EFFECTS OF MATERNAL EXPOSURE TO CHLORINATED DIPHENYL ETHERS ON THYROID-HORMONE CONCENTRATIONS IN MATERNAL AND JUVENILE RATS

Polychlorinated diphenyl ethers (PCDEs) are industrial byproducts and widespread environmental contaminants. Their structural similarity to PCBs suggests that they may exhibit subtle effects on both adult and j uvenile mammals. We examined the effects of 3 PCDEs (2,2',4,5,6'-penta chlorodiphenyl ether, 2',3,4,6'-tetrachlorodiphenyl ether, and 2,2',4, 4',5,5'-hexachlorodiphenyl ether) on maternal rat thyroid levels short ly after exposure, and on the thyroid levels of 16 day old juvenile ra ts that had been prenatally exposed. Both 2,2',4,5,6'-pentachlorodiphe nyl ether and 2',3,4,6'-tetrachlorodiphenyl ether depressed thyroxine (T-4) levels in the maternal females as well as in both sexes of juven ile rats. 2,2',4,4',5,5'-hexachlorodiphenyl ether did not alter T-4 le vels in the pregnant females, but depressed juvenile T-4 levels. None of the congeners studied significantly altered T-3 levels. Effects on thyroid hormones did not correlate with the congeners' induction of cy tochrome P450.