Organophosphate Pesticide Exposure Reduced Serum Paraoxonase1 (PON1) Activity Which Correlated With Oxidative Stress in Pesticide Factory Workers

Background & Aims of the Study: Serum paraoxonase (PON1) is a potent antioxidant that is associated with the pathogenesis of several diseases. Also, it is reported that environmental factors can modulate the PON1 activity. In this study, the association between the Organophosphates (OP) exposure and plasma Paraoxonase/Arylesterase (PON1) activity and also OP-induced oxidative stress was investigated among pesticide manufacturing factory workers. Materials and Methods: In this cross-sectional study, Plasma cholinesterase (PChE) and RBC Acetylcholinesterase activity (AChE) were measured as a biomarker of OP exposure. Also, the amount of malondialdehyde (MDA) was evaluated as a biomarker for lipid peroxidation and oxidative stress. The PON1activity was measured by two distinct substrates, Paraoxson and Phenylacetate, to measure paraoxonase (PONase) and arylesterase (AREase) activities of PON1 enzyme respectively.  Results: A significant decrease was observed inPChE and AChE activities in the blood sample of factory workers which confirmed OP exposure (p<0.001). Furthermore, the level of MDA increased that shown lipid peroxidation induced by OP (p<0.05). PONase and AREase activities decreased significantly in factory workers (p<0.05, p<0.001_). The reduction in AREase activity shown a correlation with the decrease in PChE and AChE activities (p<0.01), also a negative correlation was observed with AREase activity and lipid peroxidation (p<0.01). The Ponase activity only negatively correlated with lipid peroxidation (p<0.01). Conclusion: Our study indicates that occupational OP pesticide exposure in factory workers causes a decrease in serum PON1 activity which is associated with oxidative stress. Decreased PON1 activity is involved in the pathogenesis of several diseases such as cardiovascular disease then it is recommended that PON1 activity of OP-pesticide workers has been periodically monitored.