AN APPROACH FOR ESTIMATING ECOLOGICAL RISKS FROM ORGANOCHLORINE PESTICIDES TO TERRESTRIAL ORGANISMS AT ROCKY-MOUNTAIN ARSENAL

Ecological risk assessment for bioaccumulative chemicals at hazardous waste sites like Rocky Mountain Arsenal (RMA) is challenging, particul arly when the site is large and is characterized by heterogeneous envi ronments and patterns of contamination. Because RMA is an National Pri orities List site and a future wildlife refuge, an effective and pract ical risk assessment approach was required. This approach includes met hods to estimate contaminant concentrations below detection limits, sp atial and temporal integration, bioaccumulation, and toxicity criteria . Validation of the quantitative risk assessment approach was achieved through comparisons of observed versus predicted tissue concentration values, as well as evaluation of ecological endpoints relative to wil dlife health. The results of the assessment based on this approach pro vide a realistic representation of observed conditions at RMA, and pro vide quantitative conclusions that are consistent with qualitative obs ervations of the health and diversity of biota at RMA. In addition to supporting baseline risk assessment, the approach provides a useful fr amework for evaluation of future risk management alternatives.