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[NOTE: The following post was submitted, at my invitation, in response to Get Your Neurotoxin Off My Strawberry, which I posted on this site last week. I am presenting it as I received it, unedited and unabridged. As such, it does not necessarily reflect an endorsement by, or opinion of, me or the Proximal Kitchen blog, and should not be construed as such.]

Methyl iodide… the other side of the story

Jim Sims, Emeritus Professor and Chemist, University of California, Riverside

As the researcher who first investigated methyl iodide for use as a soil fumigant, I’m writing to share a side of the methyl iodide story you don’t often hear.

To be perfectly up front, I’m an author on the 1996 patent “Methyl Iodide as a Soil Fumigant” assigned to the University of California Regents and licensed by Arysta LifeScience North America. I do share in any royalties coming from the patent. I didn’t harness methyl iodide for use as a soil fumigant because I wanted to get rich. I began experimenting with it because farmers throughout California and the rest of the world needed a viable alternative to methyl bromide—which is being phased out because it depletes the ozone layer.

The press touts scientists who discuss the “horrors” of methyl iodide use. I have personally used methyl iodide in the lab and in the field for more than 50 years and have not had any problems. Methyl iodide does not need to be treated as illustrated on the Pesticide Action Network’s web site.  It is sold in screw cap bottles like hundreds of other chemicals.  PAN claims that methyl iodide is more dangerous than methyl bromide because it is more reactive. Examination of the actual chemical literature shows that methyl iodide is three times less reactive than methyl bromide.

Here are the facts: Methyl iodide is a volatile liquid which is applied to the soil before planting to control fungi, bacteria, nematodes and weeds.  It is not sprayed on any crop.  No crop is planted until methyl iodide has completely dissipated…about two weeks after application. The compound is applied by small crews of experienced people under plastic tarps that keep the compound in the soil as long as possible. There is no residue of methyl iodide on the crop when it is harvested and so no risk of farmworkers in the field being exposed to it. And other protective measures are taken during application to keep residents or other people from being exposed the fumigant.

The Pesticide Action Network claims methyl iodide to be a “known” carcinogen, referencing its inclusion on the California Proposition 65 list of “known carcinogens, developmental or reproductive toxicants.” Methyl iodide was added to the Prop 65 list as a carcinogen on April Fools Day in 1988. But not all agencies or organizations who study cancer are in agreement that methyl iodide is cancer-causing. There are more than 100 carcinogens recognized by the World Health Organization’s International Agency for Research on Cancer (IARC) cancer. Methyl iodide is not among them. In 1986 and 1987, the IARC ruled that methyl iodide is not classifiable as a carcinogen. In 1999, following a subsequent review, the Agency kept this classification intact. Also, the National Toxicology Program (NTP), another respected agency, does not consider methyl iodide a carcinogen. Neither do career scientists at the EPA…whose work at the agency long precede the “Bush-Era.” The truth is that smoking, dietary imbalances, chronic infections and hormonal factors are the most prevalent causes of cancer in our society today. And excluding lung cancer, cancer mortality rates have declined since 1950.

One should not expect that all scientists will agree on every question.  Years ago, a group of scientists wrote a letter to the EPA voicing their opinion that methyl iodide should not be registered as a pesticide. The EPA responded to their letter, and explained how their assessment addressed every concern. That letter is posted on the EPA’s website. There were scientists at the EPA and at the DPR who had differing opinions.  The same went for the independent Scientific Review Committee appointed by DPR. The committee supposedly overstepped their assignment and said methyl iodide could not be used safely. DPR decided it could.

Unfortunately, false and misleading information about methyl iodide continue to be circulated. In the midst of decrying its “potential effects” the opponents to methyl iodide use forget to provide a couple key facts: methyl iodide is a naturally occurring substance, produced in mass quantity by marine algae and plants. And, methyl iodide has been in use in the United States already for years in other states, without an issue.

Bottom line, I will continue to eat strawberries, grapes, peaches, carrots, plums, tomatoes, peppers and other fruits and vegetables that are grown using pre-plant fumigation with methyl iodide.  At the end of the day California needs an alternative to methyl bromide. The other “alternatives” (solarization, soil disinfestation, crop rotation, steaming, etc.) are simply not effective. I believe methyl iodide is the right tool and that its registration was the right move for California.

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