Using Ecological Risk Assessment in Hazardous Waste Site Cleanup Decisions: A Massachusetts Perspective. N. A. Bettinger and R. H. Sugatt, MA DEP/ORS
For hazardous waste sites in Massachusetts, a risk assessment must be conducted to determine whether contaminants pose a significant risk of harm to the environment and remediation is necessary. However, in many cases, ecological risk assessment results do not necessarily translate directly into remedial goals. Multiple lines of evidence are often used to characterize ecological risk, and it is not always practical to derive protective concentrations of contaminants using the same combination of measures, in part because different lines of evidence can provide conflicting results. Further, some measures of effects used for risk characterization do not lend themselves to predicting safe concentrations as readily as others. Therefore, in setting remedial goals, it is often necessary to use measures of effects that differ from those used in risk characterization. Ideally, remedial goals should be based on site-specific exposure-response relationships determined along a concentration gradient, but this approach may not be feasible for all receptors and sites. The MA DEP Office of Research and Standards generally recommends that remedial goals be based on measures of effects that allow straightforward extrapolation to concentrations that pose no risk of harm, regardless of which measures were given more weight in the risk characterization. Examples are food chain models from which allowable exposure concentrations can be derived, environmental benchmark concentrations or NOECs from site-specific toxicity tests. This presentation will also address the effect of the variability and distribution of post-cleanup concentrations on various receptorsí exposures and on the achievement of cleanup objectives.
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