Arsenic contamination of groundwater has occurred in various parts of the world, most notably the Ganges Delta of Bangladesh and West Bengal, India, causing serious arsenic poisoning among large numbers of people. It is a natural occurring high concentration of arsenic in deeper levels of groundwater, which became a high-profile problem in recent years due to the use of deep tubewells for water supply in the Ganges Delta .

Parts of Thailand, Taiwan, Argentina, Chile and China have also been affected.Approximately 20 incidents of groundwater arsenic contamination have been reported from all over the world. Of these, four major incidents were in Asia.[http://www.ehponline.org/members/2000/108p393-397chowdhury/chowdhury-full.html

Roger Smith, Professor of Pharmacology and Toxicology Emeritus, Dartmouth Medical School, has confirmed that natural arsenic contamination of drinking water has also been a problem in wells in New Hampshire.

Bangladesh and West Bengal

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In the Ganges Delta, the affected wells are typically more than 20 m and less than 100 m deep. Groundwater closer to the surface typically has spent a shorter time in the ground, and so has not absorbed a high concentration of arsenic; water deeper than 100 m is exposed to much old sediments which have already been depleted of arsenic.^*

Dipankar Chakraborti from West Bengal brought the crisis to international attention. Beginning his investigation in West Bengal in 1988, he eventually published, in 2000, the results of a study conducted in Bangladesh which involved the analysis of thousands of water samples and hair, nail and urine samples. They found 900 villages with arsenic above the government limit. Chakraborti described this as "only the tip of the iceberg."^*

Chakraborti has criticized development agencies, saying that they denied the problem during the 1990s while millions more tube wells were sunk, and later hired foreign experts who recommended treatment plants which were not appropriate to the conditions, regularly breaking down or not removing the arsenic. ^*

See also

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• Water pollution
• Water quality
• Pollution
• Groundwater

External links

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• Bangladesh’s arsenic poisoning: who is to blame? - from unesco.org, by a UK-based science journalist.
• Groundwater Arsenic Contamination in Bangladesh and West Bengal, India, Environmental Health Perspectives (EHP), May 2000
• Interview: Drinking at the west's toxic well Interview with Dipankar Chakraborti, New Scientist, 31 May 2006.

• SOS-Arsenic.net - information and awareness raising site, focused on Bangladesh.
• Contamination of drinking-water by arsenic in Bangladesh: a public health emergency - at SOS-Arsenic.net

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