PFAS: An old substance requiring a new definition

It must take a really large umbrella to provide cover for 10,000 chemicals.

At least that's what some in the rubber industry think the European Chemical Agency (ECHA) is trying to do with its proposed outright ban on the per- and polyfluoroalkyl substances commonly known as PFAS.

But many argue that lumping all PFAS together in proposing this blanket ban within the European Union is unfair, and will harm the industry if adopted as currently constructed.

What would they like to see as a cure, you ask?

Nothing short of a new definition, one that doesn't lump the PFAS polymers in the fluoroelastomers and fluoropolymer world—which they contend are known to be safe.

Taking it down to its base, PFAS is a "diverse group of chemistries characterized by the strong bond between fluorine and carbon," according to the American Chemistry Council. Because of this strong bond—characterized as the strongest bond in organic chemistry—PFAS provides products with "strength, durability, stability and resilience."

These are properties that have made them highly sought after in a broad range of critical uses. FKMs and fluoropolymers are used in high-end applications across automotive, aerospace, electronics, chemical processing, semiconductor manufacturing and medical uses, among many others.

And because these materials have long been found to be safe in these uses, separating them from PFAS materials that have potential to do harm is paramount.

"The biggest problem right now is defining what PFAS is," said Bill Stahl, who is consulting under the WMS Technologies banner after retiring recently from Rainbow Master Mixing L.L.C. "A lot of the rules and regulations are defining PFAS as any fluorinated-type chemical, or carbon-fluorine chemical. And that's what the European regulators are going after."

Tony Furio, technical director of Pinnacle Elastomeric Technology, said PFAS is very generalized, a term used to encompass such a wide range of chemicals.

"I don't like using the term PFAS," he said. "For our purposes, we deal strictly with fluoropolymers, which is a generalized PFAS, but is not one of the more dangerous, low-molecular weight, short-chain chemicals that are what's causing all of the concerns."

Fluoropolymers, by contrast, are a very high molecular weight compared to the substances that have been identified as potential bad actors.

"There is a list of substances of high and low concern when it comes to PFAS," Furio said. "Fluoropolymers were identified as materials of very low concern, because of the physical form. It's in a solid state. It doesn't dissolve into the water supply. When vulcanized, it's a solid piece of material."

Joe Walker, who retired earlier this spring from Freudenberg-NOK Sealing Technologies and now is a consultant under the Elastomer Technologies moniker, said he agrees the distinction should be made between the liquid and solid forms of PFAS materials.

He gave a presentation last year at the U.S. Council for Automotive Research where he emphasized that groundwater contamination does not occur from cured FKM rubber parts. And he referenced a prior study that detailed the phase change when a PFAS left the liquid phase and became a solid.

"When it's a solid phase, the PFAS intermediate process chemicals are trapped in that matrix, and they just simply aren't mobile," Walker said. "They just don't come out, in conditions in a landfill or in normal environment.

"It takes an extraordinary amount of effort to liberate those things. That was my approach. I don't diminish the effect of PFAS, but let's redefine what we're trying to prevent here," he said. "You're not trying to prevent the use of Teflon. You're trying to eliminate the contamination of our water and soil. I think if they would just revise that definition to a simpler one, it would be a lot more relief."

In its presentation when the proposed restriction of PFAS was announced earlier this year, the ECHA said the definition of PFAS was based on its chemical structure.

It said the "forever chemicals"—as they are known because they stay in the environment for years—are known for their persistence, and that potentially leads to harmful effects in humans and in the environment.

There are an estimated 230,000 metric tons of PFAS placed on the market every year, according to the ECHA, and there are some PFASs that were found to be carcinogens or cause harm to unborn children and have a detrimental effect on organs. PFOA and PFOS, for example, are no longer produced in the U.S.

The authors of the proposed restriction, which is in the comment stage until Sept. 25, said the measure was made purposely broad for a number of reasons, including that PFAS can be found almost everywhere.

"There are concerns growing about the whole group of PFAS, not just those on which we have good knowledge," a presenter said when the measure was unveiled. "... With this restriction we are putting forward, we want to address the problem on a large scale. We think it's way more efficient to do this in a group approach. Address it all now in one go, rather than the prior ones that were done one by one."

Those in the rubber industry who are making or using FKMs and other fluoropolymers disagree with this assessment.

The non-polymers have ended up in drinking water, said Phil Mahoney, director of engineering services for sealing device firm A.W. Chesterton and chair of government affairs and the PFAS task force for the Fluid Sealing Association.

"The fluoropolymers and fluoroelastomers are regarded as safe," he said. "They are large molecules. They don't pass through cell membranes. They are 'forever chemicals' in the sense they all are, because it's hard to break that carbon-fluorine bond.

"... The problem is society is hearing about PFAS, and assuming that all of these are bad. Our argument is we have data to show that these are not the problems."

Mahoney didn't pull any punches in calling the ECHA's proposal to ban all PFAS as "ludicrous."

And A.W. Chesterton also does business in Europe, so it has a vested interest in how that measure progresses.

"There are other chemicals we use in processing like benzene, chlorine, other dangerous materials," he said. "They are not bio-persistent, but the point being that they are dangerous and we do regulate those."

William Heslip, regulatory compliance stewardship manager for Freudenberg-NOK Sealing Technology, said most industry associations from the U.S. and Europe are pushing back hard in the broad approach taken with the proposed PFAS ban, which is proceeding under the EU's REACH Regulation. During the April webinar, one person asked why there was no separation between polymeric and non-polymeric PFAS.

"In that instance, they said they are aware of these concerns, but to them the polymers, even though they don't migrate or pose as high of a risk from a health hazard or environmental hazard standpoint, they still last a very long time," Heslip said. "So they still wanted them on the restriction list because of that.

"They aren't the ones who make the final decision, but they are the ones who brought forth the issue and are trying to have it turn into law. If it went through as proposed, the impact would be immeasurable."

And as the ECHA proposal takes its slow slog through the regulatory process, it is imperative that those in the FKM and fluoropolymer sector remind those considering the ban that it really is a question of definition, according to Konrad Saur, Trelleborg Sealing Solutions vice president of innovation and technology.

The restriction proposal is painting everything that has a fully fluorinated carbon, including fluorocarbons, with the same broad brush. But he said FKMs are inert and are used in highly demanding applications that involve extreme temperatures, high pressure and aggressive media because they don't degrade.

"I think we have to be very frank, that some of these lower molecular weight PFASs are really worrying substances," Saur said. "There is evidence that they have adverse environmental effects. There is scientific research that suggest evidence of adverse human health impacts. We should not negate that.

"But we should not draw the umbrella too big, because really, chemically we're talking about different profiles of chemicals."