Center for Biological Diversity

For Immediate Release, February 24, 2022


Stephanie Parent, (971) 717-6404,

U.S. Fish and Wildlife Service Sued for Refusing to Stop Chlorpyrifos, Diazinon From Killing Endangered Animals, Plants

EPA Found Chlorpyrifos Likely to Harm 97% of Protected Endangered Species

WASHINGTON— The Center for Biological Diversity sued the U.S. Fish and Wildlife Service today to push it to take action to stop endangered species from being harmed by the pesticides chlorpyrifos and diazinon, as required by the Endangered Species Act.

Today’s lawsuit comes after the Service failed to meet December 2017 deadlines to finalize consultations with the Environmental Protection Agency on the risks posed by the two organophosphates, which are likely to harm the majority of protected species, according to EPA assessments.

“The Fish and Wildlife Service has no excuse for taking more than five years to limit harms from two pesticides that it knows injure and kill hundreds of endangered species,” said Stephanie Parent, a senior attorney at the Center. “It shouldn’t require lawsuits to force the agency charged with protecting our most endangered wildlife from harmful pesticides to actually do that important work. But they’ve left us with no other choice.”

In January 2017 the EPA released analyses finding that 97% of the more than 1,800 animals and plants protected under the Endangered Species Act are likely to be harmed by chlorpyrifos and that 78% are likely to be hurt by diazinon. The EPA initiated formal Endangered Species Act consultation with the Service in early 2017 to establish measures to limit the harms of the two pesticides. But five years later the Service has not complied with its duties to produce a biological opinion for either pesticide.

The two pesticides are organophosphates, a dangerous old class of insecticides found in 87% of human umbilical-cord samples and widely used on crops such as corn, watermelon and wheat.

The Biden EPA is moving to ban the use of brain-damaging chlorpyrifos on U.S. food crops, pursuing an Obama-era plan that was shelved by the Trump administration at the request of pesticide makers. But the pesticide can still be used in a wide variety of non-food applications, including Christmas tree farms, plant nurseries, cattle ear tags, fence posts and bait traps. Industry groups have sued to stop the ban on food uses from taking effect.

“People across this country would be truly horrified if they fully understood how little protection federal regulators actually provide from many harmful pesticides,” said Parent. “When our regulators can’t even be bothered to complete critical assessments on the harm that two dangerous poisons like chlorpyrifos and diazinon do to our most endangered wildlife, it’s time to completely reassess how we approve the safety of pesticides. It’s a dangerously twisted regulatory process that is quick to approve pesticides but slow to limit their harm. It has to change.”


As part of a legal agreement, the Fish and Wildlife Service was supposed to issue a biological opinion by the end of 2017 identifying ways to safeguard endangered species from chlorpyrifos, malathion and diazinon, as required by the Endangered Species Act.

In January 2017 the EPA completed its part of that process when it issued a biological evaluation determining that nearly all federally protected species are likely harmed by chlorpyrifos and malathion. It also found that more than three-quarters of all endangered species are likely to be harmed by diazinon.

The World Health Organization has found that malathion and diazinon are “probably carcinogenic to humans.”

Following the EPA’s announcement, officials at Dow AgroSciences asked the Trump administration to suspend the assessments.

In May 2017 the Fish and Wildlife Service announced that after nearly four years of work, its draft biological opinion assessing the pesticide’s harms was nearly complete and would be ready for public comment within months. As career staffers at the Service were preparing to make the biological opinion available for public comment, they briefed Trump's political appointees, including then-acting Interior Secretary David Bernhardt, on the results of the agency's rigorous scientific review.

Following this briefing, top officials at the Department of the Interior, including Bernhardt, acted to indefinitely suspend the release of the Service’s assessment. The Trump administration’s unprecedented efforts to undermine those findings were highlighted in a New York Times investigation.

A document obtained by the Center through the Freedom of Information Act revealed the assessments were suspended after the top political appointees were briefed on the fact that the Service’s analysis had determined that chlorpyrifos jeopardized the continued existence of 1,399 protected species.

In the intervening years, the findings have prompted no action by the EPA or wildlife agencies to limit the insecticides’ uses in areas where endangered species are imperiled by it.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

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