Once a year, researchers, agrichemical company representatives, and government officials get together at a conference dedicated to what they call pesticide stewardship. By their definition, stewardship includes improving the safety of pesticides, from manufacture to use to disposal.
At the most recent event last February, Ed Messina, director of the Office of Pesticide Programs at the U.S. Environmental Protection Agency (EPA), spoke to the virtual crowd. After running through at least a dozen other topics, he turned to per- and polyfluoroalkyl substances, or PFAS—“forever chemicals” that companies have used for decades in products including non-stick pans, takeout containers, and cosmetics—causing long-term damage to the environment and human health.
Recent tests had detected PFAS in pesticides, Messina told the group.
The agency planned to release the results of more thorough tests done to determine whether PFAS were leaching from plastic containers into the pesticides, he added. “The data does indicate that the amount of PFAS entering the environment [via pesticides] is extremely small,” he assured attendees, “but we do want to get a handle on where the PFAS is coming from.”
Now, the EPA has released the results of the study on leaching, which confirmed the issue. But while the agency maintains Messina’s assertion that the amount getting into the environment as a result is not significant, it’s not the only source.
A Civil Eats investigation has found that leaching is only one of three sources of PFAS in pesticides. In addition, the scale of PFAS contamination in pesticides is far from understood. Using an internationally recognized definition, dozens of pesticides registered in the U.S. inherently qualify as PFAS themselves, based on their molecular structure, and some PFAS are still approved by the EPA as additives to pesticide formulations.
In a recent email, the EPA told Civil Eats it “will continue to look closely at existing pesticide products to determine whether they contain PFAS as a result of the active ingredient, inert components, or packaging. As the agency’s understanding of PFAS grows and evolves, EPA will also continue to follow the science and adjust, as appropriate, to help ensure that pesticide products do not cause unreasonable adverse effects on human health or the environment.”
While recent data suggests the levels of PFAS in pesticides are lower than the concentrations found in now-familiar sources of contamination such as firefighting foam and sewage sludge, advocates are alarmed by the volume: Every year, farmers apply about 1 billion pounds of pesticides to nearly 900 million acres, touching soil, water, and food. Since so few pesticides have been tested, it’s impossible to say how many might be contaminated, but even a tiny percentage would be significant, experts say.
“Not everybody you know is buying carpets with PFAS in them, and not everybody is exposed to firefighting foam, but everybody is exposed to pesticides, whether they like it or not.”
“Not everybody you know is buying carpets with PFAS in them, and not everybody is exposed to firefighting foam,” said Ruth Berlin, director of the Maryland Pesticide Education Network (MPEN), “but everybody is exposed to pesticides, whether they like it or not.”
Many pesticides are associated with health risks (especially at the levels that farmers, farmworkers, and people in neighboring communities are exposed to) and adverse effects on the environment, including harm to aquatic organisms and pollinators. There are thousands of chemicals classified as PFAS with a range of impacts, but some of the most commonly used are linked to an increased risk of multiple cancers, liver damage, reduced immune response, and decreased vaccine response in children. PFAS can also accumulate in fish and other wildlife and can persist in the environment indefinitely. Currently, there is no safety data on the combined effects of PFAS and pesticides.
“That’s definitely something that we’re very worried about,” said Willa Childress, organizing co-director at Pesticide Action Network North America (PANNA). “But the level of contamination we could be talking about is also a huge concern. If there is even moderate contamination in pesticides . . . the exposure and contamination of farmland could already have happened.”
It would also likely be piled onto PFAS from other sources. In mid-October, researchers at Northeastern University estimated that 57,000 sites in the U.S. can be presumed contaminated based on other confirmed sources of PFAS that are already being tracked. One of those sources was sewage sludge, which has already contaminated farms in multiple states. “I’m concerned about all sources of PFAS, because these chemicals are never going to leave our environment,” said Linda Birnbaum, a toxicologist who spent 19 years at the EPA and was later the director of the National Institute for Environmental Health Sciences. “It all adds up.”
Hunting for the Source
“Where is it coming from?” is the question that stumped environmental toxicologist Steven Lasee when he began finding PFOS—one of a few PFAS that has been found to be particularly harmful—in a greenhouse used for crop research in 2017. Lasee was studying how plants take up PFAS, but his first experiment was derailed by the fact that he was finding the chemicals in his control plants and other places where he hadn’t planned to find them. He began testing everything around until he homed in on 10 insecticides that had been used on and were stored at the site.
To his surprise, Lasee found PFOS in six out of the 10 chemicals, at levels ranging from 4 million to 19 million parts per trillion (ppt). Although the pesticides are significantly diluted before use and the amount that would end up in waterways is unknown, the levels would still be hundreds of thousands of times higher than what is considered safe to ingest. For comparison, this June, the EPA updated its lifetime health advisory for PFOS in drinking water to 0.02 ppt, a level that’s barely detectable. “The EPA is basically saying that no exposure is safe long-term,” Lasee said.
One of the insecticides he tested was imidacloprid. In addition to farmers spraying more than a million pounds of the chemical on crops annually, the neonicotinoid is a component of seed coatings used on commodity farms.