Fruits and vegetables grown in Kok River basin risk heavy metal contamination

Environmental forensic science will be employed to test samples of fruit and vegetables, taken from the Kok River basin in Chiang Rai and Chiang Mai provinces, to determine the origin of heavy metal contamination, whether it was caused by mining activities in Myanmar or overuse of pesticides, according to Dr. Suebsakun Kidnukorn, a lecturer attached to the School of Social Innovations at Mae Fah Luang University.

Dr. Suebsakun took part in a meeting held at the Tha Ton Sub-district Administrative Organisation on Sunday, convened to discuss the problem of chemical contamination of plants grown in the Kok River basin in Mae Ai district of Chiang Mai. Also attending were representatives of the Chiang Mai Council of Farmers, community leaders of Tha Ton sub-district and academics.

Findings of tests for chemical contamination of fruit and vegetable samples conducted by Mae Ai district agricultural officials since last December were presented at the meeting. They show that, of the 54 out of the 61 collected samples tested, 43 samples (80%) did not meet the required standards. Arsenic was found in ten samples, cadmium in 37 and lead in 14.

The plants found to be most susceptible to heavy metal contamination are bird’s eye chillies (Prik Khinu), cucumbers, eggplants, sweet potatoes, sweet corn and mangos.

The Mae Ai district’s agricultural chief has proposed that plant growers in the Kok River basin switch to alternatives, such as para rubber, bamboo and teak, and avoid the use of water from the Kok River.

Dr. Suebsakun, meanwhile, told the meeting that chemical contamination poses a serious challenge to farmers in the river basin, which must be addressed by all parties concerned, including the Thai government and Myanmar.

He claimed that not only the Kok River, but also the Sai and Ruak rivers have become murky, primarily due to mining of rare earth and gold in Myanmar, with some of the extracted ores being transported through Mae Sai and Chiang Saen checkpoints in Chiang Rai province.

He said that a joint research team from Naresuan and Mae Fah Luang universities, as well as the Thailand Science, Research and Innovations Office, will collect plant and water samples in Mae Ai district of Chiang Mai and along the Kok River in Chiang Rai province for environmental forensic science tests to determine the origin or origins of the heavy metals.

Racha Kamphinit, chief of Tha Ton sub-district, expressed concern that chemical contamination of fruits and vegetables grown in the Kok River basin might scare away buyers and caused the prices to plummet.

He called on all parties concerned to address the problem in earnest and quickly.