In vitro studies on organophosphate pesticides induced oxidative DNA damage in rat lymphocytes.

Organophosphate (OP) pesticides are widely used for agricultural and household pest control. We studied the genotoxicity of the commonly used OP pesticides chlorpyrifos (CPF), methyl parathion (MPT), and malathion (MLT), individually and in combination, in Wistar rat peripheral blood lymphocytes in vitro. DNA single-strand and double-strand breaks were measured by single cell gel electrophoresis (SCGE; comet assay). To test whether the DNA lesions were caused by oxidative stress, the DNA repair enzymes formamidoaminopyrimidineglycosylase (Fpg) and endonuclease (Endo III), which convert base damages to strand breaks, were used. Significant increases in strand breaks and in levels of the reactive oxygen species (ROS) superoxide anion and hydrogen peroxide were observed in lymphocytes treated with pesticides. MPT exposure caused the greatest DNA damage and ROS production, followed by CPF and ML. Our results demonstrate genotoxic potential of these OP pesticides.