Calculation of human health risk-based screening levels (RBSLS) for petroleum

Hazardous waste site managers and regulators can decide Easily,whether site contamination requires remediation to protect human health, but defining t he extent of cleanup is often an enormous challenge. When is the site clean enough for human access and use? Risk assessment tools call be used to hel p answer this question. One call calculate chemical-specific risk-based scr eening levels (RBSLs) in environmental media (e.g. soil, water, and food) t hat correspond to "acceptable" levels of risk. RBSLs can be calculated for individual chemicals and chemical mixtures, specific to various exposure pa thways. In calculating RBSLs, one must account for the fact that people may be exposed to more than one chemical by more than one exposure pathway. Fa te and transport models may be needed to predict how people might become ex posed to site contamination in the future. Example RBSLs for non-cancer eff ects are calculated to illustrate the utility and limitations of RBSLs for making risk-based decisions at petroleum release sites.