The effects of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) on mink (Mustela vison) reproduction and kit survivability and growth.

This study was conducted to determine if dietary exposure to 3,3'4,4',5-pentachlorobiphenyl (PCB 126) would have an adverse effect on the reproductive performance of female mink (Mustela vison) and survivability and growth of their kits. Standard dark, female mink were fed diets containing PCB 126 at concentrations of 0, 0.24, 2.4, and 24 microg PCB 126/kg feed (0, 24, 240 and 2,400 ng 2,3,7,8-tetrachlorodibenzo-p-dioxin [TCDD] toxic equivalents [TEQs]/kg, respectively) from 21 days prior to breeding until weaning of their kits at six weeks of age. There were no significant differences in the number of females that whelped or the average litter size between the control group and the 0.24 microg PCB 126/kg feed group. In addition, kit body weights at birth and at three, six and 28 weeks of age as well as kit survivability through weaning were similar between the two groups. In contrast, female mink fed diets containing 2.4 and 24 microg PCB 126/kg feed that had confirmed matings, failed to whelp. Histological examination of their uterine horns verified fetal implantation sites or placental scars, which indicated partial fetal development. Based on the impaired reproductive performance reported in this study, a no observable adverse effect level (NOAEL) of 0.24 microg PCB 126/kg feed (24 ng TEQs/kg) and a lowest observable adverse effect level (LOAEL) of 2.4 microg PCB 126/kg feed (240 ng TEQs /kg) were determined.