Improvement in human health risk assessment utilizing site- and chemical-specific information: a case study

This paper provides results of an effort to use site- and chemical-specific data and other factors to characterize and refine risk estimates to a community. The refined assessment illustrated the influence of additional key variables on the risk estimates. Influence of variables associated with meteorological data and decay was relatively low. Influence of exposure assumptions was somewhat higher, approaching an order of magnitude. Of the variables examined, the butadiene slope factor assumption had the greatest impact, contributing nearly three orders of magnitude to the risk estimates separating the Best and Worst Case scenarios. Monte Carlo analysis indicated a high level of uncertainty in the risk estimates. Risk estimates in this paper should be considered 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 butadiene is not carcinogenic in humans at prevailing exposure levels.