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Guest Column

Terry Davies

Terry Davies is the director of the Center

RISK ASSESSMENT IN ENVIRONMENTAL POLICY

for Risk Management for Resources for the Future in Washington,

Risk assessment has become a standard part of many environmental

term health risks (e.g., food poison- ing), long-term health risks (e.g., -

D. c. policy processes in the United States, cancer), or ecological risks (e.g., particularly at the federal level but also for states and localities. As it has become more important, the ten- sions inherent in risk assessment have become more open and obvious. The choices about how and when to perform risk assessment have become more stark and are now political controversies that will require many years to settle.

THE USE OF RISK ASSESSMENT Federal environmental policy has

been employing formal risk assessment for many years. The Food and Drug Administration instituted pro- cedures for establishing safe levels of food additives in the 1950s. About the same time, many nuclear experts applied formal analysis to risks from nuclear power plants. Since its in- ception in 1970, the U.S. Environ- mental Protection Agency (EPA) has used toxicological risk assessment methods.

There are many types of risk assessment. They can address short-

global warming). These assessments employ a variety of methodologies ranging from testing rats to doing fieldwork on a mountain stream. The results can be expressed as a safe-unsafe dichotomy or as a quan- titative estimate to six decimal places. What all these efforts have in com- mon is an explicit method to estimate the probability of some harm occurring.

Increasingly, environmental stat- utes have required the use of risk assessment. Some federal laws, such as the Toxic Substances Control Act and the law governing pesticide use, base all regulatory actions on a bal- ancing of risks and costs. The 1990 Clean Air Act Amendments require technology-defined controls on toxic emissions, but then require further controls if the technology controls “do not reduce lifetime excess cancer risks . . . to less than one in one million.” The 1996 Safe Drinking Water Act requires that the EPA Administrator consider “quantifiable and nonquantifiable

CCC 1051 -5658/99/0903145-04 Reprinted from the newsletter of the Center for Risk Management, Resources for the Future.

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health risk reduction benefits” when setting drinking water standards.

EPA reported that in 1993 it had completed 7,595 risk assessments. More than 6,000 of these were quick screening analyses, requiring from a few minutes to a couple of days, but 249 of the assessments were major projects requiring more than four person-weeks. Since the Reagan administration, EPA and the other federal regulatory agencies have been required to do cost-benefit analyses of major proposed regulations, and risk assessments are the primary way of establishing the benefits side.

FUNDAMENTAL PROBLEMS From the beginning, fundamen-

tal problems were embedded in the use of risk assessment. These problems have become more obvious and pressing as risk assessment is used more frequently and as highly quantified risk assessment of cancer has come to represent all risk assessment. The problems are both scientific and political.

Risk assessment did not emerge from questions raised by scientific disciplines or from gaps in science paradigms. It was created to help policy makers to analyze and sum- marize the adverse effects of an environmental hazard. Elements of various disciplines-toxicology, bi- ology, chemistry, and statistics, among others-were pieced together to meet a policy need. From the beginning, then, risk assessment has been a hybrid mixture of the scientific and nonscientific.

The nonscientific parts of risk assessment that have received the most attention are the assumptions made to fill gaps in data or scientific knowl- edge. Any formal risk assessment involves a number of such assump-

tions. For example, assumptions are made about exposure patterns (e.g., how much fish does the subject of the risk eat?), biological mechanisms (e.g., whether cancer is a one-step or mul- tiple-stage process), and statistical methods and political values (e.g., which of worst-case or average Val- ues should be used). Industry people tend to think that the currently used assumptions exaggerate the degree of risk; environmentalists and environmental justice advocates think the assumptions underestimate risk.

A basic scientific problem is that very few risk assessments can be empirically tested. There are, in theory, two ways that the results of human health risk assessments could be verified. The first method is deliberately exposing human subjects to the substance being examined and seeing whether they develop cancer, liver disease, or whatever endpoint the substance is suspected of causing. This would be blatantly immoral. It is usually impossible, as well, because the risks are typically so small that it would take an impossibly large number of people to test for them. One in a million is often given as the thresh- old of concern for cancer. To examine a human population for this level of risk, one would have to examine several million people.

The second method for testing the reality of assessments is to use epidemiology, the study of diseases in human populations. By definition, epidemiology cannot be used to examine the effects of new substances, so risk assessments used in a preven- tive mode cannot be verified by epidemiology. Using epidemiology to examine the effects of existing substances is usually impossible because of the very large number of people that would have to be studied and

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because the endpoints of concern (e.g., cancer) usually are caused by a variety of different things. It is not possible to control for these other factors in order to isolate the effect of the substance being studied. The con- troversy over whether the assessment assumptions are too conservative or not conservative enough can go on forever because there is no way to calibrate the results of risk assessments with the real world.

The other set of fundamental problems with risk assessment relate not to science but to politics in a broad sense. Two types of conflict charac- terize the politics of risk assessment: the differences between the experts and the lay public, and the struggle between regulated industries and organized environmentalists.

Early in the history of risk assessment it was noted that people tended to be more tolerant of voluntary risks (e.g., skydiving, cigarette smoking) than involuntary risks (e.g., pollu- tion, waste dumping). Researchers, led by Paul Slovic and others, soon discovered other characteristics that influence the perception of risks- for example, familiarity with the risk, whether the damage caused occurred all at once or gradually, and whether the costs and benefits were distrib- uted fairly. However, these characteristics are not considered in the assessments conducted by professional risk assessors. In short, experts and the public assess risks quite dif- ferently, and the differences have important political ramifications, in- cluding public distrust of risk experts.

A related but different set of political conflicts pits regulated industries and their allies against environmental organizations and their allies. Formal risk assessment tips the political bal- ance against the environmentalists.

Industry has many more risk experts and scientific resources. The enviros’ most important weapons-public mobilization and media exposure- are most effective in addressing pub- licly perceived risks rather than risks that the professional assessors rate as high priority.

Environmentalists’ opposition to formal risk assessment is also based on the fact that risk-based laws, such as the Toxic Substances Control Act and the toxics provisions of the pre- 1990 Clean Air Act, have often re- sulted in action being delayed or not taken at all.

FUTURE CHOICES The fundamental problems

identified above have been crystal- lized in the past few years by two movements, each of which combines elements of the problems in complex and sometimes paradoxical ways. Nonindustry scientists increasingly urge more involvement of the lay public in risk analysis. Many members of Congress, the elected representa- tives of the lay public, are urging more use of expert risk analysis.

The science community under- stands the scientific weaknesses of risk assessment. With this underlying understanding-and moved by the public’s evermore obvious rejection of experts’ views on everything, in- cluding risk-important segments of the scientific community have begun to urge public involvement in risk analysis. The two most recent major reports on risk assessment-ne from the National Academy of Sciences, the other from a high-level presiden- tial-congressional commission-both have as their major theme the need for more public involvement. A sig- nificant part of the expert community is trying to save (or improve) risk

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assessment by yielding some control to the public.

Headed in a very different direc- tion are a number of members of Congress, most of whom do not un- derstand the scientific weaknesses of risk assessment. Under the banner of “regulatory reform,” they are trying to give more control over risk assessment and risk priorities to the experts. Their regulatory reform legislation has had strong backing from regulated interests and is strongly opposed by the environmentalists. It would require risk assessments for major proposed regulations and would specify various requirements for how the assessment is to be conducted.

Regulatory reform legislation and a greater public role in risk assessment both highlight long-running themes in risk assessment. Both can potentially strengthen the validity and utility of assessments. Reconciliation and political compromise are possible. New methods of doing assessment, combined with improved scientific understanding, may lead to a synthesis that makes the policy process both better grounded in science and more open to democratic partici- pation. Greater public involvement, more openness, and improved science are, at least in theory, compat- ible goals, but accomplishing them will take a major effort on many fronts over a long period of time.

I 1 ElTatUln

In the article “Evaluation of Surface Water Quality Impacts of Hazardous Chemical Sites” by G. Fred Lee and Anne Jones-Lee in the previous issue of Remediation, the unit of measurement “mp” should have appeared simply as “1-1.” We regret the error.

148 ~MEDIATION/SUMMER 1999

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