Risk Variability from Uniform Soil Remediation Goals for PCBs

Abstract

A methodology for evaluating the variability of risk resulting from the use of uniform, concentration‐based soil‐quality criteria is developed and applied to polychlorinated‐biphenyl‐(PCB‐) contaminated soil as an example. A modified version of a soil risk model developed by the U.S. Environmental Protection Agency is used to assess risk variability for different levels of PCBs in soil, representing different cleanup goals. Continuous distributions representing the variability in site conditions across the United States are assigned to parameters in the fate and transport model to examine the effect that such variability has on individual risk when uniform cleanup levels for PCBs in soil are used. It is found that for a fixed cleanup goal applied uniformly to all sites, the risk varies little for the case where the hypothetical exposure occurs on‐site, but by as much as two orders of magnitude for the case where the hypothetical maximally exposed individual resides off‐site. Depending on the risk goal of the remediation program, some risk variability may be acceptable and a uniform cleanup goal may be warranted to expedite the remediation process.