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Scientific panel suggests state ban methyl iodide

The Fresno Bee ran a story on the front page this morning reporting that a scientific panel recommended that the California State Department of Pesticide Regulation reject a request by Tokyo-based Arysta LifeScience Corp. to approve the use of methyl iodide for pest control on California farms and in structures.

The eight-member Scientific Review Committee, chaired by UCLA environmental health sciencies professor John Froines, includes UC San Francisco medicine professor Paul Blanc, UC Berkeley public health professor Katharine Hammond and UC Berkeley environmental health sciences professor Tom McKone.

Methyl iodide was approved by the U.S. Environmental Protection Agency and many other states, but if California rejects the use of the pesticide, the U.S. EPA "may choose to initiate reevaluation of the methyl iodide registration," according to the panel's report to DPR.

"Based on the data available, we know that methyl iodide is a highly toxic chemical and we expect that any anticipated scenario for the agricultural or structural fumigation use of this agent would result in exposures to a large number of the public and thus would have a significant adverse impact on the public health," the panel wrote.

Farmers, however, believe methyl iodide would be an important tool in their arsenal for controlling soil pests in nursery containers and in the field before planting strawberries or establishing new orchards. The chemical could replace methyl bromide, which has been phased out because it damages the Earth's ozone layer.

"The products that we have just don't do the job," Bee reporter Robert Rodriguez quoted Barry Bedwell, president of the California Grape and Tree Fruit League.

According to the Bee article, DPR director Mary-Ann Warmerdam will review the panel's findings and DPR research as she decides if farmers can use the chemical and if so, under what restrictions. The decision is expected "soon."

The UC Integrated Pest Management Program has reported that soil solarization may be an alternative to chemical soil pest control under the right weather conditions. More information is available on the UC ANR Methyl Bromide Alternatives Web site.

Soil solarization is a possible alternative to methyl bromide fumigation.
Soil solarization is a possible alternative to methyl bromide fumigation.

Posted on Monday, February 22, 2010 at 11:17 AM


I have a Ph.D. in Env. Tox. from UCDavis 75. I point out that an alternative may be possible in using hydrogen peroxide. Fields would not need a plastic sheet saving quite an expense, but the applied liquid would have to be immediately worked into the first 8 inches of soil. It will not work by fumigant action so the working into the soil will be needed to get effective contact with various pests. Hydrogen peroxide will quickly breakdown to water and oxygen leaving no residue problems. It will require some care in handling it, but not as much as with methyl iodide. I urge people concerned with using methyl iodide as a soil fumigant to get attention to this alternative.  
Dr. J. Singmaster, Fremont, CA

Posted by Dr. James. Singmaster, on June 9, 2010 at 10:42 PM

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