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A toxic wave of arsenic from illegal rare-earth mining in Myanmar is surging down the Mekong River, placing the health of millions and the agricultural heartland of Việt Nam at severe risk.

The Latest: Pollution caused by unregulated rare-earth mining in Myanmar has driven arsenic concentrations in the Mekong River to levels nine times higher than the established safety threshold for aquatic life, according to a late April investigation.

The Details: The investigation into pollution along the Mekong River in Thailand uncovered alarming levels of arsenic and heavy-metal contamination, as reported by AFP.

In April, Thailand’s Pollution Control Department detected arsenic concentrations reaching up to 296 mg/kg in sediment near Chiang Saen. This marks the first time such severe contamination has been recorded in the main artery of the Mekong River itself, rather than solely in its tributaries.

Thai fisherman Somdet Singthong reported that his customer base had fallen significantly following the discovery of arsenic and heavy metals in a Mekong tributary last year.

Test results revealed elevated arsenic levels in his fingernails and urine.

Associate Professor Wan Wiriya of Chiang Mai University characterized the situation as a “time bomb” that could increase long-term risks of cancer and neurological disorders, particularly among vulnerable populations whose lives depend on the river.

Thai authorities have also advised residents against consuming shellfish from the river or fish organs, though many residents state they cannot afford safer food alternatives.

Cause of Contamination: Experts attribute the primary cause of this contamination to illegal rare-earth mining operations in Myanmar, where a prolonged civil war has resulted in largely uncontrolled resource extraction.

The Background: Myanmar is one of the most important suppliers of rare-earth minerals to China. These materials are indispensable to many high-tech industries worldwide, including the production of smartphones, wind turbines, and electric vehicles.

The Mekong River Commission (MRC), of which Việt Nam is a member, stated that it is increasing monitoring efforts and regional cooperation. However, both Myanmar and China—the two countries that play crucial roles in the rare-earth industry of Myanmar—are not members of the commission.

In January 2026, following repeated efforts by the MRC to promote cooperation, Myanmar agreed to work with Thailand to monitor and assess pollution conditions in the river.

Why It Matters: The contamination is currently exhibiting signs of spreading downstream. According to Pianporn Deetes of the Thai advocacy group Rivers and Rights, the pollution could eventually reach the Mekong Delta, directly threatening the largest rice-producing region in Việt Nam.

The Mekong Delta plays a central role in Việt Nam’s food security, accounting for more than 50% of national rice production and more than 90% of rice exports each year.

In recent years, the region has faced mounting environmental pressures, including land subsidence, erosion, drought, saltwater intrusion, and severe declines in sediment and water flows. These challenges stem from climate change and rising sea levels, the construction of hydropower dams on the Mekong River, and excessive sand and groundwater extraction.

Huỳnh Lam wrote this article in Vietnamese and published it in Luật Khoa Magazine on June 17, 2026. The Vietnamese Magazine has the copyrights to the English translation.