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 fem ale mink for one year (three times a week, resulting in a mean daily exposu re of 0.1 mg/mink). The mink were mated after 9 months of exposure and the reproductive outcome was studied. The darns and kits were examined for bioc hemical and toxic effects. The litter size was significantly increased (50% ) in the exposed group, and the mean birth weight was 20% lower than that o f 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 in duced (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 triiodothyr onine and total thyroxine, 30-35% of control values) in plasma were observe d in the adults. The bioaccumulation factor for the mixture of 3- and 4-met hylsuIfonyl-polychlorinated biphenyls (PCBs) was 2.1 (muscle vs feed concen tration). The 3-methylsulfonyl-PCBs accumulated 2- to 65-fold in liver rela tive 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 ki ts were 18 +/- 2 and 21 +/- 3 mu g/g, respectively (lipid weight, muscle), demonstrating significant transport from dams to kits and accumulation in t he kits.