Aims: To study the effect of smoking, passive smoking, alcohol drinking, and occupational exposure to low level of benzene on DNA strand breaks in elevator manufacturing workers in Guangzhou, China.
Methods: Three hundred and fifty-nine workers (252 men and 107 women) of a modern elevator manufacturing factory, 205 were from production departments and 154 from managerial department. Information on the workers' health conditions, smoking, passive smoking, alcohol consumption and occupational exposure history was collected by personal interview. Lymphocyte DNA damage was measured by the Comet assay.
Results: None of the women smoked and 20.6% of the men were daily smokers. In non-smokers, the prevalence of passive smoking at work was 25% for men and 11.2% for women, and at home, 37.8 and 48.6%, respectively. Smoking significantly increased tail moment (P<0.001). Daily smokers had the largest tail moment (geometric mean, 95% CI) (0.93 microm (0.81-0.94)), followed by occasional smokers (0.76 microm (0.59-0.95)), ex-smokers (0.70 microm (0.58-0.85)), and never smokers (0.56 microm (0.53-0.60)). Tail moment increased significantly with daily tobacco consumption (cigarettes per day) (r=0.26, P<0.001) after adjusting for age, gender, occupational exposure, passive smoking, and drinking. Analysis of covariance (ANCOVA) showed that smoking (P<0.001), passive smoking at home (P=0.026), occupational exposure (P<0.001), male gender (P<0.001), and age (P=0.001) had independent effects on tail moment, whereas passive smoking at work and alcohol drinking had no significant effect.
Conclusions: Smoking, passive smoking at home, male gender, age and occupational exposure independently increased lymphocyte DNA strand breaks. The presence of excess DNA damage under low level of occupational exposure to benzene or other solvents suggest that the current allowance concentrations may not be safe to prevent genotoxicity.