A Public Health Context for Residual Risk Assessment and Risk Management under the Clean

A Public Health Context for Residual Risk Assessment and Risk Management under the Clean Air Act
Author(s): Gail Charnley and Bernard D. Goldstein Source: Environmental Health Perspectives, Vol. 106, No. 9 (Sep., 1998), pp. 519-521 Published by: Brogan & Partners Stable URL: http://www.jstor.org/stable/3434224 Accessed: 29/11/2009 14:41 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=brogpart. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Brogan & Partners is collaborating with JSTOR to digitize, preserve and extend access to Environmental Health Perspectives. http://www.jstor.org
,,,Commentaries A Public Health Context for Residual Risk Assessment and Risk Management Under the Clean Air Act Gail Charnleyl and Bernard D. Goldstein2 'The Weinberg Group Inc., Washington, DC 20036 USA; 2Environmental and Occupational Health Sciences Institute, Piscataway, NJ 08855 USA The 1990 amendments to the Clean Air Act required the EPA to institute new pollution control technology requirements for industrial sources of air pollution. In part because agreement could not be reached on the best way for the EPA to determine whether any significant risks to human health will remain after the technology controls are in place, the amendments also created a Commission on Risk Assessment and Risk Management and gave the commission a broad man- date to review and make recommendations concerning risk assessment and risk management in federal regulatory programs. In its March 1997 final report to Congress and the administration, the commission recommended a tiered approach to assessing such residual risks. That approach included the idea that when decisions about managing residual risks are made, emissions should be evaluated in the context of other sources of air pollution. Evaluating risks in their larger con- texts is consistent with what the commission called a public health approach to environmental risk management. This paper describes the public health approach and how it applies to evaluat- ing residual risks under the Clean Air Act. Key words: air pollution, Clean Air Act, public health, residual risk, risk assessment, risk management. Environ Health Perspect 106:519-521 (1998). [Online 29 July 1998] http://ehpnetl. niehs. nih.gov/docs/1998/106p519-521charnley/abstract.html The EPA will soon be required to embark on a nationwide program to determine whether industrial air emissions continue to be haz- ardous to our health. The agency has yet to decide how that task should be accom- plished. New and creative approaches are needed because current emissions control programs have already achieved the more readily made pollutant reductions and because of the increased emphasis on cost- effectiveness. The Clean Air Act Amendments of 1990 authorized the EPA to develop a program to control hazardous air pollutants through the promulgation and implementation of tech- nology-based standards. Such standards are determined by identifying the maximum achievable control technology (MACT) cur- rently in place. This strategy was developed because the risk-based approach that was intended to implement earlier Clean Air Act amendments was found to be ineffective and inefficient, having resulted in only seven haz- ardous air pollutant standards between 1970 and 1990. After MACT is in place, the EPA must assess residual pollutant emissions and the residual risks associated with those emis- sions. On the basis of those assessments, deci- sions will be made about the need for further risk management of residual emissions. The 1990 Clean Air Act amendments also authorized a Commission on Risk Assessment and Risk Management, charged with the responsibility of developing a method for evaluating residual risks. In its final report to Congress in 1997 (1,2), the commission recommended a scheme for residual risk assessment as well as a frame- work for environmental health risk man- agement. The framework is intended to improve the logic, consistency, and accept- ability of decisions related to public health protection and environmental risk manage- ment and has six components (see Fig. 1): problem/context, risks, options, decisions, actions, and evaluation. One of the advan- tages of the framework is that instead of evaluating risks singly and in isolation from one another, they are evaluated in the context of the risk management decision to be made and in the context of public health. Evaluating residual risks in the con- text of public health requires a public health approach to risk management. What Is a "Public Health Approach"? Over the last 25 years, the traditional com- mand-and-control, risk-by-risk approach to environmental health protection has worked well to greatly improve the quality of our food, air, water, and workplaces. Now we are left with the more intractable, complex problems, such as urban air pollu- tion and cleaning up Chesapeake Bay, that the traditional approach is less likely to solve. Continuing the improvements of the last 25 years will depend on our ability to learn how to look at risks collectively instead of one at a time. We need to get beyond the current chemical-by-chemical, medium-by-medium, risk-by-risk approach dictated by current statutes and refocus our priorities by taking a broader view. Instead of continuing to argue about what numeri- cal regulatory standards should be for each chemical, we should be asking what expo- sures are posing the most immediate threats to our health and our environment and how we can control them. In other words, we need a public health approach to risk man- agement. Standard setting and enforcement continue to provide an important basis for environmental health protection, but to move to the next level of effectiveness, a more comprehensive approach is needed. A public health approach to risk manage- ment emphasizes prevention instead of clean- ing up after the fact and focuses on the effec- tiveness of actions instead of relying on regu- latory command and control. A public health approach evaluates the adverse health effects experienced by a population, identifies possi- ble causes of those effects, and then seeks to determine the relative contribution of each cause to the effects. A public health approach comprises an individual's complete physical and social well-being and includes nondisease end points such as odor and noise. In many cases, the public health foundation of envi- ronmental health protection has been obscured by legalistic, technical, centralized decision-making processes that are often unrelated to the problems faced by local com- munities (3). The public health basis of our regulatory statutes has been obscured by their reliance on cleaning up problems after-the- fact instead of preventing them and by their lack of a focus on whole populations. A greater focus on public health principles would better serve the environmental health objectives of our regulatory statutes, although it is the dictates of those very statutes that often pose the greatest impediments to a focus on public health (4-). Residual Risk Assessment and a Public Health Approach The problem with applying a public health approach to evaluating residual risks under the Clean Air Act is that we are already locked into a chemical-by-chemical, single- medium approach under the statute. However, the statute says that the EPA needs to evaluate residual risks and, if Address correspondence to G. Charnley, The Weinberg Group Inc., 1220 19th Street, NW, Suite 300, Washington, DC 20036 USA. Received 20 January 1998; accepted 21 April 1998. Environmental Health Perspectives ? Volume 106, Number 9, September 1998 519
Commentaries * Charnley and Goldstein Figure 1. The Risk Commission's framework for environmental health risk management required, promulgate standards, but it does not say how the EPA has to evaluate them. So, presumably, the EPA is given broad descretion to evaluate residual risks and then decide what constitutes appropriate standards. The EPA could therefore choose to evaluate risks in the context of other pol- lutant sources and other risks to health. In its final report, the Risk Commission (1,2) stated, Local, regional, and national levels of air toxics, by pollutant and by source category, must be put in the context of exposures from other air pollutant sources and from environmental pathways other than air. The goal is to build an understanding among stakeholders about the health context of residual emissions from the regulated point sources. By context, the commission means looking at a problem's role compared to, for exam- ple, other sources of the same contaminants, other exposures occurring simultaneously, or other threats to human or environmental health. Contexts can be multimedia, multi- source, multichemical, or multirisk. The intent is not to minimize the importance of any particular risk or emission, but to darify to stakeholders the impact that managing that risk is likely to have on health or the environment. Context depends on the situation. The context for the pollutant emissions from a single facility in a community could be other sources of the same pollutants, such as drinking water, food, and consumer prod- ucts. It could include other facilities in the region that emit the same or other pollu- tants. For example, consider residual risks from benzene emitted from petroleum refineries. After the technology standards mandated by the 1990 Clean Air Act amendments are in place to control benzene emissions, local and regional risk assess- ments will be performed to evaluate the leukemia risk posed by the remaining ben- zene in emissions from individual petroleum refineries. At that stage, it will be important to consider other sources of benzene in air, or the multisource context. Motor vehicle emissions are the largest single source of air- borne benzene in outdoor air in the United States, although because of indoor air expo- sure, motor vehicle emissions account for only about 20% of personal exposure (8). Benzene is in cigarette smoke and in con- sumer products used at home (9). In fact, the home is the largest source of benzene exposure that we receive, with cigarette smoking contributing 56% of personal exposure and other home activities con- tributing 21% (8). If the residual leukemia risk from refinery emissions turns out to be significant compared to the leukemia risk contributed by other sources, risk-reduction efforts should focus on further reducing refinery emissions. If the refinery risk proves insignificant by comparison, risk reduction activities might better be directed at other sources. Benzene can also be a precursor to ozone, so in some cases it may make sense to consider its indirect impacts. However, the EPA has always compartmentalized its risk assessment and management approaches. For example, its regulation of marine oil ter- minals in Valdez, Alaska, where ozone is not an issue, was no different from its regulation of marine oil terminals where ozone is a problem. And while up to 15% methyl tert- butyl ether (MTBE) is required in many places as a gasoline additive, MTBE emis- sions to air from its manufacturing facilities are tightly controlled because it is considered a hazardous air pollutant. If residual risks from arsenic and lead emitted by secondary lead smelters are of concern, the context could be multimedia. For example, an EPA study showed that the concentration of airborne arsenic in the vicinity of secondary lead smelters is about 100 times the average concentration of air- borne arsenic in the United States. When all sources of exposure to arsenic near smelters are taken into account, however, smelter emissions contribute only about 10% of total exposure, raising a broader risk management issue about what action should be taken to reduce arsenic exposure from all sources. Other major sources of arsenic exposure include seafood and cigarette smoke (10). On the other hand, lead emissions from sec- ondary lead smelters are by far the primary contributor to lead exposure in the vicinity of smelters, despite the many other sources of human exposure to lead (11). The context for an entire source catego- ry might depend on the health effects posed by the particular pollutants emitted from that category or on the extent to which other sources of the same pollutants contribute to total air pollutant levels or total exposure. For example, motor vehicle exhaust contributes 60% of the nationwide benzene outdoor air pollution, 94% of the total 1,3-butadiene air pollution, and 39% of acetaldehyde emissions. The contribu- tions of one or more source categories properly controlled by MACT to total ben- zene, 1,3-butadiene, and acetaldehyde pol- lution are likely to be small by comparison. The appropriate context will depend on the situation. Because the toxicity of a sub- stance may vary depending on route of exposure, the appropriate context might be limited accordingly. In some cases, all routes of exposure might be considered during problem identification, while the risk-management decision might be based on conclusions about the relative toxicolog- ical importance of different routes. Risk Management Using a Public Health Approach The overall goal should be to direct risk management resources where they will do the most good to protect or improve the community's health. To achieve that goal, we need to start looking at risks comprehen- sively. As Daniel Greenbaum, former Commissioner for Environmental Protection for the state of Massachusetts put it in his testimony to the commission (12), I saw far too many cases where extreme attention was placed at an industrial facility on ensuring that every last molecule of a toxic substance was kept out of the air, only to have that same substance ignored as it poured through the floor drain into the groundwater. Taking a look at the whole mix of pollutants, at whole watersheds, is fundamental. Looking at problems in their contexts should help us start to do that. The challenge for assessing residual risks in context boils down to understanding how to assess multiple or aggregate risks; making a decision about what to do about a particu- lar source or sources of risk after you have done that is another question altogether. Using a public health approach can help to assess aggregate risks and to target risk man- agement resources by focusing attention on the health effects experienced by a popula- tion-not just the individual with the puta- tive highest exposure-and the relative con- tributions of different pollutant sources or other problems to those effects (4). A public health approach is a "top-down" approach that starts by focusing on a problem and then seeks to identify what is causing the problem as a guide to determining how best to solve it. In contrast, most of our current Volume 106, Number 9, September 1998 * Environmental Health Perspectives 520
Commentaries ? Managing residual risks under the Clean Air Act - l ' I II I.I I I II I regulatory approaches are "bottom-up"; that is, they start with a cause and then try to eliminate it without determining the extent to which it actually may contribute to a problem. A bottom-up approach makes it difficult to set priorities among risks or to evaluate whether a risk management action has had an impact on a public health prob- lem. Advances in molecular biology have moved us closer to linking biomarkers of effects with biomarkers of exposure, making a top-down approach more feasible by facili- tating attribution of causality. In the mean- time, public health approach implementa- tion should target diseases with recognized environmental components, such as asthma or lung cancer. Diseases with less well-under- stood environmental components will require better-developed monitoring and sur- veillance systems and better understanding of the interplay of causative factors before a public health approach can be applied effec- tively. An intermediate step toward achieving that goal will be to replace mathematically modeled estimates of exposure with biologi- cal measures of actual exposure. Ideally, bio- logical markers that reflect both exposure and effect will provide the linkage central to an effective public health approach. Carboxyhemoglobin formation is a well- known example of a biological marker. One public health-based approach that has been proposed recently to help manage residual risks is a public health improvement market (13). A public health improvement market would bring together willing sellers of public health improvements, such as pub- lic health departments and community groups, with willing buyers seeking alterna- tives to further emissions reductions. In this proposal, a limited number of sources meet- ing current air quality standards would be offered the opportunity to make invest- ments in public health benefits rather than marginal decreases in emissions. Protections would be put in place to avoid individual source backsliding, distributional inequities, adverse health effects, and significant ecolog- ical damage. Five elements are envisioned as part of the market approach: *Tradable instruments: a common metric for risk reduction would be developed to allow the valuation of various investments. * Baseline standard of conduct: individual sources making alternative investments would be subject to legal sanctions if they did not maintain their current level of envi- ronmental performance; continuous moni- toring of the results of alternative invest- ments would be needed. * Public participation: the public must be fully engaged in the design and operation of a market approach. * Accurate, accessible information: the pub- lic and the regulators would need under- standable, standardized, and accurate information about risks being traded. * Public verification: a risk trading approach would succeed or fail depending on public confidence that the alternative investments meet expectations. The public health investment market is an innovative idea that builds on programs already in place. For example, the South Coast Air Quality Management District allows companies who do not participate in vehicle emission reduction programs to make payments to an escrow fund that is then used to buy alternatively fueled vehi- cles for city services, such as trash trucks or school buses, or to make other vehicle emission reductions. As a result of the 1996 amendments to the Safe Drinking Water Act, water suppliers can avoid costly controls on radon in drinking water and, instead, invest in measures to mitigate exposures to airborne radon, often a greater source of exposure. The EPA opened the door to such a concept in its implementa- tion plan for the new Clean Air Act stan- dards by proposing a Clean Air Investment Fund that would allow sources with con- trol costs in excess of $10,000/ton of pollu- tant to pay a set annual amount to fund more cost-effective emissions reductions by nontraditional and small sources. The EPA's recent cumulative risk guid- ance (14) and broadening concepts of risk characterization (15) are promising signs that the agency is looking beyond its tradi- tional single-chemical, single-medium focus. As it takes on the challenges of assessing residual risks, the agency needs to broaden its focus further to encompass environmental health impacts from the per- spective of public health. A nationwide public health surveillance network is needed to facilitate making connections between environmental exposures and public health outcomes. Finally, creative risk manage- ment options are needed to optimize the contributions that our limited risk manage- ment resources can make towards minimiz- ing residual risks and continuing the envi- ronmental and public health improvements we have enjoyed for the last 25 years. REFERENCES AND NOTES 1. Risk Commission. U.S. Commission on Risk Assessment and Risk Management. Final Report, Vol 1. Framework for Environmental Health Risk Management. GPO #055-000-00567-2. Washington, DC:U.S. Commission on Risk Assessment and Risk Management., 1997. 2. Risk Commission. U.S. Commission on Risk Assessment and Risk Management. Final Report, Vol 2. Risk Assessment and Risk Management in Regulatory Decision-Making. GPO #055-000-00568-1. Washington, DC:U.S. Commission on Risk Assessment and Risk Management., 1997. 3. Ruckelshaus WD. Stepping stones. Environmental Forum 15:30-36 (1997). 4. Goldstein BD. Should we set priorities based on risk analysis? Forum one. Setting environmental priorities: the debate about risk. EPA J 17:23 (1991). 5. Burke TA. Back to the future: rediscovering the role of public health in environmental decision making. In: Handbook for Environmental Risk Decision Making: Values, Perceptions, and Ethics (Cothern CR, ed). Boca Raton, FL:Lewis Publishers, 1995;93-101. 6. Goldstein BD. The need to restore the public health base for environmental control [commentary]. Am J Public Health 85:481-483 (1995). 7. Omenn GS. Putting environmental risks in a public health context Public Health Perspect 111:514-516 (1996). 8. Wallace LA. The exposure of the general population to benzene. Cell Biol Toxicol 5:297-314 (1989). 9. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Benzene. Atlanta, GA:Centers for Disease Control and Prevention, 1997. 10. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Arsenic. Atlanta, GA:Centers for Disease Control and Prevention, 1993. 11. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Lead. Atlanta, GA:Centers for Disease Control and Prevention, 1993. 12. Greenbaum D. Oral testimony to the U.S. Commission on Risk Assessment and Risk Management, Washington, DC, 14 July 1996. 13. Knopman D. Local Public Health Improvement Markets. A Tool to Increase Public Health Benefits from Environmental Regulation. Washington, DC:Progressive Policy Institute, 1997. 14. U.S. EPA. Guidance on Cumulative Risk Assessment. Part 1. Planning and Scoping. Washington, DC:U.S. Environmental Protection Agency, 1997. 15. U.S. EPA. Policy for Risk Characterization. Washington, DC:U.S. Environmental Protection Agency, 1995. Environmental Health Perspectives - Volume 106, Number 9, September 1998 521