Distribution and metabolism of 2,4,5,2', 5'-pentachlorobiphenyl.

Single doses of 2,4,5,2',5-pentachlorobiphenyl uniformly labeled with 14-C have been administered intravenously and orally to mice. Whole-body autoradiograms and scintillation counting of tissue samples have shown that most radioactivity leaves the circulation for the tissues within one hour. Peak concentrations varied, being highest in brown fat, which after 24 hours comprised the major reservoir of the unchanged compound in the body. Radioactivity disappeared rather rapidly drom most other tissues, although the longest retention occurred in bronchial epithelium and some parts of the renal tubules. The excretion of radioactivity was mainly through the bile, into feces, with a half-time of six days. There was little unchanged compound in the feces, the major metabolite was a hydroxylated derivative, both free and conjugated.