Evaluation of non-carcinogenic risks due to fluoride and nitrate contaminations in a groundwater of an urban part (Coimbatore region) of south India

Groundwater quality investigations were carried out in one of the urban parts of south India for fluoride and nitrate contaminations, with special focus on human health risk assessment for the rapidly growing and increasingly industrialized Coimbatore City. Twenty-five groundwater samples were collected and analyzed for physico-chemical parameters (EC, pH, TDS, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, PO43-, NO3-, and F-) and the piper diagram characterized 60% of them as Ca-Mg-Cl type. Analysis of fluoride (0.1 to 2.4 mg/l) shows that 32% of the groundwater samples contain F- over the permissible limit, affecting a region of 122.10 km(2). Nitrate (0.1 to 148 mg/l) is over the permissible limit in 44% of the groundwater samples spread over an area of 429.43 km(2). The total hazard indices (THI) of non-carcinogenic risk for children (0.21 to 4.83), women (0.14 to 3.35), and men (0.12 to 2.90) shows some of the THI values are above the permissible limit of the US Environmental Protection Agency. The THI-based non-carcinogenic risks are 60%, 52%, and 48% for children, women, and men. This investigation suggests higher health risk for children and also recommends that proper management plan should be adopted to improve the drinking water quality in this region in order to avoid major health issues in the near future.