Mystery of Bangladesh''s mass arsenic poisoning solved
November 16, 2009
A recent published study reveals researchers have pinpointed the source of the mass poisoning in Bangladesh, according to the Associated Press. For nearly three decades scientists have struggled to figure out exactly how arsenic was getting into the drinking water of millions of people in rural Bangladesh. The source of contamination is tens of thousands of man-made ponds excavated to provide soil for flood protection. An estimated two million people in Bangladesh suffer from arsenic poisoning, and health experts suspect the toxic, metal-like element has caused many deaths as well. A large dose can kill outright, while chronic ingestion of small doses has been linked to a large range of cancers. It has long been known that the arsenic comes from water drawn from millions of low-tech "tube wells" scattered across the country. Ironically the wells were dug -- often with the help of international aid agencies -- to protect villages from unclean and disease-ridden surface water. Tragically, millions of people continue to knowingly poison themselves for lack of an alternative source of water. Water with the highest concentrations of arsenic is roughly 50 years old, and the organic carbon in the water does not take long to filter down from the surface. A team of researchers led by Charles Harvey of MIT in Boston, Massachusetts cracked the secret. Working in the Munshiganj district of Bangladesh, the researchers analyzed the flow patterns of surface and underground water in a six square-mile area. They used natural tracers and a 3-D computer model to track water from rice fields and ponds, and tested the capacity of organic carbon in both settings to free up arsenic from soil and sediments. Chemical analysis showed that the organic compound that unleashes the poison first settles on the bottom of the ponds and then slowly seeps into the ground.