Increased frequency of sister chromatid exchanges in cigarette smokers

Abstract

The analysis of sister chromatid exchange (SCE) might be a useful technique for the study of genetic damage in humans exposed to environmental mutagens and carcinogens. To obtain reference values for such studies we have analysed SCE-frequencies in peripheral lymphocytes of 43 healthy, occupationally non-exposed human subjects. Among these subjects cigarette smokers were found to have significantly higher SCE-frequencies (16.2±SD 3.6) than non-smokers (13.1±2.9). When smokers were subdivided into moderate (<10 cig. per day) and heavy (≥10cig. per day) smokers, a clear dose-effect of smoking on the SCE frequency was noted. This observation was supported by a retrospective inquiry into the smoking habits of 18 previously analysed psoriasis patients, among whom SCE-frequencies of 16.8±2.4 and 13.7±3.1 were recorded for smokers and non-smokers, respectively. In a group of 19 laboratory workers there was no significant difference between smokers (18.6±3.3) and non-smokers (19.5±5.0). The significantly increased SCE-frequencies recorded in this group support earlier observations and strongly suggest occupational exposure as a causative factor. The present results indicate that the SCE-frequency in healthy human subjects is influenced by individual smoking habits as well.