DIETARY EXPOSURE OF MINK TO CARP FROM SAGINAW-BAY .3. CHARACTERIZATION OF DIETARY EXPOSURE TO PLANAR HALOGENATED HYDROCARBONS, DIOXIN EQUIVALENTS, AND BIOMAGNIFICATION

Mink are known to be very sensitive to the toxic effects of planar pol ychlorinated biphenyls (pPCBs), polychlorinated dibenzo-p-dioxins (PCD Ds), and polychlorinated dibenzofurans (PCDFs), collectively known as planar halogenated hydrocarbons (PHHs). Previously, we reported the re productive effects in mink fed a diet containing 10, 20, or 40% fish t aken from Saginaw Bay, Lake Huron. The present study reports the chemi cal characterization of the diets and the adult mink livers, along wit h a comparison of an additive model of toxicity with the results of th e H411E bioassay on these samples. The assessment of dietary or tissue -based exposure of the mink to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TC DD) and related compounds revealed that TCDD equivalents of the PHH mi xtures largely followed an additive model of toxicity as compared with the H411E bioassay. Consistent dietary and liver tissue-based thresho ld concentrations for reproductive toxicity in mink were determined re gardless of whether PHHs were quantified as TEQs (additive toxicity) o r TCDD-Eas (H411E bioassay). Significant reproductive effects were obs erved in the lowest treatment group (10% fish or 19.4 pg of H411E bioa ssay-derived TCDD-EQs/g). Consumption-normalized mink liver biomagnifi cation factors (BMFs) were 6.4-74.2 for PCDDs, < 1-75.8 for PCDFs, < 1 -15.9 for PCBs, and in general, increased with degree of chlorination within each class. Based on TEQs or TCDD-EQ, this study confirms that mink are among the most, if not the most, sensitive mammalian species to the reproductive toxicity of TCDD and related compounds.