Evaluation of groundwater for nitrate and fluoride in Alappuzha region from the southwestern coast of India and associated health risks

Nitrate and fluoride are two of the most prevalent pollutants in drinking water and exposure to their high concentrations could cause methemoglobinemia and fluorosis. This study attempted to evaluate the groundwater quality (pH: 4.4–9) from a relatively understudied part of the southwestern coast in India (i.e., Alappuzha, Kerala state) and assessed the associated health risks from exposures to nitrate (0.2–5.8 mg/l) and fluoride (0.2–1.9 mg/l) present in the groundwater. Pollution index (PIG: 0.35–5.43) grouped about 21% samples in high pollution and very high pollution categories because of fluoride content above the WHO guidelines. The total hazard index (THI) for adult male (0.17–1.70; average: 0.75), adult female (0.19–1.85; average: 0.81) and children (0.35–3.40; average: 1.50) suggested more non-carcinogenic risks for children from 41.6% samples compared to adult male and female from 33.3% samples in the absence of any mitigation measure. These results provide additional data from the country with highest population and the largest groundwater use in the context of sustainability in availability and supply of groundwater under the increasing risks of population growth, climate change and industrial development. •Groundwater in Alappuzha district (India) contains up to 1.9 mg/l of fluoride.•One-fifth of samples in high and very high pollution categories.•Health risk for adults from 33.3% groundwater samples.•Non-carcinogenic risk for children from 41.6% of groundwater samples.•Demarcation of areas with elevated fluoride posing health risk.