EPA approves Methyl Iodide: Ignores top scientist’s concerns about carcinogenic pesticide

October 31, 2007

On October 5, 2007, The U.S. Environmental Protection Agency announced that it approved methyl iodide (iodomethane) for use as a fumigant pesticide for preparing soil for crop production.

“The fact that EPA has ignored our concerns and legalized large-scale releases of millions of pounds of this chemical is outrageous. We’d hoped those in charge at EPA would come to their senses,” says Professor Robert Bergman, a distinguished chemist at the University of California, Berkeley and a signer of the letter.  

Bergman and Nobel Laureate Roald Hoffman, along with 52 other eminent scientists, sent a letter September 24th to EPA director Stephen Johnson warning that the cancer causing chemical is too dangerous to be used as a pesticide and urging EPA to delay registration and conduct an independent review of the agency’s assessment of the pesticide.

“It’s important for people to understand that the top chemists in the nation came together to oppose registration of this chemical,” continues Bergman. “Many who signed on have first-hand experience with methyl iodide in the laboratory. We know exactly how toxic and reactive the chemical is and how potentially dangerous it will be for workers and people who live near application sites in terms of increased risk of cancers, thyroid problems, and miscarriages.”

Methyl iodide registration was denied in April 2006 after EPA received thousands of public comments opposing the chemical. The California Department of Pesticide Regulation has expressed serious concerns about the high toxicity of this chemical and the expense and difficulty of regulating it. Methyl iodide is listed as “known to the state of California” to be a carcinogen. The California legislature is considering a bill to help growers move away from reliance on dangerous fumigant pesticides such as methyl iodide, and toward less toxic alternatives.

EPA’s approval was for the registration of the product Midas, made by Arysta Corporation. Midas contains the controversial methyl iodide along with another dangerous pesticide, chloropicrin. A chloropicrin cloud sent 130 workers to the hospital on Thursday, September 27, in Yerington, Nevada. In October 2005, 350 people were sickened in their homes in Salinas, California, when a chloropicrin cloud drifted ¼ of a mile from a strawberry field. Public health and environmental advocates worry about increased human exposure from these dangerous chemicals.

“Methyl iodide will put farmworkers, farmers and rural families at risk,” says Erik Nicholson of United Farm Workers of America. “Instead of approving such a dangerous chemical, EPA should focus on alternatives that don’t view us as disposable human beings who can risk cancer and miscarriages in the name of supposed economic gain. Where is the gain when people get sick from this chemical and they can’t work and the medical bills go unpaid? Where is the respect for human life and protection of our public health?”

Methyl iodide is viewed by EPA as a replacement for methyl bromide, a widely used pesticide targeted for a global ban as an ozone-depleting chemical. “We recognize the importance of helping farmers shift to alternatives to methyl bromide, but methyl iodide is not the answer,” says Dr. Susan Kegley, Pesticide Action Network Senior Scientist. “EPA should be helping growers adopt less toxic ways to control soil pests, not promoting continued reliance on highly toxic pesticides that put workers and communities at risk.”

Studies of less toxic control measures for soil pests show that economically viable alternatives exist and are successfully being used for all crops that are produced with soil fumigants, including strawberries and tomatoes, the commercial crops most reliant on soil fumigation.

Arysta Corporation, a Japanese-owned company, has stated it plans to market methyl iodide globally as a replacement for methyl bromide. The company is currently the focus of a bidding war among several foreign companies. Former Arysta North America CEO Elin Miller was appointed by US EPA Administrator Stephen Johnson to head EPA’s Region 10 (northwestern U.S.) last year.

Methyl iodide was initially to be evaluated alongside older fumigants as part of EPA’s assessment of a “cluster” of fumigants: methyl bromide, telone, metam sodium, chloropicrin, and dazomet. The Fumigant Cluster Assessment, a public process set for completion in November 2007, seemed likely to result in stricter safety standards for fumigant pesticides. Methyl iodide was part of the public process in 2006, but today’s decision indicates that EPA had decided to move ahead on this chemical separately, with fewer precautions in place than those being considered for the other fumigants. EPA states that the registration of methyl iodide is limited to one year.

Source: Pesticide Action Network North America
EPA’s Fact Sheet Information on Methyl Iodide: http://www.epa.gov/ttn/atw/hlthef/methylio.html

Health Hazard Information

Acute Effects:
Massive acute inhalation exposure to methyl iodide has led to pulmonary edema. Depression of the CNS, irritation of the lungs and skin, and effects on the kidneys may result in acutely exposed humans. (3-5)
Acute inhalation exposure of humans to methyl iodide has resulted in nausea, vomiting, vertigo, ataxia, slurred speech, drowsiness, skin blistering, and eye irritation. (2,3,5,6)
Tests involving acute exposure of rats and mice have shown methyl iodide to have moderate to high acute toxicity by inhalation, and high acute toxicity by ingestion. (6)

Chronic Effects (Noncancer):
Chronic inhalation exposure to methyl iodide may affect the CNS in humans. (4)
Prolonged dermal contact with methyl iodide may cause skin burns in humans and animals. (1,4)
EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for methyl iodide.

Reproductive/Developmental Effects:
No information is available on the reproductive or developmental effects of methyl iodide in humans or animals.

Cancer Risk:
No information is available on the carcinogenic effects of methyl iodide in humans.
There is limited evidence that methyl iodide is carcinogenic in animals, with lung tumors observed in studies of mice and rats. In rats that received subcutaneous injections, subcutaneous sarcomas and pulmonary metastases were reported. An increased incidence of lung tumors was reported in mice exposed to high levels of methyl iodide by intraperitoneal injection. (2,3)
EPA has not classified methyl iodide for potential carcinogenicity.


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