Risk assessment of nitrate and fluoride in drinking water sources of Golestan Province

Background and Groundwater serves as the primary drinking water source in Golestan Province. Therefore, this study aims to assess the non-cancerous health risks associated with nitrate and fluoride in the province's drinking water sources.  Physicochemical data from 139 drinking water wells were obtained from the Golestan Province Water and Wastewater Company during the spring and autumn. Significant ion variations were analyzed, and factors influencing the chemistry of drinking water sources in Golestan Province were investigated. Non-carcinogenic health risks posed by nitrate and fluoride were assessed using two indicators provided by the United States Environmental Protection Agency.  The maximum nitrate concentration in certain Golestan Province cities exceeds the Iranian drinking water standards (1053) and the World Health Organization's limits. However, fluoride levels in most cities fall below the range stipulated by domestic and international standards. The nitrate risk factor for children in select cities exceeds one, while it remains below one for other age groups. Notably, Khan Bebin City exhibits the lowest nitrate risk factor among the province's cities. Additionally, risk factor values show a slight increase during the autumn season. Non-cancerous health risk assessments for fluoride in drinking water sources across Golestan Province during spring and autumn indicate risk values below one for all age groups, including infants, children, teenagers, and adults.  The health risk assessments for nitrates and fluorides indicate that children in certain cities face a higher risk from nitrates than adults. Moreover, the low fluoride levels in the province's drinking water sources increase the likelihood of tooth decay.