ABSTRACT
The real difficulty with the reference dose concept is that while hazard index values appear to be quantitative measures of risk, they are more accurately regulatory “bright lines,” appropriate for the determination of highly protective cleanup values, but inappropriate as accurate or “best” estimates of human health risk. Uncertainties in the risk assessment need to be described and made fully transparent to all stakeholders. The communication of these uncertainties to the risk manager is most often a difficult task. A practical and robust approach to environmental decision-making requires that the risk manager understand in which areas uncertainty is irreducible and in which uncertainty can be lessened by more data. The term “background” is general, and refers to a reference against which to measure a difference. “Background” at hazardous waste sites means the concentrations in environmental media if site contamination were absent.
