A decadal analysis of drinking water quality and nitrate-related health risk assessment in groundwater sources: a case study of Poldasht County, Northwest Iran

This study aimed to evaluate groundwater quality and assess the health risks associated with nitrate contamination in Poldasht County, northwest Iran. Groundwater samples were collected from 17 wells over a ten-year period, and key physicochemical parameters including pH, TDS, total hardness, major ions, and nitrate were analyzed. The Groundwater Quality Index was applied to assess overall water quality, while non-carcinogenic risk was calculated following USEPA guidelines for four age groups: infants, children, teenagers, and adults. The results indicated that approximately 64.7% of the samples were classified as "acceptable," while 35.3% fell into the "moderate" quality range. The dominant groundwater facies were Mg-SO₄ and Mg-HCO₃, reflecting the combined effects of geological formations and, to some extent, human activities such as agriculture. Health risk assessment revealed that HQ values for all age groups were below 1.0, indicating no significant non-carcinogenic risk. However, children exhibited relatively higher HQ values due to their higher water intake relative to body weight, emphasizing their increased vulnerability. These findings highlight the need for continuous monitoring, particularly for wells with moderate quality and in areas showing signs of localized contamination. The study underscores the importance of adopting integrated groundwater management strategies, including regular quality assessment, pollution prevention practices, and targeted interventions to protect sensitive populations.