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Integral scientists prepared expert reports and provided expert witness testimony in U.S. Federal Court and at an adjudicatory hearing before the Maine Board of Environmental Protection on the relative source contributions of mercury to the Penobscot River, the impact of mercury reduction from four competing industrial waste landfill cleanup scenarios, and quantification of human health risk reductions predicted from each cleanup scenario.In preparation for testimony, Integral scientists estimated the current and future mercury loading to the 8,600-square-mile Penobscot River watershed from global, regional, and local atmospheric sources (dry and wet deposition); industrial and municipal wastewater discharges; and industrial waste landfill leachate. Estimates of mercury loading to the river were validated using a flow-based model developed by Integral scientists to quantify annual loadings of mercury in the water column. A long-range (50-year) forecast was used to assess potential impacts of future global mercury reduction efforts and carbon dioxide reduction strategies, as well as future global energy needs on atmospheric inputs to the watershed.
Integral scientists also developed a comparative microexposure Monte Carlo fish consumption risk assessment model to quantify hypothetical methylmercury exposures to anglers and their families under pre-cleanup versus the four post-cleanup alternatives. Post-remedy fish tissue concentrations were simulated using fish tissue methylmercury data from watersheds proximate to the Penobscot River that do not receive mercury from industrial or municipal point discharges or from industrial landfill leachate migration.
The expert reports and testimony defended against allegations of unacceptable risks to human health and significant adverse ecological risks to populations of fish and shellfish due to mercury in the lower Penobscot River and estuary. As part of this work, ecologically relevant target tissue and dietary mercury levels were derived for fish in the river and estuary.