Young boy drinking from a tube well
Researchers estimate that as many as half of the four million tube wells in Bangladesh are pumping out groundwater contaminated with naturally occurring arsenic. In many contaminated wells, arsenic levels exceed 500 parts per billion (ppb), a level 50 times higher than the safety recommendation from the World Health Organization (WHO). With foreign aid, the Bangladeshi government is finally tackling the problem years after its discovery in 1992. It has a tough job.

The British Geological Survey completed in October 1998, considered by some the most comprehensive study to date, estimates that 20 to 25 million people are at risk from drinking arsenic-contaminated water in Bangladesh.

However, other estimates are as high as 70 million. The uncertainty stems from the fact that only a fraction of wells have been tested, approximately 110,000. Further complicating matters is the random distribution of contaminated wells. It...

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