For, the carcinogenic, radioactive gas, Radon has been found to be present 100 times above the permissible limit in water samples analysed across the City. A detailed study on the presence of Radon in groundwater was conducted by a team of the Central Ground Water Board, based at HSR Layout, following a directive from the Centre’s Ministry of Water Resources.
The results have been published in this month’s edition of the internationally recognised ‘Journal of the Geological Society of India.’ Elaborating on the health hazards posed by this gas, widely recognised as the daughter product of Uranium, Regional Director at the Institute, T M Hunse, said that the decay products from radon form fine dust, enters lungs and get stuck to lung tissues.
“Many lung cancer cases are attributed to Radon exposure. The impact on smokers is much higher,” he informed. The solid decay products like Polonium-218, Polonium-214 and lead-210 are the most damaging as they fix themselves on tobacco smoke and enter lungs, Hunse explained.
The positive aspect of this gas is that it has a half life of only 3.8 days, states K Mohammad Najeeb, also a Regional Director. “Hence, groundwater pumped from borewells and stored in overhead tanks turn out to be safe for consumption. The radon gas escapes into the atmosphere drastically reducing its concentration in water, thus making it safe for drinking,” he elaborated.
Thirty ground water samples were taken from borewells across the City. The permissible limit for Radon in water is 11.83 Bq/L (Becquerel per litres). The study revealed that Radon concentration varied between 56 Bq/L and 947 Bq/l in the samples.
Water from a borewell at Talghatapura revealed the highest radon concentration of 1189 Bq/l while samples from a borewell at Majestic area showed 946.69 Bq/l. The lowest presence of Radon, 55.96 Bq/L was detected in a water taken from a borewell in Srinivasapura. Not a single well showed Radon to be below the permissible limits, the study concluded. The depth of borewell and radon concentration had no relation at all, he said.
“If one has no other option than groundwater for drinking, then it is imperative that water pumped for borewells be stored before consumption,” advised Hunse.