IMPROVEMENT IN HUMAN HEALTH RISK ASSESSMENT UTILIZING SITE-SPECIFIC AND CHEMICAL-SPECIFIC INFORMATION - A CASE-STUDY

This paper provides results of an effort to use site- and chemical-spe cific data and other factors to characterize and refine risk estimates to a community. The refined assessment illustrated the influence of a dditional key variables on the risk estimates. Influence of variables associated with meteorological data and decay was relatively low. Infl uence of exposure assumptions was somewhat higher; approaching an orde r of magnitude. Of the variables examined, the butadiene slope factor assumption had the greatest impact, contributing nearly three orders o f magnitude to the risk estimates separating the Best and Worst Case s cenarios, Monte Carlo analysis indicated a high level of uncertainty i n the risk estimates. Risk estimates in this paper should be considere d in comparison to the approximate 1 in 4 background fatal cancer risk in the US population. In all cases the risk would be zero if butadien e is not carcinogenic in humans at prevailing exposure levels.