REDUCTION OF BENZENE TOXICITY BY TOLUENE

BDF1 mice were exposed in inhalation chambers to benzene (900 ppm, 300 ppm) and/or toluene (500 ppm, 250 ppm) 6 hr per day, 5 days per week, for vp to 8 weeks. Benzene alone induced a slight anemia after 4 and 8 weeks and a reduction of BFU-E and CFU-E numbers in the marrow. The coexposure to toluene reduced the degree of anemia. These results conf irm previous studies where toluene was found to reduce benzene toxicit y. This protective effect was most pronounced when DNA damage was stud ied in peripheral blood cells, bone marrow, and liver using the single cell gel (SCG) assay. With benzene alone, either with 300 or 900 ppm, a significant increase in DNA damage was detected in cells sampled fr om all three organs. Toluene alone did not induce a significant increa se in DNA damage. The coexposure of benzene and toluene reduced the ex tent of DNA damage to about 50% of benzene alone. This result is consi dered a clear indication for a protective effect of toluene on the gen etic toxicity of benzene. (C) 1994 Wiiey-Liss, Inc.