A Mae Fah Luang University researcher says heavy metals from mines upstream in Myanmar are spreading into Thai rice, crops, fish and drinking water along the Kok and Sai rivers. Chiang Rai's waterworks is moving its raw-water intake at a first-stage cost of over 2 billion baht, serving about 40,000 accounts. Rice on roughly 100,000 rai in the basins is affected. The expert argues the government should stop transit imports of Myanmar ore, though no policy decision has been announced. For businesses in the north, especially food, agriculture and water-dependent operations, expect possible testing demands, supply-chain scrutiny and rising water costs; watch for official measures rather than acting now.