Three widely used pesticides driving hundreds of endangered species toward extinction, according to EPA

Three widely used pesticides driving hundreds of endangered species toward extinction, according to EPA

IF CLAY BOLT WENT LOOKING for a rusty patched bumblebee, he would head to a city. The wildlife photographer said his best bet would be Minneapolis or Madison, Wisconsin, in a botanical garden or even someone’s backyard — as long as it was far away from crop fields and neonicotinoid pesticides. 

“It’s kind of ironic. Cities have become a refuge for some of these most endangered pollinators,” said Bolt, manager of pollinator conservation for the World Wildlife Fund. “Thousands of acres of monocultural row crops leave little to no room for most pollinators.”

Clay Bolt

The rusty patched bumblebee has seen populations plummet with the rise of industrial agriculture and was given Endangered Species Act protections in 2017. The species, once broadly distributed throughout the eastern United States, is now largely found in small populations in parts of the Midwest. 

Today, the bumblebee is among more than 200 endangered species whose existence is threatened by the nation’s most widely used insecticides (one classification of pesticides), according to a recent analysis by the U.S. Environmental Protection Agency. The endangered species range from Attwater’s greater prairie chicken to the Alabama cave shrimp, from the American burying beetle to the slackwater darter. And the star cactus and four-petal pawpaw are among the 160-plus at-risk plants.

The three neonicotinoids — thiamethoxam, clothianidin and imidacloprid — are applied as seed coatings on some 150 million acres of crops each year, including corn, soybeans and other major crops. Neonicotinoids are a group of neurotoxic insecticides similar to nicotine and used widely on farms and in urban landscapes. They are absorbed by plants and can be present in pollen and nectar, and have been blamed for killing bees or changing their behaviors.

Pesticide manufacturers say that studies support the safe use of these chemicals, which in addition to seed coatings,  are also sprayed on more than 4 million acres of crops across the United States, including cotton, soybeans, grains, fruits, vegetables, and nuts. But conservation groups said that the EPA’s analysis has “gaping holes” and downplays the harm to endangered species.

“These are likely the most ecologically destructive pesticides we’ve seen since DDT,” said Dan Raichel, acting director of the Pollinator Initiative at the Natural Resources Defense Council, an environmental advocacy group that works to “safeguard the earth – its people, its plants and animals, and the natural systems on which all life depends.” 

Dan Raichel

The chemicals “jeopardize the continued existence of” more than 1 in 10 endangered fish, insects, crustaceans, plants, and birds across the United States, according to the analysis by the environmental fate and effects division in the EPA’s Office of Pesticide Programs.

In 1972, the EPA banned DDT, an ecologically destructive insecticide that had gained widespread attention because of Rachel Carson’s book “Silent Spring,” which chronicled DDT’s role in harming the environment and driving species like the bald eagle toward extinction.   

The EPA — which originally approved the three neonicotinoids in 1991, 1999 and 2003 — has been forced by a 2017 court settlement to assess the impact of the chemicals on endangered species. 

The EPA has released the analysis with the hope of soon putting into place mitigations of the harm being caused, said Jan Matuszko, director of the environmental fates and effects division in the EPA’s Office of Pesticide Programs, in an interview with Investigate Midwest. An EPA spokeswoman said the EPA is planning to announce a proposed interim decision to re-register the neonicotinoids in September. 

However, experts claim the way the agency analyzed the neonicotinoids’ predominant use — as seed coatings on crop seeds before they are planted — underestimates the amount the pesticides move off where it is applied and into species’ habitat.


Use of neonicotinoids skyrocketed in the late 2000s and has continued to rise, despite concerns about effects on pollinators and human health. In 2018, the European Union banned neonicotinoids because of concerns about harm to pollinators. On June 9, the New York state legislature passed a first-in-the-nation bill that would ban neonic-treated corn, soybean and wheat seeds; the bill is awaiting the governor’s signature. 

In addition to environmental harm, scientists have expressed concerns about neonicotinoids’ effects on human health. In 2020, NRDC filed a petition asking the EPA to ban use of the chemicals on food because of risks to human health, including neurotoxicity and neurodevelopmental issues for children. 

A 2022 study from researchers at 16 institutions across the United States found the chemicals in the urine of 95% of pregnant women in California, Georgia, Illinois, New Hampshire, and New York. A 2023 study by the U.S. Geological Survey found neonics in more than half of wells in eastern Iowa, as well as in the urine of 100% of farmers it tested.

“It’s way worse than what we’re able to pay attention to,” Bolt said.

The chemicals are manufactured by some of the largest agribusiness companies in the world. German chemical company BASF is the lead registrant on clothianidin; German multinational corporation Bayer is the lead registrant on imidacloprid; and Swiss company Syngenta, owned by ChemChina, is the lead registrant on thiamethoxam. 

“It’s way worse than what we’re able to pay attention to.”

— Clay Bolt, manager of pollinator conservation for the World Wildlife Fund

Bayer spokeswoman Susan Luke said Bayer is committed to working with the EPA to “help ensure any new measures proposed by EPA are fully informed and based on sound science.”

“Bayer remains committed to the safe use of imidacloprid under label instructions; safe use that, along with other neonicotinoids, has been reconfirmed by regulators after diligent review worldwide,” Luke said in an emailed statement to Investigate Midwest. 

Susan Luke

Syngenta spokeswoman Kathy Eichlin said in an emailed statement that more than 1,600 studies have been conducted that support the safe use of thiamethoxam. 

“Without neonics, growers would be forced to rely on a few older classes of chemistry that are less effective at targeting pests and require more frequent applications,” Eichlin said.

BASF spokesman Chip Shilling said in an emailed statement that clothianidin presents “minimal risk to humans and the environment including pollinators.” He said these products “undergo many years of extensive and stringent testing to ensure that there are minimal adverse effects to the environment, including threatened and endangered species, when used according to label directions.”

“We will continue to engage in extensive training and other stewardship activities to ensure that clothianidin seed treatment products are handled and applied safely,” Shilling said. 

EPA and the Endangered Species Act

“THIS IS, AS FAR as we know, unprecedented. I’ve never seen a determination that was this large in scope,” NRDC’s Raichel said of the EPA’s analysis, adding, “EPA violated the Endangered Species Act when it approved these pesticides.” 

Though the EPA was founded at the height of the environmental movement ignited by “Silent Spring,” the EPA has never assessed the impact of pesticides, which includes herbicides, insecticides, fungicides and rodenticides, on endangered species since the Endangered Species Act was signed into law by former President Richard Nixon in 1973.

However, the EPA has consistently lost Endangered Species Act lawsuits for decades. In April 2022, the Biden administration pledged to take action and released an Endangered Species Work Plan for pesticides.

“Silent Spring” by Rachel Carson detailed the devastation by DDT.

Under the Endangered Species Act, the federal government cannot take any action that will “jeopardize the continued existence” of a protected species. In other words, the federal government cannot drive a species toward extinction.

If the government’s action is found to do so, it is called a “jeopardy” finding — which is rare. A 2015 review of seven years of consultations found only two jeopardy calls of more than 88,000 actions taken by the federal government during that time period. Jake Li, a co-author of that review prior to joining the EPA, is now deputy assistant administrator for pesticide programs at the EPA, overseeing the pesticide office.

Any federal agency that believes an action may harm an endangered species must consult with the U.S. Fish and Wildlife Service or National Marine Fisheries Service (depending on the species at risk) to see if that harm rises to the level of jeopardy — which means the species is less likely to survive because of the action.

Jake Li

In the case of these three neonicotinoids, the EPA released a biological evaluation in 2022 finding that these specific insecticides are likely to adversely affect — or harm — between 1,225 to 1,445 listed species, depending on the active ingredient. This is between two-thirds and three-fourths of all protected species in the U.S.

The U.S. Fish and Wildlife Service or National Marine Fisheries Service are then supposed to weigh whether that harm would rise to the level of extinction. In this instance, however, the EPA did its own analysis because the two agencies are backlogged in their analyses on pesticides, Matuszko said.

“This is, as far as we know, unprecedented. I’ve never seen a determination that was this large in scope. EPA violated the Endangered Species Act when it approved these pesticides.” 

— Dan Raichel, manager of pollinator conservation for the World Wildlife FundDan Raichel

“It’s going to be awhile before (the services’ analyses) comes out,” Matuszko said. “The reason we’re doing this is to get mitigations in place for listed species much earlier. We want to be able to protect those species before we go through the entire consultation process.”

A spokeswoman for the U.S. Fish and Wildlife Service — which oversees implementation of the ESA for terrestrial species and freshwater species — declined to answer questions, instead referring questions to the EPA.

Genevieve O’Sullivan, a spokeswoman for CropLife America, said the trade organization that represents pesticide manufacturers appreciates EPA’s work on the analysis to get mitigations in place for protected species.

“The new report provides better data for industry and growers to work with the relevant federal agencies as they determine additional mitigations for the continued responsible use of pesticides,” O’Sullivan said in an emailed statement.  

The Hines emerald dragonfly is one of more than 200 endangered species whose existence is threatened by the nation’s most widely used insecticides — neonicotinoids, according to a recent analysis by the U.S. Environmental Protection Agency. (Photo courtesy of the Missouri Department of Conservation)

EPA analysis: Largest use of neonics doesn’t impact endangered species

THE EPA’S ANALYSIS, THOUGH, found that the largest use of neonicotinoid insecticides — as seed coatings – will not cause species to go extinct. Researchers who study the environmental impacts of neonicotinoids say the EPA’s analysis downplays the risks.

Justin Housenger, a branch chief in the environmental fates and effects division of the EPA’s  Office of Pesticide Programs, said in an interview that in the EPA’s analysis, they found seed treatments to be safer than other uses of the chemicals because seed treatments have “no offsite transport,” meaning they don’t run off into water or drift into the air.

However, it is “widely accepted” by researchers that seed treatments do move off of where they are applied, said Christian Krupke, a professor of entomology at Purdue University, who has published extensively about the environmental impacts of neonicotinoid seed treatments. 

Research by Krupke and others shows that treated seeds lose up to 95% of the pesticide to the environment. This happens through seed abrasion and drift during the planting process or loss to soil or waterways through erosion. Birds can also eat treated seeds that are not properly buried. 

Christian Krupke

“There is no doubt that there are important non-target effects (of seed treatments),” Krupke said. 

Housenger said because the seeds are precision planted in fields, they likely don’t move off of where they are planted. He also said that the EPA’s analysis recognized “dust off” of pesticides during planting could happen, but doesn’t “quantitatively assess it further.” 

Housenger added that seeds are physically too big for many endangered birds to eat. Further, the EPA’s analysis found that unless a species’ habitat was the treated agricultural field and its diet was primarily seeds, it would not face a jeopardy call, Housenger said.

“Unlike with foliar and soil applications, there’s no offsite transport,” Housenger said. “When you stack all these lines of evidence together, that’s why you’ve got this relatively low number, even though seed treatment considerations and uses were considered.”

The EPA’s assessment disregards well-established research in the field, said Maggie Douglas, assistant professor of environmental science at Dickinson College.

“I don’t know where that disconnect is coming from, but it does seem to exist,” Douglas said. “At this point, there’s quite a lot of evidence that this (movement) is happening. Seed treatments are not just staying in the field.”

Maggie Douglas

In recent years, the U.S. Geological Survey has found neonics in rivers across the United States, tributaries to the Great Lakes, and well water and groundwater in Iowa.

“Treated seeds are no question in my mind why we’re finding this,” said Dana Kolpin, a research hydrologist with the U.S. Geological Survey, who has been an author on many of those studies.

A 2021 study by Kolpin and others found that clothianidin was in 68% of groundwater in northern Iowa and southern Minnesota. Clothianidin is used heavily as seed treatments in corn, but rarely used otherwise in those states.

Bill Freese

That these chemicals are used on half of all cultivated cropland shows how widespread the pollution could be, said Bill Freese, science director at the nonprofit Center for Food Safety. 

“It’s a huge issue. We’re talking the biggest crops in America,” Freese said. “Yet EPA is convinced these seed treatments don’t jeopardize species. I think that’s the most glaring evidence of how bad their assessments are.”

Lack of knowledge about neonic usage

NO ONE KNOWS THE EXACT acreage planted with neonicotinoid treated seeds, but it is by far the largest-scale use of the chemicals, said Douglas, who has published extensively on tracking how, where and to what extent neonics are used.

As of 2012, about 150 million acres of crops were planted with neonicotinoid-treated seeds each year; the coatings are applied to the seed prior to planting. Neonicotinoids are considered systemic, which means that plants absorb the chemicals and spread them through their circulatory system. This makes flowers, leaves, nectar, and pollen harmful to both pests and non-target insects.

The neonicotinoids can often be taken up by non-target plants, including wildflowers and other native plants on the edges of fields. A paper by Krupke found that more than 42% of the land in Indiana is exposed to neonic pesticides during corn planting, impacting the habitat of more than 94% of the bees in the state.

“This is an avoidable problem. In most cases, it’s not helping crops, yields or farmers.”

— Christian Krupke, professor of entomology at Purdue University

The U.S. Geological Survey, which tracks overall pesticide use by purchasing data from a third-party contractor that gathers the information via farmer surveys, stopped tracking seed treatments in 2015 because the data was too complex and full of uncertainties, according to the USGS website. Many farmers also do not know which seed coatings they are planting, making accurate information difficult to get, Douglas said. 

After the USGS stopped tracking seed treatments, recorded use of the chemicals — through applications by growers, such as spraying — fell significantly. Imidacloprid usage immediately dropped in half, while thiamethoxam use has dropped about seven-fold, and clothianidin usage has dropped more than 35-fold, USGS data shows.

Housenger said the EPA also does not know exactly how many acres currently are treated with neonic-coated seeds. An EPA spokeswoman, though, said the agency estimates that between 70% and 80% of all corn, soybean and cotton acres are planted with neonicotinoid-treated seeds. In 2023, that would range from 135.3 million to 154.64 million acres. This does not include treated seeds of other crops, including fruits and vegetables.

Hands hold coated corn in a corn field near Mansfield, Illinois, on Tuesday, May 30, 2023. (Photo by Darrell Hoemann, Investigate Midwest)

Coated seeds unregulated

THE ENDANGERED SPECIES ACT is the sole way to mitigate environmental harm from treated seeds, because of a loophole in how these seeds are regulated. 

The EPA regulates all pesticides through the Federal Insecticide, Fungicide and Rodenticide Act, or FIFRA. Using that standard, the EPA must weigh whether a pesticide causes “unreasonable adverse effects on the environment.” But unlike the Endangered Species Act, the EPA has the discretion under FIFRA to make a determination of whether environmental harms outweigh the benefits caused by the use of pesticides.

Seed coatings, however, aren’t regulated by FIFRA. 

The EPA exempts seed coatings because of a loophole called the treated article exemption. Originally designed so the EPA didn’t have to evaluate the safety of lumber treated with chemicals for preservation, the EPA has since expanded that definition.

On May 31, the Center for Food Safety, a nonprofit that promotes environmentally safe and healthy food systems, filed a lawsuit against the EPA arguing that the agency cannot exempt coated seeds under FIFRA because they, unlike other “treated articles,” have widespread devastating impacts that EPA does not properly assess. 

RELATED STORY: Bees, plants among the more than 200 species in jeopardy, due to neonicotinoid use

Krupke said there is little research that supports the effectiveness of seed coating to protect corn and soybeans under typical field growing conditions. A 2014 analysis by the EPA found that soybean neonicotinoid coatings “provide negligible overall benefits to soybean production in most situations.”

“We don’t need to be using nearly as much of these as we’re using,” Krupke said. “This is an avoidable problem. In most cases, it’s not helping crops, yields or farmers.”

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