Comparative investigation in Single Cell Gel Electrophoresis (Comet) Assay in lymphocytes and the Ames-fluctuation test in the urine of workers of a rubber factory.

P Franceschetti, PhD a, L Perbellini, MDb, S Tieghi, MDc, S Soldaa, ME Fracasso, MPH a

Department of Medicine and Public Health a Section of Pharmacology b Section of Occupational Health, University of Verona, Policlinico Borgo Roma, Verona, Italy; c Enveronmental Health Service, ASL, Mantova, Italy.

AIM. In a previous study we used bacterial mutagenicity assay and chemical methods to investigate the genotoxicity of air in a rubber factory. The samples, which were taken in fixed positions and from several workers employed in different processing operations, showed a consistent direct and indirect mutagenicity in S. typhimurium strains. The use of a battery of different biomarkers would be convenient to evaluate individual workers's health risk. We considered two genotoxic assays, urinary mutagenicity and lymphocytes DNA strand breaks on the same workers, followed by a comparative evaluation. METHODS. Urinary mutagenicity was determined by Ames-fluctuation test using S. typhimurium strains, +/- S9 (TA 98; TA 98/1,8DNP6; YG 1024). Lymphocytes DNA damage was evaluated by comet assay. The three parameters characterizing DNA strand breaks were tail moment (TM), tail intensity (TI) and tail length (TL). RESULTS. Urinary mutagenicity obtained on S. typhimurium strains always showed positive responses after exposure. The mutagenicity was increased in YG 1024 (acetyltransferase-overproducing) and decrease in TA 98/1,8DNP-6 (acetyltransferase-deficient mutant) compared to conventional strain (TA 98). Comet assay on worker-lymphocytes showed higher TM and TI than controls. Significant correlation among urinary mutagenicity, TI, TM and years of exposure were observed. CONCLUSIONS. The workers are exposed to mutagenic chemical substances: the urine samples show mutagenic activity in all S. typhimurium strains. Using the alkaline comet assay as another biomarker of exposure we note an increase DNA damage in worker-lymphocytes and a positive correlation between urinary mutagenicity and DNA strand breaks.

KEY WORDS: urinary mutagenicity, comet assay, fluctuation test, exposed workers, rubber factory.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Environment and Occupation.