atic for at least three reasons. First, the determination of what constitutes an influential risk assessment may be unclear at the outset. Although some agencies may be able to identify an influential risk assessment at the onset of the analysis,1 others may not be able to.2 The impact of an agency activity that led to the development of the risk assessment may not be known a priori. Some degree of iteration is necessary and appropriate, but the application of additional standards when some arbitrary impact threshold is crossed may lead to needless and inappropriate delays in implementation of the action.

Second, the effort to separate risk assessments arbitrarily into two broad categories does not appropriately recognize the continuum of risk assessment efforts in terms of potential impact on economic, environmental, cultural, and social values. Any attempt to divide that continuum into two categories is unlikely to succeed and will not substantially improve the quality of risk assessments. The use of two categories will tend to lead to costly and slow iterative processes in which a risk assessment may not be judged influential initially but on completion may be found to cross an arbitrary threshold that triggers the additional standards. It may be that additional evaluation and analysis may be appropriate as the impacts of the risk assessment are better identified, but an arbitrary triggering of a new set of standards is not appropriate.

Third, the specific standards to be required of all influential risk assessments appear to be targeted at types of risk assessments and supporting information that may not be appropriate for the broad array of risk assessments that are conducted by federal agencies. Several standards proposed for influential risk assessments appear to be related specifically to human health risk assessments; these standards might not be appropriate for engineering risk assessments that evaluate the safety of structures or systems. Other issues associated with the standards are discussed in the remainder of this chapter.

RANGE OF RISK ESTIMATES AND CENTRAL ESTIMATES

One focus in the bulletin is the presentation of a range of risk estimates and a central estimate; statements on this topic in the bulletin and

1

See Appendix E, pp. DOE-4 and DOL-5.

2

See Appendix E, pp. HHS-13, DOD-9, and CPSC-4.



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