Arsenic in Salween River 55 times above safe levels, study warns

The quality of the water in the Salween River, along the Thai-Myanmar border in Mae Hong Son province, is below standard and contains excessive amounts of heavy metals, such as arsenic, lead and mercury, according to findings by the Faculty of Science at Chiang Mai University.

A team of researchers from the faculty, led by Assistant Professor Wan Viriya, collected samples of water from the river, as well as of soil and plants from the river basin in Sob Moei district of Mae Hong Son and areas in the Karenni state of Myanmar in last December.

The findings of testing show excessive amounts of arsenic especially, which was measured at 0.55mg/L against the standard level of 0.01mg/L. Or 55 times higher than the standard level.

The high content of heavy metals in the river is blamed on unregulated lead mining operations and the widespread ore dressing (processing) carried out by Karen civilians in the Karenni state. The water used in processing the ores is discharged directly into the river without treatment.

Assistant Professor Wan said that the hazardous substances were found in sediments washed downstream during heavying flooding. He expressed concern that more contamination will follow if flooding is repeated.