The U.S. Environmental Protection Agency has withdrawn its plan to approve a highly toxic fumigant for strawberries and other high-value crops after California officials, labor unions, environmentalists and others objected that nearby residents and farmworkers could be in danger.
The new pesticide, methyl iodide, is designed to replace methyl bromide, which is banned under an international treaty because it damages the Earth’s ozone layer.
Strawberry growers, concentrated mostly in Ventura and Santa Cruz counties, have been searching for nearly 15 years for a fumigant to replace methyl bromide, which they have been phasing out but are still using under exemptions granted by the United Nations. Facing criticism that it was substituting one dangerous chemical for another, the EPA decided not to register methyl iodide, also known as iodomethane. It will reevaluate the pesticide next year.
“EPA’s refusal to automatically approve the use of another dangerous chemical as an alternative to methyl bromide is encouraging,” said Susan Kegley, senior scientist at the environmental group Pesticide Action Network North America. “They didn’t knock it out for good, but it’s a good sign that they are holding off.”
Fumigants are considered particularly risky among agricultural pesticides. But they also are valuable to growers because a single injection into the soil before planting will sterilize the field and destroy an array of insects, weeds and diseases.
The new pesticide, a gas, does not leave residue in food. But it does evaporate from the soil, exposing farmworkers during application, and small amounts can drift off fields into nearby communities. In animal tests, breathing large doses of methyl iodide killed fetuses, caused thyroid tumors, damaged respiratory tracts and altered thyroid hormones, which can disrupt the development of infants’ brains.
Scientists at the California Department of Pesticide Regulation raised numerous health concerns about methyl iodide, which the state has declared a cancer-causing chemical.
“While residues may not be present in crops grown in treated soil, workers and bystanders, as well as residents living near the treated fields, will be exposed to it in the air,” Tobi Jones, an assistant director at the state agency, told the EPA in a letter.
Ventura County Supervisor Steve Bennett, acknowledging that a substitute for methyl bromide is “desperately needed” by farmers in his county, was among those who contacted the EPA to oppose the new pesticide because he considered the EPA’s evidence of its safety for nearby communities inadequate.
The EPA received about 13,000 such letters, mostly in campaigns led by environmental groups and the United Farm Workers. “Rural communities have repeatedly been poisoned by existing fumigants,” UFW letters said. “It is time to move to much safer methods of pest control, not backwards to a chemical that is even more toxic.”
Other pesticide companies also objected. Methyl bromide manufacturers complained that the EPA was requiring looser safety precautions for methyl iodide than it did for the chemical it would replace. They said the agency inadequately addressed risks of neurological damage to infants and children near the fields.
The EPA said in a statement Tuesday that it decided not to register iodomethane because of “the uncertainty associated with the risks and benefits.”
EPA spokeswoman Enesta Jones said the agency will reevaluate the chemical after it completes a review of all fumigants. “At that time, the agency can better determine if iodomethane is a viable replacement for methyl bromide,” Jones said.
The manufacturer, Arysta LifeScience Corp., said it has not given up on its new chemical, which it plans to market under the name MIDAS.
Tokyo-based Arysta has spent seven years and more than $11 million collecting toxicological and environmental data to persuade the EPA to register methyl iodide for use on strawberries, tomatoes, peppers, ornamentals, grapes and several other crops.
“We were disappointed that the EPA did not register [methyl iodide] at this time. However, Arysta LifeScience remains confident, and we are committed to the long-term success of this product for growers and the industry,” Arysta spokeswoman Donna Uchida said. “We are developing additional scientific information for the EPA to have full confidence that the use of MIDAS presents no unreasonable risk and is a legitimate, commercial replacement for methyl bromide.”
California -- particularly the Oxnard and Watsonville areas -- has a lot at stake in the search for a new fumigant because the state produces 88% of the nation’s strawberries, worth about $1.3 billion last year.
Strawberry growers alone could use 3 million pounds of methyl iodide annually to replace methyl bromide, which was banned last year under the U.N.'s Montreal Protocol. Only areas with special “critical use” exemptions, largely in California and Florida, are allowed to still use some methyl bromide. The exemptions must be renewed annually by the U.N.
In a letter to the EPA, the California Strawberry Commission called methyl iodide a “highly promising alternative” that is “essential to our continued transition away from fumigation with methyl bromide.” But spokeswoman Mary DeGroat said many growers do not use fumigants because they are expensive and require many safeguards, such as tarps and buffer zones.
During tests at fields in California -- in Oxnard, Camarillo, Guadalupe and Watsonville -- EPA scientists determined that farmworkers applying methyl iodide would breathe harmful doses and that low concentrations would drift off fields.
But the EPA also concluded that the applicators would be safe as long they wore respirators, and other workers would not be at risk if they waited several days before entering fields. They also said that any bystanders would breathe small doses that pose no known health risks.
California’s Department of Pesticide Regulation, which is conducting its own review, disagreed, citing concerns for pregnant women and children. State scientists told the EPA that fetuses of laboratory rabbits are killed at doses comparable to those found in the air at the test fields and that the EPA’s “safe” dose is five times higher than what they deem appropriate. They also said they are “very concerned” about the pesticide’s potential to disrupt the neurological growth of fetuses.
If the EPA does register the new pesticide, it still could not be used in California unless the state agency also approves it.