Influence of gender, age and lifestyle factors on micronuclei frequency in healthy Japanese populations.

Cytogenetic biomarkers such as chromosomal aberrations (CAs), sister chromatid exchanges (SCEs) and micronuclei (MN) have been applied to the study of individuals exposed to known or potential genotoxic agents. Recent evidence also suggests the usefulness of MN tests for screening carriers of specific mutations that indicate cancer susceptibility . Nevertheless, these biomarkers have not demonstrated as high values in exposed individuals as had been expected, perhaps because they had been influenced by dietary factors such as folate deficiency, the plasma levels of vitamin B12 and homocysteine, and habitual (exercising, drinking and smoking) and demographic factors (age and gender): it is suggested that age and gender are the most important variables affecting MN frequency. Our review of the literature found few reports about MN frequency in healthy Japanese populations as control groups , but these reports did not refer to the contributions of either demographic or habitual factors in detail. MN assay is one of the most sensitive markers for detecting DNA damage, and has been used to investigate genotoxicity of a variety of chemicals. MN testing with interphase cells is more suited as a cytogenetic marker because it is not limited to metaphases, and has the advantage of allowing rapid screening of a larger numbers of cells than in studies with SCEs or CAs. MN is formed from acentric chromosomeor chromatid-type fragments and whole chromosomes that have lagged behind in cell division, being left outside both daughter nuclei. MN analysis therefore appears to be a good tool for investigating the effects of clastogens and aneuploidogens in occupational and environmental exposure in human epidemiological s tudies 7) and a lso in animal experiments , but several factors could be associated with intraand inter-individual variations of MN. This study aimed to investigate the effects of demographic variables and several lifestyle factors on MN frequency in healthy Japanese subjects.