Evidence too thin to support chlorpyrifos regulation, panel concludes

By Stephen Davies

© Copyright Agri-Pulse Communications, Inc.



WASHINGTON, July 28, 2016 - A Scientific Advisory Panel convened by EPA said the agency should not rely on a Columbia University epidemiological study to determine safe levels of exposure to chlorpyrifos, a widely used insecticide.

The SAP's concerns, expressed in a report submitted to EPA, echoed those expressed by pesticide manufacturers and commodity groups who said there were too many unanswered questions about the study, which used umbilical cord blood data from pregnant women to extrapolate exposure levels for children.

They also said using the epidemiological study would upend decades of regulatory practice that relied on animal studies to set safe tolerance levels. Indeed, it would be the first time that EPA used epidemiological data instead of looking at how a substance interfered with acetylcholinesterase, key enzyme in the nervous system, to help determine the safe level of an organophosphate pesticide.

EPA now must consider the report in determining how to address the regulatory status of chlorpyrifos, which was banned for residential use in 2000. Dow AgroSciences sells the product, developed by Dow Chemical, under the trade name Lorsban for crops, and Dursban for golf courses and sod.

Lets Talk Food

Jim Jones, assistant administrator for EPA's Office of Chemical Safety and Prevention, told Agri-Pulse that agency scientists are trying to determine how to take the SAP conclusions into consideration.

“We just got (the report) last week, so we're digesting it right now,” he said Wednesday, July 27. “We're going to take their advice very seriously and figure out what it is that they're telling us." 

The EPA's Jim Jones

 

Chlorpyrifos is used on more than 50 crops, including soybeans, alfalfa, wheat, citrus, fruit, tree nuts, vegetables, sugarbeets and cotton. It is “the leading insecticide active ingredient to control a number of different insects in crops, including soybean aphids in soybeans, aphids and armyworm in alfalfa, European asparagus aphid and cutworm in asparagus, corn rootworm and lesser cornstalk borer in peanuts, and leafrollers and San Jose scale in apples,” CropLife America (CLA) and commodity groups said in a brief recently filed in the 9th Circuit Court of Appeals.

That court ordered EPA to make a final decision by Dec. 30 on the agency's Oct, 30, 2015, proposal to revoke all food tolerances for the chemical.

EPA recently asked the court for a six-month extension so it could adequately consider the SAP's review. CLA and the commodity groups argued that EPA needs at least a year - until the end of 2017 - to conduct additional scientific analyses.

But the environmental groups that succeeded in obtaining the court order argued in a brief filed July 27 that the risks from chlorpyrifos exposure to farmworkers and the population in general justify taking action now.

Pesticide Action Network North America (PANNA) and the Natural Resources Defense Council quoted the court's own order from a year ago, which called EPA's lack of action “egregious.”

“Chlorpyrifos causes acute pesticide poisonings when people come into contact with residues in the air, on the ground, on their food, and in their drinking water. through food and drinking water, as well as in the fields,” PANNA said.

“It is time to say enough is enough,” PANNA said. “The requests for further delay should be denied.”

But CLA and the commodity groups argued that “EPA should not be forced to rush to judgment on such a precedent-setting regulatory action, particularly one that would have far-reaching consequences for U.S. agriculture and consumers.”

“EPA's proposal would effectively replace over four decades of established science based on a robust, animal-based toxicology database - a complete sea change in the pesticide risk assessment process,” their brief said.

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At their April meeting, many SAP members were skeptical of EPA's proposal to use the epidemiological study, which found IQ and memory deficits in seven-year-olds who had been exposed to chlorpyrifos in the womb.

Most of the SAP members agreed that there was too much uncertainty surrounding the Columbia Center for Children's Environmental Health study to justify using it as the basis to establish a “point of departure” - the level the agency starts at before applying additional safety or uncertainty factors.

In its written report, the SAP said, “Most of the panel was not in favor of using cord blood chlorpyrifos levels as a surrogate for exposure of infants,” defined as less than 1 year old. “The use of the cord blood measurements to inform an ex-utero infant's exposure-response to chlorpyrifos raised many concerns … Most of the panel was not in favor of using the chlorpyrifos concentration in cord blood at birth as a surrogate for the chlorpyrifos blood concentration during the 1- to 2-year age period.”

Another concern was the lack of raw data for the Columbia study. As CLA and the commodity groups noted, Columbia has not provided that data to EPA.


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