Evaluation of early DNA damage in healthcare workers handling antineoplastic drugs

Objectives: This study evaluates by comet assay the induction of early DNA damage in healthcare workers of an oncology hospital regularly handling antineoplastic drug mixtures. The aim was to identify a suitable biomarker of DNA damage by exposure to low levels of such drugs. Methods: We studied 12 day hospital nurses and 13 oncology ward nurses who performed up to 300 and up to 35 drug administrations per week, respectively, and five pharmacy employees who regularly prepared mixtures of antineoplastic agents. Thirty healthy subjects were selected as controls. For exposure evaluation, we performed environmental monitoring of 5-fluorouracil, cytarabine, gemcitabine, cyclophosphamide, and ifosfamide in selected work areas of pharmacy and day hospital units and biological monitoring of urine for the 5-fluorouracile metabolite, alpha-fluoro-beta-alanine. We evaluated early DNA damage in lymphocytes and exfoliated buccal cells by comet assay measuring tail moment (TM) parameter that indirectly indicates the presence of DNA damage. Results: Environmental monitoring detected cyclophosphamide, 5-fluorouracil and ifosfamide, with higher levels of contamination in day hospital unit. The biological monitoring measured detectable levels of alpha-fluoro-beta-alanine only in three nurses. Comet assay showed an increase on exfoliated buccal cells, even if not statistically significant, of mean TM with respect to controls in day hospital nurses (43.2 vs. 28.6, respectively) while ward nurses and pharmacy technicians did not show differences. Comet assay performed on lymphocytes did not show appreciable differences between exposed and controls. Conclusions: The employment of the sensitive comet assay, which is able to detect early the effects of a recent exposure to genotoxic substances, allowed us to find a slight DNA damage, only on exfoliated buccal cells of day hospital nurses, the group handling the highest amount of drugs during the administration process. This finding suggests that comet assay on exfoliated buccal cells could represent a useful tool to evaluate early and still repairable genotoxic effects of exposure to antineoplastic drug mixtures and then contribute to the improvement of the hospital safety practices.