WASHINGTON, Jan. 25, 2017 - One of the major manufacturers of pyrethroids says the Environmental Protection Agency did not use “real world” data to assess the chemicals, which led it to overstate the insecticides’ risk in a preliminary review released in November.

FMC Corp., one of the six manufacturers comprising the Pyrethroid Working Group (PWG), was also one of several companies, state agencies and environmental groups that recommended EPA extend its comment period on the preliminary ecological risk assessment for the chemicals, used on tens of millions of cropland acres across the country.

John Cummings, FMC’s registration and regulatory affairs manager, told Agri-Pulse EPA has agreed to extend that comment period until March 31, which will give the makers and formulators needed time to plow through the 800-page risk assessment.

But Cummings says growers “have a voice with EPA” and need to weigh in about how they use the chemicals.

“It is really important for the growers and commodity organizations to get comments in to EPA,” he said, adding that EPA has not incorporated “any real-world grower input on how these products are really used.” The ecological risk assessment, which looks at the environmental fate of nine pyrethroids and pyrethrins, found the chemicals can harm aquatic life – particularly invertebrates such as water fleas.

Cummings said that unless EPA’s conclusion changes, “it’s not unreasonable” to think that some uses could be eliminated entirely.

EPA is using the assessment to make registration decisions on additional pyrethroids. The nine were chosen because the PWG “has generated a large amount of data on these active ingredients, which are predominantly used in agriculture but also have residential and public health uses,” EPA said in a document explaining its process.

“In general, this assessment concludes that the use of bifenthrin (Capture); cypermethrin, cyfluthrins, deltamethrin (Decis); esfenvalerate (Asana); cyhalothrins, fenpropathrin (Danitol); and permethrin (Ambush), plus the pyrethrins, in accordance with registered labels, results in exceedances of acute and/or chronic risk Levels of Concern (LOCs) for freshwater and estuarine/marine invertebrates by up to three orders of magnitude.”

But Cummings said EPA relied too heavily on lab studies instead of looking at field data. “The assessment should take into account discrepancies between laboratory and field effects data,” he said in a written summary of FMC’s concerns. “For example, EPA did not cite the large number of mesocosm studies (many requested by EPA themselves, pre-2000) that provide evidence for the resilience of aquatic ecosystems, nor did they account for well-documented differences in sensitivity between laboratory strains and natural populations of some species.”

A mesocosm is often described as an experimental environment that falls between a lab study and a full-blown field study.

In addition, Cummings said that the PWG “has done a lot of field testing, where we have measured concentrations of pyrethroids in streams. That kind of higher tier data is important for EPA to include in their assessment.”

EPA also assumes that growers “ignore the label recommendation to avoid applications when rain is expected or that no growers use drift-reducing technologies,” Cummings said. “However, this is not a realistic assumption and is not consistent with actual grower practice.”

He also criticized the agency’s assessment for not taking into account mitigation measures imposed in 2008, including 150-foot aerial/25-foot ground no-spray buffers, spray droplet size and application wind speed restrictions, and requirements for a 10-foot maintained vegetative buffer strip next to water.

Pyrethroids are important tools for growers, Cummings said. They’re used to control insect pests on about 120 crops nationwide, including almonds, apples, tomatoes and citrus, as well as feed crops such as corn, soybeans and alfalfa. Total acreage applied is about 46-50 million acres, with bifenthrin making up about 14 million acres of that total.

But some groups are convinced they pose a threat to some species, and possibly to humans.

For example, Nathan Donley, a scientist with the Center for Biological Diversity, said that pyrethroids “have well established impacts to water quality and high toxicities to fish and aquatic invertebrates” and that “it is clear from these risk assessments that the current labels are not nearly protective enough of these important populations.”

And the California Stormwater Quality Association said, in asking for a 120-day extension of the comment period, that its “overriding concern with pyrethroid pesticides is that they pose a significant risk to water quality in urban and suburban areas.”


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