ES&T
OUTLOOK Risks: How to get more science in assessments A proposed, independent board within the National Research Council would provide standard procedures for estimating the health effects of human exposure to hazardous chemicals, drugs, and food additives When federal agencies reach a stalemate on a scientific issue, Congress often goes to the National Academy of Sciences (NAS) for a study. One of the latest problems referred to the N A S deals with chemicals and public exposure to them. One scientific issue still unsettled is the determination of the cancer risk associated with the exposure of humans to toxic substances. It's a controversial topic, and for many years the regulation of suspect carcinogens by federal agencies has come under fire. In the recent past, for example, decisions on saccharin, nitrites in food, formaldehyde, asbestos, air pollutants and a host of other chemicals have been called into question. The evidence on the health effects of a few chemicals, such as asbestos, has been clear; however, in most cases the evidence is meager, indirect, and inconclusive. Although there is no legal requirement for risk assessment in any present law, federal agencies have been involved in such activity before establishing their regulations. But agencies that perform risk assessments are often hard pressed to present the scientific basis for their regulatory decisions clearly and convincingly. In the past, these agencies have confused the science issues and policy issues; consequently many of their decisions in regulating chemicals associated with chronic health hazards have been bitterly controversial. One problem has been that the agency doing the risk assessment is the agency that eventually regulates a specific chemical. For the past one-and-one-half years, a committee of the N A S has grappled 0013-936X/83/0916-0199A$01.50/0
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with the historical information on risk assessment, especially cancer risk. The committee concentrated on cancer for two reasons. First, it was ordered to focus on cancer by the Food and Drug Administration (FDA), which authorized the study in the first place. Second, controversial regulatory actions in the past have concentrated on carcinogenicity. New view Formed in response to a congressional mandate, the Committee on Institutional Means for Assessment of Risks to Public Health found that some of the controversy surrounding regulatory actions has resulted from a blurring of the distinction between risk assessment policy and risk management policy. Risk assessment is only one aspect of risk management—the scientific component. Whereas risk management involves choices between the broader social and economic policy issues, risk assessment considers only scientific problems and docs not involve socioeconomic matters. The scientific findings and judgments embodied in risk assessment should be explicitly distinguished from the political, economic, and technical considerations that influence the design and choice of regulatory strategics. By separating the two, there will be for the first time a clear demarcation between science and the policy aspects of regulatory decision making. The study was undertaken to strengthen the reliability and objectivity of scientific assessment that forms the basis for federal regulatory policies applicable to carcinogens and other public hazards. In March the committee released its report. Chaired by Rcuel A. Stallones of the School of Public Health at the University of Texas, Houston, the committee recommended that a clear distinction be made between risk assessment and risk management. It advised the federal government to adopt a package of standard procedures for estimating health effects from hazardous chemicals, drugs, and food additives. It also called for uniform risk assessment guidelines and proposed that a Board of Risk Assessment Methods be established within the National Research Council oftheNAS. What it is Risk assessment uses factual information from laboratory and other sources to estimate possible human health effects from exposure to hazardous substances. It uses a scientific 200A
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base, for example, dose-response relationships to define the health effects of exposure of individual populations to hazardous materials or situations. Risk management, on the other hand, weighs policy alternatives and selects the most appropriate regulatory action; risk management integrates the results of risk assessment with engineering data and with social, economic, and political concerns to reach a regulatory decision.
Risk assessment What it is: the use of a factual scientific base to define the health effects of exposure of individuals or populations to hazardous materials and situations. The four scientific steps: • Hazard identification—the determination of whether a particular chemical is or is not causally linked to particular health effects. • Dose-response assessment— the determination of the relationship between the magnitude of exposure and the probability of occurrence of the health effects in question. • Exposure assessment—the determination of the extent of human exposure before or after application of regulatory controls. • Risk characterization—the description of the nature, and often the magnitude, of human risk including the attendant uncertainty. The goal: to come up with uniform guidelines that would provide standard procedures for estimating health effects on individual populations from hazardous chemicals, drugs, and food additives. Source: NAS report
Although risk assessment is a factual determination there are some real problems with it. One problem is the sparscness and uncertainty of the scientific knowledge of the health hazards. For example, the significance of benign tumors in animal tests as indicators of carcinogenicity is unknown. One agency could decide to include such tumors in calculating cancer risk, while another agency might not, according to the report. Another problem: In the absence of complete dose response data for a particular substance's hazardous effects, one of several possible models -some more conservative than others - may be used to calculate health risks.
The report Among the 10 recommendations in the risk assessment report, one is that the proposed Board would prepare descriptions and would quantify the risk. In other words, it would concern itself with the science of risk assessment and present it in a standard fashion so that all agencies could use it uniformly. This assessment would be reviewed by scientific peers, and written explanations would be made available to the public before any regulatory action is taken. The use of uniform risk assessment would take a major part of the controversy out of regulations by federal agencies, certainly in the regulation of cancer-causing chemicals. When two or more agencies are involved in the risk assessment of a specific chemical, a joint risk assessment might be prepared by the National Toxicology Program or other agency. The report has four chapters. Chapter 1 describes the structure of risk assessment, the role of science in the assessment process, and current federal uses of risk assessment. Chapter 2 examines the feasibility and desirability of the development and use of uniform guidelines. Chapter 3, the longest in the report, examines the historical record for setting standards and reviews various organizational arrangements for risk assessment. The 10 recommendations and conclusions are found in Chapter 4. According to the report, the entire concept of the Board of Risk Assessment and its functions should be reviewed after 6-8 years. During the question and answer period at a recent briefing, at which time the report was released, there was a guarded, optimistic "yes" from the committee chairman that the Board be established. The Board would consist of scientists with training and experience in the areas of risk assessment, of course, but would also include experts in biostatistics, toxicology, epidemiology, environmental engineering, and clinical medicine. Other relevant fields such as law, ethics, and the social sciences should be included to ensure due appreciation of the scientific risk assessment policy content of the Board's activities. Copies of the committee's report, "Risk Assessment in the Federal Government: Managing the Process" are available for $1 1.75 (prepaid) from the National Academy Press, 2101 Constitution Ave., N.W., Washington, D.C. 20418. - Stanton Miller
