The influence of ethanol on the stem cell toxicity of benzene in mice.

BDF1 mice were exposed to 100, 300, and 900 ppm benzene vapor, and the numbers of hematopoietic progenitor cells, early and late erythroid progenitors (BFU-E and CFU-E) and granuloid progenitors (CFU-C), were determined with and without additional exposure to ethanol (5, 10, 15 vol%) in the drinking water. The duration of benzene inhalation was up to 4 weeks, 6 hr per day, 5 days per week. It was shown that the number of CFU-E per femur was depressed in a dose-dependent manner by benzene alone and also by ethanol combined with a given benzene concentration. CFU-E showed rapid regeneration after the end of the exposure, but not BFU-E and CFU-C. Prolongation of the ethanol exposure after withdrawal of benzene had only a marginal effect on progenitor cell regeneration.