The micronucleus assay in human lymphocytes: screening for inter-individual variability and application to biomonitoring

Micronuclei levels were assessed in cytokinesis-blocked lymphocytesof 200 male and female healthy donors not occupationally exposedto genotoxic risks and of 33 male industrial painters handlinggenotoxic substances. Frequency of micronucleated cells was9.87 ±3.1 per 1000 in the control population and wasshown to have a large inter-individual variability. The studyof factors contributing to this variability showed that onlysmoking could affect micronucleated cell rate, inducing an increaseof 25%, whereas age and sex had no effect. Among the industrialpainters, frequency of micronucleated cells averaged 18.30 ±7.39 per 1000: the difference between the two populations studiedwas shown to be statistically significant by the Mann-Whitneyrank sum test (one-sided U test) and indicated that exposedpainters need preventive measures.