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Twelve Indian states have uranium levels beyond permissible limits in their groundwater, the most recent report on the state of groundwater released by the Central Groundwater Board, revealed.
Uranium concentrations in the country’s shallow groundwater range from 0-532 parts per billion (ppb), according to the document titled Groundwater yearbook 2021-2022 released in January, 2023.
Uranium concentration is found to be within safe limits in 13 states and none of the samples collected from Kerala had its presence.
Punjab is the worst-affected state in terms of the percentage of wells found to have uranium concentration of more than 30 ppb — the safe levels prescribed by the Bureau of Indian Standards (BIS) and the World Health Organization (WHO).
Nearly 29 per cent, or about three in every 10 wells tested in Punjab, is contaminated with uranium. The concentration of the element in 96 of the 329 wells breached the safe limit prescribed by BIS and WHO.
Uranium presence in Punjab’s groundwater is found to be 17.7 times more than the safe limit prescribed by WHO. The concentration of the element was also highest in the state, with 532 ppb.
| State | Maximum value of Uranium observed (in ppb) |
Percentage of samples beyond permissible limit of BIS (U >30ppb) |
| Punjab | 532 | 29 |
| Haryana | 518 | 14.4 |
| UP | 239 | 9.2 |
| Rajasthan | 186 | 8.6 |
| TN | 159 | 3.4 |
| MP | 149 | 1.3 |
| Odisha | 61.4 | 0.69 |
| Delhi | 58.3 | 3.9 |
| Telangana | 36.1 | 1.43 |
| Chhattisgarh | 32 | 0.12 |
| Bihar | 31.4 | 0.36 |
Source: Groundwater yearbook 2021-22
Haryana is the second state in terms of uranium prevalence in groundwater. The element’s concentration in 14 per cent of the samples, or 67 out of 464 wells, exceeded the safe limit.
The state also recorded the second-highest concentration of uranium in the country, with 518 ppb or 17.3 times the WHO-prescribed safe limit.
Groundwater in Uttar Pradesh, Rajasthan and Delhi was also found to have a toxic concentration of uranium.
For example, 9.2 per cent of the samples from Uttar Pradesh had a high concentration of uranium. The concentration of the element in 84 wells in the state exceeded the safe limit. The state was the third-highest in terms of uranium concentration, with 532 ppb or 7.9 times more than the safe limit.
Uranium concentration was found to be higher than the threshold level in localised pockets of seven other states — Madhya Pradesh, Tamil Nadu, Chhattisgarh, Gujarat, Odisha, Telangana and Bihar.
In a 2019 assessment, groundwater in 18 states was found to be contaminated with uranium. Of those, the uranium levels in six states — Andhra Pradesh, Himachal Pradesh, Maharashtra, Goa, Karnataka and West Bengal — are currently upgraded to ‘within the prescribed limits’ zone.
Does this mean that the groundwater in these states is uranium-free? Not necessarily, because sample size of three of these states is considerably small compared to 2019.
For instance, only 55 samples from Andhra Pradesh were analysed in 2022, compared to 588 in 2019. Similarly, merely 104 samples were analysed in Maharashtra compared to 1,115 in 2019.
Uranium is a nephrotoxic element and can have an adverse impact at very high concentrations. This means that people dependent on groundwater containing the element are at a higher risk of impaired renal function and kidney disease. Exposure to uranium may also lead to other adverse health impacts, including bone toxicity.
A 2022 study by Panjab University also detected higher than the permissible limit of uranium in the state's groundwater. The study warned about the health risk of consuming contaminated water for a long time.
Uranium contamination of groundwater is a persistent problem in Punjab and has been reported widely since the 1990s. It has been discussed and debated over the last three decades.
The presence of uranium in these states was also acknowledged by the United States' Duke University in a 2018 pan-India study.
Geogenic processes are responsible for uranium contamination, but the overexploitation of groundwater can also be a reason for it.
High levels of uranium are largely due to natural uranium content in aquifer rocks, oxidation state and groundwater chemistry, noted researchers from Duke University.
Extreme bicarbonate levels were also found at the sites with high uranium levels. Bicarbonates help to bring the uranium out of the source rocks and is a reason for the high occurrence of the element, said Rachel Coyte, the lead author of the study.
The study also alerted that human-made causes too could be behind this. Groundwater-table decline, nitrate pollution and over-exploitation of groundwater from irrigation further exacerbate uranium mobilisation, said the study.
Overexploitation of groundwater has been observed in all types of aquifers in the country, confirmed another 2021 study by researchers from Bhabha Atomic Research Centre (BARC) and Homi Bhabha National Institute.
Also read: Hazards of using fertilisers in Punjab
India’s most comprehensive study ever by BARC was revived in the face of the Centre denying health repercussions due to uranium contamination of groundwater.
Overexploitation of groundwater resources is likely to be one of the reasons for uranium and other geogenic contaminants, including arsenic and fluoride, according to the BARC study published in 2021.
So, uranium contamination has been attributed to geogenic processes coupled with the overexploitation of groundwater in the country.
This assessment of uranium contamination in groundwater across India highlights the need for an urgent response. Reverse osmosis (RO) is one of the latest membrane-based technologies used in water purification systems to remove uranium.
BARC has conducted studies on the removal of uranium from drinking water using a hybrid membrane technique. Field studies are also being carried out in a few districts of Punjab based on RO technique at a village level to provide potable water, stated the BARC researchers.