Methyl iodide, also known as iodomethane, will be allowed to control soil pests "under highly restrictive provisions governing its use," the EPA said in a statement.
"When used according to EPA's strict procedures, iodomethane is not only an effective pesticide, but also meets the health and safety standards for registering pesticides," the agency said.
Methyl iodide was developed by Tokyo-based Arysta LifeScience Corp. as an alternative to the widely used fumigant methyl bromide, which has been banned under an international treaty because it depletes the ozone layer. The fumigant kills off weeds and soil pests in the soil before planting a wide variety of fruits and vegetables.
The EPA said its decision was based on four years of risk assessment studies, constituting "one of the most thorough analyses ever completed by the agency for a pesticide registration action."
"The agency concluded that there are adequate safety margins and the registration of iodomethane does not pose unreasonable risks," the agency said. Last week, however, a group of 54 scientists, including six Nobel Prize winners, sent a letter to EPA urging that the pesticide not be registered for use because of the potential danger to pregnant women and children, the elderly and farmworkers.
In a letter to Robert Bergman, a University of California chemistry professor who was the lead author on the scientists' letter, EPA Assistant Administrator Jim Gulliford said the EPA's scientific analysis had taken into account their concerns and the agency concluded that its risk assessments "are realistic and demonstrate adequate protection for the most sensitive individuals."
Agency scientists spoke this week by telephone with Bergman and two other signers of the letter, and Bergman said he had reiterated his own concerns about the potential danger to fetuses and infants.
Conditions imposed by EPA on use of the product include use of government-approved respirators for workers applying the fumigant on fields, buffer zones around the fields to protect bystanders and five-day restriction on anyone entering the fields after the chemical is applied.
The fumigant is used to control pests on crops and plants such as strawberries, tomatoes and peppers. Farmers have been struggling to find alternative products that work as well as the banned methyl bromide.