The comet assay as a tool in human biomonitoring exposure to pesticides-A systematic review and meta-analysis.
Exposure to pesticides, most usually in occupational settings, is associated with different adverse health effects. In this systematic review and meta-analysis, we have assessed the effects of pesticide exposure on the level of DNA strand breaks in human peripheral blood cells, measured by the comet assay, in human biomonitoring studies. The literature search led to 80 studies included in the review. Of these, 66 studies met the criteria to be used in the meta-analysis. Using standardized mean difference and 95 % confidence interval (CI), the meta-analyses show an increased level of DNA strand breaks in subjects exposed to pesticides (2.02, 95 % CI: 1.69, 2.35). Results originate mainly from studies on workers, with only a few studies on environmental pesticide exposure. Subgroup analysis indicates that all studies combined from middle-income countries have a higher effect size (2.22, CI: 1.84, 2.59, n = 55) than studies from high-income countries (1.09, CI: 0.41, 1.76, n = 11). This difference between middle- and high-income countries may be mostly due to legislative, economic, and socio-cultural aspects. It has to be pointed out that only 9 % of the studies were classified as having an overall low risk of bias, while 12 % of studies used exposure biomarkers. In conclusion, this systematic review and meta-analysis shows that exposure to pesticides is associated with increased levels of DNA strand breaks in human peripheral blood cells.