Chronic and reproductive toxicity of a mixture of 15 methylsulfonyl‐polychlorinated biphenyls and 3‐methylsulfonyl‐2,2‐bis‐(4‐chlorophenyl)‐1,1‐dichloroethene in mink (Mustela vison)

A synthetic mixture of 16 aryl methyl sulfones was given in the feed to female mink for one year (three times a week, resulting in a mean daily exposure of 0.1 mg/mink). The mink were mated after 9 months of exposure and the reproductive outcome was studied. The dams and kits were examined for biochemical and toxic effects. The litter size was significantly increased (50%) in the exposed group, and the mean birth weight was 20% lower than that of the controls. Kit survival was 47% by 2 weeks after birth in the exposed group, as compared to 73% in the control group. Both adults and kits had induced (5‐ to 11‐fold) hepatic activities of pentoxyresorufin‐ O ‐dealkylase. In livers from the dams, catabolism of progesterone in vitro was increased almost twofold. Decreased thyroid hormone concentrations (total triiodothyronine and total thyroxine, 30–35% of control values) in plasma were observed in the adults. The bioaccumulation factor for the mixture of 3‐ and 4‐methylsulfonyl‐polychlorinated biphenyls (PCBs) was 2.1 (muscle vs feed concentration). The 3‐methylsulfonyl‐PCBs accumulated 2‐ to 65‐fold in liver relative to muscle and lung. At the cessation of the exposure period, the total concentrations of aryl methyl sulfones in the dams and their 5‐week‐old kits were 18 ± 2 and 21 ± 3 μg/g, respectively (lipid weight, muscle), demonstrating significant transport from dams to kits and accumulation in the kits.