title: Inhibition of N-2-fluorenylacetamide-induced mammary tumorigenesis in rats by dietary polybrominated biphenyls.
abstract: Female SD rats were maintained for approximately 1 year on diets containing 300 ppm N-2-fluorenylacetamide (2-FAA), 50 ppm polybrominated biphenyls (PBB), or a combination of these chemicals (PBB + 2-FAA). Ingestion of 2-FAA significantly reduced the average survival time of the rats; this effect was virtually blocked by the simultaneous ingestion of PBB. Simultaneous ingestion of PBB also significantly reduced the overall incidence of 2-FAA-induced tumors during the examination period. The lower incidence of tumorigenesis was accompanied by an increase in the latency time for tumor induction; tumors were found in 100% of the animals given 2-FAA after 29 weeks of carcinogen ingestion, whereas only 50% of the PBB + 2-FAA-fed animals had tumors at the end of the experiment (53 wk of carcinogen ingestion). PBB significantly reduced the incidence of 2-FAA-induced tumors at nonhepatic locations (mammary gland and ear duct) but did not affect the incidence of hepatic tumors to a statistically significant extent. PBB ingestion did not significantly increase the incidence of tumors when compared with controls; 1 tumor was found in 1 of 12 rats fed 50 ppm PBB for 57 weeks, and no tumors were detected in 8 controls.
mesh_terms: D015073:2-Acetylaminofluorene / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001711:Biotransformation / Q000187:drug effects; D001713:Biphenyl Compounds / Q000494:pharmacology*; D004032:Diet; D004428:Ear Neoplasms / Q000139:chemically induced / Q000517:prevention & control; D005260:Female; D008113:Liver Neoplasms / Q000139:chemically induced; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000517:prevention & control*; D009374:Neoplasms, Experimental / Q000139:chemically induced; D011075:Polybrominated Biphenyls / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors
chemical_list: D001713:Biphenyl Compounds; D011075:Polybrominated Biphenyls; D015073:2-Acetylaminofluorene