Toxic effects of subchronic combined exposure to n-butyl alcohol and m-xylene in rats.

Effects of combined exposure to m-xylene and n-butyl alcohol in the conditions of subchronic inhalation experiment in rats were examined. Rats were exposed to vapours of individual solvents at concentrations of 50 and 100 ppm and their 1:1 mixture at concentrations of 50 + 50 ppm and 100 + 100 ppm, 6 h/day, 5 days/week for 3 months. No significant changes in body weight gain, in absolute and relative organ weights and clinical biochemistry parameters were observed. The motor coordination disturbances caused by mixture of m-xylene and n-butyl alcohol at concentrations of 100 + 100 ppm were identical as those caused by n-butyl alcohol at concentration of 100 ppm. Thus, in condition of combined exposure, the toxic effect of m-xylene was not added to the effect of n-butyl alcohol. Significant increase in sensitivity to pain in animals exposed to m-xylene at both concentrations, and parallel lack of changes in the pain sensitivity in animals exposed to n-butyl alcohol and to the solvent mixtures was observed. n-Butyl alcohol provoked the increase of lipid peroxidation in hepatic microsomes without any induction of cytochrome P-450 monooxygenases, m-Xylene did not affect the activity of monooxygenase and lipid peroxidation rate in hepatic microsomes and moreover, in the case of combined exposure it abolished the effect on n-butyl alcohol. Results obtained in condition of acute and subchronic inhalation exposure interpreted jointly, indicate the less than additive toxic effect of combined exposure to m-xylene and n-butyl alcohol.