METHODOLOGY FOR CONDUCTING SCREENING-LEVEL ECOLOGICAL RISK ASSESSMENTS FOR HAZARDOUS-WASTE SITES - PART III - EXPOSURE AND EFFECTS ASSESSMENT

The Idaho National Engineering and Environmental Laboratory (INEEL) ha s implemented a phased approach to ecological risk assessment (ERA). T he first step in this process is a screening-level ERA at each facilit y. Basic to this approach was the development of ecologically based sc reening levels (EBSLs), defined as concentrations of chemicals in soil (or other media) that are not expected to produce any adverse effects on selected ecological receptors under chronic exposure conditions (a nalogous to preliminary remediation goals or soil screening levels). E BSLs are calculated by rearrangement of standard exposure equations to solve for soil concentration when chemical intake rate is set at a de veloped toxicity reference value (TRV). A TRV is defined as a chronic dose that is likely to be without appreciable risk of deleterious effe cts, This definition was extended to define TRVs and ultimately EBSLs for the functional groups used in the INEEL screening-level ERAs.