It’s called methyl iodide, and critics say the chemical is even more toxic to humans than methyl bromide, the controversial pesticide it’s intended to replace.
But barring any last minute surprises, the state’s Department of Pesticide Regulation (DPR) will soon approve its use as a fumigant on strawberries throughout California.On April 30, the DPR proposed registering the chemical as a pesticide, following an extensive study of its potential health and environmental effects.
The decision came despite a 2009 report from the agency stating methyl iodide fumigation “results in significant health risks for workers and the general population.” A subsequent independent scientific risk assessment commissioned by the DPR confirmed those findings in February of this year.
In a June 17 statement to the California Senate Committee on Food and Agriculture, DPR director Mary-Ann Warmerdam defended the agency’s decision to move forward with methyl iodide registration.
“Some have accused DPR of ignoring its risk assessment or, worse, of changing its conclusions. These accusations are untrue,” Warmerdam said in the statement. “What some critics have misunderstood or ignored is the role risk managers play in the regulatory process.”
According to Warmerdam, the risk assessments weren’t intended to act as recommendations for decisions, but to help the agency determine whether or not methyl iodide could be used safely.
“We concluded the answer is yes, with requirements for more health-protective measures than the U.S. EPA imposes,” she said.
The U.S. Environmental Protection Agency reports no information on the carcinogenic effects of methyl iodide in humans, but does have “limited evidence” it causes cancer in animals. The agency approved the chemical for use as a fumigant in October 2007 as a potential replacement for methyl bromide, a pesticide banned by the 1989 Montreal Protocol for its ozone-depleting properties.
Methyl iodide does have at least one advantage over methyl bromide; it doesn’t affect the ozone layer. However, California classified the chemical as a carcinogen under a provision of Proposition 65 in 1986, and was one of three states—including Washington and New York—that refused to approve its use.
According to Susan Kegley, a chemist and director of the Pesticide Research Institute, methyl iodide is four times more neurotoxic than methyl bromide, and carries a greater risk than its predecessor of contaminating groundwater due to its iodine content.
“It’s one of these kinds of chemicals that chemists treat with great respect,” Kegley said. “It adds a methyl group to pretty much anything it can find, including DNA.”
As a result, the chemical can cause miscarriages in humans by interfering with thyroid hormone levels during pregnancy, as well as birth defects and brain damage in high doses.
If approved for use, Kegley said, areas near strawberry fields would likely see more instances of cancer and thyroid problems, and higher rates of miscarriages among pregnant women.
“If this chemical is registered, Californians will be exposed at levels that are going to cause an increased incidence of disease, and it’s something that we should keep from happening in the first place,” she said. “If we get to the point where 10 years from now, we see a massive increase in mental retardation in children, or increased ADHD, and we knew we had a chance to stop it but we didn’t, we’re going to feel really bad about it.”
Arysta LifeScience, a Japanese company, manufactures methyl iodide. The company has lobbied Gov. Arnold Schwarzenegger heavily for the chemical’s registration in California, a state representing a large market for its product.
How widespread methyl iodide use could become in Santa Barbara County is hard to ascertain at this point, according to Susan Bryant, Deputy for Pesticide Use Enforcement with the Santa Barbara County Ag Commissioner’s Office.
“Nobody can really say for sure how much it would be used,” Bryant said. “It’s expected to be more expensive than the other fumigants and there’s a certain tarp you have to use, which is more expensive, so it’s hard to say what kind of effect it would have.”
Bryant said farmers have yet to find a viable, economical alternative to methyl bromide, and declined to say whether methyl iodide was the answer.
“If it’s approved and registered through DPR, and available to farmers to use within the regulations, then they’re entitled to use it,” she said.
If methyl iodide becomes registered in California, DPR officials say the state will impose tighter controls on its application than any other state or federal regulator.
California’s allowable exposure levels, according to DPR’s Warmerdam, would be half of the EPA regulations, and only professional applicators—those with extensive safety training, a fumigator license, and a permit from the local agricultural commissioner—would be allowed to use the chemical on farmland.
The fumigant, like methyl bromide before it, would be injected into the soil before planting. In her statement to the Senate committee, Warmerdam said the application wouldn’t present a safety hazard to food or water.
The California DPR is proposing additional controls for methyl iodide, including a minimum half-mile “buffer zone” around schools, hospitals, and nursing homes. Workers and the public would be cleared out of zones during and for 48 hours after fumigation.
Regulations would also allow county agricultural commissioners to impose additional restrictions on use, above and beyond those outlined by the DPR.
The DPR will take public comment on the issue until June 29. From there, the agency has indicated it will take several months to respond to the comments and make their final decision.
Staff Writer Jeremy Thomas can be contacted at jthomas@santamariasun.com.
This article appears in Jun 24 – Jul 1, 2010.