Taking Ecological Risk Assessment to the Next Level. P. Sheehan, B. Alsop, and R. Wenning, ChemRisk Division McLaren/Hart, 1135 Atlantic Avenue, Alameda, CA 94501
Ecological risk assessments for contaminated sites have largely been conducted at a screening level. These assessments are largely comparisons of the 95 percent UCL of media concentrations with brightline criteria and/or the comparisons of conservative point estimates of average daily dose with benchmark dose criteria. In neither case, are the likelihood of adverse effects (risks) characterized. We suggest four improvements to this screening approach which will greatly enhance the quality and utility of these assessment. First, evaluate both exposure and effect data as representative distributions rather than point estimates and compare these distributions to characterize risks. Two, use site-specific toxicity tests to characterize expected effects. Three, use GIS analysis to spatially characterize exposure and risk. Four, use conditional simulations to characterize the 3-dimensional extent of media posing significant risk. Examples of how to incorporate each of these advances into your assessments are provided.