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Methyl iodide background


Methyl iodide will be one of the most toxic pesticides used in California.

Methyl iodide has been approved for use as a fumigant pesticide in California, primarily for use on strawberry fields. Because it is highly prone to surfacing and then drifting away from where it is applied, the registration of this pesticide will put the health of farmworkers and rural community members at risk.

  • Methyl iodide is used to induce cancer in laboratory animals for scientific research and is so toxic that scientists take extensive precautions when using the chemical.  These precautions include wearing a ventilation hood and only handling it in very small quantities, much lower than the amounts to be used for soil fumigation.
  • Methyl iodide is listed as a carcinogen under California’s Proposition 65 statute.
  • Methyl iodide affects the nervous system, the lungs, liver and kidneys, and could be especially damaging to the developing brains of children and fetuses. EPA’s own evaluation indicates that methyl iodide is a thyroid toxin and causes permanent neurological damage as well as fetal harm including late-term miscarriages in experimental animals.
  • Methyl iodide is a known water pollutant. Soil fumigation with methyl iodide poses a high risk of groundwater contamination.
  • 54 scientists from the National Academy of Sciences, including six Nobel Laureates in Chemistry, urged former US EPA Administrator Stephen Johnson not to register methyl iodide as a soil fumigant because of the high risks it poses to human health and the environment. Read their letter.
  • Methyl iodide is much more toxic than methyl bromide, which it is proposed to replace.  As dictated by the Montreal Protocol, methyl bromide is being phased out of use because of its ozone-depleting qualities.
  • Alternatives to fumigation exist and are already in use in California. Since 1983, Swanton Berry Farms, on the central coast of California, has been growing strawberries organically.  Swanton Berry is now joined by farmers large and small – from Driscoll’s to Martinez Farms – in a thriving organic strawberry business. Specific pest control alternatives include the use of resistant cultivars, cultural methods such as crop rotation, the use of cover crops, as well as physical methods such as soil solarization. 

Farmworkers and rural communities would be at serious risk from methyl iodide exposure.

As we have seen with methyl bromide, fumigant accidents are all too frequent occurrences that can have devastating consequences.  Applied as gases, these pesticides often drift away from their targets, poison nearby communities and cause long-term health problems.  DPR has proposed buffer zones of 100 to 2,500 feet around fields being fumigated with methyl iodide, but due to the inevitability of high winds and torn tarps (meant to trap the fumigant), buffer zones will not be able to adequately protect neighboring communities.

Symptoms of acute poisoning from inhalation include dizziness, sleepiness, nausea, diarrhea, slurred speech, lack of coordination and muscle convulsions. Methyl bromide and other fumigants have caused many injuries to farmworkers and neighbors; the impacts of methyl iodide are projected to be worse due to its higher toxicity level and DPR’s own dramatically under-protective proposed mitigations. These proposed mitigations set an acceptable exposure limit for adults that is 100 times higher than the limit recommended by DPR's own scientific review committee.

We must support safe & healthy agricultural practices.

The mitigations put forward in DPR’s proposed registration are not adequate to protect the public or the farmworkers from dangerous exposure to this pesticide.  In fact the panel of internationally-renowned scientists the DPR asked to assess the pesticide has concluded that methyl iodide is so toxic any agricultural use, “would result in exposures to a large number of the public and thus would have a significant adverse impact on the public health,” adding that, “adequate control of human exposure would be difficult, if not impossible.”

Dr. Theodore Slotkin, professor of pharmacology and cancer biology at Duke University who reviewed DPR’s science commented: “It is my personal opinion that this decision [to approve methyl iodide] will result in serious harm to California citizens, and most especially to children.” 

Methyl iodide is the first new fumigant registered in California in nearly 10 years and adds to the list of highly hazardous chemicals used in the fruit and vegetable industry. Contrary to the flawed arguments put forward by the agrochemical industry, California’s commercial crops can be grown without hazardous pesticides. DPR’s decision to substitute an ozone-depleting chemical with a carcinogenic neurotoxin is both scientifically unfounded and unnecessary.

DPR, California Department of Food and Agriculture and University of California Cooperative Extension should research and promote safe and effective pest management methods for growers, and develop policies to support organic agriculture and protect the health of rural communities.

Read more detailed information about methyl iodide. Take action to prevent the registration of methyl iodide in California!