Read the full story in Science.
It has been called the largest mass poisoning in history. After wells were drilled in Bangladesh and the rest of the Indian subcontinent in the 1970s, millions of people have been exposed to arsenic in drinking water. When leached into water from surrounding rocks and soil, the metal can—at high concentrations—cause skin lesions, cancer, cardiovascular diseases, and neurodevelopmental delays. Now, a study suggests Pakistan might be grappling with its own arsenic emergency, with up to 60 million people exposed to contaminated water.