Hyderabad groundwater study flags high nitrate, fluoride levels

This can potentially cause blood disorders, birth defects, and poor bone quality in children.

Hyderabad: A recent study has flagged elevated levels of nitrate and fluoride in Hyderabad’s groundwater, potentially posing non-carcinogenic health risks to children, like blood disorders, birth defects, and poor bone quality.

A total of 44 groundwater samples from the pre-monsoon and post-monsoon seasons of 2023 were analysed, revealing nitrate exceeding the permissible drinking-water limit of 45 mg/L in 36 per cent of samples taken before the monsoon and 40 per cent of samples taken after the monsoon, The New Indian Express reported.

The samples were found to have 3 to 230 mg/L of nitrate before the monsoon and 5 to 797 mg/L afterwards. Higher concentrations were observed mainly in southwestern and central areas.

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The contamination was largely linked to fertiliser use, sewage infiltration, septic-tank leakage and urban wastewater. Monsoon rains can further carry nitrogen compounds from soil into groundwater.

Fluoride levels

On the other hand, Fluoride was found to exceed the acceptable limit of 1 mg/L in 64 per cent of pre-monsoon and 59 per cent of post-monsoon samples.

Levels ranged from 0.21 to 3.03 mg/L before the monsoon and 0.28 to 5.94 mg/L afterwards, with higher concentrations in northern, southern and southwestern areas.

The fluoride enrichment has been attributed to the weathering of granitic rocks and prolonged interaction between groundwater and aquifer materials.

Children at higher risk

Under US Environmental Protection Agency guidelines, a hazard quotient (HQ) above 1 indicates a potential non-carcinogenic health risk.

The study puts the mean fluoride hazard quotient for children at 1.04 before the monsoon and at 1.11 afterwards. Nitrate increased from 1.81 to 3.78.

The combined total hazard index (THI) for children rose from 3.07 to 3.78, compared with 2.27 to 2.79 for adults. 

Children are considered more vulnerable than adults because they have a greater exposure relative to body mass.

Researchers have called for closer groundwater monitoring and stronger measures against nitrate contamination through sewage and agricultural sources.

The study was conducted by Achiraju Pallavi and Allam Edukondal of Osmania University, Laxman Kumar Duvva of Jawaharlal Nehru Technological University and Ratnakar Dhakate of the Council of Scientific & Industrial Research (CSIR)-National Geophysical Research Institute.