Chromosomal aberration and single cell gel electrophoresis (Comet) assay in the longitudinal risk assessment of occupational exposure to pesticides.

In recent years the use of pesticides in agriculture has been increasing steadily. At present there are more than 1000 chemicals classified as pesticides. Therefore, the widespread use of pesticides and their potential genetic hazard suggests that evaluation of their genotoxicity should be extended using the newer assays now available. In the present study chromosomal aberration analysis and the alkaline single cell gel electrophoresis (Comet) assay were used to evaluate the extent of DNA damage and DNA repair in peripheral blood lymphocytes of subjects employed in pesticide production. In order to determine possible primary genotoxic effects in workers blood samples were taken after an 8 month long period of exposure to a complex mixture of pesticides. To detect the possible occurrence of DNA repair in lymphocytes of the same subjects the second blood sample was taken after an 8 month long period of absence from the pesticide exposure zone. Regardless of the period of sampling, in the exposed group statistically significantly increased numbers of aberrant cells, chromatid and chromosome breaks, acentric fragments and dicentric chromosomes compared with the controls were found. After the workers had spent 8 months out of the pesticide exposure zone the number of aberrant cells and all types of chromatid and chromosome aberrations decreased significantly compared with sampling after the high exposure period, but it still remained significantly higher in comparison with the control group. After the period of high exposure to a mixture of pesticides statistically significantly increased levels of DNA damage in the Comet assay in terms of tail length and tail moment were found. After the workers were removed from production for 8 months both Comet assay end-points decreased significantly compared with the first sampling point, but they remained increased compared with the control.