Background: This study aimed to determine the spatial assessment and risk assessment of three widely used pesticides, chlorpyrifos (CPF), malathion, and diazinon, in the tap water distribution network and surface water of Ardabil Province, northwest Iran.
Methods: Sampling was conducted at 41 points in the water distribution network and 30 surface water points. Pesticide values were detected by gas chromatograph-flame ionization detector (GC-FID) after solid-phase extraction.
Results: The ranking of pesticide compounds in tap water was CPF > malathion > diazinon. The mean concentrations of CPF, malathion, and diazinon in surface water were found to be 0.006, 0.013, and 0.003 mg/L, respectively. The highest pesticide concentrations were detected in the northeast region. CPF concentrations exceeded the maximum concentration level (MCL) in 7% of tap water samples.
Conclusion: Based on USEPA standards, the average non-carcinogenic health risks from exposure to pesticides through water consumption remained within the acceptable limits, with a hazard index (HI) below 1 (HI < 1 indicates “acceptable risk” per USEPA). Sensitivity analysis indicated that CPF
concentration and the exposure duration to malathion had the most significant influence on chronic daily intake (CDI) and potential noncancer health effects. Although pesticide levels in drinking water mostly stayed within safe limits, concentrations in the northern region exceeded permissible levels. Therefore, further efforts are essential to regulate pesticide contamination and reduce related health risks in the future.