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(T/MF178) 2,3,7,8 - Tetrachlorodibenzo-p-dioxin Equivalents (TCDD-EQs) in Tissue Samples from Three Species in the Denver Metropolitan Area. Kemler, Katherine1, Jones, Paul1, Blankenship, Alan1, Giesy, John1, 1 ABSTRACT- Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are possible contaminants of concern in areas with a history of organochlorine pesticide production or other industrial chlorination processes. The Rocky Mountain Arsenal (RMA), a Superfund site near Denver, CO, has a history of various industrial processes that may have led to the release of these compounds and subsequent exposure risk to surrounding biota. Non- and mono-ortho-substituted PCBs, PCDDs, and PCDFs cause a common set of toxic effects that are mediated through the aryl-hydrocarbon receptor (AhR). From 1995 through 1998, carp eggs, great horned owl livers, and American kestrel eggs were collected from the RMA and from off-post reference sites by the U.S. Fish and Wildlife service. AhR activities, measured as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs and TEQs), were determined in these samples by use of the integrative H4IIE-luc cell line bioassay and instrumental techniques. Concentrations of TCDD-EQs and TEQs were compared among locations. Mean concentrations of TCDD-EQ in extracts of carp and kestrel eggs were not significantly different between groups of samples collected on and off the RMA. Concentrations of TCDD-EQ in several owl livers collected on the RMA were significantly greater than concentrations in owl livers from off of the RMA. Significant differences in TCDD-EQ concentrations were also observed between different age classes of great horned owls. Detected concentrations of dioxin equivalents were used to assess risk to exposed wildlife through the use of Hazard Quotients (HQs). Key words: Dioxins, Furans, PCBs, Risk Assessment |
