Groundwater nitrate contamination and associated human health risk assessment in southern districts of Punjab, India.

Consumption of high NO3 containing water may pose serious health hazard especially in children (< 5 years). The source of NO3 in groundwater includes surface leaching from wastewater and waste dump sites, animal excreta disposal, industrial effluents, and N-based fertilizers, etc. This study aimed to investigate the concentration of NO3 in groundwater of 14 intensively cultivated districts of Malwa Punjab, India, and its possible health hazards in local residents. The sampling of 76 sites revealed the concentration of NO3 in ranges of 38.45-198.05 mgL-1, and over 92% sites showed the high level of it than the safe limits as decided by the Bureau of Indian standards (45 mg L-1) and World Health Organization (50 mg L-1). The possible health hazards of high NO3 intake was estimated using USEPA human health risk assessment (HHRA) model for both adult and children. Results of this study suggested the chronic daily intake (CDI) in the ranges of 1.09-5.65 and 2.56-13.20 in adult and children population of this region, respectively. The hazard quotient (HQnitrate) value was > 1 in most sampling locations ranging 1.09-5.65 for the adult and 2.56-13.20 for children population of Malwa. This study indicates that 93.42% adult and 100% young population of the Malwa are at higher risk of chronic toxicity by excess NO3 intake. The HHRA results suggested a high vulnerability of a local community to NO3 toxicity in this region; therefore, there is an instant need to take preventive measures to safeguard the health of local residents.