International researchers working in Bangladesh say they have found the source of contaminated drinking water that has caused widespread poisoning in the country for years.
In a report released Sunday by the journal Nature Geoscience, the researchers say thousands of man-made ponds are the primary source of arsenic contamination in Bangladesh's groundwater.
The study says the artificial ponds are a dumping ground for organic waste. It found that water passes through the sediment, carrying organic carbon into the ground, where it interacts with microbes that release arsenic into water that is pulled up from shallow wells. Consuming small amounts of arsenic over a long period can cause cancer and even death.
The researchers also examined whether water from Bangladeshi rice fields was the source of the contamination, but found that such water has low arsenic concentrations. The report's authors include Charles Harvey, an associate professor of civil and environmental engineering at the Massachusetts Institute of Science and Technology in the northeastern U.S. city of Boston.
The study recommends that Bangladeshi villagers dig deeper wells into aquifers (underground layers of water-bearing rock) that have low arsenic concentrations, or relocate shallow wells below rice fields.