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Controversial fumigant OK'd for use

Published on December 10, 2010 3:01AM

Last changed on January 7, 2011 8:38AM

Tim Hearden/Capital Press
California’s $1.6 billion strawberry industry will provide one of the biggest markets for methyl iodide, a soil fumigant.

Tim Hearden/Capital Press California’s $1.6 billion strawberry industry will provide one of the biggest markets for methyl iodide, a soil fumigant.

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Department crafts emergency rules to speed adoption


Capital Press

A decision to register methyl iodide in California means fumigants containing the chemical will be allowed on the market late this month.

The decision by the state's Department of Pesticide Regulation caps a contentious public battle surrounding a scientific review that the agency's director has called the state's most extensive ever.

As a cost-effective, broad-spectrum fumigant, methyl iodide is meant to replace methyl bromide, which has been phased out under an international agreement to reduce ozone-depleting emissions.

Registration of the chemical takes effect once DPR finalizes emergency orders that allow it more swiftly onto the market.

The regulation classifies the chemical, also known as iodomethane, as "restricted," the most tightly controlled of DPR's classifications. It means applicators must have approval from county agricultural commissioners before applying it, and commissioners can implement local rules more strict than those of the state.

Agency Director Mary-Ann Warmerdam said in the agency's announcement that methyl iodide is the "most evaluated pesticide in the department's history."

The state's consideration of the chemical stretches back to 2007, when the U.S. Environmental Protection Agency registered it. Most states don't conduct their own investigations before following suit, instead deferring to EPA's work.

Florida registered the chemical in 2008, implementing stricter use rules than those of EPA. Arysta LifeScience, the Tokyo-based chemical giant marketing methyl iodide-containing products, is still pushing for registration in New York and Washington state.

The agency said it received 50,000 public comments on the deregulation proposal it published in April. DPR said the rules it will enact this month aim to keep exposures below 96 parts per billion, half of what federal rules allow. For the public, it keeps exposures at 32 pbb, one-fifth of what U.S. EPA allows, the agency says.

Buffer zones extend from 1,000 to 1,400 feet around applications. They also apply up to a half-mile from schools, hospitals, prisons and playgrounds.

Where EPA rules allow 40 acres to be treated at once, California's rules allow only up to 30, DPR said. Treated ground must be covered in specially designed tarps instead of the standard tarps allowed by EPA rules.

The state rules also aim to protect ground water more aggressively than do federal rules, while reducing the pounds allowed per acre and increasing the time that workers are kept out of a treated field.

The state's investigation process involved DPR's study, which was reviewed by other agencies as well as a panel of researchers, a step not normally included. The review panel angered Arysta when it gave a negative assessment of the chemical early this year. While it characterized the state's study as sound, it also drew its own conclusion, saying it would be "difficult, if not impossible" to protect workers from exposure.

Arysta said the panel hadn't sufficiently considered the company's extensive training and safety program for licensing applicators.

Lawmakers kept pace, holding legislative hearings in which laboratory scientists described methyl iodide as highly toxic, saying they handle it with extreme care while performing such laboratory tasks as inducing cancer in lab cells.

Extension researchers downplayed risks from field use. Despite its high toxicity from direct contact, the chemical quickly reaches an inert stage and does not significantly pollute ground water, field scientists and farmers have contended.


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