Environmental hypothesis: is poor dietary selenium intake an underlying factor for arsenicosis and cancer in Bangladesh and West Bengal, India?

To reduce the incidence of dysentery, cholera and other water-borne diseases and mortality of people drinking from surface contaminated sources of water, the World Bank and United Nations Children's Fund began to sink tube wells into the underlying aquifers of Bangladesh and West Bengal, India, in the 1970s. Many of the tube wells were drilled into underground aquifers that provided microbiologically clean water that was later determined to contain arsenic (As). As contamination of drinking water is a problem of natural occurrence throughout the world and domestic water often exceeds the World Health Organization limit of 50 microg As/l in the countries of Bangladesh, West Bengal, India and Nepal as well as other areas occupying much of the Ganges-Brahmaputra delta.…