Michigan Correspondent

WASHINGTON, D.C. — Lately, it’s been a real roller coaster ride for methyl iodide.

Late last week, the U.S. Environmental Protection Agency (EPA) granted a one-year registration for the soil fumigant, also known as iodomethane.

“Iodomethane is an effective pesticide that has been peer-reviewed by independent scientists at EPA,” said Jim Gulliford, EPA assistant administrator for prevention, pesticides and toxic substances.

But late last month, EPA backtracked on a limited use permit it gave for Arysta LifeScience’s new soil fumigant. The agency was reacting to a group of scientists and environmentalists who wrote a letter to EPA last month, decrying the chemical as too toxic for agricultural use.

“We are skeptical of U.S. EPA’s conclusion that the high levels of exposure to methyl iodide that are likely to result from broadcast applications are ’acceptable’ risks,” the letter states.

Among its signers are several Nobel Prize winners. James L. Dye, professor emeritus of chemistry at Michigan State University, also signed the letter. In an interview, Dye stated that although he isn’t an expert on methyl iodide’s toxicity, it’s best to be cautious when introducing new chemicals into the environment.

“As I understand the objections of the signators, the FDA (Food and Drug Administration) has used toxicity studies by the manufacturer extensively, without similar tests by outside scientists,” Dye said. “If this is true, it indicates that no widespread use should be permitted without independent studies.

“Sometimes economic factors win over safety, however. For example, we are cautioned in the lab that benzene is a known carcinogen whose use should be avoided except when absolutely necessary. Yet, every time we pump our own gasoline, we are exposed to benzene vapor.”

EPA posted a letter online, dated Oct. 5, responding to the scientists’ concerns.

In it Gulliford restates his assertion that the agency’s analysis of methyl iodide is “one of the most thorough ever completed on a new pesticide.”

There are a number of restrictions on the use of methyl iodide. They include use of the chemical being prohibited from within one-quarter mile of any occupied sensitive site such as a school, day care facility, nursing home, hospital, prison or playground.

Certified applicators must be “on site within the line of sight of the field” during application.

Application sites must be limited to 40 acres per day, and the buffer zone of the field to be treated cannot overlap the buffer zone of another field treated within the last 48 hours. Entry to a treated field is restricted for five days.

The permit will allow the application of Midas, Arysta LifeScience’s trade name for methyl iodide, on 1,000 total acres in a seven-state area that includes Michigan, Florida, Georgia, North Carolina, South Carolina, Tennessee and Virginia. The experimental program would evaluate efficacy, market yields and economic comparisons across several crops.

The limited use permit will allow only selected growers – those who have completed the company’s certified applicators program – to try out the product. All growers participating in the program will receive specific training on how to handle Midas.

According to the company, Midas effectively controls a broad range of soil-borne diseases, nematodes, weed seeds and insects that threaten high-value crops such as ornamentals, strawberries, fresh market tomatoes, peppers and turf. The fumigant is applied using conventional techniques and equipment.

Methyl iodide is being promoted as a replacement for methyl bromide, another soil fumigant that’s being phased out due to environmental concerns. The Pesticide Action Network of North America lobbied against approval of methyl iodide.

“This is very disappointing, but not a shock,” said a spokesman for the group.

More information about the registration for methyl iodide is available online at www.epa.gov/pesticides/factsheets/ iodomethane_fs.htm#workers

This farm news was published in the Oct. 10, 2007 issue of Farm World, serving Indiana, Ohio, Illinois, Kentucky, Michigan and Tennessee.