DOUBLE HEALTH RISK IN ARSENIC CONTAMINATED DRINKING WATER ----- EVIDENCE OF ENHANCED ALPHA RADIOACTIVITY

The immense scale of the human tragedy is being noted in Ganga basin in India. The alluvial Ganges aquifers are polluted with naturally occuring arsenic, which adversely affects the health of millions of people. Ground water can also accumulate radionuclides, since uranium is a naturally occuring radionuclide present in all rocks and soils. This has also added a new element of deep concern, as it is carcinogenic in nature. In our preliminary study we found high alpha radioactivity in ground water samples collected randomly from some arsenic affected zones in West Bengal¹. In the present work we have collected-- i) 24 samples from deep level below the earth surface (37m-408 m) and ii) 85 samples from comparatively shallow levels.

Estimation of alpha activity has been performed using CR-39 which is a very good detector for alpha particles.

The alpha activity in shallow level water samples varies from 2,100 pCi/l to 21,600 pCi/l and varies from 1,300 pCi/l to 14,000 pCi/l in deep level water samples. The major contributor to this alpha radioactivity is radon. The values are much higher than MCL value of 300 pCi/l² and also than the world average value of 270 pCi/l^3,4.

The correlation coefficient ‘R' between arsenic and radioactive contamination is found as 0.62 in shallow water samples and only 0.06 in the samples of deep level. Thus a strong correlation appears in first case, but no such correlation is apparent in the second case. Further analysis of deep-water samples is required to obtain a reliable statistical parameter.

The present analysis indicates that the severely arsenic contaminated drinking water is alpha active and one can suspect that occurring health hazards in these areas may also be due to the continuous alpha radioactive exposure.

References 1. Ghosh, D. et al. 2004. Measurement of alpha radioactivity in arsenic contaminated tubewell drinking water using CR-39 detectors. Radiation Measurement 38, 19-22. 2. US EPA 1996. Radon in water. 3. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 1993. Sources and effects of ionizing radiation. Report to the General Assembly. United Nations. New York. 4. World Health Organization (WHO) 1996. Indoor quality: a risk-based approach to health criteria for radon indoors: report on a WHO working group, Eilat, Israel, 28 March – 4 April 1993. EUR/ICP/CEH 108(A). WHO Regional Office for Europe, Denmark.