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Poisoned land

  • 30/01/1999

A health crisis is quietly unfolding in West Bengal. High levels of arsenic have leached from natural underground sources into thousands of village wells, informed K C Sahu, former professor of Indian Institute of Technology, Mumbai. He was speaking at a health conference organised by the Centre for Science and Environment, New Delhi, in July 1998. Reports of deaths and diseases due to high arsenic contamination of drinking water in eight surveyed districts of the state have been alarming. Since 1978, there has been a phenomenal spread in the incidence of arsenic poisoning. According to estimates, 16 million people spread over 3,860,000 hectare (ha) area in these districts are feared to be at risk, with 1.5 million people already drinking water with arsenic levels above the WHO limits.

Sahu said that the reason is not clear. However, heavy groundwater withdrawal may be one of the reasons. In the eight districts 1,012 cubic metres of groundwater is extracted for agriculture through tubewells (even in the high lands during the monsoon). Due to this high-level withdrawal of groundwater and the fluctuation of the water table, air enters the aquifer. The arsenic-rich pyrite then decomposes, due to the available oxygen, leaching the deadly metal into the water. Another view, according to Sahu, is that because of the high use of phosphate fertilisers, pesticides and herbicides and activities arising out of coal combustion, large amounts of arsenic leach into groundwater.

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