Hepatic microsomal enzyme induction by aroclors 1248 and 1254 in cynomolgus monkeys

Aroclors 1248 (2 mg/kg body weight) and 1254 (5 mg/kg body weight) produced a 3-methylcholanthrene type of mixed-function oxidase induction, in the livers of adult female cynomolgus monkeys after 69–122 days of dosing, when the animals were moribund. Both Aroclor 1248 and 1254 produced a mixed pattern of induction in mouse liver 66 hr after ip treatment with 1000 mg/kg body weight including changes characteristic of 3-methylcholanthrene-type induction. However the same dose of Aroclor 1016 did not produce 3-methylcholanthrene-type enzyme induction in mice. The results in adult monkeys are consistent with the hypothesis that PCB isomers capable of inducing aryl hydrocarbon hydroxylase and causing a ‘blue’ shift in the cytochrome peak, are associated with increased toxicity. However the lack of response with Aroclor 1016 in mice suggests that the reported toxicity of this aroclor to infant monkeys may not result from isomers producing a 3-methylcholanthrene-like effect.