RESUMO
The goal of this study was to determine if inhalation of benzene leads to an increase in the mutant frequencies in the tissues of male C57BL/6 mice. Mutant frequencies were measured using a previously described assay in which bacteriophage lambda lacI transgenes are rescued from mouse genomic DNA as infectious phage and scored for their LacI phenotype. Eight experimental mice were exposed to a target concentration of 300 ppm of benzene for 6 h/day x 5 days/week x 12 weeks, and eight control mice were treated similarly except that they were not exposed to benzene. Mutant frequencies were calculated as the ratio of LacI-/total phage recovered from organs of interest. The mean mutant frequency measured in lung tissues of mice exposed to benzene was (10.6 +/- 1.4) x 10(-5), which is about 1.7-fold higher than that of the unexposed controls. In spleen tissues from benzene-exposed mice the mean mutation frequency was (12.6 +/- 4.1) x 10(-5), which is about 1.5-fold higher than that of spleen tissues from unexposed controls. The differences in mean mutant frequencies between benzene-exposed and unexposed lung and spleen tissues are statistically significant. In liver tissues, however, the mean mutant frequencies of benzene-exposed mice and unexposed mice are not significantly different. These results demonstrate that inhaled benzene results in a statistically significant increase in the mutant frequencies in lung and spleen, but not in liver tissues of mice.