Environmental and occupational biomonitoring using the Comet assay

Biomonitoring of human populations exposed to potential mutagens or carcinogens can provide an early detection system for the initiation of cell disregulation in the development of cancer. In recent years, the Comet assay, also known as a “single cell gel” (SCG) electrophoresis assay, has become an important tool for assessing DNA damage in exposed populations. This is the method of choice for population-based studies of environmental and occupational exposure to air pollutants, metals, pesticides, radiation, and other xenobiotics as we show in this review. To appreciate the role of the Comet assay in the field of biomonitoring, we review data from 122 studies that employed the assay. These studies evaluated environmental versus occupational exposures and the levels of DNA damage in cells of individuals exposed in each case. Our review of the literature reveals the importance of the need to establish standard methodological conditions that affect unwinding and electrophoresis times and tail values (tail length, tail DNA, tail moment), with the goal of being able to compare data collected in different laboratories throughout the world. The Comet assay is susceptible to subtle artifacts of manipulation depending on the type and timing of sampling performed. Therefore, in the reporting of DNA damage detected by the Comet assay, the context of how the DNA damage was created also needs to be reported and considered in the interpretation of Comet assay results. The success of the Comet assay is reflected by its use over the past 20 years in the field of biomonitoring, and by the increasing number of studies that continue to report its use. As the shortcomings of the assay are identified and considered in the interpretation of DNA damage detection, the Comet assay will continue to provide improved reliability as a biomarker in human biomonitoring studies.