Concomitant dietary exposure to polychlorinated biphenyls and polybrominated biphenyls: tissue distribution and arylhydrocarbon hydroxylase activity in lactating rats
Mccormack, K.M.; Melrose, P.; Rickert, D.E.; Dent, J.G.; Gibson, J.E.; Hook, J.B.
Toxicology and Applied Pharmacology 47(1): 95-104
1979
ISSN/ISBN: 0041-008X PMID: 218325 Document Number: 144548
Polybrominated biphenyls (PBB) and polychlorinated biphenyls (PCB) stimulate microsomal mixed function monooxygenases in liver and extrahepatic tissues. These compounds accumulate to high concentrations in fatty tissues and are excreted into milk. Human populations that are exposed to PBB are also likely to be exposed to PCB. To assess potential hazard of simultaneous exposure to PCB and PBB, the distribution of PCB (Aroclor 1254) and PBB (Firemaster BP6) was determined in several tissues of lactating rats and in milk, and the effects of these agents were studied on hepatic and extrahepatic arylhydrocarbon hydroxylase (AHH) after concomitant dietary exposure. Sprague-Dawley rats were placed on diets containing PBB and/or PCB from the 8th day of pregnancy to 14 days postpartum. Treatment with the highest dose of PBB (200 ppm) retarded dam and pup body weight gain. Stimulation of AHH was greater after treatment with PBB alone than PCB alone. Extrahepatic tissues concentrations of PCB and PBB were similar whether these agents were administered together or alone. Liver and milk contained lower concentrations of PBB after treatment with an equal mixture of PCB and PBB than when PBB were administered alone. Milk contained higher concentrations of PCB than PBB, indicating that this route of excretion may be more important for PCB.