Diethyl thiophosphate

Diethylthiophosphate (DETP) induces DNA damage only in the hepatic cell lines, and this effect could be related to a secondary non-diffusible metabolite generated by the activity of P450 enzymes since P450 enzyme inhibitors also inhibited the induction of DNA damage in hepatic cells. This organophosphorous (OP) metabolite has shown some toxicity in human peripheral blood mononucleated cells (PBMC). DETP is a cytotoxic compound in human PBMC. A relationship between urinary levels of DETP and the number of sperm susceptible to chromatin alteration has been reported among rural agricultural workers. In addition, a correlation between the frequency of aneuploidy in sperm and the levels of DETP in urine was identified in a rural population exposed to OP pesticides, indicating that the potential for genotoxicity following OP exposure may depend on the type and quantity of specific metabolites produced, such as DETP. (A15411)

Metabolism of organophosphates occurs principally by oxidation, by hydrolysis via esterases and by reaction with glutathione. Demethylation and glucuronidation may also occur. Oxidation of organophosphorus pesticides may result in moderately toxic products. In general, phosphorothioates are not directly toxic but require oxidative metabolism to the proximal toxin. The glutathione transferase reactions produce products that are, in most cases, of low toxicity. Paraoxonase (PON1) is a key enzyme in the metabolism of organophosphates. PON1 can inactivate some organophosphates through hydrolysis. PON1 hydrolyzes the active metabolites in several organophosphates insecticides as well as, nerve agents such as soman, sarin, and VX. The presence of PON1 polymorphisms causes there to be different enzyme levels and catalytic efficiency of this esterase, which in turn suggests that different individuals may be more susceptible to the toxic effect of organophosphate exposure.