Firefighting foam — and the products of combustion — have long been known to pose dangers to firefighters’ health. In the last few years, groups of firefighters across the country have sounded the alarm over carcinogenic chemicals contained in their gear. Some have taken legal action.

Dubbed ‘forever chemicals,’ perfluoroalkyl and polyfluoroalkyl substances, or PFAS, are a group of synthetic compounds that breakdown slowly in the environment and the human body, and have been linked to cancer.

PFAS are used in textiles to repel water and oil, and have been found in clothing, raincoats, stain-resistant carpets, cosmetics and food packaging.

PFAS also are used in the outer layer and moisture barrier of firefighting gear, helping create a material that both protects firefighters from flames and ensures breathability.

“The concern with that is the repeated exposure and direct skin-to-skin contact with those chemicals in our gear,” said Scott Frederick, director of emergency services for Butler Township who oversees the Butler Township Volunteer Fire District.

In 2022, a health advisory issued by the U.S. Environmental Protection Agency said that even in very low concentrations, PFAS pose a hazard to human health.

The compounds absorb into the skin, eventually making their way to the liver or kidneys to be metabolized, said Ryan Sullivan, associate professor of chemistry and mechanical engineering at Carnegie Mellon University in Pittsburgh.

“Some of the established health effects are that they are carcinogens, especially for bladder cancer,” Sullivan said. “They interfere with the function of the liver because they tend to accumulate in the liver.

“More recently, a very, very disturbing discovery is that they also impact our immunity, so they can reduce the immune response we acquire from a vaccine, for example.”

So far, PFAS in firefighting gear is an issue mostly discussed at the national level.

Butler Bureau of Fire Chief Chris Switala said it is something the department is continuing to learn about and monitor.

“There’s not a lot of data yet on how much exactly is actually present in firefighter gear,” Switala said “Not a lot is known right now on how much of the chemicals lead to exposure to the firefighter wearing (gear).”

Firefighting gear is made up of three layers: a thermal lining, a moisture barrier and an outer shell. PFAS are present in the moisture barrier and outer shell of gear, Switala said.

Switala said PFAS help strike a balance between thermal protection and breathability. The chemicals help with moisture resistance; without them, gear can become bulky, restrictive and not as comfortable to wear, he said.

“Nobody wants to be operating on a high-temperature day in a set of gear that is so bulky and doesn’t let you breathe,” Switala said. “That can contribute to other issues (such as) the firefighter going down due to heat exhaustion. All those (considerations) come into play.”

Guidelines for firefighting gear are set by the National Fire Protection Association, making it difficult for fire departments to issue their own guidance.

“You can’t really buy a set of gear that isn’t certified to meet (association) standards,” Switala said. “No one will sell you that gear because of liability issues.”

The revelation about PFAS in firefighters’ gear sparked a campaign by firefighters to find safer alternatives and to hold companies that manufacture the gear accountable.

Lawsuits on behalf of firefighters argue they were exposed to significant PFAS levels and that companies knew the gear contained PFAS that could cause serious health problems for wearers. The suits also allege companies misrepresented their products as safe.

The International Association of Fire Fighters, which represents more than 340,000 U.S. and Canadian firefighters, decided in 2021 to no longer accept sponsorships or advertising from the chemical industry and to oppose PFAS in gear. A Congressional bill introduced in July would accelerate the search for safer alternatives and support firefighter training to reduce exposure from existing gear.

Seven states including Washington, New Hampshire and New York passed bills requiring companies to disclose PFAS in their gear, according to Safer States, a coalition of environmental health groups. Several more states introduced or enacted bills this year that provide funds to purchase PFAS-free gear or prohibit the manufacture or sale of gear containing the chemicals, according to Emily Sampson, an environment policy analyst at the National Conference of State Legislatures.

Some companies are promoting a PFAS-free outer layer, but that doesn't solve the problem because the other two layers still contain PFAS, according to the international association.

Among the hurdles, according to an international association lawsuit filed in March, is that the National Fire Protection Association standard for gear can only be met with PFAS-infused material. The suit accuses the national association of working with several gear makers to maintain that requirement. It seeks damages and an end to the standard.

“It’s a pretty well accepted at this point that firefighters have higher levels (of PFAS) in their blood serum,” said Carrie McDonough, assistant professor of chemistry at Carnegie Mellon University.

Fire departments are considering alternative ways firefighters can minimize the time they are exposed to carcinogens that are present in firefighter foam, soot, smoke and, as firefighting departments have discovered, gear.

Switala said there can be a lot of exposure on turnout gear (a widely used, alternate term for gear — simply the protective clothing worn by firefighters). Switala said firefighters must abide by rules to minimize exposure from toxins.

“You take your hood off a certain way, you take your gear off, wipe areas of your body at risk of exposure like your neck, and then before you (get in the fire truck) you take your gear off; you hose and rinse it completely off,” said Mike Pflugh, Unionville Volunteer Fire Company chief. “And don’t eat before you get in the shower; that decreases the chance of ingesting a carcinogen.”

Some fire departments, like Unionville, have an additional set of rescue gear not intended for interior firefighting.

That is something the Butler Bureau of Fire is considering, Switala said. The bureau, like most fire departments, offers its firefighters two sets of structured gear: one clean set can be worn when the other is being cleaned. At this time, both sets issued to firefighters are structure fire gear, Switala said.

Purchasing another set of gear that could be used during rescue calls or brush fires could help minimize exposure to PFAS, he said, but it would come at a high cost and would require firefighters to carry both sets of gear at all times.

While it doesn’t come close to the cost of a fire truck or breathing apparatus, purchasing gear is a big expense, Pflugh said.

Frederick said gear at Butler Township fire district costs upward of $4,000 per firefighter and is the department’s largest recurring expense from year to year.

Carla Ng, associate professor of civil and environmental engineering at the University of Pittsburgh, said researchers are trying to understand whether exposure to PFAS in firefighting gear occurs by absorbing the compounds, or whether they can be breathed in when gear is exposed to high heat or abrasion.

“Firefighters are exposed to very high temperatures when they’re fighting the fires and that can liberate or make the PFAS in that layer more mobile and might accelerate the transfer of the PFAS onto the firefighters,” Sullivan said.

McDonough shared that one of the roadblocks researchers face is quantitatively measuring PFAS when there are thousands of such substances.

“It’s really difficult to measure them quantitatively, if we don’t have the actual compound to analyze,” McDonough said.

The compounds are persistent and ubiquitous, moving through the environment between organisms and accumulating up the food web, Sullivan said.

On top of “legacy PFAS” (those from years ago), compounds continue to be released and put into use, he said, adding fuel to the fire.

“(PFAS) don’t breakdown in the environment,” Ng said. “So every use we have of PFAS, once they’re released, they stick around.

“What everyone needs to understand about PFAS is they’re in pretty much everything,” McDonough said. “They’re found in more than 99% of people’s blood, in drinking water. There have been reports recently that (PFAS) are in 50% of drinking water and they’re in a lot of consumer products. Low-level exposure is something we should all be concerned with.”

McDonough’s students are currently analyzing samples of turnout gear in the lab to see “what might leech out,” she said.

“Turnout (gear) can be a vehicle for a lot of different things,” McDonough said.

Some exposure is known to come from retardants, firefighting foam and products of combustion, but there are likely other sources, as well, she said.

McDonough said she is mostly concerned with PFAS given not much is known about the compounds.

“These molecules … all have a carbon-fluorine ‘tail,’ which is difficult to degrade by natural processes. These things are extremely persistent in the environment; because of that, it’s important to realize how little we know about their biological impact,” McDonough said.

“Maybe we shouldn’t be releasing compounds that don’t degrade when there’s so much we don’t understand about how they interact with the body,” she said.

The Associated Press contributed to this report.