Application of the alkaline comet assay in human biomonitoring for genotoxicity: a study on Croatian medical personnel handling antineoplastic drugs

The alkaline comet assay was used to evaluate the genotoxicity towards peripheral blood lymphocytes of medical personnel regularly handling various antineoplastic drugs with different safety precautions. The study population consisted of 50 exposed subjects working in the oncology, pulmology, gynaecology and haematology units of nine Croatian hospitals and 20 unexposed control subjects. Peripheral blood lymphocytes from the subjects were embedded in agarose on a microscope slide and lysed; the DNA was unwound and subjected to electrophoresis at pH 13. Staining with a fluorescent dye was used to identify cells with DNA damage, as judged by increased migration of genetic material from the cell nucleus. DNA damage was quantified by measuring the displacement between the genetic material of the nucleus and the resulting tail using an image analysis system. Three parameters were used as indicators of DNA damage: i.e. tail length, percentage of DNA in the tail and tail moment. Statistically significant differences in all three parameters were observed between the exposed and control groups. Within the exposed group, there were marked differences between individuals in the comet tail parameters. In the majority of exposed subjects an effect on DNA damage of age or duration of occupational exposure could be excluded. In the exposed group, the highest level of DNA damage was recorded in subjects who used only latex gloves in their work with antineoplastic drugs. The observed DNA damage was lower in exposed subjects who used more than one type of protective equipment and who worked in a well-ventilated safety cabinet. No statistically significant differences were found between the mean values of comet tail parameters for smoking and non-smoking subpopulations from the exposed group. In view of the results obtained, the alkaline comet assay, as a simple, rapid and sensitive method, appears to be a promising additional test for biomonitoring purposes in human populations.