Heavy metals (cadmium, lead, pesticide residue) have contaminated 21 crop types in Mae Ai district, Chiang Mai, along the Kok River. Test results were delayed by 8 months, allowing contaminated produce to reach consumers and accumulate toxins in bodies. The core issue is not just contamination detection but systemic gaps in food traceability and post-market food-recall mechanisms—authorities lack rapid response protocols to remove unsafe products from shelves. Consumer Council warns that delayed testing, weak supply-chain transparency, and absent market-withdrawal procedures mean warnings cannot help the public protect themselves.