Carp (Cyprinus carpio) collected from Saginaw Bay, Michigan, containing 8.4 mg total polychlorinated biphenyls (PCBs)/kg and 194 ng of 2,3,7,8-tetrachloro-dibenzo-p-dioxin equivalents (TEQs)/kg, were substituted for marine fish at levels of 0, 10, 20, or 40% in the diets of adult ranch mink (Mustela vison). The diets, containing 0.015, 0.72, 1.53, and 2.56 mg PCBs/kg diet, or 1.03, 19.41, 40.02, and 80.76 ng TEQs/kg diet, respectively, were fed to mink prior to and throughout the reproductive period to evaluate the effects of a naturally-contaminated prey species on their survival and reproductive performance. The total quantities of PCBs ingested by the mink fed 0, 10, 20, or 40% carp over the 85-day treatment period were 0.34, 13.2, 25.3, and 32.3 mg PCBs/mink. respectively. The corresponding quantities of TEQs ingested by the mink over the same treatment period were 23, 356, 661, and 1,019 ng TEQs/mink, respectively. Consumption of feed by mink was inversely proportional to the PCB and TEQ content of the diet. The diet containing Saginaw Bay carp caused impaired reproduction and/or reduced survival of the kits. Compared to controls, body weights of kits at birth were significantly reduced in the 20 and 40% carp groups, and kit body weights and survival in the 10 and 20% carp groups were significantly reduced at three and six weeks of age. The females fed 40% carp whelped the fewest number of kits, all of which were stillborn or died within 24 hours. Lowest observable adverse effect levels (LOAEL) of 0.134 mg PCBs/kg body weight/day or 3.6 ng TEQs/kg body weight/day for adult female mink were determined. The potential effects of exposure of wild mink to contaminated Great Lakes fish were assessed by calculating "maximum allowable daily intakes" and "hazard indices" based on total concentrations of PCB residues in several species of Great Lakes fish and mink toxicity data derived from the study.

Mink are known to be very sensitive to the toxic effects of planar polychlorinated biphenyls (pPCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs), collectively known as planar halogenated hydrocarbons (PHHs). Previously, we reported the reproductive effects in mink fed a diet containing 10, 20, or 40% fish taken from Saginaw Bay, Lake Huron. The present study reports the chemical characterization of the diets and the adult mink livers, along with a comparison of an additive model of toxicity with the results of the H4IIE bioassay on these samples. The assessment of dietary or tissue-based exposure of the mink to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds revealed that TCDD equivalents of the PHH mixtures largely followed an additive model of toxicity as compared with the H4IIE bioassay. Consistent dietary and liver tissue-based threshold concentrations for reproductive toxicity in mink were determined regardless of whether PHHs were quantified as TEQs (additive toxicity) or TCDD-EQs (H4IIE bioassay). Significant reproductive effects were observed in the lowest treatment group (10% fish or 19.4 pg of H4IIE bioassay-derived TCDD-EQs/g). Consumptionnormalized mink liver biomagnification 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.

The effects of consumption of environmental contaminants contained in carp (Cyprinus carpio) from Saginaw Bay, Michigan on various hematological parameters and liver integrity of adult female mink (Mustela vision) were determined. Mink were fed diets that contained 0 (control), 10, 20, or 40% carp prior to and throughout the reproductive period (182 days). The diets contained 0.015, 0.72, 1.53, and 2.56 mg polychlorinated biphenyls (PCBs)/kg diet and 1.0, 19, 40, and 81 pg 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs)/g diet, respectively. Mink fed the diets containing carp showed a general dose-dependent occurrence of clinical signs commonly associated with chlorinated hydrocarbon toxicity, including listlessness, nervousness when approached, anorexia, and melena. Erythrocyte counts were less in mink exposed to Saginaw Bay carp than in controls, while the number of white blood cells was greater than in controls. Significant differences (p < 0.05) in the concentrations of neutrophils, lymphocytes, monocytes, and eosinophils were also found between the control and carp-fed groups, but are considered to be of limited clinical or biological importance. Hematocrit values for the mink fed the 20 and 40% carp diets were significantly less than those of mink in the control and 10% carp groups. There were no significant differences in hemoglobin concentrations among the groups. Necropsies revealed enlarged yellowish livers in many of the carp-fed mink, especially those fed the 40% carp diet. Liver, spleen, and lung weights of carp-fed mink were significantly greater than those of control mink.(ABSTRACT TRUNCATED AT 250 WORDS)

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