Correlation of human lymphocyte SCE frequency with smoking history.

Sister-chromatid exchange (SCE) frequency in lymphocytes of 24 active cigarette smokers was compared to that of 24 age and sex matched controls and 7 persons who had stopped smoking an average of 15.6 years. The results indicated that cigarette smoking was associated with a significant elevation (p less than 0.001) in the frequency of SCEs observed in otherwise healthy cigarette smokers. Furthermore, the increase in SCE level was shown to be dose-related to years of exposure when smoking history was measured in cumulative pack-years. The mean SCE frequency of the ex-smokers was not significantly different from nonsmoking controls.