Nitrate contamination in groundwater and associated health risk assessment for Indo-Gangetic Plain, India

Groundwater supplies are progressively being degraded by anthropogenic pollution, making it challenging to meet the Sustainable Development Goals (SDGs) of access to safe and clean drinking water (SDG 6.1 and 6.3) and reduction of illness and death from hazardous pollutants (SDG 3.9). Nitrate is one such widespread groundwater pollutant, mainly emanating from agricultural activities and improper waste disposal, posing global health concerns like blue baby syndrome, thyroid disorders, and cancers due to prolonged exposure to high concentrations. Indo-Gangetic Plain (IGP) in India, is known for its intensive agricultural practices, which support a vast population of about 500 million people. This study aims to investigate the geospatial distribution of nitrate concentration in IGP, along with their potential sources and associated non-carcinogenic health risks (HHR). Employing PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework, this paper reviews 94 peer-reviewed articles on nitrate pollution in the groundwater reported throughout the IGP. Specifically, north-western regions of IGP were more contaminated than eastern regions. From this systemic review, it was evident that land use was the determining factor for the sources of nitrate contamination in IGP. In agricultural areas, fertilizers and manures; whereas in settlement areas, open drains and leakage from the septic tank were the major sources. HHR assessment indicates that children of age group 0-6 years were at higher health risks than adults. HHR assessment of groundwater samples of the IGP reveals that consumption of 34%, 29.3%, and 25.2% of samples may cause a potential health risk for children, males, and females, respectively. Overall, the hazard index estimate illustrates that northern and western parts had a very high potential risk of diseases for all age groups, whereas eastern regions mostly appeared safe. This review provides a comprehensive