Induction of xenobiotic metabolism in rats by short-term administration of brominated diphenyl ethers

Commercial preparations of fire retardant brominated diphenyl ethers were tested along with bis (p-bromophenyl) ether and diphenyl ether for their ability to alter xenobiotic metabolism. The materials, 0.1 mmol/kg/day, were administered p.o. to male rats for 14 days. Pentabromodiphenyl and octabromodiphenyl ether preparations increased O-ethyl O-p-nitrophenyl phenylphosphonothioate (EPN) detoxification, p-nitroanisole demethylation, NADPH-cytochrome c reductase, cytochrome P-450, liver weight, UDP-glucuronyltransferase and benzo[a]pyrene hydroxylase. Diphenyl ether increased only EPN detoxification and decabromodiphenyl ether only liver weight. Bis(p-bromophenyl) ether increased liver weight, cytochrome c reductase and cytochrome P-450. The data indicate that these materials are inducers of xenobiotic metabolism with activity dependent upon degree of bromination.