechanisms act separately as well as in combination. However, the larger communityand population-based issues of environmental justice require a public health perspective. A public health approach will contribute to environmental justice most effectively by examining issues on a broad, population basis, comprehensively identifying hazards to human health, carefully evaluating the adverse health effects of such hazards, developing alternative interventions to reduce or prevent risks, and evaluating such interventions rigorously to determine the most effective way to reduce risk and improve the health of the population (Institute of Medicine, 1988a).

A public health approach to environmental justice will also require a special relationship to the communities being studied, entailing unusual degrees of collaboration if research is to be responsive to the population's needs and if the findings are to be effectively implemented. As the existing literature in this area demonstrates, however, environmental justice research is an evolving and complex endeavor. This chapter describes the role of the public health sector in environmental



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--> 3 Research As discussed in Chapter 2, there is substantial evidence that communities of concern bear disproportionate burdens of exposure to environmental hazards and the subsequent adverse health effects. Although environmental justice has many facets (e.g., legal, economic, and political), it may be approached appropriately in a variety of ways by the public and private sectors, and the health community should naturally focus on the health aspect of environmental justice. This aspect is most appropriately viewed as a public health issue—one for which pubic health perspectives and methodologies can contribute constructively to the clarification and resolution of the environmental health issues raised by the communities of concern about environmental justice. The committee recognizes that the diagnosis, treatment, and prevention of adverse health outcomes caused by environmental health hazards require a good understanding of the biological and physiologic mechanisms by which such hazards cause disease and that these mechanisms act separately as well as in combination. However, the larger communityand population-based issues of environmental justice require a public health perspective. A public health approach will contribute to environmental justice most effectively by examining issues on a broad, population basis, comprehensively identifying hazards to human health, carefully evaluating the adverse health effects of such hazards, developing alternative interventions to reduce or prevent risks, and evaluating such interventions rigorously to determine the most effective way to reduce risk and improve the health of the population (Institute of Medicine, 1988a). A public health approach to environmental justice will also require a special relationship to the communities being studied, entailing unusual degrees of collaboration if research is to be responsive to the population's needs and if the findings are to be effectively implemented. As the existing literature in this area demonstrates, however, environmental justice research is an evolving and complex endeavor. This chapter describes the role of the public health sector in environmental

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--> health and the particular challenges facing environmental health sciences research in terms of both data and resources. The committee describes the current state of the research in environmental justice, discusses the research methodologies that best serve the communities of concern, and makes recommendations to improve current efforts to respond to environmental justice concerns. Research Methodologies Public health research on environmental justice issues incorporates two tasks: (1) assessment of the health status of the community and (2) determination of the contributions of specific environmental factors to that status. The public health community has developed a great deal of experience and competence in assessing the health status of the population. However, assessment of the health of racial or ethnic minorities, or low-income subpopulations in support of environmental justice poses difficult challenges because both the numbers of individuals and the incidence of disease may be quite small. Even greater challenges are posed by the second task—determination of the contributions of specific environmental factors. These challenges include documentation of excessive exposures, including their strengths and pathways; assessment of the susceptibilities of the communities of concern to environmental hazards; and measurement of the health effects of exposure, including the contribution of a specific hazard relative to the contributions of a variety of other potential factors. These analyses are also complicated by the problem of small numbers. The following section explores these environmental research challenges, with a strong emphasis throughout on the need for substantial involvement of the affected communities. Documenting Excessive Exposures A variety of sources of data might be useful for a public health assessment of a suspected environmental justice problem. The Environmental Protection Agency's (EPA's) Inventory of Exposure-Related Data Systems Sponsored by Federal Agencies (Environmental Protection Agency, 1992) lists 67 databases used by federal agencies to fulfill their responsibilities for research, regulation, and risk communication on environmental health issues (Environmental Protection Agency, 1992). The databases are managed by 17 federal agencies, the United Nations Environment Program, and the World Health Organization. In addition, a number of private-sector databases focus on environmental health. Regulatory support is provided by 19 systems, and 29 systems focus on research. Twelve separate federal departments and agencies collect data relevant to the issue of environmental justice (see Table 3-1). Each has its own mandate and collects the data that meet its specific needs. Because the data are frequently received from local and state computer databases and are largely developed

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--> Table 3-1 Selected Environmental Health Issues and Responsible Federal Departments or Agencies Environmental Health Issue Responsible Federal Agency Potential hazards, occupational or environmental, and accidental exposures Department of Defense (DoD), Department of Energy (DoE), Department of Health and Human Services, Department of Labor, Department of Veterans Affairs, Environmental Protection Agency (EPA), Federal Emergency Management Agency Manufacture, transportation, storage, and disposal of hazardous chemicals Department of Commerce (DoC), DoD, DoE, Department of Transportation, Consumer Product Safety Commission Exposure pathways (including air, water, and soil) Department of Agriculture, Department of the Interior, DoC, and EPA   SOURCE: Institute of Medicine, 1997. independently, few standardized methods for data collection, storage, analysis, retrieval, or reporting exist. The data gathered at the federal level are of various qualities and scopes (Council on Environmental Quality, 1993). The result is a patchwork of data that can be difficult to analyze comprehensively. Efforts are under way to coordinate federal environmental health data. These include the Department of Health and Human Services' Interagency Environmental Health Policy Committee and the National Environmental Data Index. Examples of the various types of environmental health databases are discussed below. The Toxic Chemical Release Inventory (TRI) database is an example of a factual database based on geographic and industrial information. The databases that make up the Toxicology and Environmental Health Information Program (TEHIP) are either bibliographic (with citations and abstracts of the scientific literature) or factual (with data from scientific studies). Toxic Chemical Release Inventory Those concerned with environmental health often rely on EPA's TRI for information on the environmental releases of more than 300 toxic chemicals. Facilities are required to report emissions if, among other requirements, they process or manufacture more than 1,300 kilograms (25,000 pounds) of the chemical per year. Data in TRI include facility identification and the extent of environmental releases (including air emissions, water discharges, waste treatment, and releases to underground injection). The TRI database is particularly useful for community organizations in assessing local environmental hazards

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--> because it can be searched to identify facilities by zip code, city, county, or state. TRI is available through the National Library of Medicine. Toxicology and Environmental Health Information Program The mission of TEHIP, which is run by the National Library of Medicine, is to provide selected core toxicology and environmental health information resources and services, facilitate access to national and international toxicology and environmental health information resources, and strengthen the information infrastructure of toxicology and environmental health (National Library of Medicine, 1993). Each database has its beginning in several different federal agencies, which in and of itself leads to fragmentation of authority, responsibility, and accuracy. TEHIP is composed of 15 on-line environmental health databases that are developed or reviewed by the National Library of Medicine or another federal agency (including EPA, the National Cancer Institute, the National Institute of Environmental Health Sciences, and the National Institute for Occupational Safety and Health). Six of the databases are bibliographic; the other 10 databases provide factual data on chemical identification, carcinogenicity, mutagenicity, general toxicity and risk assessment, and environmental releases. Implementation of a public health approach to environmental justice problems requires a solid research base and a reliable, comprehensive surveillance and reporting system. However, bibliographic and factual databases that can assist in research on and in understanding environmental health issues are available. Although substantial data are being collected, there are problems due to the lack of standardized definitions and methods and to the lack of standardized methods of data collection and retrieval, as well as significant gaps in the types of data that are needed to evaluate the effects that exposures to environmental hazards may have on the health of exposed populations. These shortcomings underscore the need, when undertaking an assessment of a potential environmental justice problem, to involve the affected community integrally in the process, particularly for the purpose of supplementing other sources of data with specific information pertinent to local conditions. Strategies and issues regarding such community involvement are discussed more fully later in this chapter. Assessing Susceptibility to Environmental Hazards When examining environmental justice from a public health perspective, it is important to recognize that communities of concern might be disproportionately affected not only because of their higher levels of exposure to environmental hazards but also because, for a variety of reasons, such exposures have a greater effect on them than on other communities. It is therefore important to examine potential differences in the susceptibilities of members of these communities

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--> to adverse health effects. Rios and colleagues (1993) have reviewed inborn and acquired variations among minority populations in their susceptibilities to the effects of environmental exposures. They reported that susceptibility can be affected by genetic factors (e.g., the sickle cell trait may increase one's susceptibility to the toxic effects of carbon monoxide), dietary factors (e.g., lower calcium intake among African American children may act to increase gastrointestinal absorption of ingested lead), other lifestyle factors (e.g., smoking increases lung cancer susceptibility in asbestos-exposed workers), or other environmental exposures (e.g., concurrent solvent exposure may increase the likelihood of hearing loss due to high levels of noise) that may be associated with variations among minority populations. Additional factors that Rios and colleagues concluded may differentially affect minority populations include compromised health status (e.g., people with diabetes may be less able to detoxify organic solvents), social inequality of access to health care (e.g., poor control of asthma by primary care providers may increase susceptibility to particulate air pollution), and inadequate education and communication skills (e.g., non-English-speaking workers may not be able to read health and safety warnings at work). Frumkin and Walker (1997) also reviewed some of the mechanisms that act to increase the risk of environmental and occupational diseases among minority workers and communities. In addition to disparities in exposures and susceptibilities to environmental agents in the community and workplace, the investigators pointed out that the racial or ethnic and socioeconomic disparities that exist in access to health care in general may contribute to observed differences in occupational and environmental illnesses, although further research is needed to clarify this. One tool that can be used to identify increased susceptibility is biomarkers. Biomarkers are measurements of the body's response to external events or substances such as environmental hazards. A biomarker of susceptibility would measure limitations, either inherited or acquired, in a person's ability to mount a protective response to a hazard. The development of biomarkers of susceptibility would allow further analysis of differentials in susceptibility among minority or, possibly, low-income populations. A more complete discussion of biomarkers is provided later in this chapter. Measuring the Health Effects of Exposure to Environmental Health Hazards Establishment of the causal relationship between exposure to environmental hazards and adverse health outcomes and measurement of the scope and severity of such outcomes are critical steps in the analysis of environmental justice issues. As noted at the beginning of this chapter, a better understanding of the disease mechanisms and the processes involved is needed. The committee's principal focus, however, is the use of epidemiologic studies in communities of

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--> concern. Such studies are designed to discern relationships between health effects and potential causes. In his recent review of environmental justice, Foreman asserts, "For environmental justice to contribute measurably to public health in low-income and minority communities, it would almost certainly have to stress an epidemiologic perspective … to a far greater extent than is currently the case" (Foreman, 1998, p. 70). Here, again, much of the research to date has been undertaken in occupational health. Two of the biggest challenges to an epidemiologic analysis of health effects are the existence of multiple exposures in the community of interest and the possibility that an adverse health outcome may have multiple determinants. Multiplicity of Hazards A community of concern may be exposed to multiple environmental hazards, which may act cumulatively or which may even interact in complex ways to magnify their risks to human health. Researchers have long recognized the need for knowledge about the separate and collective health effects of multiple chemicals (National Research Council, 1988). Recent research into the risks from mixtures has begun to provide some insight into the toxicological issues underlying the interactions of chemical and physical agents and the interactions of external exposures and chemotherapeutic drugs, as discussed in the recent report Interactions of Drugs, Biologics, and Chemicals in U.S. Military Forces (Institute of Medicine, 1996). Research on multiple exposures has tended to focus on the occupational setting. It is important for new research, however, to take other settings into account, especially residential settings (see Box 3-1). Although it will never be feasible to study the health effects of every specific mixture that may occur because the possible number of combinations is very large, it should not be difficult to select those combinations that should be given priority because of their larger concentrations or greater likelihood of having toxic effects. Multiplicity of Potential Determinants A given health condition identified in a community of concern may have several possible etiologies. A major challenge for conducting research on a population with a high prevalence of diseases with multiple causes, such as asthma, is to identify the important environmental determinants from the multiple other factors that affect that disease's expression in populations or individuals. Current models of exposure assessment do not adequately capture this type of interaction. Existing health or environmental exposure databases do not include information on all the relevant factors that need to be investigated to answer many of the research questions posed. Allergens, for example, are notably absent from the majority of environmental exposure databases. Even if a

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--> Box 3-1 Altgeld Garden, Chicago Altgeld Garden is a public housing community in southeast Chicago built in the mid-1940s. Since its construction, it has been surrounded by industrial facilities. Initially, these were heavy industry (steel, petrochemical, and manufacturing). Currently, they include manufacturing and water and waste treatment facilities. In the surrounding area are more than 100 industrial plants and 50 active or closed waste dumps. The area contains 90 percent of the city's landfills. As a consequence, the 10,000 residents of Altgeld, who are predominantly African American, have been exposed to a broad variety of environmental stressors, raising concerns about the impacts of these exposures on their health. In addition to worrying about airborne exposures, many members of the community also believe that their houses are constructed on top of chemical and biological wastes. Well water has been found to contain cyanide, benzene, and toluene. According to EPA, this section of Chicago has the city's highest concentration of ambient lead and the second highest concentration of fine dust particles (Motavalli, 1998). Community health concerns have focused on several endpoints, with childhood cancer, prostate, bladder, and lung cancer, endocrine disease, hypertension, infant mortality, and asthma being the most prominent. In response to these concerns, several federal, state, and local agencies have evaluated or investigated the community. single cytokine or other biomarker (see below) is eventually identified, for example, as a means of diagnosing asthma, it is unlikely that the environmental factors most responsible for the expression of asthma in communities of concern will be identifiable by a single biomarker of exposure. Different exposures act by different biological mechanisms and will require different biomarkers. Even after a reliable assay for a biomarker of exposure, susceptibility, or biological effect is developed in the laboratory, its clinical and public health applications remain to be determined. For these reasons, among others, research into exposure assessment needs to be multidisciplinary. Biomarkers In the 1980s, the inability to link exposures to health outcomes by population studies and traditional methods for the classification of exposures led to the study of biological markers, or biomarkers, as possible tools for exploration of the effects of environmental exposures (Cullen and Redlich, 1995). As initially described by the National Research Council (NRC, 1989a,b), biomarkers, in the context of environmental health, are indicators of the effects of external exposure as manifest internally, in biological systems or samples. They reflect molecular

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--> and cellular alterations that occur as a disease begins and progresses (DeCaprio, 1997). According to the conceptual paradigm first proposed by NRC in 1987, these events (biomarkers) can be indicative of exposure, susceptibility, or effect (National Research Council, 1989b)(Table 3-2). (The designation of the status of the marker is sometimes subjective and may not be mutually exclusive [DeRosa et al., 1993].) The value of biomarkers for epidemiologic studies of environmental justice lies in their potential to indicate that an exposure has occurred and to predict the likelihood of adverse health effects. To be able to relate events to a specific health effect, however, one needs to know which events are associated with which disease outcomes and the degree of that association. The application of biomarkers to environmental health research requires extensive research on disease mechanisms, which is the linking of exposure to hazards at various doses to the preclinical signs of disease (Henderson, 1995). The following sections describe the three types of biomarkers and the research needs for each type. Biomarkers of Exposure One of the first areas of focus in biomarker research was the determination and measurement of exposure. These efforts moved the environmental health field from estimates of external exposures to measurements of internal biological events (Cullen and Redlich, 1995). Much of this early work measured carcinogens at the molecular level, examining, for example, DNA adducts, sister chromatid exchanges, and micronuclei in epithelial tissue. Although these markers are routinely used as evidence of exposure, they might also be considered biomarkers of effect; that is, in some cases, they might also be predictive of potential adverse health effects (DeCaprio, 1997). Although these markers provide plausible dose-response models, they do not adequately identify exposures with unknown carcinogenicities. Table 3-2 Types and Definitions of Biomarkers Type Definition Exposure An exogenous substance or its metabolite(s) or the product of an interaction between a xenobiotic agent and some target molecule or cell that is measured in a compartment within an organism Susceptibility An indicator of an inherent or acquired limitation of an organism's ability to respond to the challenge of exposure to a specific xenobiotic substance Effect A measurable biochemical, physiologic, or other alteration within an organism that, depending on the magnitude, can be recognized as an established or potential health impairment or disease   SOURCE: National Research Council, 1989b, p. 2.

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--> Commonly measured pharmacokinetic values can also be used as markers of exposure, for example, the presence of parent compound or metabolites in exhaled breath, blood, or urine or the appearance of macromolecular adducts or their degradation products in urine. Some markers of chemical exposure, such as the hematological changes that accompany high levels of exposure to lead or benzene, have been measured for decades. As early as 1976, hemoglobin adducts were being used as internal dosimeters of exposure to ethylene oxide and were later used as internal exposure biomarkers for aromatic amines, nitrosamines, and polycyclic aromatic hydrocarbons (DeCaprio, 1997). In essence, exposure biomarkers are useful for measurement of the actual absorbed dose and the extent of delivery of the exposure to the putative site. These measurements are superior to ambient monitoring and questionnaire data (DeCaprio, 1997). To understand the relationship of such markers to prior exposures, however, one must know the rates of formation and clearance of the marker and the factors that influence those rates. Because of safety concerns about determination of these rates in humans, historically these studies have been limited to those that use animal models (Henderson, 1995). Interspecies variations in absorption and uptake complicate extrapolation of results of studies with animal to human populations. To address the issue of the nonspecificity of these biomarkers, more recent work has focused on early-effect markers, such as oncogenes and tumor suppressor genes. These markers not only serve as indicators of exposure, for example, in studies of aflatoxin and lung cancer in asbestos workers (Brandt-Raut et al., 1992; Hollstein et al., 1993), but they also provide insights into the mechanism of the disease process itself (Cullen and Redlich, 1995). However, the utility of these markers is limited as well because they cannot adequately account for variability in individual susceptibility factors; that is, the dose-response curve differs among individuals due to differences in metabolic pathways. Still, better biomarkers of exposure could be very useful in verifying claims of environmental exposure in communities of concern. Biomarkers of Susceptibility A biomarker of susceptibility is an indicator of an inherent or acquired limitation of an individual's ability to respond to the challenge of exposure to an environmental hazard. The variation in individual responses to environmental exposures is wide, even within racial or ethnic classifications (see discussion in Addressing Race below). Investigators have studied an extensive range of enzymes that are known to be important toxicologically and that also demonstrate substantial variation in activity levels within the population (e.g., N-acetyl-transferase or P-450 cytochromes). Such enzymes are likely to play an essential role in the activation or detoxification of potent carcinogens or other chemical exposures. Different susceptibilities are likely to account for at least some of the different responses to exposures such as metals, solvents, or pesticides (Bock,

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--> 1992). A deeper understanding of susceptibility and the biomarkers that indicate heightened susceptibility would be a valuable tool in preventing avoidable adverse health effects due to environmental exposures to health hazards. Biomarkers of Effect The 1989 NRC report defined a biomarker of effect as ''any change that is qualitatively or quantitatively predictive of health impairment or potential impairment resulting from exposures" (National Research Council, 1989b). Although these markers are more predictive of ultimate toxicity, they are less clearly associated with exposure to specific chemical agents (DeCaprio, 1997). That is, the presence of such a marker can be indicative of more than one exposure. Some mutational events can be considered biomarkers of effect, especially if they have already been demonstrated to be the immediate precursors of clinical disease, for example, oncogene activation and tumor formation. In some cases, however, the distinction between a biomarker of exposure and one of effect is not clear. Thus, DNA adduct formation (biomarker of exposure) might or might not lead to subsequent mutations that are precursors of disease. Limitations and Potential of Biomarkers in Environmental Health Risk Assessment Biomarkers measure events along the continuum from exposure to effect. They are signal events but are not necessarily an explanation for an underlying pathophysiology. Nevertheless, they can be tremendously useful in environmental epidemiology. More work is needed to develop biomarkers of exposure and effect suitable for improving the power of epidemiologic studies, including molecular epidemiology. For example, biomarker screening studies could be conducted with residents living in close proximity to a site to provide information on the actual levels of uptake of the contaminant(s) of concern. Large, collaborative research efforts that use batteries of biomarkers are needed. Markers selected for use in the screening of populations must be sensitive, specific, predictive, and selective (DeRosa et al., 1993). Selectivity refers to the ability to unequivocally identify a specific substance to which an individual is exposed. For example, urine phenol levels can be influenced by the ingestion of vegetables, exposures to several aromatic compounds, ingestion of ethanol, and inhalation of cigarette smoke; thus, their value as a selective marker is low (DeRosa et al., 1993). Markers must also be sensitive to short- versus long-term exposure. For example, the presence of trichloroethanol (a short-half-life metabolite of trichloroethylene [TCE]) in urine is a good biomarker for use in the monitoring of populations after short-term exposure to TCE, whereas the presence of trichloroacetic acid (a long half-life metabolite) in urine would be a more appropriate

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--> marker for use in the monitoring of populations after long-term exposure (DeRosa et al., 1993). Of particular value would be markers that improve the attribution of disease endpoints to causes (e.g., allowing determination of which specific mutations in lung cancer tissue are a fingerprint for which environmental cause or which asthma attack is due to an industrial pollutant rather than a natural pollen). For biomarkers to be useful in characterizing human health effects associated with environmental hazards, they must be validated with human populations (National Research Council, 1989b, 1992a,b). This will generally require a clinical research setting and the use of epidemiologic and multivariable biostatistical methods that adjust for the important potential confounding and effect-modifying factors that could be masking a real environmental effect or causing spuriously positive results. Improved epidemiologic and clinical research methods that can better distinguish truly harmful from harmless environmental exposures in humans, that can detect lower doses, and that require smaller sample sizes need to be developed and validated. A challenge that faces researchers is the need to link biomarkers to the disease with which they are associated and to determine at what levels disease is induced. Two strategies should be used to determine the link between biomarkers of exposure and an individual's prior exposures. The first strategy, according to Henderson (1998), is physiologically based toxicokinetic modeling. In order to develop such a model, data regarding the rate of formation of a biomarker following exposure to a toxic agent and its rate of removal or repair in the body (e.g., rate of excretion or degradation half-life) must be obtained. Physiologic parameters (e.g., cardiac output or breathing rate), as well as the physical-chemical characteristics of the chemical and its metabolites must be determined. Second, multiple biomarkers can be used to elucidate prior exposures more in depth than what may be obtained with a single biomarker. For example, if both the amount and the half-life of a biomarker vary, this knowledge can be used to give more perspective on a previous exposure. This knowledge will be able to determine whether an individual was recently exposed to a high level of a chemical or was continuously exposed to low levels in the past. The committee supports the view that one of the most promising ways to accomplish this is by incorporating appropriate biomarkers to improve the accuracy of measurement of exposures, susceptibility factors, or disease outcomes in well-designed epidemiologic studies (Hulka et al., 1990; Schulte and Perera, 1993). Research Challenges Current research in toxicology, epidemiology, molecular biology, clinical medicine, and social sciences can make important contributions to the study of environmental health but cannot adequately address the range of issues raised by environmental justice. Collaborative approaches to research that incorporate

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--> these and other relevant disciplines should be developed to address specific public health problems. It is important that research concerning environmental justice use both traditional and nontraditional methodologies to best serve the communities of concern. These include creating new epidemiologic tools to assess small populations better, addressing race and relevant socioeconomic considerations in the analysis, and involving the community in every stage of the research through participatory research. Improving Epidemiologic Studies Questions of environmental justice tend to be raised on behalf of relatively small populations. Many of the problems associated with the study of small populations, such as minority and economically disadvantaged individuals, have to do with the fact that study size requirements, (in addition to other requirements, such as isolation of exposures) for traditional epidemiologic studies can rarely be met. Populations that are (or that are believed to be) dealing with illness as a result of a high level of exposure to environmental health hazards are often isolated, either in urban or in rural areas, and are typically subject to other factors that affect health and well-being. Moreover, environmental and health data for populations whose health may be affected because of exposure to environmental health hazards are not routinely collected or analyzed by demographic categories (Environmental Protection Agency, 1992). Various socioeconomic factors are associated with different rates of morbidity and mortality among different racial or ethnic groups (National Center for Health Statistics, 1998b; Warren, 1993). To the extent that they are correlated with environmental exposures, these socioeconomic factors could be considered confounders (in the epidemiologic sense) of the relationships between the environmental exposures and the disease outcomes. Typically, even in the event that they are measured in environmental epidemiologic studies, the studies' designers attempt to control for these potential "confounders" statistically to assess whether an association exists between the disease and the exposure variables of primary interest. Several investigators have commented on reasons for the paucity of data on the roles of race, ethnicity, and other socioeconomic factors in studies of occupational diseases (Friedman-Jiménez, 1994; Kipen et al., 1991; Zahm et al., 1994). Some research deliberately excludes analysis of differential disease occurrences in minority workers because the small number of minority subjects would have provided an unacceptably low statistical power to test the primary hypotheses of the study. This is unfortunate because the small body of published occupational health literature that does explicitly include data from studies with these populations suggests that racial, ethnic, and economic disparities continue to influence the risk for adverse health effects due to environmental hazards in the workplace. Research is needed to improve the capacity of epidemiologic studies to detect adverse health impacts in small populations and to evaluate clusters of effects

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--> observed in populations. (Appendix A discusses these and other related issues in greater depth.) Researchers need to design environmental health studies that will provide adequate measurement, classification, and reporting of data on race, ethnicity, and relevant socioeconomic variables and to develop improved methods of descriptive, analytic, clinical, and molecular epidemiology that are accurate and practical for investigating relationships between environmental exposures and disease in low-income and minority populations. One tool that can help epidemiologic studies is geographic information systems (GISs). Geographic data can be used to relate the location of a known or a suspected environmental health hazard to public health trends and racial distributions, among other factors. Because GISs can provide powerful summaries of relationships that may be lost in numerical analyses, they have been found to provide clues to relationships that can then be investigated by quantitative techniques (Elliott et al., 1996). Such techniques can also merge environmental and public health data collected from many different sources. Addressing Race Because a central focus of environmental justice is on disparities among racial groups, it is important that studies and research take account of race and socioeconomic factors. However, the committee took cognizance of concerns being raised about conventional definitions and classifications. The use of racial and ethnic categories for health surveillance is often confounded with other differences, such as geography, economic status, culture, lifestyle, or behavior. In his synopsis of a workshop, Health Surveillance and Communities of Color, sponsored by the Centers for Disease Control and Prevention and the Agency for Toxic Substances and Disease Registry, Rabin (1994) stated that surveillance needs to "pay more careful attention to differentiation within minority populations regarding year of migration, family status, income, age, daily work habits, religion, [and] media habits" (p. 45). The categorization of individuals simply by race ignores other variables that can lead to valuable insights into predictors of risk. Many groups, including the American Anthropological Association and the Institute of Medicine (IOM) Committee on Cancer Research Among Minorities and the Medically Underserved, have been critical of the use of the term "race" in health research, primarily because the term implies the existence of distinct human subgroups that differ fundamentally in biological makeup and origin and ignores the tremendous heterogeneity within such groups (American Anthropological Association, 1997; Institute of Medicine, 1999). In reality, "genetic diversity appears to be on a continuum, with no clear breaks delineating racial groups" (Marshall, 1998, p. 654). The vast majority of health research on human population groups in the United States, however, has categorized populations according to familiar terms such as "white," "African American" or "black," "Hispanic," ''Asian American," and other terms. Such categorizations may be reinforced by federal research

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--> agencies, such as the National Institutes of Health, which are required to comply with the U.S. Office of Management and Budget's guidelines for data collection with regard to U.S. population groups. The U.S. Office of Management and Budget's Directive 15 requires federal agencies to report population data on the basis of five "racial and ethnic" groups (U.S. Office of Management and Budget, 1978). The U.S. Office of Management and Budget notes that such classifications do not carry scientific or anthropological validity; rather, they are based on social and historical considerations. The American Anthropological Association and the IOM Committee on Cancer Research Among Minorities and the Medically Underserved note that this reporting requirement may handicap health researchers, who are often unable to draw meaningful inferences regarding the source of group differences because "racial" groups do not vary systematically with regard to biological or genetic makeup, socioeconomic status, culture, or other relevant variables. The use of "race" in health research will be further complicated in the future because the U.S. census will allow respondents to list more than one "racial" category to describe themselves. Although it is expected that only a small fraction of the U.S. public will seek to describe themselves as belonging to more than one "racial'' group (U.S. Bureau of the Census, 1997), health researchers will have to develop means of accounting for such populations. Notwithstanding these concerns, the committee believes that the collection of race- and class-specific data is crucial if environmental justice is to be achieved. Data that lack specificity or that gloss over demographic and material realities will not support adequate analysis, regulatory intervention, or remediation of environmental health risks. In many instances, race is a critical variable with respect to environmental justice because (1) the racial segregation of neighborhoods remains a common feature of the United States, and (2) lower-income, predominantly minority neighborhoods may be especially vulnerable to environmental degradation and abuse primarily because of relatively lower levels of political and economic clout of the populations in those neighborhoods to gain redress or restitution from environmental polluters. "Race" therefore remains an important term because of its social and political implications, but it should not be assumed to have scientific validity in the absence of evidence. Participatory Research To better understand the consequences of exposure to environmental hazards, public health officials and researchers should pay close attention to the experiences of individuals in local communities and should systematically collect and validate data on those experiences. Adverse health effects from environmental hazards are often suspected first by the people who experience them rather than by the health care or scientific community. In other cases, a toxicant's effects may be known to the health or science professionals but particular routes of exposure may have yet to be discovered for a particular community. In

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--> still other cases, affected individuals may be the initial source of knowledge about multiple exposures or confounding physical conditions (e.g., compromised health because of disease or nutritional problems, as is observed in iron deficiency and lead absorption). In all of these cases, these individuals are first-hand observers, with unique and essential knowledge about the activities or places that may lead to exposure. An organized, methodical system of collecting these experiential data is an essential part of the scientific process (National Research Council, 1991b, 1996, 1997). Frequently, affected individuals bear the burden of proof for establishing the legitimacy of their problems (see for example, Box 3-2). Without the assistance of those with scientific training and financial resources, this can be an impossible task. If early data are ignored pending conclusive confirmation, however, there is a risk of presuming a hazard to be safe on the basis of inadequate data, thereby subjecting exposed people to unnecessary harm. Public health officials and researchers need to develop ways to help community activists and local medical personnel document health outcomes and health status in a reliable and unbiased manner. Even if the methods are imperfect, they could produce evidence for the justification of more thorough medical surveillance and measurement. Epidemiologic data obtained by laypeople cannot supplant data obtained by epidemiology professionals; they can, however, help identify issues or supplement the data obtained by professionals (National Research Council, 1991b, 1997). One of the best methods for capitalizing on local knowledge is participatory research. Participatory research has been defined as research that involves the affected community in the planning, implementation, evaluation, and dissemination of results (Banner et al., 1995; Drevdahl, 1995). In this regard, scientists serve as a resource to the community and work with the community in identifying and finding solutions to environmentally related health problems. In addition to allowing researchers to capitalize on local knowledge, the involvement of the affected community ensures that the research addresses the issues that are important to the community and reinforces the social validity of "the goals, procedures, and effects" of the research—that is, participatory research ensures that the community truly benefits from the research being done (Fawcett, 1991, p. 235). Although participatory research can greatly benefit and advance environmental health sciences, it still poses unique challenges. Challenges of Participatory Research Cultural differences between a minority community exposed to an environmental health hazard and the majority of Americans may be a barrier to communication and may affect the collection of data and the understanding of the relationship between exposure and disease. For example, the American Indian and Alaskan Native communities hold as sacred free-ranging animals, wild herbs, and other flora and fauna, values that have resulted in the discussion of endangered

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--> Box 3-2 Tucson, Arizona In 1951 a group of companies began aircraft maintenance operations around the Tucson Airport in Arizona, using a variety of toxic solvents, including trichloroethylene (TCE). The occupational medicine literature of the 1970s and 1980s also documented acute episodes of neurotoxicities (e.g., dizziness, confusion, memory loss, blurred vision, elevated anxiety, headache, and reduced visuospatial relations and psychomotor speed) among workers who received short-term exposures to high concentrations of TCE vapors. For approximately 30 years, the companies in Tucson stored the used solvents, including an estimated 7,570 liters (2,000 gallons) of TCE, in large evaporative pools, from which they gradually leaked into the aquifer of the Santa Cruz River, the principal source of water for the city. Over the same period, new industries and low-cost housing developments spread throughout southern Tucson, adjacent to the airport. An estimated 90 percent of the new residents of southern Tucson were low-income Mexican Americans. The drinking water for this high-growth area was drawn from wells that tapped directly into the contaminated plume spreading within the Santa Cruz River aquifer. In 1981, the Arizona Department of Health Services tested the wells for contamination and discovered that several municipal wells contained levels of TCE above the level requiring state action (5.0 µg/liter), ranging from 1.1 to 239 µg/liter (Agency for Toxic Substances and Disease Registry, 1996). The affected wells were immediately shut down, as were others that were later discovered through continued monitoring to have become contaminated. Still, the residents had been exposed to indeterminable concentrations of TCE. It was not until Jane Kaye described higher rates of disease in the Arizona Daily Star in May 1985 that there was a much heightened awareness of the contamination and speculation of a link to health effects. Similarly, Carol Roos, a school district social worker, investigated the area's seemingly high rates of disease by spending 4 months in house-to-house "shoeleather epidemiology" (Brown, 1993; National Research Council, 1991a,b). These articles had the effect of creating intense community concerns about disease and a desire for information, health studies, and environmental cleanup. Despite their scientific shortcomings, both studies had the effect of raising the public's concern about a potential link of TCE to adverse health events. Although no consistent link between disease (i.e., mortality rates of all diseases and incidence rates of birth defects, childhood cancers, and testicular cancer) and the contaminated area was found in the studies subsequently conducted by government agencies, it was the community's efforts that raised the visibility of the problems in the area and created a climate that drove all parties to seek answers and solutions.

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--> wild foods not only in terms of environmental health but also in terms of a violation of cultural mores. Unfortunately, the public health sector often does not include trained personnel from these communities of concern, nor is it rich in individuals from the larger community who are able to understand, empathize, and sympathetically work in the cultural context of small communities. The committee's site visit to the Hanford Nuclear Reservation served as an example of the need to consider cultural differences among populations that might not only affect the extent of environmental exposure to toxic compounds but also influence policies toward public health research and policy (see Box 3-3). Box 3-3 Hanford Nuclear Reservation In 1943, the federal government acquired 1,450 square kilometers (560 square miles) on the Columbia River in south central Washington State to use as a site for the production of plutonium for use in nuclear weapons. After it was discovered that underground tanks containing toxic radioactive waste from the Hanford Nuclear Reservation had leaked, allowing the waste to enter the Columbia River and the local groundwater (Harden, 1996; Zorpette, 1996), the federal government attempted to determine the level of exposure of the local population to the toxic material. According to the Hanford Dose Reconstruction Project, Hanford's releases resulted in low whole-body doses. Those living near Hanford before 1960 may have received high doses of radiation. Unfortunately, the initial dose reconstructions did not consider the American Indian population separately. American Indian people live on a number of reservations located in this region, as close as 80 kilometers (50 miles) to the Hanford site and at distances of up to several hundred miles. The Yakima Indian Nation is the largest tribe with an interest in Hanford. Tribal lands were directly ceded to the Hanford Reservation. The Confederated Tribes of the Umatilla Indian Reservation and the Nez Perce also directly ceded land to form the Hanford Reservation. Fishing from the Columbia River, hunting, and gathering remain a central part of these cultures and economies; thus, environmental contamination would have more than an adverse health impact. Historically, the Nez Perce lived outdoors, in camps, and moved around the land seasonally. They were not informed of the contamination at Hanford, potentially placing them at greater risk than the non-Indian population (Nez Perce Tribe, 1995). Later dose reconstructions described to the committee have taken special account of the diet and societal tradition of these people and provide a template for consideration of individual subpopulations in the dose reconstruction and prediction of levels of exposure to radioactive or chemical pollutants. Nevertheless, the complexities in filing, storing, and retrieving the myriad classified and unclassified documents associated with site activities pose significant challenges to tracing the information needed to assess human exposure to radiation.

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--> Often, differences between the scientific and lay communities may also obstruct interactions between them. Typically, the two groups speak different languages, live in different places, and have different stakes in the proceedings. Their communication difficulties can lead to mistrust as well as misunderstanding. If the residents of an affected community distrust the researchers, for example, they may choose to withhold information. That distrust can come from the perceptions that the researchers are working against their interests, are advancing their own careers at the community's expense, or are simply disrespectful. Solicitation of community input prior to the beginning of the research, active community participation in the research implementation, and communication of results to the community could prevent these misperceptions. Participatory research has been used in a variety of health-related areas (Banner et al., 1995; Cornwall and Jewkes, 1995; Drevdahl, 1995; Lillie-Blanton and Hoffman, 1995). There are inherent difficulties, however, in incorporating community input into scientific research. These difficulties can include the time required to undertake community participation, the need for an established community structure with which to work, and the process by which new knowledge is validated (Drevdahl, 1995). Lillie-Blanton and Hoffman (1995) discussed five major areas that are important to building a mutually beneficial relationship between the scientist and the community. These areas include (1) scientist knowledge of the community, (2) the development of an appreciation for the policy and programmatic issues underlying the research, (3) clarification of the decisionmaking process, (4) the development of trust and respect, and (5) the development of community expertise and capacity. The committee believes that public health research on environmental justice issues would be substantially improved by the development of one or more standard models of how best to undertake participatory research. The committee is also mindful, however, of the suggestion by Cornwall and Jewkes (1995) that the most important facet of participatory research lies not so much in methods but in researchers' attitudes. Enhancing Support for Research The foregoing discussion demonstrates that greater attention and greater resources are needed to improve the science base and research methodologies required to address environmental justice issues effectively. Such commitments are difficult, however, given the current status of research in this field. Environmental health and environmental justice are relatively young, emerging fields of inquiry. consequently, it is often hard to marshall the resources warranted to pursue promising research. Large numbers of research scientists have not yet developed research proposals in these areas. Nor are large numbers of scientists who are knowledgeable about these fields or who consider them to be of high priority participating on review panels for research awards. In the highly

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--> competitive world of biomedical and public health research, the result is that research projects on environmental health and environmental justice represent a small proportion of the approved and funded projects. It also means that talented young researchers will be hesitant to assume the risk of committing to work that is considered unconventional and for which future funding is highly uncertain. Conclusions and Recommendations Public health research will be particularly important to improving environmental health and achieving environmental justice. The committee believes that an epidemiologic approach should be the central means of dealing with the environmental health problems in disadvantaged communities. This approach is hindered at the present time, however, by the shortcomings in current databases and data collection methodologies. New research models and techniques are needed. Communities of concern must participate in the identification of problems needing research and in the design and implementation of research. Recommendation 1. A coordinated effort among federal, state, and local public health agencies is needed to improve the collection and coordination of environmental health information and to better link it to specific populations and communities of concern. Strategy 1.1 Expand efforts and resources for in-depth evaluations of health status and risk monitoring in communities of concern. These efforts should involve the members of the affected population in discussing and making decisions related to issues that may have adverse environmental effects on communities and making decisions related to the remediation of existing environmental health concerns. Strategy 1.2 Develop longitudinal, communitywide, baseline health assessments that provide both reason and context for studies specific to the impact of the environment. Strategy 1.3 Construct a reliable surveillance system that not only tracks health status (e.g., through the use of biomarkers) but that also signals disproportionate exposure. Strategy 1.4 Include members of minority groups in research to better describe specific susceptibilities and health effects. Strategy 1.5 Connect environmental exposure databases and up-to-date demographic data, including data on age, gender, race, ethnic background, employment, housing, educational attainment, and income. Strategy 1.6 Build strong links between public health practitioners and the community's broader array of medical, dental, and nursing professionals to stimulate greater sharing of data and experience. Strategy 1.7 Promote the wider distribution and dissemination of public environmental health databases.

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--> Recommendation 2. Public health research related to environmental justice should engender three principles: improve the science base, involve the affected population, and communicate the findings to all stakeholders (see Box 3-4). The following strategies are recommended as a means of achieving Recommendation 2. Strategies for Improving the Science Base Strategy 2.1 Develop improved biomarkers of exposure, susceptibility, and biological effect as well as improved exposure assessment technologies. Strategy 2.2 Focus additional research on human susceptibility, both genetic and nongenetic, to environmental causes of disease. Strategy 2.3 Allocate a portion of all environmental health sciences research portfolios to environmental justice issues. Strategies for Involving the Affected Populations Strategy 2.4 Develop and use effective models of community participation in the design and implementation of research on environmental health and environmental justice. Strategy 2.5 Give high priority to participatory research when addressing the research needs of communities with environmental justice concerns. Strategy 2.6 Involve the affected community in designing the protocol, collecting data, and disseminating the results of research on environmental justice issues. Strategy for Communicating with Stakeholders Strategy 2.7 Ensure that communities of concern have a full understanding of the purposes, methods, and results of any research done in their communities.

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--> Box 3-4 Three Principles for Public Health Research to Address Environmental Justice Issues 1.   Improve the science base. More research is needed to identify and verify environmental etiologies of disease and to develop and validate improved research methods. 2.   Involve the affected populations. Citizens from the affected populations in communities of concern should be actively recruited to participate in the design and execution of research. 3.   Communicate the findings to all stakeholders. Researchers should have open, two-way communication with communities of concern regarding the conduct and results of their research activities.

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