EN TH
Watch what you eat

As authorities drag their heels over the prohibition of toxic herbicides, the public must take their own precautions

The highly toxic weedkiller paraquat is known to be associated with serious diseases and has already been banned in 53 countries over health concerns. Thailand is not among those countries.

"After years of campaigning to prohibit the use of the herbicide, some 700 organisations from across the country have been left disappointed after the national committee on hazardous substances rejected their request for a total ban on paraquat as well as glyphosate and chlorpyrifos -- three widely used toxic agricultural chemicals. Their proposal was backed by the Ministry of Public Health and the Office of the Ombudsman, who submitted to the committee in December that paraquat should be banned by Jan 1, 2020.

"For their part, the committee insisted that they will only support the use of the substances in farming until safer alternatives are available. Nevertheless, consumers are left bewildered and fearful as exposure to the chemicals can lead in the short-term to vomiting, nausea, diarrhoea and stomach pain, and in the long-term to Parkinson's and cancer.

"And it's not just consumers who are at risk. Farmers lives are being put in danger as well, according to Asst Prof Chaniphun Butryee from the Toxicology and Nutrition for Food Safety Division under Mahidol University's Institute of Nutrition.

""Product labels for herbicides, insecticides and fungicides usually contain specific warnings on how long after use the crops should be left before being harvested. But in circumstances where market demand is high, farmers fail to follow the instructions. They pick their crops before the chemicals have had a chance to wear off, so the produce still carries hazardous residue," she explained.

"Last year, Chaniphun, together with the Food and Drug Administration (FDA), conducted a countrywide study of chemical residue found in fruits and vegetables. The team collected 1,131 random samples from retail stores, markets and packing plants, which were then sent for analysis to the Department of Medical Sciences' laboratories, as well as private ones, where they were screened for 132 chemicals, mostly pesticides and fungicides. They were also checked for chlorpyrifos, a widely-used pesticide.

"Of the 1,131 samples, 83% or 943 samples passed the test, meaning they did not contain chemical residue exceeding the Maximum Residue Limit (MRL). The rest failed.

""Of the 188 samples that exceeded the maximum residue limit, the largest group was holy basil, sweet basil and hairy basil, followed by kale and string beans," Chaniphun said. The worst-affected fruits were tangerines, followed by longans, bananas and grapes.

"As well as the direct impact of the chemicals on farmers and consumers, the indirect consequences are also potentially very serious, according to dietitian Pakatima Chaopadit .

""The chemicals can make their way into canals and rivers as well as nearby plantations," she said. "And whenever these chemicals reach waterways, they affect marine life."

"With all this hazardous residue in our food supply, it's understandable that many consumers are going organic. However, this is not necessarily the solution people may think it is, according to Chaniphun.

"As part of the study, they collected samples of products which claimed to be chemical-free. Many were found to be contaminated, some even exceeding the MRL.

""Of all the samples we collected, six were certified by IFOAM [International Federation of Organic Agriculture Movements]. They all passed," she said. "Fifty-three samples were products certified by Organic Thailand [a label issued by the Ministry of Agriculture and Co-operatives to certify organic farming standards]. They all passed.

"As for those containing a Q-mark [quality certification label], 16 out of 125 samples did not pass the Maximum Residue Limit test.

""Even when consumers decide to opt for organic products, it is really difficult to avoid chemical residue altogether, unless consumers buy them from extremely reliable sources. These products can't be judged only on how they look."

"Raising awareness among farmers is fundamental. It is essential that they follow the instructions of how to use chemical herbicides, pesticides and fungicides properly, so their crops can be harvested safely.

""After years of research, I've found that the best solution for farmers is to encourage them to not be overly marketing- and profit-oriented," said Chaniphun. "I also encourage them to use more organic herbicides and pesticides because apparently they are safer."

"For consumers, being aware of the potential risks, and taking measures to safeguard against them, is also of utmost importance. Pakatima advises washing the food prior to consumption.

""Washing fruit and vegetables before consumption is not a 100% guarantee that they will be safe to eat but it's better than doing nothing," she said. "Paraquat can be broken down at 300C, so boiling alone can't destroy it. At least washing produce before eating it helps remove the residue as much as possible." Vinegar can get rid of up to 60-80% of chemical residue, running water 40%, potassium permanganate 30% and salt 20%.

"Chaniphun echoes Pakatima's sentiments: "Even if you only wash the produce with running water and by rubbing it with your fingers, it really does help. But organic products can also be contaminated with microorganisms. Potassium permanganate can help to get rid of them, but some people might find it inconvenient to use."

"Consumers are advised to eat a wide variety of fruits and vegetables. This is not just a nutritional mantra, it is also a shield against the overconsumption of chemical residue.

""Consumers should be educated to eat smart," said Pakatima. "Eating different types of fruits and vegetables instead of sticking to only one helps cut the risk of taking in too much chemicals. Chemical residue is mostly found in leaf vegetables. If people eat a greater variety of vegetables, the chances of chemical accumulation are lower."

"Consumers should avoid eating fruit and vegetables that are out of season and do what they can to clean food before eating. At the same time, Chaniphun said there is no need to be overly anxious.

"Chemical substances are lethal only in high doses," she pointed out. "When in the body, chemical residue is metabolised by the liver. In low doses, your body can purge it naturally on a daily basis. But if you eat the same vegetables every day with the same chemicals, it can accumulate to the point where the liver is unable to purge it. If you eat a variety of produce that you wash thoroughly and cook at heat, it should be safe enough."

สาระสุขภาพที่เกี่ยวข้อง
Copyright © 2019 Central General Hospital. All Right Reserved.