Bangalore groundwater carcinogenic?

It is common knowledge that the quality of groundwater in Bangalore
is poor. But it now appears that the situation may be graver than
initially thought. A study taken up by the Bangalore University's
Department of Environmental Studies in collaboration with the Bhabha
Atomic Research Centre, Mumbai, has found large quantities of radon, a
carcinogen, in groundwater. According to the study, taken up by R.K.
Somashekhar, professor and chairman of the department, Deljo Davis, K.
Shivanna and K.L. Prakash, groundwater in Bangalore has high radon
concentration, which makes the population highly vulnerable to health
risks, especially stomach cancer. Radon is a colourless, odourless,
water-soluble radioactive gas. The source of radon gas is the city's
subterranean granite rock. Prof. Somashekhar told The Hindu that the
radon concentration ranged from 11 Becquerel (Bq)/l to 1,000 Bq/l,
which is far higher than the permissible limit of 11.1 Bq/l. The study
also pointed out that Chickpet and Hebbal had the highest radon
concentration. Occurrence of radon in groundwater is often found in
areas with uranium-rich rocks and soils and granite terrain. Radon
emanates from the rocks and dissolves in groundwater easily as it is
highly soluble. Its release also depends on the porosity of the rocks
and flow intensity of water. This is perhaps why the incidence of
stomach cancer is more than other cancers, according to the cancer
registry of Bangalore. According to figures available, over the past
three years, the number of stomach cancer cases has seen an increase
of 9.29 per cent among men, and 4.3 per cent among women. Prof.
Somashekhar said that as part of the study, the team collected 90
samples from different parts of the city. "We are yet to see if
quarrying has contributed to the radon release into groundwater. If
due to quarrying cracks occur in granite rocks, then the chances of
radon emanating from them is high."The study, the first on radon
concentration in groundwater in Bangalore, has found that radon
activity is a function of depth, with higher activities at deeper
depths, with some exceptions.

The Hindu, 8th January 2009