[Induction of cytochrome P-450 monooxygenase after combined exposure of rats to xylene and ethanol].

Increased biological risk following from combined exposure to xylene, an industrial solvent, and ethanol, the most likely additional factor to occupational exposure, may result from inductive effects of the chemicals on cyt. P-450 monooxygenase, where biotransformation of xylene and, in part of ethanol, takes place. Studies were carried out on rats: 1) preinduced with ethanol (10% solution in drinking water for 8 months) and for next 9 days jointly exposed to xylene vapour at concentration of 12,000 mg/m3; 2) preexposed to m-xylene vapours at concentration of 4,000 mg/m3 for 6 and 12 weeks or at concentration of 400 mg/m3 for 5 months and for next 3 days jointly administered ethanol (5 doses of 2.5 g/kg in 12 hours intervals). It has been found that ethanol and xylene in both models of combined exposure exert additive stimulatory effects on the activity of cyt. P-450 monooxygenases (aniline p-hydroxylase, microsomal ethanol oxidizing system, NADPH-cyt. c reductase, cytochrome P-450) and intenseness of the effects depends both on the level and duration of exposure to xylene/m-xylene and ethanol.