Toxic effects of combined exposure to toluene and m-xylene in animals. III. Subchronic inhalation study.

Effects of combined exposure to toluene and m-xylene in the conditions of subchronic inhalation experiments in rats were examined. Rats were exposed to vapours of individual solvents and their 1:1 mixture at concentrations of 1000 ppm or 100 ppm, 6 h/day, 5 days/week, for 3 or 6 months, respectively. In rats exposed for 3 or 6 months to toluene, m-xylene and their mixtures (1:1) at concentrations of 1000 ppm and 100 ppm, respectively, the observed disturbances in rotarod performance test and decrease in spontaneous motor activity were statistically significant in comparison to control. In animals exposed to mixtures (1:1) of toluene and m-xylene, changes were not significantly different but more pronounced when compared to single solvent groups. The decrease of red blood cells count and increase of rod neutrophil cell counts were observed only in rats exposed for 3 months to mixture of solvents. Results obtained in condition of acute and subchronic inhalation exposure and toxicokinetics data interpreted jointly indicate the more than additive toxic effects of combined exposure to toluene and m-xylene.