Study of Toxicity of Parathion and Its Major Degradation Products to Human Lymphocytes and Keratinocytes

Abstract: Organophosphorus pesticides (OPs) and their transformation products become a concern when these compounds are released into the environment. To understand the effects of these pesticides on human health, toxicity of a widely used organophosphorus pesticide, parathion and its transformation products, i.e. paraoxon and 4-nitrophenol, were investigated by using T4 lymphocyte cells and HaCaT keratinocyte (skin) cells. Paraoxon showed greater cytotoxicity to lymphocyte cells at concentration of 7.5 μM and 30 μM compared to parent compound and was more toxic to the HaCaT cells at concentration of 15 μM and 30 μM. Genotoxicity of parathion and its degradation intermediates was investigated in both cell lines using the Comet assay. Neither parathion nor its major degradation products, i.e. paraoxon, 4-nitrophenol, produced significant levels of DNA damage in the human HaCaT and A3 cells. Since Comet assay mainly detects DNA damage by strand breaks and incomplete excision repair sites, results of genotoxicity study of OPs and their degradation products in human cell lines should not preclude us from conducting further in vivo investigation to have a thorough understanding on cellular toxicity of these pollutants in the environment.