Arsenic in drinking water threatens up to 60 million in Pakistan

t 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.

The extent of the problem first became clear in the 1990s, when a series of studies found high arsenic concentrations across the Ganges-Brahmaputra Delta. The World Health Organization (WHO) warned that 35 million to 77 million people in Bangladesh could be at risk of drinking water with unsafe levels of arsenic. And in 2014, WHO estimated that about 200 million people worldwide are exposed to concentrations exceeding the recommended limit of 10 micrograms per liter of water. Most live in Bangladesh, India, Vietnam, and Nepal.

Previous studies had revealed that groundwater in some areas of Pakistan also contained high levels of arsenic. But the extent of those risks was unknown, says Joel Podgorski, an environmental scientist at the Swiss Federal Institute of Aquatic Science and Technology in Dübendorf  and lead author of the new study.

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