Certain occupational groups are exposed to much higher concentrations of potentially hazardous genotoxins than the general population. The possibility exists that these exposures may significantly increase the risk of cancer for certain of those occupationally exposed. Genotoxicity tests reflect irreversible damage resulting from a toxic interaction, either at the molecular target or at an analogous side target, which is considered to be pathogenically linked to cancer. Occupational groups, which are at genotoxic risk, have been evaluated by using sensitive, reliable biomarkers (such as comet assay and sister chromatid exchange). These types of biomonitoring assays are cost effective and valuable indicators which signal genotoxic risk in occupational toxicology, and they also encourage the regulatory agencies to take preventive actions against carcinogenic risk within workplaces.