Metabolism of 2,4,5,2',5'-pentachlorobiphenyl in the rat. Qualitative and quantitative aspects.

The metabolism of 2,4,5,2',5'-pentachloro [14C] biphenyl (5-CB) was studied in the male rat. Following iv administration of 5-CB (0.6 mg/kg), 84% of the total dose was excreted within 7 days and 89% of the radioactivity excreted was in the form of 5-CB metabolites. Mass spectral and proton nuclear magnetic resonance analysis or chemical methods in conjunction with mass spectral analysis were used to identify the metabolites. The major metabolite was identified as 3'-hydroxy 5-CB. One minor metabolite was identified as the 3',4'-dihydrodiol of 5-CB and a second minor metabolite was tentatively identified as 3',4'-dihydroxy-5-CB. The relative amounts of 5-CB and its metabolites excreted in the urine and feces were also determined.