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too resource-intensive and thus impedes action. Given the substantial uncertainties in the results of risk assessment, it seems inappropriate to devote so much effort to its conduct. Moreover, no good mechanisms exist to resolve controversies, so debates over the appropriateness of various risk-assessment outcomes can be endless. (4) Some reviewers, particularly those with state governments, believe that more effort needs to be devoted to defining the uses to which a risk assessment is to be put before it is attempted. Such planning will help to deal with the problem of resource allocation, because the amount of effort needed for a risk assessment can be more appropriately matched to its ultimate uses. (5) Some analysts have pointed out that the failure to pay sufficient attention to the results of risk assessment has resulted in misplaced priorities and regulatory actions that are driven by social forces, not by science. They note that the fact that risk assessment is imperfect does not justify the use of decision-making approaches that suffer from even greater imperfections. (6) On the other hand, some commentators feel that risk assessment has been given too much weight, especially in light of its methodological limitations and inability to account for unquantifiable features of risk, such as voluntariness and fear. (7) Some analysts also point out that far too little attention has been devoted to research to improve risk-assessment methods. It is unfair simply to criticize the methods without offering risk assessors the means to improve them.

Are any of those criticisms justified? If so, what responses can be made to them? Can improvements be made? If so, how will they affect the conduct of risk assessment and the use of risk-assessment results in regulatory decision-making? These and related issues are the primary focus of Chapters 6-12 of this report.

Note

1. The chemicals listed as hazardous air pollutants under the National Standards for Hazardous Air Pollutants (NESHAP) (with the date of public notice): asbestos (3/71); benzene (6/77); beryllium (3/71); coke-oven emissions (9/84); inorganic arsenic (6/80); mercury (3/71); radionuclides (12/79); and vinyl chloride (12/75).