DNA damage in mononuclear leukocytes of farmers measured using the alkaline comet assay: modifications of DNA damage levels after a one-day field spraying period with selected pesticides

The alkaline comet assay was used to assess DNA damage in mononuclear leukocytes of farmers before and after a 1-day spraying period with selected pesticides under usual conditions. Two blood samples were collected, one in the morning of the day of spraying (S0) and the second in the morning of the day after (S1). Here, we assessed variations in DNA damage levels between these two sampling times. Four groups of farmers were formed, according to exposure to: (a) various fungicide-insecticide mixtures (including chlorothalonil; group 1, n = 8), (b) the herbicide isoproturon (group 2, n = 11), (c) fungicide triazoles (group 3, n = 14), and (d) a fungicide (chlorothalonil)-insecticide mixture (group 4, n = 8). An increase in DNA damage levels was observed at S1 for groups 1 and 4, who were exposed to similar pesticides. This increase was correlated with area sprayed between S0 and S1 and with the number of spraying tanks used over this 1-day period. No effect was observed on cell viability or on hematological parameters for these two groups. No statistically significant modification of DNA damage level was observed the day after spraying for groups 2 and 3, when each was observed as a whole. However, some farmers presented significantly more DNA damage after exposure, and others presented less damage. In these two groups, a significant decrease of neutrophils was observed at S1, and a decrease of red blood cells was observed in group 3. In parallel, a significant loss of lymphocyte viability was observed in these two groups. A 1-day spraying period seems to be sufficient to significantly modify DNA damage levels in mononuclear leukocytes, but the correlation of this change with pesticide-related exposure parameters depends on the kind of pesticide concerned.