Chromosome aberration, sister-chromatid exchange, proliferative rate index, and serum thiocyanate concentration in smokers exposed to low-dose benzene.

Cytogenetical endpoints, i.e., chromosome aberration (CA), sister-chromatid exchange (SCE), and proliferative rate indexes (PRI), were measured in peripheral blood lymphocytes (PBL) of 42 workers exposed occupationally to low-dose benzene, and of 42 controls. The role of smoking habit as a confounding factor of genotoxic effects caused by occupational low-dose benzene exposure was also studied. The benzene concentrations in the ambient air samples varied from 3 to 20 mg/m3 (mean: 7 mg/m3). The continuous low-dose benzene exposure significantly increased the CA and SCE frequencies, but did not influence PRI. Smoking levels were characterized by subjective accounts and by serum thiocyanate concentrations (SCN). CA and SCE were not significantly increased in smokers compared to nonsmokers, but the differences were expressed to a greater extent in the case of measurement of SCN concentrations. Determination of SCN proved to be more objective in the assessment of genotoxic effects of smoking as a confounding factor of occupational low-dose benzene exposure.