Up to 20 million people in Bangladesh are at risk of suffering early deaths because of arsenic poisoning - the legacy of a well-intentioned but ill-planned water project that created a devastating public health catastrophe. Four decades after an internationally funded move to dig tube wells across the country massively backfired, huge numbers of people still remain at higher risk of contracting cancer and heart disease. The move, spearheaded by the UN and the World Bank, was fatally flawed. Although checks were carried out for certain contaminants in the newly sourced water, it was not tested for arsenic, which occurs naturally in the Ganges and Brahmaputra deltas. By the early 1990s, when it was found that up to half of 10 million tube wells were contaminated with arsenic, Bangladesh was confronting a huge problem. The World Health Organisation called it the largest mass poisoning of a population in history. The scale of the environmental disaster is greater than any seen before; it is beyond the accidents in Bhopal, India, in 1984, and Chernobyl, Ukraine, in 1986". Some subsequent studies predicted that, ultimately, one person in 10 who drinks water from the arsenical wells would go on to die from lung, bladder or skin cancer. Even though some of these conditions take decades to develop, by 2004, about 3,000 people a year were dying from arsenic-related cancers.