Two-dimensional Monte Carlo simulation and beyond: A comparison of severalprobabilistic risk assessment methods applied to a superfund site

Four different probabilistic risk assessment methods were compared using th e data from the Sangamo Weston/Lake Hartwell Superfund site. These were one -dimensional Monte Carlo, two-dimensional Monte Carlo considering uncertain ty in the concentration term, two-dimensional Monte Carlo considering uncer tainty in ingestion rate, and microexposure event analysis. Estimated high- end risks ranged from 2.0 x 10(-4) to 3.3 x 10(-3). Microexposure event ana lysis produced a lower risk estimate than any of the other methods due to i ncorporation of time-dependent changes in the concentration term.