DETERMINING TARGET CLEANUP LEVELS - A RISK ASSESSMENT-BASED DECISION-PROCESS FOR CONTAMINATED SITES

This paper presents methodologies for estimating target cleanup levels at Superfund sites. The methodologies follow those in the EPA Superfund risk assessment guideline but are performed in reverse order. This is done to determine cleanup levels that correspond to reference doses for noncarcinogens or to a reference risk level for carcinogens as recommended by the U.S. EPA. The target cleanup levels thus derived should be considered adequate to protect public health when multiple pathways of exposure to contaminants in air, soil, food, and water are possible. The transient nature of contaminant concentrations in soil, subject to change over time due to volatilization, leaching, and other phenomena, is also addressed. An example is given which indicates that when the exposure is attributable predominantly to a single pathway, the calculation needed for estimating the target cleanup levels can be considerably simplified.