Carbofuran in Thailand: A Public Health Risk

Following the incident surrounding the plant disease “natural disaster” in Kudchum district, Yasothon province, the AAN has compiled further research to raise public awareness about the impacts of carbofuran (Furadan) on the environment and human health.

The Alternative Agriculture Network – Esan (AAN) is a network of more than 3,000 small-scale farmers, working to develop sustainable agricultural techniques, support local food systems and community livelihoods.  We also monitor agriculture and trade policies at both the domestic and international levels.  The continued promotion of chemical fertilizer and pesticide imports is of major concern to our network, given the Thai government’s spoken commitment to supporting small-scale farmers and organic agriculture.

Carbofuran is a broad spectrum, systemic insecticide that is used on a range of crops, including rice, corn, watermelon, eggplant, and a number of other fruit and vegetable crops.  Thailand imports over ten thousand tons of carbofuran per year. In 2004, Thailand exported to neighboring countries 1,160 tons of insecticides, 1,203 tons of fungicides, and 1,333 tons of herbicides.

Carbofuran is highly toxic and depresses the human nervous system. Pesticide poisonings have stayed at a low level since the late 1990s, but unsafe levels of blood cholinesterase activity (direct result of carbamate chemicals) has doubled from about 15% to 30% by occupation in Thailand.
Farmers are reported to have the highest number of poisonings within 2,342 cases in 2003. The Extension Toxicology Network has found symptoms of carbofuran poisoning to include, “nausea, vomiting, abdominal cramps, sweating, diarrhea, excessive salivation, weakness, imbalance, blurring of vision, breathing difficulty, increased blood pressure, and incontinence. Death may result at high doses from respiratory system failure associated with carbofuran exposure.”

Canada and the EU have banned carbofuran since 2008.  The United States Environmental Protection Administration (EPA) recently banned its use, finding that “Exposure to the pesticide carbofuran resulting from existing legal uses is unsafe—unsafe for the general population, and particularly unsafe for infants and children.” Carbofuran commonly causes burns on the skin and eyes of farmers, but there is a range of serious impacts on farmer health.  Long-term effects may include permanent damage to both the nervous and reproductive systems.

In a 1998 carbofuran exposure case study by The Centers for Disease Control, 34 cotton farm workers reported nausea, headache, eye irritation, muscle weakness, tearing, vomiting, and salivation. Additionally, thirteen cases of unintentional carbofuran poisoning in farm workers were examined between January 2002 and August 2004.  The patients reported nausea, vomiting, headache, weakness, dizziness and blurred vision. In a 2005 study of pesticide applicators in the United States, it was found that the risk of lung cancer was 3 times higher for those with more than 109 of lifetime exposure to carbofuran than those with less than 9 days of lifetime exposure to the chemical.

Carbofuran poses significant environmental risks.  Because of its long soil half-life (up to 60 days) carbofuran also has a high potential for groundwater contamination and is mobile in sandy and silt loam soils. Compared to other pesticide residues tested in water resources in Fang and Chaiprakan districts, Chiang Mai province, carbamate residues, including carbofuran, were found at the highest levels, between 0.018 and 0.269 micrograms per liter (ug/L).

The use of pesticides also has significant impacts on ecological systems.  Carbofuran pellets often resemble plant seeds commonly eaten by birds and are often applied on newly cultivated soil.  One highly toxic granule can kill a small bird and carbofuran moves up the food chain when birds are eaten by predatory species.  This chemical is also highly toxic to fish, and is believed to be one of the main contributors to the reduction of salmon populations in the northwestern United States.  It is also highly toxic to catfish, a fish commonly consumed in Thailand.  In early 2009, it was reported that carbofuran was being used to poison African lions in Kenya.

Consumers also risk serious health effects from pesticide residues on food and drinking water contamination.  It is our understanding that carbofuran is on the government’s “Dangerous Chemicals Watch List.”  This dangerous agrochemical should be banned in Thailand and Thailand must work to be a leader in regional food safety.  Ending the use of carbofuran will positively address the current public health crisis affecting farmers and ecological systems throughout Thailand.