Water quality index and human health risk assessment for heavy metals in groundwater of Bedkot Municipality, Kanchanpur, Nepal: A cross-sectional study

This study assessed groundwater quality and associated human health risks in Bedkot Municipality, Nepal, where 68.6% of households rely on tube wells (TWs). Twenty-three shallow TWs water samples (urban:10, semi-urban:6, and rural:7) were analyzed for physiochemical parameters (pH, temperature, turbidity, electrical conductivity, total dissolved solids, total hardness, calcium, ammonium, nitrate, total iron (Fe), and total arsenic (As)), following standard methods and assessed using the water quality index (WQI) and USEPA’s human health risk assessment (HHRA). Results revealed slightly acidic freshwater, with hardness varying (hard to very hard: urban/semi-urban, and moderately hard to very hard: rural). WQI classified 80% of urban, 90% of semi-urban, and 100% of rural samples as “excellent” for drinking, with none deemed unsuitable (WQI > 300). However, health risks emerged: children in all areas faced non-carcinogenic risks (Hazard Index, HI: 1.5–6.31). Some urban adults also showed risks (HI: 0.73–2.98), whereas no such risks were identified for adults in semi-urban and rural areas (HI: 0.73–0.95). Carcinogenic risks from As ingestion were significant for children (7E-04– 2.5E-03) and adults (3.3E-04– 1.2E-03) in urban, as well as children (7E-04– 9E-04) and adults (3.3E-04– 4.2E-04) in semi-urban and rural areas, exceeding acceptable thresholds (1E-06–1E-04). Children were 2.12 times more susceptible to non-carcinogenic and carcinogenic health risks than adults. These findings can guide sustainable groundwater quality management strategies in the region.