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Perfluoroalkyl and polyfluoroalkyl substances, or PFAS, are called “forever chemicals” because of how long they last in the human body and the environment. They are a growing health problem.
The hormone-disrupting chemicals are present in the blood of an estimated 98% of Americans and are so concerning that the National Academies of Sciences, Engineering, and Medicine in July 2022 established “nanogram” levels of concern and called for testing of high-risk individuals, including infants and the elderly.
In April, the U.S. Environmental Protection Agency announced historic rules designed to tightly control the levels of five of the most studied PFAS in the nation’s drinking water, one route of human exposure. Contamination can also come from the presence of PFAS in food packaging, stain-resistant textiles and thousands of consumer products such as cookware, tampons and cosmetics.
However, a new study looks at another, little-studied potential route of exposure: the existence of PFAS in pesticides used to control agricultural and residential pests, including flea treatments for pets.
“This is really the first study in the U.S. to comprehensively examine how pesticides may be contributing to global PFAS contamination,” said Alexis Temkin, a co-author of the study published Wednesday in the journal Environmental Health Perspectives. She is a senior toxicologist for the Environmental Working Group, or EWG, an environmental health organization based in Washington, D.C.
Staple foods such as apples, corn, kale, spinach, strawberries and wheat are regularly sprayed with PFAS-containing pesticides, said co-author David Andrews, senior scientist and deputy director of research at the Environmental Working Group.
“These pesticides are applied in fairly large quantities to tens of millions of agricultural fields in the United States, and they contribute to PFAS contamination,” Andrews said. “The use of these pesticides may also partly explain some of the unidentified PFAS contamination that scientists are seeing in our waterways.”
According to research conducted by scientists at EWG, the Center for Biological Diversity in Tucson, Arizona, and Public Employees for Environmental Responsibility in Silver Spring, Maryland, PFAS pesticides are also used in flea treatments for pets and insect sprays for home use.
“One of the pesticides mentioned in (the article) was fipronil, which is found in specific flea/tick products that can be applied to pets! I had no idea this was a PFAS,” environmental toxicologist Dr. Jamie DeWitt, director of Oregon State University’s Pacific Northwest Center for Translational Environmental Health Research, said in an email.
“The study provides empirical evidence of the extent to which PFAS are present in pesticides,” said DeWitt, who was not involved in the study.
More supervision needed
Despite the presence of PFAS, the chemicals are not often considered in federal pesticide regulations or in toxicological evaluations of pesticides, said Stephanie Eick, an environmental and reproductive epidemiologist and assistant professor at Emory University in Atlanta. She, too, was not involved in the new study.
“Pesticide regulations are currently outdated and ineffective, so this discovery of PFAS in pesticide formulations represents a new opportunity for the U.S. EPA to improve the scientific validity of pesticide risk assessments to better capture real-world exposure scenarios,” Eick said in a commentary published with the study.
As with other scientific contributions, the Environmental Protection Agency will review the new report and remains “committed to addressing the risks of PFAS from all sources, including pesticides,” an EPA spokesperson told CNN via email.
In addition, the EPA has taken “significant steps” in recent years to understand and address PFAS in pesticides, including removing 12 PFAS ingredients from pesticide production, the spokesperson added.
The American Chemistry Council trade association told CNN that pesticides are among the most heavily regulated products in the United States.
““We need time to look at everything carefully, but it appears that these researchers are considering a lot of pesticides to be PFAS when they are not,” said Tom Flanagin, senior director of product communications for ACC.
While farmworkers and others who work with or around pesticides are at the highest risk, pesticide exposure is widespread. More than 90% of the U.S. population has detectable levels of pesticides in their urine or blood, according to estimates.
PFAS makes pesticides last longer
The study authors submitted Freedom of Information Act requests to several U.S. state and federal government agencies, including the EPA.
The analysis found that 66, or 14 percent, of all active ingredients in pesticides are PFAS, which are intentionally added to make the product better at killing pests, Andrews said.
“They add PFAS components to pesticides because it also increases the stability of the pesticide in the fields,” he said. “The pesticide breaks down less quickly and can therefore remain effective for a longer period of time without having to be reapplied.”
Pesticides also contain inert ingredients, which don’t kill pests but are added as “a carrier of the active ingredient, like a capsule with a pharmaceutical product,” said Rainer Lohmann, a professor at the University of Rhode Island Graduate School of Oceanography who studies sources of PFAS. He was not involved in the study.
Inert ingredients are not required to be listed on product labels, Andrews said. The analysis found that eight EPA-approved inert ingredients were PFAS, including the nonstick chemical Teflon. In February, the EPA proposed removing Teflon from pesticide products.
The analysis also found that nearly a third of new ingredients approved by federal agencies for use in pesticides over the past decade contained PFAS, likely because of their longer duration of action and other benefits, Temkin said.
“Registration of pesticides requiring PFAS is increasing,” she said. “This seems to be a trend.”
PFAS-creating containers
Another unusual source of PFAS is the pesticide packaging itself, as a result of a chemical reaction, Andrews said.
“Fluorine gas is put into a plastic container and the fluorine reacts with the surface to make it more stable,” he said. “The EPA has found that the reaction creates byproducts — long-chain PFAS like PFOA and PFOS, which are banned.”
According to the report, an estimated 20% to 30% of plastic packaging containing pesticides and fertilizers is fluorinated, which can allow PFAS to leach into the contents.
After the EPA first became aware of potential PFAS contamination in fluorinated plastic pesticide packaging in 2020, the company developed new ways to detect PFAS at low levels in pesticide packaging and products, a spokesperson said.
“The chemical reaction is not just limited to pesticide containers,” Andrews said. “It’s also happening in some perfumes and other consumer product packaging. It’s a big problem that goes beyond pesticides and could be a significant contributor to how long-chain PFAS of concern are released into the environment.”
The long-chain PFAS chemicals perfluorooctanesulfonic acid, or PFOS, and perfluorooctanoic acid, or PFOA, are among the most studied of the nearly 15,000 types of PFAS used by the industry. Both chemicals have been linked to increased risks of serious health conditions including cancer, obesity, thyroid disease, high cholesterol, decreased fertility, liver damage and hormone disruption, the EPA says.
“These are hidden sources of PFAS that are an underestimated source of contamination to our waterways, the environment and potentially our bodies,” Andrews said.
How significant are these exposures? More research is needed, experts say. However, the paper “makes a good case that fluorinated pesticide compounds are a large contributor to the unrecognized PFAS that are out there and appear to be a much larger contributor than previously expected,” DeWitt said.
“(This study) confirms that PFAS are present in pesticide products, either as an active ingredient in the pesticide or as a contaminant introduced through the pesticide packaging,” he said.
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