The Trump administration appears ready to go to the mat for chlorpyrifos, a widely used pesticide that has been linked to developmental disorders in children whose mothers were exposed to it during pregnancy.

The Justice Department filed an appeal on behalf of the Environmental Protection Agency on Monday, saying the San Francisco-based U.S. 9th Circuit Court of Appeals erred when it reinstated an Obama-era ban on the chemical. The appeal asks the court to allow a full panel of 22 judges to reconsider the case.

A rejection by the appeals court would leave the administration with one final attempt to keep the chemical on the market — the Supreme Court.

Scott Pruitt, then the newly approved director of the federal EPA, overturned the ban in March 2017, in what was widely seen as a bellwether move for an administration that had promised less regulation to its agribusiness supporters.


In August, however, an appeals court called Pruitt’s actions improper and reinstated the ban.

Chlorpyrifos is the most widely used pesticide in agriculture. The agriculture and chemical industries pushed hard to keep it available for more than 60 crops, including grapes, citrus fruit, almonds, walnuts, alfalfa and cotton. California growers apply about 900,000 pounds of the organophosphate compound, which attacks the nervous system, on about 640,000 acres, according to the state Department of Pesticide Regulation.

The department said use has declined steeply from more than a decade ago. Growers have struggled to find a replacement. They have switched to more pest-resistant crop varieties and tried alternative ways to control pests, including disruption of their mating cycles.

The original ban, enacted in November 2015, was the result of pressure from lawsuits brought by environmental groups. Those groups cited studies that linked the nerve-agent chemical to enduring intellectual deficits in children born to mothers who were exposed to the pesticide during pregnancy.


The court said the EPA had violated the Federal Food, Drug, and Cosmetic Act and the Federal Insecticide, Fungicide, and Rodenticide Act. The laws require the EPA to ban a pesticide from use on food unless there is reasonable certainty that it will cause no harm, the court said.

“The EPA has never made any such determination and, indeed, has itself long questioned the safety of permitting chlorpyrifos to be used within the allowed tolerances,” New York District Judge Jed S. Rakoff, who was filling in on the 9th Circuit, wrote for the panel in August.

Agriculture Secretary Sonny Perdue disagreed Monday, saying the decision to ban the chemical was “based on a misunderstanding of both the available scientific information and EPA’s pesticide regulatory system.”

Environmentalists vowed to continue their opposition to chlorpyrifos.


“The Trump administration is shameless in its refusal to ban this dangerous chemical that is poisoning our children’s brains,” said Erik Olson, senior director of health and food at the Natural Resources Defense Council, one of the environmental groups that originally petitioned the EPA to ban the chemical in 2007.

Earlier this month, California’s Department of Pesticide Regulation proposed listing chlorpyrifos as a toxic air contaminant, which would bring tighter rules on its use in the state.

geoffrey.mohan@latimes.com

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