A Burning Question: The Risks of Incinerating Forever Chemicals

Every day, Jerry Grabarek looks out for a plume of smoke a couple miles from his dairy farm. Grabarek, a 73-year-old from Preston, Connecticut, can’t always see the plume. Some days are too rainy. Or too foggy. But when the sky is clear, he can see a gray cloud stretch just past the tree line, a smudge on the horizon. And when it’s windy, especially when the breeze blows from the southwest, he worries.

The plume comes from a local incinerator, roughly 2.5 miles away, that began operating in 1991 — the same year Grabarek built the milking center on his now-102-year-old family farm. “I was milking here, and every time I opened that door, I could see the stack,” he said. (Grabarek still keeps cows on the farm, through he stopped selling their milk in 2022.)

He wondered: What was he breathing in?

So, in December 2024, he paid $357 to get his blood tested. “If anybody is a guinea pig for incineration, for the incinerator,” he said, “it’s me.”

Grabarek’s blood panel tested for compounds known as PFAS — short for per- and polyfluoroalkyl substances — a group of chemicals commonly found in consumer goods and industrial products. Those chemicals, though, are notoriously tough to break down in the natural environment, earning them the nickname “forever chemicals.”

When he got his results, Grabarek’s levels for one type of PFAS, known as PFHxS, were about six times that of the average American male. Another type, known as branched PFOS, was more than three times the average.

Now, he said, “it’s on my mind all the time. You know, you wake up in the night, that’s what you think of.”

In recent decades, PFAS have emerged as a growing public health and environmental concern, and they can come from any number of sources. The chemicals are so widely used, and so tenacious, that nearly everyone has some amount of PFAS in their blood. And there are related health risks, too; certain types of PFAS have been linked to conditions like kidney cancer, increased cholesterol, thyroid dysfunction, and a weakened immune system.

“My soapbox as a clinician taking care of people affected by PFAS is, like, it’s a risk factor” — meaning it’s not guaranteed to cause a particular symptom or condition, said Rachel Criswell, an epidemiologist and physician who treats patients who have been exposed to very high levels of PFAS. (Grabarek said he visited her clinic for a consultation in April.)

Grabarek’s PFAS levels weren’t as high as some other people’s — individuals who work in manufacturing, or live near heavily contaminated areas, can have levels that are hundreds of times higher. But still, his results sounded high to him, and he was concerned.

The science on PFAS incineration is still nascent, though, which leaves Grabarek and other concerned citizens in limbo. Most research and regulation have focused on the compounds’ presence in water. But relatively few studies have examined the prevalence — and potential health risks — of PFAS in air. And while some states have petitioned the Environmental Protection Agency to consider certain types as hazardous air pollutants, the federal government has yet to regulate PFAS in this way, in part because the ability to test for the chemicals in the air is still limited.

On Monday, the EPA announced new plans to combat PFAS contamination — including launching “additional efforts on air-related PFAS information collection and measurement techniques related to air emissions ,” though the announcement lacked specifics, including on how this would square with ongoing budget and personnel cuts at the agency.

“We need people to be able to evaluate the science and then decide if regulations are necessary, or what type are necessary, and then move forward from there,” said Phil Taylor, an environmental chemist and waste incineration specialist. “So I think we’re still behind in that regard.”

Meanwhile, although most waste in the U.S. ends up in landfills, some waste containing PFAS continues to be incinerated in combustors — including the one near Grabarek’s farm. Michael Van Brunt, the vice president of environmental and sustainability at Reworld Waste, which operates the Preston incinerator along with others across the country, said that they don’t market their municipal waste combustors to destroy PFAS, but “we know that it’s in the waste that comes in.”

Expert opinions, though, differ on whether that should be a matter of concern. Taylor, for one, said that PFAS air emissions are more likely to come from manufacturing than from incineration. “Number one, I don’t think it will survive incinerator exposures. And number two, there’s not that much PFAS being incinerated period.”

At the same time, researchers are exploring incineration as a potential solution to the PFAS crisis. Studies suggest that given the right conditions — for example, at very high temperatures for a specific amount of time — incineration can effectively destroy the compounds, though the process can leave behind byproducts that present their own risks.

But experts say more research and development is needed to make sure the incineration process is both scalable and safe. “There’s a lot of people who think that incineration is this magic thing for PFAS,” said Gail Carlson, an assistant professor of environmental studies at Colby College, “which it’s not.”

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The proliferation of PFAS traces back to the mid-20th century, when companies like DuPont and 3M — then known as the Minnesota Mining and Manufacturing Company — embraced the chemicals for their versatile and unique properties. Chief among those attributes is their ability to repel water and oil, which made them popular in household goods from nonstick pans to stain-resistant fabrics to dental floss.

It wasn’t until several decades later that the public began to realize PFAS could be a problem.

“They’ve detected PFAS just about everywhere,” said Keith Weitz, an environmental scientist at RTI International, a research institute headquartered in North Carolina. The compounds have been found as far as the Arctic circle and the Amazon rainforest.

There are thousands of different types of recognized PFAS chemicals, some of which have been studied more than others in terms of both environmental impact and health risks. PFOA and PFOS, for example, have been linked with increased cholesterol, along with a host of other health conditions. These chemicals have also been associated with reduced antibody response to certain vaccines, as have PFHxS — the kind that Grabarek had elevated levels of in his blood.

What all PFAS have in common, though, is a chain of linked carbon and fluorine atoms. And the endurance of so-called “forever chemicals” comes down to that carbon-fluorine bond.

It’s a tough bond to break — one that, based on the development and availability of technology, high temperatures under controlled conditions seem to have the best chance at severing.

“It’s recognized that the key way to treat PFAS is thermal destruction,” said Weitz, who co-authored a 2024 review summarizing the latest research on how PFAS could be effectively destroyed at high temperatures. “There currently aren’t many alternatives to that,” he said — though he added that “It’s an evolving field, so it changes every other day.”

Studies vary on the suggested parameters to destroy PFAS: Some, like Weitz’s 2024 review, say temperatures above 850 degrees Celsius (roughly 1,560 degrees Fahrenheit) for two seconds should be sufficient for certain types of PFAS. Other studies put the figure at closer to 1,100 degrees Celsius (or 2,000 degrees Fahrenheit). Most of that research, though, has been done in small-scale, controlled studies.

“I would say there’s a growing consensus,” said Taylor, who has consulted for both industry and class action lawsuits, and has done independent work for the EPA. “But there’s not a complete consensus.”

Meanwhile, combustion is a complicated process. While studies suggest that PFAS introduced to an incinerator operating at ideal conditions are unlikely to survive, that doesn’t mean harmful byproducts — including other types of PFAS compounds — won’t form at various points in the system.

“To say that the PFAS are completely destroyed is just so tricky, because you’re going to end up with some sort of fluorocarbons in the air, some sort of fluorocarbons in the ash,” said Carlson, the Colby College environmental studies professor. “Did the actual PFOS go away? Maybe. But, you know, what are you left with?”

In Taylor’s assessment, “PFAS is not difficult to destroy,” but he noted that if a unit isn’t operating under the appropriate conditions, say, at a high enough temperature or for a long enough time, “then all bets are off and you won’t get complete combustion of the material.”

That’s been backed up by research: One 2023 study sampled emissions at a plant in Sweden, which operated between 850 and 1,100 degrees Celsius, and found PFAS emissions in the exhaust, as well as other byproducts.

Further complicating matters is the fact that testing methods are limited. No tests currently exist to detect PFAS in ambient air. And, so far, only two tests exist to measure certain types of PFAS in closed containers — for example, an incinerator stack — but those tests are still being studied for efficacy. Plus, they only measure for a limited number of types of PFAS and other potential byproducts. “It’s not like you can just go out and measure these things. It’s an evolving sort of analytic playing field,” said Weitz.

“In some ways, this is a chicken and egg problem,” said Melvin Keener, the executive director of the Coalition for Responsible Waste Incineration, a nonprofit that represents companies operating hazardous waste incinerators, along with other industry members, and says that it advocates for practical regulations. “You know, what do you test for? Well, you don’t know until you test, but I don’t have any measurements to test it for, so I have to design something to test for something.”

He noted that the EPA’s two existing pilot test methods are a step in the right direction, but that overall “it’s just that this is a long, complicated process.”

The challenge, Keener said, is to find a way to destroy PFAS so that they don’t lead to additional problems. And that, he said, “is the part that the agency can’t quite get their hands wrapped around yet.”

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Against this backdrop of advancing research, incinerators in the U.S. continue to burn waste. Today, there are 75 operating facilities that process municipal waste — that includes the incinerator near Grabarek’s farm; 22 commercial hazardous waste incinerators, which burn material that is dangerous to human health or the environment; and 170 incinerator units — at 86 facilities — that burn the byproduct of wastewater treatment known as sewage sludge.

PFAS can end up at any one of those units.

If waste is known to have a high concentration of PFAS, it will typically get sent to hazardous waste incinerators, said Nathan Weber, a research fellow at the EPA’s Office of Research and Development who studies PFAS incineration. Those incinerators burn at higher temperatures. Municipal waste combustors, meanwhile, “could potentially destroy low concentrations of PFAS if they operate at high enough temperatures and are equipped with secondary combustion chambers (e.g., afterburners),” he wrote in an email to Undark. “However, a major challenge is that these facilities typically do not have precise control over the types of waste they process.”

In other words: PFAS are so common that municipal waste incinerators likely end up with at least some amount. Though Weber also noted: “We do not currently know how much PFAS exposure is due to incinerators. Under well designed operating conditions, exposure from incinerators should be negligible or none.”

Still, it’s unclear how many incinerators in the U.S. are operating under the conditions that are necessary to destroy PFAS. Many facilities weren’t designed to handle the chemicals. “These units were never built to destroy something that we didn’t know was affecting us,” said Jaimeson Sinclair, the director of the Bureau of Air Management’s Engineering Division at the Connecticut Department of Energy and Environmental Protection, or DEEP.

In Connecticut, where Grabarek lives, the incinerators aren’t permitted to account for and control PFAS emissions, in part because PFAS aren’t recognized by the EPA as an air pollutant, and thus aren’t regulated as such.

Federal mandates set the baseline for regulations, Sinclair said, but individual states can always have stricter rules based, for instance, on specific local environmental considerations: “They set the floor for what we can do.”

When it comes to PFAS in the air, EPA hasn’t yet been able to set that floor, Sinclair noted, in large part due to the limitations of existing testing methods — one of which is the ability to contextualize findings. If an incinerator were to test their stack emissions using one of the pilot tests, “We don’t have anything that says, ‘Well if you’re above X, then it’s going to hurt your lungs,’” he said. “We don’t have that right now, so you’re just testing and getting a number.”

That may be cold comfort to Grabarek, who said he has been asking state agencies to test the nearby incinerator for years now: “The Department of Environmental Protection, DEEP, and Department of Public Health, they just ignore me.”

“There’s just no way they can tell me that there’s no PFAS coming out of that stack,” he said. (Grabarek said he’s tested his well water to make sure he’s not exposed to the chemicals via his drinking water.)

In response to a request for comment, Will Healey, the director of communications at DEEP, said that agency staff have replied to Grabarek several times, and explained that the agency’s testing abilities are limited by several factors. Among them: the lack of federally approved test methods “for credible identification and quantification of emissions,” since the existing two test methods can only test for a limited number of PFAS compounds; the lack of state and federal air emissions standards; and the “lack of data regarding the health impacts of inhaled PFAS.”

However, Healey noted that “It is possible that PFAS are being emitted from the Preston Plant based on the materials burned there and limited data from other countries.”

In addition to the Reworld Waste incinerator in Preston, there’s a second incinerator about 6 miles away from Grabarek’s farm, operated by WIN Waste Innovations. Representatives from both Reworld and WIN Waste Innovations say they operate according to state permits, which require burning material for a minimum temperature of 1,800 degrees Fahrenheit, or 982 degrees Celsius, for one second, though both said the facilities regularly reach temperatures beyond that. “You can get 2,000 degrees retention time for a second, easily. So the 1,800 degrees is sort of the permit required minimum,” said Van Brunt, of Reworld Waste.

Taylor said that he would conservatively recommend incinerating at just above 2,000 degrees Fahrenheit to fully destroy any PFAS, for a period of two seconds. (Taylor said he has done consulting work for Reworld Waste, though not at their Connecticut facilities.)

Meanwhile, in its 2024 interim guidance on PFAS destruction and disposal methods, the EPA noted that “Two possible sources of PFAS emissions from thermal treatment are stack emissions and the management of scrubber water and bottom ash/fly ash.”

Linda Ribakusky, a senior communications manager at Reworld Waste, noted that the company has conducted voluntary stack testing in Pennsylvania using pilot test methods. That testing, she said, revealed “several areas of improvement in the testing procedures” though it also found that temperatures at which Reworld facilities operate are “very effective at destroying PFAS.” She acknowledged that the company has not conducted any tests at the Preston plant.

Win Waste Innovations has similarly not tested their plant in Lisbon, said Mary Urban, the senior director of communications and community: “The current testing methods are neither comprehensive nor can they verify accuracy or precision, so no, we would not use tests that have not been subject to federal rulemaking.”

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Since PFAS first emerged as a topic of public concern a couple decades ago, most attention has been paid to eliminating its presence from drinking water and halting production of the compounds in the first place.

That’s in line with DEEP’s approach, Healey wrote in an email to Undark, noting that the Connecticut agency’s policies have primarily focused on reducing the amount of PFAS that enter the environment. However, he also said that “both DEEP and EPA have developed and are in the midst of implementing PFAS action plans designed to minimize exposures to PFAS.” Once the EPA develops standards for PFAS in the air, he noted, DEEP will enforce them.

Two of the most commonly used PFAS compounds — PFOS and PFOA — have already been phased out of U.S. manufacturing. And according to one analysis by the organization Safer States, which says it seeks to protect public health by “transitioning away from harmful chemicals and holding chemical polluters accountable,” 30 states have adopted measures related to limiting or banning the use of PFAS or products that contain PFAS. But that doesn’t mean the chemicals don’t end up in U.S. waste. Products get imported from other countries with looser regulations. Waste gets shipped between states.

“All waste treatment facilities or management facilities are passive receivers of PFAS. So they’re not generators of PFAS. They’re not producing PFAS. They’re managing waste,” said Weitz. “So whatever PFAS is resulting from the processes is a result of what’s going into the facility, and that is not always well understood.”

Meanwhile, absent a surefire eradication method, PFAS produced over decades has stuck around — and more research is needed to figure out how to best address it, whether it be through destruction or secure disposal.

Weitz said that his research team at RTI International has identified two areas of study they think should be prioritized: testing at operating incineration facilities and testing for PICs, or products of incomplete combustion.

In an email, Weber, the EPA fellow, wrote: “Future research should focus on demonstrating that full-scale hazardous waste incinerators can successfully mineralize PFAS” with minimal byproducts — those products of incomplete combustion or incomplete destruction. However, he noted that “These types of studies are expensive and require extensive partnership and cooperation among thermal treatment facilities, states, and the EPA.” (Ribakusky, with Reworld Waste, wrote that the company has worked with the EPA on testing and monitoring PFAS; Urban, with WIN Waste Innovations, wrote that “we are actively supporting academic associations and regulatory agencies with data to continue efforts to better understand the needs in managing PFAS.”)

Ultimately, Keener said, it’s up to policymakers to decide what level of risk is adequate. “There is no such thing as no risk,” he said. “But it comes down to what is acceptable risk. And different people have different versions of what acceptable risk is.”

For residents like Grabarek, who says he’s received limited information on what his potential exposure may be, the slow churn of research and policymaking can be frustrating. He’s also aware of the long history of regulators ignoring citizen concerns about local PFAS contamination in drinking water.

Grabarek says he’s still waiting on the state to test the local incinerator stack. “You want me to go away? Test. Prove to me that there’s nothing there,” he said. “To me it’s so simple.”