Metabolic and Toxicologic Evaluation of 2, 3, 4, 3', 4'-Pentachlorobiphenyl in Rats and Mice

When 2, 3, 4, 3', 4'-pentachlorobiphenyl (PenCB), a component of Kanechlor 400, was administered orally at a single dose of 150 mg/kg or 60 mg/kg to 3 rats, all died in 8 days or 9 to 11 days, after treatment, respectively, with approximately a 30% decrease in body weight. Marked disappearance of fat from adipose tissues and severe fatty change in the liver were observed within 3 days after treatment, and became enhanced after 7 days. No metabolites possessing phenolic nature could be detected in the feces, urine or tissues, although about 34% of the dose was recovered unchanged in the feces collected for 8 days following administration. Treatment with 2, 4, 3', 4'-tetrachlorobiphenyl (2, 4, 3', 4'-TCB) did not induce either a decrease in body weight nor damage of any tissues of the rat. The lethality of PenCB in mice, on the other hand, was much weaker than in rats, because the 14-day i. p. LD50 was determined to be 0.40 g/kg. This value is about 5 times as high as that of 2, 4, 3', 4'-TCB in mice (i. e., LD50, 2.15 g/kg).