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Science and Decisions: Advancing Risk Assessment 2 Evolution and Use of Risk Assessment in the Environmental Protection Agency: Current Practice and Future Prospects OVERVIEW EPA risk-assessment concepts, principles, and practices are products of many diverse factors, and each agency program is based on a “unique mixture of statutes, precedents, and stakeholders” (EPA 2004a, p. 14). With respect to statutes, Congress established the basic plan through a series of environmental laws, most enacted during the 1970s and most authorizing science-based regulatory action to protect public health and the environment. Another factor is EPA’s case-by-case experience with implementing these laws and the resulting supplementary principles and practices. Equally important, advisory bodies have drawn on the expertise of scientists and other environmental professionals in universities, private organizations, and other government agencies to recommend corrections and improvements. The net result is that risk assessment in EPA is a continually evolving process that has a stable common core but takes several forms. This chapter traces the origins and evolution of risk assessment in EPA with an emphasis on current processes and procedures as a stepping-off point for the future improvements envisioned in later chapters. This chapter first describes the diverse statutory requirements that have led to a broad array of agency programs with correspondingly varied approaches to risk assessment; it then highlights current concepts and practices, outlines EPA’s multifaceted institutional arrangements for managing the process, and identifies extramural influences. The record shows that EPA continually updates the process with new scientific information and policies, often in response to new laws or advice from advisory bodies as to general principles or individual assessments. Not all external recommendations necessarily warrant agency action, but it is clear that implementation of some recommendations has been incomplete. The chapter closes with process recommendations for implementing some of the substantive recommendations in the chapters that follow.
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Science and Decisions: Advancing Risk Assessment STATUTORY PLAN AND REGULATORY STRUCTURE The environmental laws enacted by Congress shape EPA’s regulatory structure, which, in turn, influence EPA risk-assessment practices and perspectives. The statutes give EPA authority to regulate many forms of pollution (for example, pesticides, solid wastes, and industrial chemicals) as they affect different aspects of the environment (for example, air quality, water quality, human health, and plant and animal wildlife). The premise central to EPA risk-assessment practices can be found in enabling legislation for its four major program offices: air and radiation, water, solid waste and emergency response, and prevention, pesticides, and toxic substances. Selected provisions appear below. The Clean Water Act calls for standards “adequate to protect public health and the environment from any reasonably anticipated adverse effects” (CWA § 405 (d)(2)(D)). The Clean Air Act, when addressing criteria pollutants, directs the agency to develop criteria “reflecting the latest scientific knowledge” and, on the basis of those criteria, to issue “national primary ambient air quality standards to … protect public health with an adequate margin of safety” (CAA §§ 108,109). The primary purpose of the Toxic Substances Control Act is “to assure [that technologic] innovation and commerce in such chemical substances and mixtures do not present an unreasonable risk of injury to health or the environment” (TSCA § 2 (b)(3)). Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), one criterion for registering (licensing) a pesticide is that “it will perform its intended function without unreasonable adverse effects on human health and the environment” (FIFRA § 3). The Superfund National Contingency Plan specifies that “criteria and priorities [for responding to releases of hazardous substances] shall be based upon relative risk or danger to public health or welfare or the environment” (CERCLA § 105 (a)(8)(A)). The term risk assessment does not appear often in the statutes, and it is important to note that these statues were enacted prior to the emergence of risk analysis as an integrative discipline in the late 1970s and early 1980s. Rather, EPA risk-assessment principles and practices stem from statutory provisions calling for information on “adverse effects” (EPA 2004a, p. 14), “relative risk” (p. 82), “unreasonable risk” (p. 14), and “the current scientific knowledge” (p. 104) and for regulatory decisions on protecting human health and the environment. The statutes provide various standards and procedures related to the scientific analyses used to evaluate the risk potential of pollutants subject to the statutes.1,2 1 Different emphases and terminology lead to different risk-assessment approaches, sometimes for the same pollutant, in different agency programs. That can confuse and confound observers. For example, Clean Air Act provisions related to four air-pollution topics use different terms for what is essentially the same statutory finding: • Clean Air Act provisions related to pollutants regulated as national ambient air quality standards are designed to “protect the public health with an adequate margin of safety” (CAA § 109, emphasis added). • For welfare (environmental) effects, this provision directs the office to “protect the public welfare from any known or anticipated adverse effects” (CAA § 109, emphasis added). • Standards for “hazardous” pollutants from stationary sources (for example, factories) are to “provide an ample margin of safety to protect public health or prevent an adverse environmental effect” (CAA § 112, emphasis added). • Regarding mobile sources (for example, cars), the statute calls for ensuring that these vehicles do not “cause or contribute to an unreasonable risk to public health, welfare or safety” (CAA § 202 (a)(4), emphasis added). 2 Some statutes call for technology-based standards that require, for example, specific control techniques or technology-forcing standards that specify emission limits to be achieved within given periods. Such standards are based on costs, engineering feasibility, and related technical considerations. Examples include Clean Air Act Sections 111 (new-source review) and 202 (mobile-source emissions).
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Science and Decisions: Advancing Risk Assessment The existence of several medium-oriented statutes explains why EPA has multiple risk-assessment programs. This circumstance often draws criticism as “stovepiping” that leads to delay and inconsistency in both risk assessment and regulation. In the early 1990s, Congress considered but did not pass legislation to incorporate common risk-assessment terminology, concepts, and requirements into comprehensive risk-assessment legislation.3 Instead, recent enactments are notable for precise terms that amplify and clarify legislative objectives in individual statutes by specifying elements that assessments subject to particular statutes must include The 1996 Food Quality Protection Act specifies that “in the case of threshold effects … an additional ten-fold margin of safety for the pesticide chemical residues shall be applied for infants and children” (FFDCA § 408 (b)(2)(C)). 1996 amendments to the Safe Drinking Water Act are similarly explicit about the presentation of risk estimates and uncertainty: “The Administrator shall, in a document made available to the public in support of a regulation promulgated under this section, specify, to the extent practicable Each population addressed by any estimate of public health effects The expected risk or central estimate of risk for the specific populations Each appropriate upper-bound or lower-bound estimate of risk” (SDWA § 300g-1 (b)(3)). Provisions like those that apply to individual programs (the examples above appear in pesticide and water legislation, respectively) account for some of the variation in risk-assessment practices and results. However, although the new terms apply directly only to the program governed by the statute, other programs have adopted some of the changes. Despite differences in statutory language, environmental media, and pollutants, several factors common to the major statutes continue to shape EPA’s regulatory structure and function and its perspectives on risk assessment: The emphasis in each statute on protecting human health and the environment provides the basis of EPA’s purported conservative approach to risk assessment. Examples range from generic “adequate margin of safety” language in the Clean Air Act (CAA) amendments of 1971 (§ 109) to the required additional safety factor of 10 for protection for infants and children in the 1996 Food Quality Protection Act (FQPA; FFDCA § 408 (b)(2)(C)). As explained recently, “consistent with its mission, EPA risk assessments tend towards protecting public and environmental health by preferring an approach that does not underestimate risk in the face of uncertainty and variability” (EPA 2004a, p. 11). Except as noted above (footnote 2) and later in this chapter (page 51), the statutory provisions related to EPA’s main standards for protecting human health and the environment treat scientific analysis as a central element in regulatory decision-making and call for collection and evaluation of scientific information related to the pollutant undergoing regulatory review. Statutes often detail the kinds of information, analyses, and formal documentation required in the rule-making record. 3 A bipartisan coalition of senators sponsored the Thompson-Levin bill (S981), titled “Regulatory Improvement Bill,” which would have codified the Office of Management and Budget (OMB) role in review of agency regulations; some provisions later appeared in the OMB Bulletin (70 Fed. Reg. 2664 ). The Moynihan bill (S123) called for comparative risk assessment.
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Science and Decisions: Advancing Risk Assessment Although some sections of statutes focus solely on health-effect considerations,4 many also identify information and analyses from other fields—such as economic analysis, technical feasibility, and societal impacts—for use in making regulatory decisions. “It is generally recognized—by the science community, by the regulatory community, and by the courts—that it is important to consider other factors along with the science when making decisions about risk management” (EPA 2004a, p. 3). The resulting decisions—whether or not to regulate and, if so, the nature and form of regulation—seek to protect human health and the environment where appropriate, in part on the basis of scientific analysis and in part on the basis of consideration of information on costs, societal values, legal requirements, and other factors. As the proponent of any new regulation, EPA generally5 has the burden of proving that the proposed regulation meets statutory standards. That is not a requirement for EPA to prove “cause and effect” in the customary scientific sense, but rather to demonstrate by way of science-based analysis that the proposed regulation meets statutory criteria related to adverse effects, unreasonable risks, and other statutory thresholds for regulation: Although regulatory agencies do not have the technical burden of proving that a particular company’s products or activities have caused or will cause a particular person’s disease, they do have the practical burden of assembling a record containing sufficient scientific information and analysis to survive a reviewing court’s “hard look” review under the “substantial evidence” or “arbitrary and capricious” tests for judicial review of administrative action [McGarity 2004]. The environmental statutes administered by EPA and general administrative law require documentation and review of relevant data and analyses. Some statutory provisions for pesticides facilitate gathering data for risk assessment by enabling the agency to impose data requirements on producers and others (for example, FIFRA § 3); the agency’s ability to impose data requirements has proved far more limited under the Toxic Substances Control Act (TSCA; GAO 2005) and other statutes. As the primary scientific rationale for many EPA regulations, risk assessment is subject to scientific, political, and public controversy. Building on the statutory foundation, the 1983 Red Book introduced principles, terminology, and practices that have become mainstays of the process. That report, which provided for a common framework for reconciling, to some extent, the differing requirements of the statutes, led to changes in the 1980s and 1990s and continues to shape the process today. THE PIVOTAL ROLE OF THE RED BOOK The 1983 National Research Council Report During the 1970s, the scientific assessment practices of EPA and other federal agencies faced with similar responsibilities—the Occupational Safety and Health Administration, the Food and Drug Administration (FDA), and the Consumer Products Safety Commis- 4 Section 109 of the CAA of 1970 is the most often cited example; note, however, that the statute expressly provides for consideration of costs, feasibility, and other factors in state implementation plans (§ 110). Such considerations influence the time allowed for compliance with the standards. 5 The situation differs for pesticides. The pesticide statute, FIFRA, requires manufacturers to submit data showing a “reasonable certainty of no harm” before pesticides can be registered and marketed and to maintain the registration.
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Science and Decisions: Advancing Risk Assessment sion—came under close scrutiny as decisions resulting from those practices took on greater social importance. In 1981, Congress (PL-96528) directed that FDA support a National Research Council study of the “merits of an institutional separation of the scientific functions of developing objective risk assessments from the regulatory process of making public and social policy decisions and the feasibility of unifying risk assessment functions.” The National Research Council organized the Committee on the Institutional Means for Assessment of Risks to Public Health in October 1981, and the committee’s report, the Red Book, was issued on March 1, 1983. In his letter transmitting the report to the commissioner of FDA, the chairman of the National Research Council, Frank Press, stated, The Congress made provision for this study to strengthen the reliability and objectivity of scientific assessment that forms the basis for federal regulatory policies applicable to carcinogens and other public health hazards. Federal agencies that perform risk assessments are often hard pressed to clearly and convincingly present the scientific basis for their regulatory decision. In the recent past, for example, decisions on saccharin, nitrites in food, formaldehyde use in home insulation, asbestos, air pollutants and a host of other substances have been called into question. The report recommends no radical changes in the organizational arrangements for performing risk assessments. Rather, the committee finds that the basic problem in risk assessment is the incompleteness of data, a problem not remedied by changing the organizational arrangement for performance of the assessments. Instead, the committee has suggested a course of action to improve the process within the practical constraints that exist. As noted in Press’s letter, the “course of action” recommended by the committee focused primarily on the process through which complex and uncertain, and often contradictory, scientific information derived from laboratory and other types of research could be made useful for regulatory and public-health decision-making. The committee was also sensitive to the concern, expressed in the congressional language, that scientific assessments should be “objective” and free of policy (and political) influences. Because all assessments of scientific data are subject to uncertainties and because scientific knowledge is incomplete, it is possible for different analysts to arrive at different interpretations of the same set of data. If the assessment involves risks to human health from chemical toxicity or other types of hazards, the differences in interpretation can be large. The committee therefore recognized that risk assessments could be easily manipulated to achieve some predetermined risk-management (policy) outcome. Much of the work of the committee was directed at finding ways to minimize that potential problem while avoiding the undesirable step of institutional separation of scientific assessment from decision-making. The 1983 report was not directed at the technical analyses involved in risk assessment. Rather, it offered a coherent and generally applicable framework within which the process of risk assessment could be undertaken. That framework was shown to be necessary to fill the gap between the research setting within which general scientific knowledge and diverse types of information on specific threats to human health are developed and the various types of risk-management activities undertaken by regulatory and public-health agencies to minimize those threats. The committee’s recommendations gave order to the developing field of risk assessment by defining terms and elucidating the four (now well-known) steps of the risk-assessment process. The committee chose the term risk characterization to describe the fourth and final step of the risk-assessment process, in which there is an integration and synthesis of the information and analysis contained in the first three steps (see Figure 2-1). The committee stated that the term characterization was chosen to convey the idea that both quantitative and qualitative elements of the risk analysis, and of the scientific uncertainties
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Science and Decisions: Advancing Risk Assessment FIGURE 2-1 The National Research Council risk-assessment–risk-management paradigm. Source: NRC 1983. in it, should be fully captured for the risk manager. Risks associated with chemical toxicity necessarily involve biologic data and uncertainties, many of which are not readily expressed in quantitative terms. Again, it was beyond the charge of the committee to offer specific technical guidance on the modes of scientific analysis appropriate for each of the steps of risk assessment. The first recommendation of the Red Book is the following (NRC 1983, p. 7): We recommend that regulatory agencies take steps to establish and maintain a clear conceptual distinction between assessment of risks and consideration of risk management alternatives; that is, the scientific findings and policy judgments embodied in risk assessments should be explicitly distinguished from the political, economic, and technical considerations that influence the design and choice of regulatory strategies. Two aspects of that critical recommendation are especially noteworthy. First, the committee emphasized that the distinction between risk assessment and risk management is a conceptual one; that is, it concerns the fact that the content and goals of the two activities are distinguishable on a conceptual level. The Red Book nowhere calls for any other type of “separation” of the two activities. Second, the phrase “policy judgments embodied in risk assessment” (which are said to be different in kind from those involved in risk management) points to one of the most important insights of the committee. In particular, the committee recognized that almost no risk assessment can be completed unless scientific information (data and knowledge) is supplemented with assumptions that have not been documented in relation to the particular risk assessment at hand, although they have probably been supported by substantial evidence
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Science and Decisions: Advancing Risk Assessment or theory for the general case.6 The clearest examples of such assumptions related to risks posed by chemical toxicity concern the shape of dose-response curves in the region of very low doses and the relevance to humans of various toxicity responses observed in high-dose animal experiments; assumptions regarding these and many other aspects of the data used for risk assessment are necessary to provide risk managers useful risk characterizations based on consistent approaches. The Red Book committee recognized that for a given analytic component of any of the steps of a risk assessment for which an assumption is necessary, several scientifically plausible assumptions might be available. The committee used the phrase “inference options” to describe the array of possibilities. To bring order and consistency to risk assessments conducted by the federal government and to minimize case-by-case manipulations of risk-assessment outcomes, the committee recommended the development of specific “inference guidelines”; these were to contain “an explicit statement of a predetermined choice among alternative inference options” (NRC 1983, p. 4) (see Box 2-1). Thus, agencies should take steps to describe, in explicit guidelines, the technical approaches used to conduct risk assessments, and these guidelines should include specification of the assumptions (including, in some cases, models) that would be consistently used to draw inferences in all the analytic components of the risk-assessment process where they are needed. Inference options have come to be called default options, and the inferences selected for risk assessments have come to be called defaults. The development and consistent use of technical guidelines for risk assessment, with the specification of all the necessary defaults, were seen by the Red Book committee as necessary to avoid the institutional separation of scientific assessment from policy development and implementation while minimizing inappropriate and sometimes invisible policy influences on the risk-assessment process. As noted later in this chapter, some critics of the Red Book have raised the concern that the committee’s commendable effort to avoid “inappropriate influences” can readily be taken to mean “no influence” from risk managers and other stakeholders. One additional feature of the Red Book’s recommendations bears on the current committee’s task. Thus, as part of the statement of Recommendation 6, which concerns the criteria for useful risk-assessment guidelines, can be found the following (NRC 1983, p. 165): Flexibility The committee espouses flexible guidelines. Rigid guidelines, which permit no variation, might preclude the consideration of relevant scientific information peculiar to a particular chemical and thus force assessors to use inference options that are not appropriate in a given case. Also, rigid guidelines might mandate the continued use of concepts that become obsolete with new scientific developments. Large segments of the scientific community would undoubtedly object to such guidelines as incompatible with the use of the best scientific judgment for policy decisions. Flexibility can be introduced by the incorporation of default options. The assessor would be instructed to use a designated (default) option unless specific scientific evidence suggested otherwise. The guidelines would thus permit exceptions to the general case, as long as each exception could be justified scientifically. Such justifications would be reviewed by the sci- 6 No scientific knowledge is without uncertainty, but it is generally subject to empirical verification; when the empirical evidence is supportive and no contrary evidence can be found, documentation is said to have been established, at least tentatively. The assumptions needed to complete risk assessments are generally well supported for the relevant set of past assessments; however, in any specific case it will often be difficult, if not impossible, to verify empirically that a given assumption also holds for the substance at issue.
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Science and Decisions: Advancing Risk Assessment BOX 2-1 Agencywidea Risk-Assessment Guidelines 1986 Guidelines for Carcinogen Risk Assessment (EPA 1986a) Guidelines for Health Assessment of Suspect Developmental Toxicants (51 Fed. Reg. 34028 ) Guidelines for Mutagenicity Risk Assessment (EPA 1986b) Guidelines for Estimating Exposures (51 Fed. Reg. 34042 ) Guidelines for Health Assessment of Chemical Mixtures (EPA 1986c) 1991 Developmental Toxicity Risk Assessment (revised and updated) (EPA 1991) 1992 Guidelines for Exposure Assessment (EPA 1992a) 1996 Guidelines for Reproductive Toxicity Risk Assessment (EPA 1996a) 1998 Guidelines for Ecological Risk Assessment (EPA 1998a) Guidelines for Neurotoxicity Risk Assessment (EPA 1998b) 2000 Supplementary Guidance for Health Risk Assessment of Chemical Mixtures (EPA 2000a) 2005 Guidelines for Carcinogen Risk Assessment and Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens (EPA 2005a,b) These guidelines, which are consistent with Red Book recommendations (NRC 1983, p. 7), “structure the interpretation of scientific and technical information relevant to the assessment” and “address all elements of risk assessment, but allow flexibility to consider unique scientific evidence in particular instances.” Each guideline is a multiyear project developed by multioffice teams composed of scientists in EPA laboratories, centers, program offices, and regional offices. Draft guidelines are peer-reviewed in open public meetings and published for comment in the Federal Register. In general, each guideline follows the 1983 Red Book paradigm, providing guidance on the use and interpretation of information in each field of analysis, including the role of defaults and assumptions and approaches to uncertainties and risk characterization. Some guidelines are accompanied by supplementary reports on special topics, for example, “Assessing Susceptibility from Early-life Exposure to Carcinogens” (EPA 2005b) and “Guiding Principles for Monte Carlo Analysis” (EPA 1997a). aEPA’s guideline library includes many other guidance documents and policies, including those specific to individual programs (see, for example, Tables C-1 and D-1 and references). entific review panels and by the public under procedures described above. Guidelines could profitably highlight subjects undergoing relatively rapid scientific development (for example, the use of metabolic data for interspecies comparisons) and any other components in which exceptions to particular default options were likely to arise. They should also attempt to present criteria for evaluating whether an exception is justified. As will be evident throughout this report, it has proved difficult to achieve scientific consensus on judgments regarding the adequacy of scientific evidence to justify, in specific cases, departures from one or more defaults. One of the objectives of the present committee’s work might be seen as determining whether 25 years of scientific research and of scholarly thinking about the conduct of risk assessments provides new insights into whether there might be better ways of approaching the uncertainties that give rise to the need for defaults.
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Science and Decisions: Advancing Risk Assessment Later National Research Council Studies NRC (1993a) advocated the integration of ecological risk assessment into the 1983 Red Book framework. The framework for risk assessment and its four-step analytic process were adopted and promoted in the National Research Council’s Science and Judgment in Risk Assessment (NRC 1994) and Understanding Risk: Informing Decisions in a Democratic Society (NRC 1996). Indeed, the framework has been widely adopted in other expert studies of risk assessment (see PCCRARM 1997 and references cited therein) and has been adopted outside the United States (in the European Union and the World Health Organization) (see Figure 2-2). Moreover, as regulatory and public-health institutions have had to bring a greater degree of scientific analysis and consistency to health threats posed by microbial pathogens (Parkin 2007), excessive nutrient intakes (IOM 1997, 1998, 2003; WHO 2006), and other environmental stressors, they have found the Red Book framework both scientifically appropriate and useful. One additional theme regarding the risk-assessment process is given great attention by the National Research Council in Understanding Risk (NRC 1996, p. 6): The analytic-deliberative process leading to a risk characterization should include early and explicit attention to problem formulation; representation of the spectrum of interested and FIGURE 2-2 The World Health Organization’s framework for integrated health and ecologic risk assessment. NOTE: Figures 2-1 and 2-2 show different renditions and evolving emphases as to the basic elements of the Red Book paradigm. Source: Suter et al. 2001.
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Science and Decisions: Advancing Risk Assessment affected parties at this early stage is imperative. The analytic-deliberative process should be mutual and recursive. Analysis and deliberation are complementary and must be integrated throughout the process leading to risk characterization: deliberation frames analysis, analysis informs deliberation, and the process benefits from feedback between the two. That recommendation provides nuance to the Red Book’s call for “separation” of assessment and management to facilitate the supreme goal of risk assessment: to provide the scientific basis for public-health and regulatory decisions. As long as “analysis and deliberation” does not involve efforts by risk managers to shape risk-assessment outcomes to match their policy preferences, but rather involves efforts to ensure that assessments (whatever their outcomes) will be adequate for decision-making, interactive processes involving “the spectrum of interested and affected parties” are seen as imperative. The 1994 National Research Council report Science and Judgment in Risk Assessment evaluated EPA’s risk-assessment practices as they apply to hazardous air pollutants from sources subject to Section 112 of the CAA amendments of 1990. That report did not alter the principles for risk assessment set forth by the Red Book but rather examined EPA guidelines and practices and then recommended ways in which various technical improvements in the conduct of risk assessments and in the presentation of risk characterizations might be accomplished. Thus, the present committee’s efforts resemble in many ways those undertaken by the Science and Judgment committee. The issue of default options was given much consideration (see Box 2-2). Indeed, the 1994 National Research Council committee found EPA’s existing technical guidelines for risk assessment to be deficient with respect to their justifications for defaults and with respect to evidentiary standards and scientific criteria to be met for case-specific departures from them.7 The committee offered a long series of recommendations, each preceded by a discussion of the state of technical understanding, on issues of data needs for risk assessment, uncertainty, variability, aggregation of exposures and risk, and model development. The 1994 committee’s recommendations extended beyond the technical content of risk assessment and included issues of process, institutional arrangements, and even problems of risk communication. Although there was much focus on air-pollutant risks, particularly the technical issues related to exposure assessment, most of that committee’s recommendations had broad applicability to risk assessment. In Appendix D to the present report, the committee has selected representative recommendations contained in the three National Research Council reports cited above and attempted to provide a view of how EPA has responded to many of them. It can be seen that EPA has devoted considerable effort to ensuring that its guidelines conform to many National Research Council recommendations, although the record on accepting and implementing recommendations is uneven and incomplete (see, for example, Boxes 2-4 and 2-5 and Chapter 6). The present committee has been asked to review current EPA “concepts and practices,” taking into account the previous National Research Council studies and studies in which new scientific approaches are being evaluated. The present committee is not specifically charged with modifying the fundamental concepts first elucidated in the Red Book unless the scientific understanding on environmental hazards and the research on the conduct of risk assessment that have developed over the past 25 years demand such a modification. Thus, as 7 Appendix N to the 1994 report contains two views of the issue of defaults, one of committee member Adam Finkel and one of members Roger McClellan and D. Warner North; their papers represent a range of committee perspectives on the appropriate balance of science and policy considerations in a system for departure from default assumptions.
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Science and Decisions: Advancing Risk Assessment BOX 2-2 Science Policy and Defaults Science and Judgment (NRC 1994) describes defaults as the “science policy components of risk assessment” (p. 40) and points out that “if the choice of inference options is not governed by guidelines, the written assessment itself should make explicit the assumptions used to interpret data or support conclusions reached in the absence of data” (p. 15). The report recognizes “choice” as an aspect of science policy (p. 27): The [1983 Red Book] committee pointed out that selection of a particular approach under such circumstances involves what it called a science-policy choice. Science-policy choices are distinct from the policy choices associated with ultimate decision-making…. The science-policy choices that regulatory agencies make in carrying out risk assessments have considerable influence on the results. Those principles are the basis of EPA’s call for “transparency,” “full disclosure,” and “scientific conclusions identified separately from default assumptions and policy calls” in the Risk Characterization Handbook (EPA 2000b). EPA’s recent Staff Paper (EPA 2004a, p. 12) embraces and expands on the principles: “Science policy positions and choices are by necessity utilized during the risk assessment process.” The Superfund program’s supplemental guidance document Standard Default Exposure Factors was developed in response to requests to make Superfund assessments more transparent and their assumptions more consistent. The guidance states that defaults are used when “there is a lack of site-specific data or consensus on which parameters to choose, given a range of possibilities” (EPA 2004a, p. 105). as the committee undertook its technical evaluations, it remained sensitive to the question of whether the Red Book’s framework for risk assessment and its conceptual underpinnings are adequate to meet the challenges of understanding and managing the array of environmental threats to health and the environment that we are expected to face in the foreseeable future. These considerations have also shaped other approaches to thinking about risk assessment including PCCRARM (1997) and a recent publication by Krewski et al. (2007). CURRENT CONCEPTS AND PRACTICES EPA’s statement of task for this committee (Appendix B) seeks a “scientific and technical review of EPA’s current risk analysis concepts and practices.” In addition, EPA invites the committee to develop “recommendations for improving” EPA’s risk-analysis approaches, “taking into consideration past evaluations.” At the outset, the committee approached its task in part by reviewing major National Research Council reports published since 1983. It also examined EPA risk-assessment activities in light of themes and trends in those reports. The discussion that follows highlights EPA’s progress in many spheres and shortfalls and committee uncertainty about the nature and extent of progress. The National Research Council reports and EPA documents arrayed in the timeline diagram in Figure 2-3 and the timeline table in Appendix C are the primary sources for this analysis. The implementation table in Appendix D isolates and highlights National Research Council recommendations on selected risk-assessment topics with relevant EPA responses as documented in a recent EPA Staff Paper (EPA 2004a), guideline documents, and other EPA sources; it also draws on a Government Accountability Office (GAO) study requested by Congress (GAO 2005).
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Science and Decisions: Advancing Risk Assessment In sum, many factors—statutory requirements, the diverse array of environmental problems and agency programs, executive orders, OMB directives, and the vagaries of the risk-assessment process—give rise to risk-assessment practices and individual assessments that differ in form, information content, and analytic quality. Such diversity demands informed and experienced attention to managing the process. Executive Orders: Regulatory Policy Several executive orders illuminate the role of the White House in risk management and regulatory decision-making. Described as a “cornerstone of White House administrative policy” (OMB Watch 2002), Executive Order 12866 (October 4, 1993)24 calls for each agency head to designate a regulatory-policy officer and outlines requirements related to risk assessment, cost-benefit analysis, performance-based regulatory standards, and other aspects of regulation development. A recent amendment, Executive Order 13422 (Jan. 18, 2007), requires the regulatory-policy officer to be a presidential appointee. The present committee did not assess the impact of those and other executive orders on EPA risk assessment. Public Participation EPA relies on information from the public in developing both general principles and risk assessments of individual chemicals. By law, EPA, like other federal agencies, is required to publish proposed regulations (including any underlying scientific analysis) in the Federal Register, invite public comments, and consider the comments in its final decision. EPA often follows that process for guidance documents that apply only internally (for example, risk-assessment guidelines) and for preliminary analyses used in rule-making. In addition, separately from the peer-review activities discussed above, the agency often convenes scientific experts to discuss strategic planning and research priorities and to introduce and develop background documents. Notice is given in the Federal Register, and the public is invited to observe and comment during the session. Public meetings, workshops, and the notice and comment process are avenues for stakeholders to present risk-assessment-relevant information and opinion. One example is the Pesticide Program Dialogue Group, a forum established in 1995 for a diverse group of stakeholders to provide feedback on issues from nonanimal testing to endangered species to risk assessment. The group includes pesticide manufacturers, public-interest and advocacy groups, and trade associations. It is one of several groups on pesticide issues, with corresponding groups in other agency offices, such as those which involve air-program consultation with state and local air-pollution programs and waste-office consultation with responsible parties and community groups regarding Superfund sites. EPA regional offices work closely with the Indian tribes on selected issues. Thus, EPA expressly solicits information from interested and knowledgeable parties, whether scientists or nonscientists. EPA’s statement of task anticipates near-term and long-term improvements in risk assessment as a result of the present report. New approaches can be expected to require ad- 24 Executive Order 12866 replaces and extends Executive Orders 12291 and 12498, issued during the Reagan administration. It directs federal regulatory agencies, including EPA, to “assess both the costs and the benefits of the intended regulation and, recognizing that some costs and benefits are difficult to quantify, propose or adopt a regulation only upon a reasoned determination that the benefits of the intended regulation justify its costs” [Sec. (b)(1)]. The order requires EPA to conduct a formal RIA for proposed regulations expected to impose economic costs in excess of $100 million per year.
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Science and Decisions: Advancing Risk Assessment BOX 2-9 Risk-Assessment Planning: Multiple Participants The committee that produced Understanding Risk (NRC 1996) identified several criteria for judging success at the end of the process: getting the science right, getting the right science, getting the participation right, getting the right participation, and developing an accurate, balanced, and informative synthesis. As discussed below (Chapter 3), achieving those objectives depends in part on informed “planning and scoping” activities involving risk assessors, risk managers, and interested and affected parties. The emphasis on the “right” participants as well as the “right” science is important (McGarity 2004): There is little evidence that the scientific information that the agencies are currently using and disseminating is unreliable. Virtually all of the challenges that have been filed so far under the [2004 Information Quality Act] have involved disputes over interpretations, inferences, models and similar policy issues, and not the “soundness” of the underlying data. justments of agency processes for allocating funds, scheduling research, expanding training, and other activities. New methods may also require enhanced peer review and expanded public participation to ensure that affected and interested parties in and outside the regulated community have an opportunity to contribute to new approaches and are prepared for change (see Box 2-9). Peer Review, Quality Control, and Advisory Committees Quality-control and peer-review procedures are particularly important when new approaches are introduced into the risk-assessment process. EPA uses several mechanisms to ensure the quality and relevance of laboratory and field data. In addition to general methods and guidelines, including uniform guidance applicable to all federal agencies, the major programs have program-specific methods related to, for example, air emissions, microbiologic contaminants, and underground storage tanks (EPA 2007c). Similarly, EPA’s peer-review program gives attention to new approaches and individual risk assessments. For example, a subcommittee of EPA’s SAB monitored the development of EPA’s first guidelines for ecologic risk assessment. Of course, assessments of individual chemicals based on new methods are subject to statutory requirements for peer review, such as the CAA requirement for review of the scientific basis of national ambient air quality standards and the FIFRA requirement for EPA’s Scientific Advisory Panel (SAP) review of the scientific basis of some pesticide decisions. Other statutes require SAB review of a wide variety of analyses (see Box 2-10).25 Independent advisory committees that provide information and advice on special topics may contribute to new approaches. In addition to advisory committees required by statute, 25 In response to recommendations from the EPA SAB and others (EPA 1992d), EPA peer-review policies issued in 1992 call for external review of scientific assessments not subject to statutory requirements. The processes were reinforced and augmented (and in some ways redefined) by OMB’s 2002 governmentwide directive on peer review applicable to all federal agencies (67 Fed. Reg. 8452 ). EPA risk assessments and underlying scientific analyses are also peer-reviewed when laboratory scientists, as well as those in program and regional offices, publish work developed for risk-assessment use in scholarly journals. That work includes individual laboratory or field studies on toxicology, epidemiology, and monitoring and subunits of risk assessment, such as hazard identification and exposure analysis.
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Science and Decisions: Advancing Risk Assessment BOX 2-10 After Peer Review Peer review is not an end in itself. Ideally, peer review identifies deficiencies, suggests modifications, and otherwise leads the agency to improve a risk assessment to conform more fully with scientific standards and to guide decision-making and support regulatory standards. Two situations invite inquiry and attention because, while enhancing the assessment, they also cause delays and add costs to the risk-assessment process. Peer-review “spirals” involve repeated reviews that return assessments to the agency for further revision because the agency has not responded adequately to science-based recommendations in earlier reviews or because of science-policy debates or inadequacies in the peer-review process itself (GAO 2001). Recent examples include the reviews of dioxin and the cancer risk-assessment guidelines (see 68 Fed. Reg. 39086 ; EPA 2005a; NRC 2006). Some assessments fail to reach closure or completion within a typical period after peer review. An example of such an unfinished assessment is that of dichloromethane (methylene chloride), which was peer-reviewed by the SAB in 1987; the health assessments remain in draft form (EPA 1987b,c), and the SAB comments have never been incorporated (EPA 2003e). The EPA assessment (EPA 1987b,c) at the time was regarded as a good example of the use of pharmacokinetic modeling. Specifically, the SAB review stated (EPA SAB 1988, p. 1) that “the Subcommittee concludes that the Addendum [EPA 1987c] was one of the best documents it has reviewed in terms of its clarity, coverage of the data and analysis of scientific issues. This document clearly demonstrates the potential utility of pharmacokinetic data in risk assessment. EPA should continue to use this approach in future risk assessments, whenever scientifically possible.” A confluence of factors may explain extended timeframes and unfinished assessments, including scientific complexity and controversy, a continually evolving database, and stakeholder and advocacy-group demands. Contributing factors in the case of dichloromethane were the absence of strong regulatory pressure for the assessment; the increasing importance of other chemicals, including trichloroethylene and tetrachloroethylene; and the replacement of dichloromethane with substitutes (L. Rhomberg, Gradient Corporation, Cambridge, MA, personal commun., May 31, 2007). EPA is scheduled to update the IRIS value for dichloromethane in the middle of 2009 (Risk Policy Report 2007; 40 CFR Part 63 ). such as the SAB and SAP, EPA has chartered committees to provide advice on selected issues pertinent to risk assessment, such as research planning and priorities (the Board of Scientific Counselors), endocrine-disrupting chemicals (the National Committee on Endocrine Disrupting Chemicals and Toxic Substances), and children’s health (the Children’s Health Protection Advisory Committee) (www.EPA.gov). International Organizations EPA consults and collaborates with programs associated with the risk-assessment arms of numerous international organizations. EPA scientists sit on numerous international committees including the IPCS, the International Agency for Research on Cancer (IARC)/WHO, the International Commission on Radiological Protection, and the Intergovernmental Forum on Chemical Safety; participate in the writing of scholarly papers; and conduct risk-assessment training in conjunction with these international organizations. As with state and local regulatory bodies, EPA and these organizations share scientific data, exchange information on developments in risk assessment, and work to harmonize risk-assessment concepts and
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Science and Decisions: Advancing Risk Assessment guidelines. Those interactions provide opportunities for EPA scientists to be alert to advances made in the organizations that will contribute to new approaches under way in EPA. In sum, several mechanisms are available to inform and upgrade EPA risk-assessment processes. Beyond the basic procedures outlined above, complementary planning and oversight activities make it clear that the risk-assessment enterprise involves more than its basic scientific elements. Numerous overarching factors—tangible and intangible, scientific and nonscientific—shape the process and influence the quality of agency assessments. CONCLUSIONS AND RECOMMENDATIONS Congressional mandates give EPA a diverse set of risk-assessment and regulatory responsibilities. The process is informed by many factors, including congressional legislation, generic guidance, and advice from scientific advisory bodies, peer-review recommendations specific to individual risk assessments and guidelines, information from stakeholders and other interested parties, and the principle of comity with other government entities (state, local, and international) on risk-assessment issues. The result is a complex set of risk-assessment activities that have drawn high praise in many cases and sustained criticism in others. The process recommendations below identify institutional and management issues that require sustained attention by agency leadership. Except for the longer timeframe expected for new guidelines (see final recommendation), the committee contemplates implementation in the immediate and near future. Conclusions Some deficiencies in current EPA risk-assessment practices can be attributed in part to the unavailability of relevant data and methods. Those limitations head the list of EPA concerns about implementing future recommendations for improvement (Appendix E). Implementing several of the recommendations in the present report will require additional data and methods related to each of the three analytic fields in the Red Book paradigm. In addition, new kinds of data or methods will be required to enable EPA to undertake analyses that are given new emphasis or recommended for the first time here. Although EPA has a 20-year history of issuing guidelines and other reports designed to implement recommendations for improvement offered by the National Research Council and other advisory bodies, moving from policy to practice has in some cases been incomplete or only partially effective (as to provisions put into practice) and in others uneven (as to use for all assessments in all parts of the agency, where applicable). Effective use of new methods and attention to new policies require instruction and training for both experienced risk assessors and newcomers. And putting new policies and methods into practice—that is, moving beyond policy documents—requires understanding and appreciation on the part of agency managers and decision-makers. Historically, guideline development in EPA has taken from as little as 3 years to more than 15 years (for example, the cancer guidelines were issued in 2005 after a 15-year development period). Improvements in risk assessment will involve issuing new guidelines, revising existing guidelines or issuing supplemental guidance, and implementing existing guidelines more effectively.
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Science and Decisions: Advancing Risk Assessment Recommendations The committee seconds the Government Accountability Office recommendation that the administrator of the Environmental Protection Agency direct agency offices to “more proactively identify the data most relevant to the current risk assessment needs, including the specific studies required and how those studies should be designed, and communicate those needs to the research community” (GAO 2006, p. 69). The committee recommends that the Environmental Protection Agency consider recommendations in the present report as part of that process. Putting recommendations from this report into practice will require additional staff in fields that are now lightly staffed (for example, epidemiology and quantitative uncertainty analysis) and new staff in fields that are generally understaffed relative to this report’s emphasis on the social-science components of environmental decision-making (for example, psychology, sociology, economics, and decision theory). Agency leaders should give high priority to establishing and maintaining risk-assessment and decision-making training programs for scientists, managers responsible for risk-assessment activities, and other participants in the process. This reinforces the Government Accountability Office recommendation that the Administrator of the Environmental Protection Agency “ensure that risk assessors and risk managers have the skills needed to produce quality risk assessments by developing and implementing in-depth training” (GAO 2006, p. 69). A regular schedule of refresher courses is critical for such a program. This recommendation calls for training to ensure that all relevant managers and decision-makers are fully informed on risk-assessment principles and principles related to the other disciplines (such as economics and engineering) that, with risk assessment, influence regulatory decisions. To reduce the effects of the compartmentalization resulting from the Environmental Protection Agency’s organization around diverse statutory mandates, the administrator can buttress the scientific talent brought to bear on improvement activities by revitalizing and expanding interoffice and interagency collaboration through existing structures (for example, the Risk Assessment Forum, the Science Policy Council, and the National Science and Technology Council Committee on Environment and Natural Resources) and by joining scientists from other agencies (for example, the National Institute of Environmental Health Sciences and the Food and Drug Administration) in these activities. This reinforces the Government Accountability Office recommendation that the administrator of the Environmental Protection Agency “develop a strategy to ensure that offices engage in early planning to identify and seek the expertise needed, both within the EPA workforce and from external subject matter experts” (GAO 2006, p. 69). The administrator of the Environmental Protection Agency should give special attention to expanding the scientific and decision-making core in the regional offices to ensure that they have the capacity to use improved risk-assessment methods and to meet their obligations for interaction with stakeholders, local agencies, and tribes. The Environmental Protection Agency should establish a tiered schedule for guideline implementation: (1) immediate and uniform use and oversight as to existing guidelines and risk-assessment policies (for example, 1-2 years), except where inapplicable; a shorter-term schedule for revision or updating of existing guidelines where appropriate (for example, 2-6 years); and a longer-term but definite schedule for development and issuance of new guidelines (for example, 6-15 years).
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