Nitrate pollution index and age wise health risk appraisal for the Pambar River basin in south India

Water and human healthcare are common concerns for everyone, resonating with the sustainable development goal. In Pambar River basin, south India, groundwater samples were obtained in 100 locations from open and bore wells to assess the quality of groundwater based on hydrochemical constituents like pH (Hydrogen Ion Concentration), CO₃²- (carbonate), Ca²⁺ (calcium), HCO₃- (bicarbonate), Cl- (chloride), Mg²⁺ (magnesium), SO₄²- (sulfate), K⁺ (potassium), Na⁺ (sodium), TDS (Total Dissolved Solids) with a special focus on NO₃- (nitrate) enrichment in groundwater and health risk computed from consumption of nitrate enriched water by different age categories of people, and acceptableness of water for consumption depends on the range of NPI (Nitrate Pollution Index). The nitrate content in subsurface water samples falls from 0.7 to 187.5 mg/L. Out of 100 samples, 31 samples surpassed the WHO, 2017 recommended limit for drinking purpose (> 45 mg/L). The calculated nitrate pollution index (NPI) values of samples  represent clean class (n = 43), light pollution class (n = 26), moderate pollution class (n = 9), significant class (n = 11) and very significant class (n = 11). The correlation matrix explains nitrate is weakly correlated with pH, magnesium, calcium, and potassium, and negatively associated with TDS, sodium, bicarbonate, chloride, and sulfate. The human health risk assessment computed from oral intake and dermal contact indicated that 36%, 34%, 31%, 36%, and 31% of samples for children, younger women, elder women, younger men, and elder men respectively, had a total hazard index (THI) > 1, indicating potential health risks. The nitrate enrichment in the subsurface water is caused by human-induced factors like fertilizers usage for agriculture, and leaching of animal waste. The health risk and water quality study suggest regular monitoring and managing the quality of groundwater for making the healthy society.