. "The Evaluative Process: Part II. Integration of Toxicity and Exposure Information." Evaluating Chemical and Other Agent Exposures for Reproductive and Developmental Toxicity. Washington, DC: The National Academies Press, 2001.
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which the values are derived from actual data or reflect the use of default assumptions.
Certainty of judgment and data needs. The use of default assumptions, while often necessary, represents a tangible expression of uncertainty. To clarify that point, this section discusses the magnitude of an assumption's influence on the judgments made in the evaluation. Where the effect is large and the uncertainty great, the evaluators might sometimes defer a judgment. Where a default assumption has a major effect on the evaluative judgment, the evaluative summary clearly defines the kind of data needed to supplant the default and identities that as a critical data need.
Only some aspects of the assessment might involve uncertainty of judgment. For example, although there might be great certainty that the data qualitatively predict human health risk potential, the nature and degree of exposure might be poorly understood. In that case, the evaluative summary will clearly state that there is reasonable certainty of human risk potential and explain why the quantitative uncertainty (missing, inadequate exposure data) leads to the use of a conservative default assumption that is likely to overestimate the degree of exposure and risk.
References. In any evaluation of this nature, a bibliography is imperative. All literature reviewed should appear in a reference list. A separate listing of references reviewed but not used in the evaluation also should appear in the document.