Widespread arsenic contamination found in Myanmar’s Ayeyarwady Delta wells
Around 71 percent of wells in Myanmar’s Ayeyarwady Delta exceed World Health Organization (WHO) safe drinking water limits, placing up to 12 million people at risk of long-term arsenic exposure, a new study led by the University of Portsmouth finds. Travelers and residents relying on untreated well water may be exposed if they consume or use it for cooking.
Image credit: JonasKIM
A large-scale study published in GeoHealth on November 19 reports that arsenic contamination in Myanmar’s Ayeyarwady Delta groundwater significantly exceeds international safety standards.
The findings suggest that roughly 12 million people rely on wells with arsenic levels higher than those recommended by the World Health Organization (WHO).
The research, led by the University of Portsmouth’s School of the Environment and Life Sciences, analyzed national data from nearly 124 000 wells across the delta. Their results show that 71 percent of wells surpass the WHO guideline of 10 micrograms per litre, while 8 percent exceed Myanmar’s national limit of 50 micrograms per litre.
Although national standards classify most wells as safe, long-term exposure even to moderate levels of arsenic is associated with chronic health effects such as skin lesions, cardiovascular disease, and certain cancers.
Arsenic concentrations were found to be highest in the mid-central regions of the Ayeyarwady Delta, where dense networks of streams and shallow surface depressions accumulate organic matter.
This organic material is transported into the shallow aquifer system, promoting the chemical processes that release arsenic from sediment into groundwater. Areas with steeper slopes generally showed lower concentrations, likely due to faster water movement that prevents arsenic accumulation.
The study combined water chemistry analyses from 81 sampling sites across a 170 km (105 miles) stretch of the delta with spatial modelling techniques to identify high-risk landscapes. The resulting predictive model highlights hotspot zones where systematic testing and safe-water interventions would be most effective.
According to lead author Dr Mo Hoque of the University of Portsmouth, the results strengthen scientific understanding of how surface organic matter influences arsenic mobilization in deltaic aquifers.
“Our study shows how organic matter from the land surface is transported into shallow aquifers, where it plays an important role in the conditions that allow arsenic to enter groundwater,” said Dr Hoque. “By examining the Ayeyarwady Delta as a whole, we provide the first comprehensive picture of arsenic distribution across the region.”
Professor Dr Khin Kay Khaing of the University of Magway emphasized the public health implications. “In many villages, households rely on shallow wells for drinking and cooking water. Arsenic cannot be seen, tasted, or smelled, so people often use water without knowing the risk,” she said. “The effects of arsenic exposure develop slowly, so the risks are not always recognised in the community.”
The researchers note that although arsenic concentrations in the Ayeyarwady Delta are typically moderate compared to other Asian deltas such as the Ganges–Brahmaputra, the sheer number of affected wells makes exposure widespread.
The authors recommend blanket testing of wells in the highest-risk areas, community awareness campaigns, and stronger institutional support to achieve Myanmar’s goal of providing safe drinking water for all by 2030.
“Our findings call for urgent international attention, as many rural communities, especially children, are unknowingly exposed to unsafe drinking water,” Dr. Hoque said.
References:
1 Millions at risk as Myanmar wells surpass World Health Organization arsenic guidelines – University of Portsmouth – November 19, 2025.
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