Comparative health risk assessment of arsenic and fluoride toxicity in the rural area groundwater in the middle Gangetic plain at Muzaffarpur, India

Abstract Groundwater contamination with arsenic and fluoride poses a critical global issue and has been documented extensively across the middle Gangetic plains of India. Rural regions are particularly vulnerable due to limited access to safe drinking water and alternative resources. Therefore, the study aims to assess the health risks and identify the contamination sources of fluoride (F-) and arsenic (As) in the groundwater of some rural areas of Muzaffarpur, India. Forty groundwater samples were collected and were assessed for 16 physicochemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS), turbidity, total hardness (TH), Ca 2+ , Mg 2+ , Na + , K + , Fe 2+ , SO 4 2− , NO 3 − , CI − , total alkalinity (TA), F − , and As following standard procedures. The results reveal the alkaline nature of groundwater, where rock weathering has contributed primarily to Mg-HCO 3 and mixing water types. Nearly 20% (range = 0.001–0.021 mg/L) of the groundwater samples exceeded the acceptable level of arsenic, and 60% (range = 0.2–1.2 mg/L) exceeded the acceptable fluoride limit in the groundwater according to International Society for Fluoride Research (ISFR) standards. The HQ value for arsenic was > 1 in 40% samples for adults and 47.5% in children, which highlight vulnerability to the adverse effects of elevated arsenic concentrations. Moreover, dental fluorosis was also prevalent among children, with a maximum hazard quotient (HQ) value of 1.04. These findings emphasize the urgent need for targeted actions to ensure safe drinking water and protect the health of rural populations.