Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 14 3 2020 07 30 1352 1352 Mohammad Safari Student Research Committee, Semnan University of Medical Sciences, Semnan, Iran AND Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Ali Ahmadfazeli Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Hassan Vatandoost Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Department of Environmental Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Silences, Tehran, Iran Mostafa Karimaee Department of Environmental Health Engineering, Semnan University of Medical Sciences, Semnan, Iran Davood Panahi Student Research Committee, Semnan University of Medical Sciences, Semnan, Iran Mohammadali Shokri Student Research Committee, Semnan University of Medical Sciences, Semnan, Iran Mehdi Moradian Student Research Committee, Semnan University of Medical Sciences, Semnan, Iran Zahra Soleimani Student Research Committee, Semnan University of Medical Sciences, Semnan, Iran AND Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2020 09 22 Background: Organophosphate pesticides are of concern to the drinking water supply and high risks on human health. Methods: An occurrence survey was performed in the spring and summer of 2016 for 6 months to assess the preva­lence of organophosphate pesticides in the Hablehrood River that is located in Semnan Province. Besides, 10 kinds of organophosphate pesticides were sampled in 5 stations. Moreover, were measured by Gas Chromatography (GC) was supported by an electron capture detector (ECD) and Turbochrom software. In all stations, Diazinon was detect­ed in the spring and summer, but Malathion only in the spring. Results: The highest concentration of Diazinon was observed at the Mahmoud Abad station in spring (0.94ppb) and the Bonekooh station in the summer (0.93ppb). The highest and lowest concentrations of Malathion were detected in Mahmoud Abad (0.35ppb), and Gache station, respectively. Conclusion: The concentration of pesticides in BoneKooh and Mahmood Abad was higher than the standard. https://jad.tums.ac.ir/index.php/jad/article/view/1352 https://jad.tums.ac.ir/index.php/jad/article/download/1352/504