There is a new addition to the list of water quality problems plaguing India’s groundwater. Recently published research has shown that the level of uranium is significantly higher than 30 µg/L, the limit suggested by the WHO, in several parts of the country, particularly in Gujarat and Rajasthan. This is a concern because a high concentration of uranium in the body has been linked to chronic kidney disease.
Groundwater concerns are not new in India. One of the most prominent issues that has gained global attention is arsenic contamination in the Ganges and Brahmaputra basins, affecting several states, such as West Bengal, Uttar Pradesh, Bihar and Assam. Prolonged exposure to arsenic can lead to different types of cancers and ultimately death. The permissible limit of arsenic in drinking water according to the Bureau of Indian Standards (BIS) is 10 µg/L, relaxed to 50 µg/L if no alternate sources are available.
However, unlike the limits for arsenic and other toxic or heavy metals specified in the Indian standards for drinking water, there is no limit maintained for uranium, another heavy metal, although the Atomic Energy Regulatory Board has set a radiology-based limit of 60 µg/L. Uranium in drinking water raises concerns not because of radioactivity but mainly because of its chemical toxicity. Studies have shown that ingestion of high quantities of uranium can lead to chronic kidney problems. It may also accumulate in crops irrigated with uranium-containing water.
As part of a project investigating different aspects of water quality in India, Avner Vengosh, a geochemist at Duke University, North Carolina, and an author of the new study, has been looking at various water quality issues. Tracking uranium was the first step.
Vengosh and team, including members from the department of groundwater resources in Gujarat and Rajasthan, sampled water from 324 wells in the two states and analysed their chemical composition. The samples were collected before any treatment, analysed for temperature, pH and specific conductivity in the field and shipped to Duke University, where they were checked for anion/cation content, bicarbonates, nitrates and trace elements. In addition, the researchers also compiled results from previously published data for 16 Indian states to map uranium levels across several regions in the country.