Pesticide active ingredient comes under EPA scrutiny

California nut-crop farmers could lose a valuable crop-protection tool if a U.S. Environmental Protection Agency review of pyrethroids concludes they pose a hazard to waterborne creatures.

By law, registered pesticides have to be reassessed every 15 years by the EPA, and this time it's the pyrethroid class being reviewed. One active ingredient in particular, bifenthrin, is under scrutiny. The EPA released a preliminary risk assessment in November in which it concluded bifenthrin and other pyrethroids had high levels of toxicity to aquatic life, a claim also pursued by anti-pesticide groups.

"EPA is assessing all of them as one group," said John Cummings, North American manager of registration and regulatory affairs for pesticide manufacturer FMC. "At the current time, based on EPA's assessment, none of those active ingredients and none of the crops they're registered for pass the risk assessment. All of them are subject to severe limitations."

Cummings said he considers the assessment overly conservative. FMC argues the EPA risk assessment doesn't take into account the insecticide's use patterns and chemical qualities.

"Given what EPA has published so far, we don't think the best science has been used," Cummings said. "If they don't change how they've done the risk assessment, then certainly several pyrethroids could be significantly restricted."

EPA is taking comments on its assessment until March 31.

Chelsea Molina, a federal policy analyst for the California Farm Bureau Federation, encouraged Farm Bureau members to file comments.

"It will be important for our growers to share exactly how it is used," Molina said, "and more specifically, how it is applied, where and why. CFBF will be providing comments to EPA, but what the agency really needs is to hear from the growers themselves with examples and the great potential for crop loss as our tool kit continues to shrink."

In California, bifenthrin is used mainly on nut crops and to a smaller extent on tomatoes, citrus and strawberries. The product has a crisis exemption in California for use on pomegranates as a means of combating the leaf-footed plant bug. Navel orangeworms, a major threat to almonds, are another target of bifenthrin.

"Bifenthrin is primarily used for navel orangeworm control in almonds," said Gabriele Ludwig, director of sustainability and environmental affairs for the Almond Board of California. "The navel orangeworm is still our most significant insect pest."

Bifenthrin became a critical part of navel orangeworm control when the EPA outlawed Guthion about a decade ago, Ludwig said.

Cummings said bifenthrin is part of a pest-management program in which different chemicals are rotated so insects don't have a chance to build up tolerance for any one pesticide and render that product useless.

Pyrethroids are restricted-use pesticides that can only be applied by certified applicators, and then only under certain conditions, such as observing buffer zones around bodies of water and not spraying when wind speeds are 15 miles per hour or greater. FMC also argues that innovations in pesticide-application technology minimize the potential for runoff, as do closely following the directions on the label and observing environmental safeguards.

The Pyrethroid Working Group, an alliance of pesticide manufacturers, also said it believes the risk is overstated.

"Many studies over decades of testing show that when used under real-world conditions according to the federally approved labels, they do not cause adverse ecological effects," the group said.

FMC contends the EPA assessment process doesn't take into account the actual potential for bifenthrin exposure in the environment. Bifenthrin is hydrophobic—meaning it doesn't like water very much—and biodegrades in sunlight, leaving very little in the environment. FMC said EPA standard risk assessment models exaggerate the potential for exposure to plant and animal life that is not the chemical's intended target.

Those who wish to comment can go to www.defendbifenthrin.com or directly to www.regulations.gov/comment?D=EPA-HQ-OPP-2010-0384-0044. Postal mail should be addressed to OPP Docket, Environmental Protection Agency Docket Center (EPA/DC), (28221T), 1200 Pennsylvania Ave. NW, Washington, DC 20460-0001.

(Kevin Hecteman is an assistant editor of Ag Alert. He may be contacted at khecteman@cfbf.com.)