Toxic PFAS chemicals have been detected in seven out of 10 insecticides tested in the US, according to new research. Six contained what the study's lead author characterized as "screamingly high" levels of PFOS, one of the most dangerous PFAS compounds.
The Environmental Protection Agency (EPA) has known about the findings for more than 18 months but appears to have not yet investigated the products or taken any action against the manufacturer.
PFAS, also known as forever chemicals, can be taken up by crops. Such high levels in pesticides creates a health risk if spread on fields where food is grown, public health advocates say.
"We know PFOS is a carcinogen, we know it's a deadly chemical and there's no safe level in drinking water," said Kyla Bennett, a former EPA official and science policy director with the non-profit Public Employees for Environmental Responsibility (PEER), which issued a press release on the study. "Our soil and water are now contaminated."
In a statement, the EPA told the Guardian it's reviewing active ingredients used in pesticides - those which kill pests - to determine if any are PFAS. However, PFOS could be an inert ingredient.
Per-and polyfluoroalkyl substances, or PFAS, are a class of about 12,000 chemicals typically used to make thousands of products water-, stain- and heat-resistant. They do not naturally break down and accumulate in humans and the environment. A growing body of evidence links them to serious health problems such as cancer, birth defects, liver disease, kidney disease, autoimmune disorders, high cholesterol and decreased immunity.
Researchers from Texas Tech University checked 10 insecticides that were being used on cotton, but can also be used on food and other crops. The peer-reviewed study, published in Journal of Hazardous Materials Letters, found PFAS in seven of these "widely used" insecticides, said environmental toxicologist and lead author Steve Lasee, who was at Texas Tech University at the time of the study. He is now an independent consultant with Lasse Research and Consulting and a research fellow for the EPA.
Testing revealed PFOS at a level as high as 19m parts per trillion (ppt) in one insecticide. The EPA hasn't set limits for PFAS in pesticides, but in June it lowered its advisory health limit in drinking water to 0.02 ppt, a level so low as to suggest no amount of exposure to the compound is safe.
Lasee said he presented his findings in March 2021 to staff members at the EPA's Office of Research and Development and at a conference attended by environmental science professionals and EPA staff. He said he received an email from leadership in one of EPA's divisions asking him to present his study to more EPA staff, but never heard anything beyond that.
Lasee said he named the insecticide's active ingredients but he never received requests for the brand names, meaning the EPA could not know which companies had sold tainted products.
The EPA did not respond to direct questions about the study's findings or about Lasee's presentation to the agency.
Lasee said the Massachusetts Department of Environmental Protection (DEP) contacted him after his presentation to say it was interested in learning more about the research. A DEP spokesperson told the Guardian that the agency has been testing some pesticides for PFAS and has "discontinued use" of those that contain the chemicals. The agency is reviewing the information in the Texas Tech study and determining what's next, the spokesperson said.
It's unclear what purpose PFAS in insecticides may serve, but Lasee said they could be used as a dispersing agent, to help the pesticide spread evenly.
The study was published amid increased scrutiny of PFAS in pesticides because of the potential for widespread food and water contamination. Multiple studies have established that crops uptake PFAS and can be ingested by humans. The Food and Drug Administration (FDA) began monitoring PFAS in food in 2019 and has detected them in fruits and vegetables, but has not set any limits.
The EPA earlier this year found PFAS added to plastic barrels and containers used to store pesticides can leach into the products. An EPA spokesperson said the agency alerted companies that they may be in violation of the law.
However, Lasee said the type of PFAS compounds he found are different from those that leached from plastic containers, and the level of PFAS the Texas Tech study is several orders of magnitude higher, suggesting that the chemicals are from a different source.
In September, the EPA proposed banning some PFAS that can be used as inert ingredients that were approved for use in pesticide products, but it said active ingredients are being reviewed. "EPA will share results of that investigation as soon as possible", an agency spokesperson said.
The agency also updated a webpage with information about PFAS in pesticides in September that claims PFOS is not used in the products. "The EPA Office of Pesticide Programs previously determined that there were no pesticide active or inert ingredients with structures similar to prominent PFAS such as PFOS," it reads.
That could be contradicted by Lasee's research. The reason for the presence of PFOS in the insecticides is unclear. It could be the result of chemical companies illegally adding the compound, Bennett said. It could also be that a different PFAS compound is added to the fertilizer, then breaks down into PFOS after the pesticide is manufactured. The EPA did not reply to specific questions about the statement on its site.
Bennett said there is little consumers can do to immediately protect themselves beyond eating organic food, but she noted that many people don't have access to or can afford organic products.
That leaves it up to the EPA to take swifter and more forceful action to get PFAS out of pesticides, Bennett added.
"We have to get the EPA to stop allowing PFAS in pesticides," she said. "We've got a toxic chemical in them that doesn't need to be there, and pesticides are bad enough on their own without adding another carcinogen."