Civil Service Essay — Uranium contamination of ground water in India
Uranium contamination of ground water – A new health threat
Contamination of ground water has long been a threat to public health in India. Arsenic in the basins of Ganga and Brahmaputra has been the subject of discussion of geologists and public health experts. Now, one more element, Uranium, has been found to be rampantly present in India’s underground water sources, posing new, unmapped danger to the population.
In the ground water sources of the north western states, Rajasthan and Gujarat, uranium accompanied by other contaminants like arsenic, fluorides and nitrates have been found to be present in alarming levels.
It has been medically established that prolonged consumption of arsenic-rich water leads to higher incidence of cancer. The Bureau of Indian Standards has laid down the upper permissible limits of most contaminants of ground water, such as arsenic and the fluorides and nitrates, but lack of awareness, and no access to safe contaminant-free water, people consume the contaminated water inviting health hazards on to themselves.
Curiously, the BIS has not yet specified the upper limit of uranium concentration in ground water for human consumption. Such silence of the government’s standard setting body is hard to understand.
The Atomic Energy Regulatory Board has set a radiology-based level of 0.60 mg/L of uranium in the water, although WHO limits it to 0.30 mg/L—almost half of the AERB limit. It has to be acknowledged that at such low levels, uranium’s radioactivity is less of a health hazard than its toxicity for the body.
Some scientists of Duke University in the United States came to India to conduct surveys on the state of ground water in Rajasthan and Gujarat and elsewhere. They were joined by some experts pooled from different government establishments of India. The joint team took samples from hundreds of wells that dot Rajasthan and Gujarat and tested the water samples here. The same samples were flown to Duke University for testing of radioactive contaminants in the University’s specialized labs. In order to get a country-wide picture of the state of ground water, the scientists also analyzed the water samples in other states and got their uranium content assessed.
The laboratory findings were quite alarming. The ground water in other states of India was also found to be contaminated with uranium. In Gujarat, nearly 28.7% of the wells had uranium well above the WHO limits. For Rajasthan, the percentage was 5.1. With such endemic contamination, the danger the population face is easily imaginable.
The geology of uranium is such that it occurs naturally in various type of rocks especially granite and gradually percolates into underground water. However, human activities such as excessive extraction aggravates this process. Moreover, the aquifers formed with the residue flowing down from the Himalayan region bolster the formation of granite and too much mining causes the dissolution of uranium in water.
There is a geological explanation to the widespread presence of uranium contaminant in ground water. Uranium is generally found to be found in minute quantities in granite. Long contact with water with the granite rock dissolves the uranium, making it to enter the water stream. Excessive extraction of ground water by humans accelerates such transfer of uranium from granite to ground water.
Studies carried out in different parts of India point to the fact that streams flowing down from the Himalayas invariably make contact with granite rock deposits along the way and pick up uranium. This causes uranium contamination level to shoot up. Additionally, overuse of these aquifers for agriculture or human consumption depletes ground water levels and creates oxidizing conditions. This further accelerates the leaching process. There is a third factor too. Widespread granite mining increases the dissolution of uranium in water as virgin rock surfaces get exposed to rain and other kinds of flowing water.
Another independent study was conducted by the Chennai-based geologist, Elango Lakshmanan. He attributes the high level of uranium in ground water in South India to the large scale presence of granite rock deposits in the states like Andhra, Tamil Nadu, and Karnataka. He says that uranium in ground water will cause definite health hazards only if a person regularly uses such water, and more importantly, if the contamination level reaches a few hundred instead of just 30% specified by the WHO. So, he suggests that people need not be unduly worried on this count.
However, Elango Lakshmanan does not underestimate the danger of uranium entering human body through water. At elevated levels, it surely leads to fatal consequences. The safe limits must be decided upon and made available to public. In this regard, he wrote letters to BIS, but the latter has not responded so far. If BIS could specify arsenic limits, why is it silent on uranium, he wonders.
As an ongoing public health measure, uranium’s level in ground water should be monitored in different areas. Presence of bicarbonates in water almost surely points to higher uranium presence. So, both bicarbonate and uranium concentrations need to be measured simultaneously. To protect the population from the hazards of contaminated water, clean and safe water has to be made available to communities in adequate measure. Irrigation, where ground water is used the most, should be a subject of research to see if anything can be done to neutralize the danger at this stage.