A PROPOSAL FOR IMPROVING THE ROLE OF EXPOSURE MODELING IN RISK ASSESSMENT

This paper explores the adequacy of using currently available exposure assessment models for indoor air inhalation exposures in the context of the uncertainty that exists in both the dose-response assessment an d the exposure assessment. A tiered system is proposed for implementin g exposure assessments. Each tier involves additional research, but al so would lead to reductions in uncertainty. The authors discuss a poss ible comprehensive research program that will permit the building of w ell-validated models for indoor air inhalation exposures among classes of chemicals, building types, and exposure scenarios. The authors bel ieve that until such a research program is undertaken, modeling of exp osures (and therefore risks) using the current, unvalidated modeling a pproaches provides little more than worst-case estimates that are usef ul primarily for making screening decisions about risks.