Thailand’s importing a lot more critical minerals from Myanmar these days, and it’s starting to worry people on both sides of the border. Weak checks on where the stuff actually comes from, plus the pollution that’s coming with it, are the main headaches.

More than 50 Thai companies are bringing in antimony, tungsten, copper, lead and manganese from Myanmar. A big chunk of it ends up heading to China later. In the first nine months of 2025 alone, Thailand took in 105,752 tonnes of these minerals worth over 13.9 billion baht, more than double what came in during the whole of 2024, according to the data independent news org Mongabay looked at.

At the Pheung Khleung border crossing up north, trucks loaded with antimony from Myanmar’s Karen state were seen rolling into Thailand back in June. That particular mineral gets used in ammunition, armour, aerospace parts and electronics.

The mining boom in Myanmar is also being blamed for heavy metals showing up in rivers that flow into Thailand. Authorities have found arsenic, cadmium, lead and other nasties in the Kok, Sai and Ruak rivers, and in parts of the Mekong and Salween systems too.

Thai traders who spoke to Mongabay said they usually get the minerals through middlemen and often have no idea which mine or company produced them. Some admitted they can’t even tell if what they’re importing is connected to the pollution problems.

Opposition lawmaker Phattarapong Leelaphat is pushing for tougher customs checks and better tracking of the supply chain. He says the government needs to know exactly where these minerals are coming from and whether they’re making the environmental mess worse.

There’s also talk of possible mislabeling. Traders say Thai officials simply don’t have the manpower to inspect every single shipment and confirm what’s really inside and where it originated.