Arsenic contamination of groundwater in Bangladesh

A survey of well waters (n=3534) from throughout Bang- ' ladesh, excluding the Chitt;agong Hill Tracts, has shown that water from 27% of the 'shallow' tubewells, that is wells less than 150 m deep, exceeded the Bangladesh standard for arsenic in drinking water (50 flg L -I). 46% exceeded the WHO guideline value of 10 flg L-I. Figures for 'deep' wells (greater than 150 m deep) were 1% and 5%, respectively. Since it is believed that there are a total of some 6-11 million tubewells in Bangladesh, mostly exploiting the depth range 10-50 m, some 1.5-2.5 million wells are estimated to be contaminated with arsenic according to the Bangladesh standard. 35 million people are believed to be exposed to an…