Health Screening Initiated in Mae Sai Following Arsenic Contamination in Local Rivers
Authorities in Chiang Rai are testing over 200 residents for heavy metal exposure after water samples from the Sai and Ruak rivers showed arsenic levels 28 times above safety standards.
On October 14, 2026, the Department of Disease Control and the Department of Health launched a screening program in Mae Sai and Koh Chang sub-districts, Chiang Rai province. Over 200 volunteers underwent urine testing to detect potential heavy metal exposure following reports of significant arsenic contamination in the Sai and Ruak rivers.
Recent water quality tests revealed arsenic concentrations of 0.284 milligrams per liter, which is approximately 28 times higher than the established safety standard. These rivers serve as vital water sources for local agriculture and daily household use for some residents. During the screening, health officials collected data on water consumption habits—including the use of tap, village, and groundwater—as well as dietary patterns and proximity to the affected waterways.
Laboratory results are expected within one month. Officials are screening for arsenic, cadmium, and mercury levels to assess individual health risks. For residents or travelers in the area, this situation highlights a potential environmental health concern regarding local water sources. While the screening aims to determine the extent of human exposure, it remains to be confirmed whether the contamination has impacted specific food chains or if further mitigation measures will be required. Authorities will conduct follow-up assessments for any individuals whose test results exceed established safety thresholds.
