Effect of phenobarbital and polychlorinated biphenyls on the toxicity and disposition of 1,2,4,5-tetrachlorobenzene in the rat.

Control and phenobarbital (PB) or polychlorinated biphenyl (PCB) pretreated rats were given single oral doses of 14C-1,2,4,5-tetrachlorobenzene (TCB) at 30 or 300 mg/kg b.w. Urine and feces were collected daily for the determination of 14C-content. Five animals per group were killed 2 days after dosing and another five animals were killed 7 days later for the determination of hepatic microsomal enzyme activities, histological changes and 14C-content in the major organs and tissues. Pretreatment with PCB or PB did not alter the effects of TCB biochemically or histologically. Both PB and PCB increased the rate of TCB excretion and decreased the levels of radioactivity in most tissues examined at 7 days after dosing. It was concluded that, at the dose ranges studied, pretreatment with PB or PCB did not significantly alter the toxic effects produced by TCB.