Your strawberries and tomatoes: How toxic is Methyl Iodide?

If agricultural lobbying groups have their way with the EPA over state
regulators, California strawberries and tomatoes may soon be sprayed
with a compound called methyl iodide. AP Photo: Danny Johnston

If agricultural lobbying groups have their way with the EPA over state regulators, California strawberries and tomatoes may soon be sprayed with a compound called methyl iodide.

For the last year, a battle has been waging in California over the use of methyl iodide, which is used mainly on commercially grown strawberries and tomatoes. California farmers are some of the largest users of soil fumigants in the nation.

Methyl iodide is one of the main replacements for methyl bromide, another soil fumigant with a history colored by claims of adverse health and environmental effects.

The US Environmental Protection Agency (EPA) found methyl iodide safe, approved it for agricultural use in October 2007. However, California's own Department of Pesticide Regulation assessed methyl iodide as much riskier than did the EPA, concluding in a 2009 report that methyl iodide posed "significant health risks" to the public, and advised against approving the compound. Moreover, several Nobel prize winners asked the U.S. EPA not to approve it.

Meanwhile, after the EPA's approval, the DPR commissioned its own independent review, led by chemist John Froines, in an effort to reach a firm conclusion.

The Froines review sided with the assessment of the California DPR. That report, released in February, notes that "in every instance where the DPR findings differed from the US EPA risk assessment for methyl iodide, this was attributable to a more insightful and scientifically rigorous approach having been undertaken by the DPR".

To accept the EPA's position that methyl iodide is "safe" for agricultural use, Froines says that people "have to have a lot of faith that there won't be accidents."

Froines' report concluded that "adequate control of human exposure would be difficult, if not impossible," and "any anticipated scenario for … 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".

Since strawberries hold onto the chemicals with which they're treated, it's especially important to use only the safest anti-pest treatments.

According to farmers, there are a numerous viable alternatives to the methyl iodide, including solarization, anaerobic soil disinfestation and natural pesticides, such as including planting strawberries alongside mustard or broccoli, which release chemicals that deter insects.

However, many commercial growers feel that such alternatives eat into their bottom line. Lobbying for approval of methyl iodide is the largest world's pesticide manufacturer, Arysta LifeScience. The California Strawberry Growers Commission has taken no position on the matter.

The possible risks to the public and to agricultural workers has led Oakland-based non-profit environmental law firm Earthjustice to petition the EPA to remove methyl bromide from its national registration list.

The proposed approval of Methyl Iodide will become final pending the outcome of a final public commentary. Unless the public responds with overwhelming opposition, Methyl Iodide will likely find its way into our food and environment. The public may comment through June 14. Please let your comments be heard.