Sustainability and the U.S. EPA (2011)

5


How Risk Assessment and Risk Management Relate to the Sustainability Framework

As described in Chapter 4, risk assessment is an important analytic tool used to evaluate the effects of environmental stressors on ecosystem and human health. This tool has been applied over the past 25 years to facilitate management of environmental threats and remains a key analytic method in support of sustainability decision making, as envisioned by the Committee on Incorporating Sustainability in the U.S. EPA.

The formal risk assessment and risk management framework derives from a 1983 NRC report Risk Assessment in the Federal Government: Managing the Process, now known as the Red Book (NRC 1983). The goal was to help federal agencies, including EPA, make informed decisions about chemical agents in the setting of a growing understanding and public concern about the link between exposures to toxins and adverse effects, including cancer and birth defects. This setting of growing understanding and growing concern is similar to that faced by EPA in dealing with the challenges posed by the need for decision-making processes that fully support sustainability goals.

The NRC Red Book considered risk assessment to be an input into risk management. Building on work done in the United States and around the world, the four-step risk assessment paradigm was described as hazard identification, dose-response assessment, exposure assessment, and risk characterization. Risk management decisions were fully acknowledged to be based not only on risk assessment but also on economic, legal, and other policy-based evaluations. The risk management process involved development of regulatory options, and “evaluation of public health, economic, social, and political consequences of regulatory options.” Those evaluations plus the “risk characterization,” the fourth step of the risk assessment, are weighed for agency decision and actions, as illustrated in Figure 5-1.

FIGURE 5-1 Elements of risk assessment and risk management in the Red Book.
SOURCE: NRC 1983.

EPA was over a decade old and had achieved many of its original objectives before the formal risk assessment paradigm was proposed in the NRC Red Book. EPA also needed the risk assessment paradigm to deal with risks that were below what was readily observable—particularly cancer risks, which were and are of great public concern (NRC 1983). EPA had already promulgated National Ambient Air Quality Standards for major air pollutants under the Clean Air Act based on non-cancer health effects. This involved direct observations of epidemiologic associations without inferring the existence of effects at air concentrations much lower than ambient levels. Risk assessment enabled effective and defensible decisions at more stringent levels corresponding to small but significant risks and was a valuable adjunct to EPA’s existing “command and control” approach to regulating overt pollution of air, water, and soil.

The elements of risk assessment were already in place and being used in the United States and elsewhere, particularly for food and occupational health issues related to chemicals, before the publication of the Red Book. The NRC committee gathered ideas and did a superb job formulating a coherent approach. The Red Book committee was particularly effective in articulating the strengths and limitations of the various parts of the paradigm.

The NRC Red Book committee also had a major role in clearly defining key terms, such as “risk” and “hazard.” The terms had been subject to various definitions or were used interchangeably, complicating communication and development of an agreed upon approach to risk issues. Also of note, the 1983 Red Book was not immediately adopted within EPA or elsewhere. It required several years for its general acceptance at EPA and its diffusion to state and local agencies.

INFERENCE GUIDELINES AND OPERATIONAL PROCEDURES

The Red Book (NRC 1983) stated that regulatory agencies had difficulty making decisions about a chemical agent because of the “inherent limitations,” particularly uncertainties, in the science and limited analytic capacity. To bridge gaps in knowledge, the Red Book recommended that uncertainties be addressed through default inference guidelines— “an explicit statement of a predetermined choice among the options that arise in inferring human risk from data that are not fully adequate or not drawn directly from human experience” (p.51). It acknowledged the impossibility of distinguishing among such options based purely on scientific observations. These inference guidelines were seen as a way to promote consistency in analyses and avoid manipulation of outcomes. A system of guidelines, default options, and practice has developed over the years to support assessment, and a recent NRC (2009) review of EPA’s risk assessment practice endorsed and emphasized the need for a clear system of defaults to support agency decision making.

LIMITATIONS OF THE RISK ASSESSMENT AND RISK MANAGEMENT PARADIGM

EPA has had many successes in addressing the environmental problems of significant concern in the 1980s when the risk paradigm was developed. Major improvements in air and water are evident; wastes are being handled in ways less likely to pollute soil and other media; substantially lower levels of dioxins and polychlorinated biphenyls (PCBs) are present in the environment and in humans (EPA 2008).

Yet it is evident that standard risk-based regulatory approaches have limitations, including difficulty in dealing with complex problems that are not readily addressed by analyses that seek to “simplify the multidimensionality of the risk or make sense of the uncertainty” (NRC 1996) or require a volume of information and analyses that far outstrip the resources available to provide them (NRC 2006). Examples include global climate change (WHO 2003), environmental justice (NRC 1996, 2009), green chemistry (NRC 2006), nanotechnology (GAO 2010), and species loss. Recognition of the limitations in approaching these complex issues has led to approaches to widen the risk paradigm, to include the context in which the analysis is performed, the early consideration of a broad range of decision options, and the cumulative threats of multiple social, environmental, and economic stressors to health and the environment. These recent approaches can be considered to be attempts to widen the risk paradigm so as to more readily confront concerns that are central to sustainability.

Risk assessment as an analytic tool is limited in part because it works best for those chemical and physical agents that have already been emitted, in part because the nature and degree of exposure is better understood and can be monitored. In terms used in public health, risk assessment is pertinent mostly to secondary prevention (there already is a problem) rather than primary prevention (the problem never occurs) which arguably is included within the Sustainability Framework. Other issues include the inability to scientifically verify low-level risks; significant delays in risk assessment, particularly at the national level (NRC 2009); challenges to the toxicologic basis underlying risk assessment presented by agents such as nanoparticles (Tsuji et al. 2006) or endocrine disruptors (Welshons et al. 2003); and the absence of data on hazard or exposure for quantitative risk assessment (NRC 2009). Default assumptions developed or used in the Sustainability Assessment and Management approach need to be evidence-based and used according to current EPA policy.

EVOLUTION OF THE RISK ASSESSMENT AND RISK MANAGEMENT PARADIGM

Risk assessment has been used by the agency as the main means for translating various types of biologic information about health effects of chemicals into measures of harmfulness to people. The growing understanding from biomedical

and toxicologic research on how chemicals contribute to disease, coupled with better technologies and analytic tools for characterizing exposures, has resulted in continuing calls for refinement in risk assessment.

The increasing understanding of how people might differ in their responses to chemicals has led to calls for explicit treatment of human variability (NRC 1994, 2009) and vulnerable populations in risk assessment. The NRC’s (1993, p. 3) finding that children are not little adults in terms of sensitivity and require consideration in risk assessment resulted in changes in practice, some through legislation. Along with genetics, preexisting health conditions also can drive individual differences in response to chemicals. Psychosocial stress may also influence risk (e.g., those exposed to violence have increased asthma in response to traffic-related air pollution). Environmental chemicals can add to endogenous exposures to agents that affect the same disease processes. All the above factors have raised concerns about some of the underlying default assumptions used in dose-response assessment and overall approaches to risk assessment (NRC 2009). There has been tension over taking these factors into account because defaults developed to address them may ultimately translate to greater stringency in risk management, and there is uncertainty over how these factors translate to risk.

Coincident with calls for a fuller incorporation of variability in risk assessment has been a push toward more sophisticated approaches toward uncertainty assessment. Cautionary notes have been given regarding the “unknown unknowns” and the limits of uncertainty analysis (NRC 1996). Approaches to such limitations and to scale the analysis to the decision at hand (NRC 1996, 2007, 2009) have been advanced.

At the same time, the scope of assessment has expanded. Multiple, related chemical exposures (NRC 2008), multiple environmental sources, psychosocial stressors in underserved communities, and other aspects of vulnerability has led to calls for cumulative risk assessment (NRC 2009). There is an explicit recognition that the current quantitative risk assessment system of defaults and techniques cannot address problems of such complexity adequately and that simpler approaches are needed (Callahan and Sexton 2007; NRC 2009). Over time, approaches to formally assess ecologic risk conditions that take a systems perspective have emerged. Finally, the great number of chemicals of potential concern is always increasing. The vast array of chemicals that are potential environmental contaminants include synthetic chemistry products, industrial chemicals, off releases from consumer products, combustion by-products, and environmental transformation by-products following chemical release—an array too vast to address by the chemical-by-chemical approach of toxicity testing in animals of each health effect of concern and then predicting human risk (NRC 2006).

Nanomaterials share many of these same characteristics. A recognition of the limited capacity to generate toxicity data to make evidentiary decisions about risk led a 2007 NRC committee to recommend initiating a 10-20 year national effort of developing new approaches for establishing the evidence base that would rely

to a large extent on toxicogenomic screens. To reduce the costs and facilitate the development of new toxicity-testing approaches, interagency collaborations have been established within the United States, and the United States has also been a major supporter of, and contributor to, the OECD Chemicals Programme and its work on the “Mutual Acceptance of Data” and “Code of Good Laboratory Practices” (Ruffing 2010). As a result of recent chemical registration requirement, it is now apparent that over 100,000 chemical substances are in use in the European Union (EC 2011), a number far greater than expected, albeit some are used in low volumes. This finding provides further indication of the extremely limited capacity of the current risk-based system to deal with chemical management needs. Thus, although risk assessment provides a useful tool for looking at health effects for a circumscribed problem in a systematic way, it may not be up to the task of addressing many of the complex problems facing the agency.

The framework for risk-based decision making has been confused with risk assessment. For some sectors in the nongovernmental and business communities, the term “risk assessment” is of concern. For environmentalists the term can sometimes be code for license to pollute up to levels just below those that would be labeled a de minimis risk under traditional risk assessment methodology (Long et al. 2002). Further, the methodology may not account for all chemicals of concern to the community (NRC 1996), for environmental hazards from other facilities in the community, for community vulnerability (Morello-Frosch et al. 2011). Ultimately, risk assessment can be taken by the community as emblematic of their powerlessness (Freeman and Godsil 1993). From the business community perspective, risks just over a preset de minimis “bright line” can be characterized harmful and result in costly mitigation measures (Long et al. 2002). The identification of hazards even with vanishingly low exposures and risks can sometimes be felt as stigmatizing and a liability for the business community. In implementation of some environmental programs, a bright line can translate directly to a risk management response without consideration of other concerns (Goldstein 1993). These experiences can lead to challenges of the risk assessment and the science underlying it as a means to delay the possibility of costly actions.

Further the separation of risk assessment and risk management without consideration of the specifics of the regulatory decision to be made has resulted in protracted analyses that are not focused on the specific decision to be made. To address these issues, the NRC (2009) recently altered the risk assessment and risk management framework. As shown in Figure 5-2, risk assessment and other analytic tools are used as approaches to discriminate among potential alternatives or options for risk mitigation, identified early in the process.

The risk assessment and risk management paradigm forms the basis for risk-based decision making within EPA programs, such as the legacy cleanup programs Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Resource Conservation and Recovery Act (RCRA) and in standard setting programs, for example, NAAQS and maximum contaminant

FIGURE 5-2 Framework for risk-based decision making.
SOURCE: NRC 2009

levels (MCLs) set under the Safe Drinking Water Act. In these programs, factors other than risk are also considered and are consistent with the risk management framework in the Red Book (NRC 1983) and Science and Decisions (NRC 2009). However, with risk reduction as the primary objective, full consideration has generally not been given to all three sustainability pillars.

Here are two examples showing how factors other than risk are taken into account in risk management—one from setting drinking-water standards and the other from the legacy cleanup programs. In these programs, EPA often defines an ideal goal. An analogue in the legacy cleanup programs is the setting of preliminary remediation goals (PRGs)—starting points for setting cleanup levels in soil. In this situation, the risk management decision may involve an assessment of the technical feasibility of achieving a given goal. In comparing alternative risk management options in the legacy cleanup programs, numerous factors can be considered under the EPA National Contingency Plan. More explicit consideration of sustainability factors is now being considered by EPA under its green remediation strategy and is applied in some cases. Efforts have been accelerated to perform cleanups in the most environmentally sustainable manner (e.g., renewable energy use, minimum waste generation, and reduction of life-cycle greenhouse gas emissions) and to address environmental justice inequities. Analyses to characterize risks to the community, costs, community improvements, and trade-offs can provide the basis for choosing practicable management options that mitigate significant risks while providing benefits for the surrounding community, and meeting other sustainability goals. Thus, elements of sustainability assessment and thinking are increasingly being incorporated into environmental remediation decision making.

As required by the Safe Drinking Water Act, a maximum contaminant level goal (MCLG) of zero is specified for chemicals suspected of being carcinogens and having linear dose response relationships. Zero is clearly an unattainable goal. The actual enforceable standard, however, is based on a small number of technical factors, such as analytic detection limits and cost, resulting in a regulatory standard—a Maximum Contaminant Level (MCL)—that is greater than zero. For example, the MCLG for trichloroethylene is zero, but the MCL is currently 5 ppb.

THE INTERFACE BETWEEN THE RISK ASSESSMENT AND RISK MANAGEMENT PARADIGM AND SUSTAINABILITY

The committee’s Statement of Task includes the question, “How can the EPA decision-making process rooted in the risk assessment/risk management paradigm be integrated into this new sustainability framework?” To respond to this charge, the committee has separated risk assessment from risk management. The four-step risk assessment paradigm will continue to be valuable in identifying and managing risks, quantitatively or qualitatively. The conceptual approach

to identifying an intrinsic hazard, understanding the link between the hazard and an unwanted effect, calculating the extent to which humans or ecosystems are exposed to that hazard, and characterizing the resultant risk in a manner pertinent to policy makers and the public can be extended beyond the risk of chemical and physical agents in the environment. It can also incorporate qualitative approaches and other approaches to express risk or cumulative risks to address a wider range of issues, but tools will be needed to make that a reality. Accordingly, the committee reaffirms the value of risk assessment, finds it to be a useful tool for sustainability, and encourages the further development of risk assessment tools, such as to address cumulative risks, to improve its usefulness.

The committee notes that the term “risk management” is used in two ways: as a formal description of EPA’s policies related to control of environmental risks and as an informal term denoting any EPA approach to management of current or potential threats. Sustainability goes beyond risk management in being primarily concerned with maximizing benefit, while addressing risks of concern, rather than being an exercise focused mainly on achieving de minimis risk. The focus on de minimis risk sometimes includes risk-risk and risk-benefit trade-offs in management decisions, but does not necessarily or typically encompass the social (including health), environmental, and economic pillars of sustainability. Risk management in either the formal or informal use of the term does not fully encompass the sustainability paradigm in which the management of risk is perceived as an opportunity to maximize benefits while controlling environmental harm. Table 5-1 presents the committee’s comparison of key features of risk assessment/risk management framework with sustainability.

The Sustainability Framework can include each of the basic elements of the Red Book and recent (NRC 2009) risk assessment and risk management paradigms. In some cases, however, a formal four-step risk assessment will not help to discriminate among potential decision options and should not be performed. For example, the time frame for the decision may not permit the type of data gathering needed to support risk assessment, or the nature of the problem is such that a risk assessment would be noninformative. For decision processes in which four-step risk assessment is included, the Sustainability Framework can be viewed as representing the risk paradigm expanded and adapted to address sustainability goals, as illustrated in Figure 5-3, where the first two steps are dealt with in Phase I.

Under the Sustainability Framework, in addition to considering possible technology options to minimize risk, consideration of opportunities and options for improvements along social, environmental, and economic dimensions would also be elements corresponding to the risk assessment and risk management (RA/RM) framework’s phase I, the problem formulation and scoping phase. Phase I would also include identifying possible state, local, and other federal collaborators that may participate in the project. Stakeholders—interested parties affected by the decision—could help identify options.

TABLE 5-1 Differences Between Features of Risk Assessment and Risk Management and Sustainable Development

FIGURE 5-3 Correspondence between sustainability assessment and management elements and risk assessment and risk management (RA/RM) framework.

Corresponding to an RA/RM phase II under the Sustainability Framework in addition to planning and conducting the risk assessment, other assessments would be included to help discriminate among policy options. Analysis would address critical social, environmental, and economic features associated with the different options. Analyses of trade-offs between different features associated with the different policy options would also be conducted. All analyses would be sized in terms of intensity and scope to provide outcomes that enable selection across options. It is in this phase that analyses would, if required or desirable, receive technical peer review and stakeholder comment.

Corresponding to an RA/RM phase III under the Sustainability Framework, the decision makers would deliberate on the results of these assessments, struggle with trade-offs, and make decisions. The implementation of the decision would be followed by an evaluation of its effectiveness.

FINDINGS AND RECOMMENDATIONS

5.1. Key Finding: The risk assessment and risk management frameworks articulated by the NRC (1983-2009) are analogous with the committee’s proposed Sustainability Assessment and Management approach. However, differences in their overall goals how greater complexity in the Sustainability Framework components of scoping, analysis, deliberation, and decision making. The four-step risk assessment process, as envisioned by the NRC

(1983) Red Book, is an important component and tool used to inform decisions in the Sustainability Assessment and Management approach (p.86-89).

5.1. Key Recommendation: EPA should include risk assessment as a tool, when appropriate, as a key input into its sustainability decision making.

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