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This study aimed to investigate the residue levels and dissipation rates of chlorpyrifos, diazinon, and their oxon derivatives in greenhouse-grown tomatoes and to evaluate the acute and chronic Hazard Quotients (HQ) for consumption of these products. The quantification analyses of chlorpyrifos and diazinon and their degradation products were performed using Gas Chromatography Coupled with Mass Spectrometry (GC-MS/MS). The Monte Carlo simulation technique was used to evaluate the variability and uncertainty of the data and to achieve more accurate results in the health risk assessment process. The chronic HQ values of chlorpyrifos and diazinon residues ranged from 0.24 to 0.85 and 0.06 to 1.09 for adults, 0.45 to 1.34 and 0.12 to 1.66 for adolescents, and 0.71 to 1.80 and 0.21 to 3.78 for children, respectively. After five days of storage in room and refrigerator temperatures, the HQ values of diazinon and chlorpyrifos were higher than the acceptable limits. According to the Monte Carlo simulation, the HQ and the estimated daily intake (EDI) values were more affected by the consumption rate followed by pesticide concentration and body weight. Therefore, due to the high frequency of tomato consumption, it is necessary to reduce the concentration of pesticides in this product in order to reduce human health risk.