Health activists have urged the government to ban "paraquat", a popular grass-and-pest killing chemical, as scientific studies have proved it is a health threat to farmers and consumers, but the Agriculture Department has raised concerns over the economic impact of a ban.
Paraquat is banned in more than 50 countries around the world due to its high toxicity, as only a small amount of consumption can kill a human being.
Speaking at a seminar held by the Anti-Corruption Organisation of Thailand, Pornpimol Kongtip, a health expert at the Department of Occupational Health and Safety, said she had studied 113 pregnant women in Amnat Charoen, Kanchanaburi and Nakhon Sawan provinces who had been exposed to paraquat.
The study conducted in 2012 found medium ranges of paraquat residue in the mothers' blood at 15.1-58.3 nanogrammes per millilitre and babies' umbilical cords at 7.7-47.6 nanogrammes per millilitre, she said.
It also found the risk of paraquat concentration in farming areas is six times higher than in non-farming areas.
In farming areas, mothers who are in their sixth to ninth month of pregnancy working on farms have a 5.4 times higher risk of contamination than pregnant women who do not work on farms, she said.
"Although there is no study to show the direct impacts of paraquat on babies, laboratory tests on animals show problems with brain development, muscles and the nervous system. So, it's important to have measures to limit the risk, including a limitation on paraquat use in the farming sector," said Ms Pornpimol.
Kannika Kittiwetchakun, a health activist and adviser to the Foundation for Consumers, said the impact of the toxic chemicals was not only limited on farmers, but all consumers as there are already findings of paraquat contamination in many varieties of food. Critics claim the chemical is also damaging to the environment.
"No one is safe from the chemical. A recent study even found that people who live in cities have residue from paraquat in their blood higher than farmers and people who live outside cities," she said.
Ms Kannika urged the government to respect people's rights to live in healthy environments and have access to clean and safe food.
However, Chanya Maneechote, a botanist from the Department of Agriculture, said authorities should not impose a ban because there is no "credible study" proving its negative impacts on health and the environment.
She said a ban on paraquat would increase farm production costs by 40 billion baht annually and would have a major impact on exports of Thai agricultural products, which generate up to 1.2 trillion a year.
Ms Chanya said she disagreed with the total ban on paraquat as the chemicals are inexpensive and effective while their potential harm, according to scientific research, is rated as "little to mild".
She said the substances should be allowed for use with restrictions in place and suggested a policy to devise a licensing and registration system for the purchase of paraquat.
The seminar yesterday was held as a national panel is mulling a decision, reportedly to be announced in May, on whether to impose a ban on the use of paraquat, chlorpyrifos, and to regulate the use of glyphosate.
According to Thailand's FTA Watch, Thailand ranks as the sixth largest importer of paraquat.
The country imported 31.5 million kilogrammes of paraquat in 2016.