Which country has natural arsenic water contamination ?

Bangladesh is widely recognized as having the most severe natural arsenic contamination of groundwater in the world. The contamination is geological in origin, occurring due to the leaching of arsenic from minerals in the sediments of the Ganga-Brahmaputra-Meghna river delta. In the 1970s, millions of tube wells were installed to provide pathogen-free drinking water, but it was later discovered that many of these wells tapped into arsenic-rich shallow aquifers.

According to the World Health Organization (WHO), this situation represents the "largest mass poisoning of a population in history." Chronic exposure to arsenic through drinking water leads to arsenicosis, which can cause skin lesions, cardiovascular disease, and various cancers. While parts of India (particularly West Bengal and Bihar) and Pakistan also report contamination, the scale and impact in Bangladesh are uniquely catastrophic.