Chronic exposure to environmentally relevant concentrations of PCB causes reproductive toxicity in mink

Female mink (Mustela vison) were exposed to the technical PCB preparation Clophen A50 (0.3 or 0.1 mg/animal/day) in the feed for 18 months, including two reproduction seasons. Isomer-specific PCB-analysis of the technical mixture was made and the concentrations of toxic equivalents (TEQs) in the feed were calculated. In addition, Clophen A50 was separated into two fractions, one containing the non and mono-ortho-chlorinated PCB congeners (planar fraction) and the other containing congeners with 2-4 chlorines in ortho-position (non-planar fraction). Animals in two separate groups were exposed daily to these individual fractions extracted from 0.3 mg Clophen A50. No effect on the reproduction outcome was observed during the first reproduction season. However, reduced birth weights were noted in the kits born to animals treated with 0.3 mg Clophen A50 per day. The reproductive performance was seriously affected in the second season. Only 39% of the females exposed to 0.3 mg Clophen A50 per day whelped, compared with 93% in the control group. All whelps in the group exposed to the high dose of Clophen A50 died within 1 day after birth. Kit survival and growth were reduced also in the group treated with the low dose of Clophen A50. Treatment with themore » non and mono-orthochlorinated PCB congeners strongly reduced kit survival and body weight gain. Only 8% of the kits survived until 2 weeks of age. It is concluded that the non and monoortho-chlorinated PCB congeners were responsible for the major part of the reproductive toxicity caused by Clophen A50. PCB residue concentrations in the mink, determined at the end of the experiment, were within the range of the levels that have been observed in wild mink in Sweden.« less