Critical Evaluation of the Toxicity and Exposure Assumptions in USFWS, 2001 Environmental Conference Proceedings

Paul D. Anderson, Allison Nightingale, Kate Geoffroy, Steve Clough--In 2000, the U.S. Fish and Wildlife Service (USFWS) issued a draft biological opinion (dBO) on the potential effects of dioxins and furans in kraft mill effluents on bald eagles in Maine. The dBO concludes that, even at discharge limits more stringent than those allowed by the Cluster Rule, dioxins and furans have the potential to result in the "incidental take" of bald eagles. The dBO relies primarily upon a hazard assessment model first developed by USFWS in the early 1990’s to evaluate the potential effects of dioxins and furans on bald eagles living along the Columbia River. This paper summarizes information developed over the last 10 years that indicates the hazard assessment model, as used by the USFWS, overestimates potential risks to bald eagles by more than 100-fold. Use of the more recent data and the hazard assessment model indicates that dioxins and furans from kraft mill effluents do not pose a risk to bald eagles in Maine. This finding is consistent with recent data on the productivity of Maine eagles, which show that eagles near mills have productivity that is similar to or slightly higher than productivity of eagles living far from mills. The combination of these different lines of evidence shows that dioxins and furans in kraft mill effluents will not harm bald eagles or result in an incidental take.