Combined Effects of Chemicals on Rat Hepatic Microsomal Monooxygenases. I. Combination of Polychlorinated Biphenyls and Di-(2-ethylhexyl) phthalate

Abstract

The combined effects of polychlorinated biphenyls (PCB) and di-(2-ethylhexyl) phthalate (DEHP) on rat hepatic microsomal monooxygenases were investigated in 16 dose-groups consisting of 4 PCB-doses (0, 20, 67, and 200 mg/kg) and 4 DEHP-doses (0, 1, 3.3, and 10 g/kg). The additive or synergistic interaction between PCB and DEHP was estimated by analysis of variance by using orthogonal polynomials and by deviation from parallelism among dose-response curves. The combined effects of PCB and DEHP on liver weight and aminopyrine N-demethylase were additive and the effect on cytochrome P-450 was synergistic. Aniline hydroxylase was mainly induced only by PCB.