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Scientists find new way to break down dangerous 'forever chemicals'

Two figures in silver protective suits spray foam from a hose
A1C Nathaniel G. Bevier, USAF
PFAS are used in firefighting foams used to put out jet fuel fires.

Per- and polyfluoroalkyl substances, or PFAS, are a large class of human-made chemicals used in many everyday products. Characterized by strong bonds between carbon and fluorine atoms, PFAS are difficult to degrade.

While their stability makes them useful, they’ve become known as “forever chemicals” because they persist in the environment, contaminating wastewater and biological materials. Scientists recently published a novel method to degrade PFAS using relatively common and safe chemicals.

William Dichtel, Professor of Chemistry at Northwestern University and one of the paper’s co-authors, said PFAS were in general use by the 1950s and ‘60s.

"So they are in a lot of consumer products, such as food packaging, as water and oil barriers. They are in dental floss and makeup and many other things," Dichtel said.

"They are used because they are thermally resistant, so temperature resistant. They are used in waterproofing applications. They're used in, unfortunately, fast food wrapping so that the grease from the food didn't show up in the wrappings," Ryan Dupont said. Dupont is a Civil and Environmental Engineering professor at Utah State University. He studies contamination from chemicals like PFAS in the environment.

One of PFAS’ main applications is in firefighting foams used to put out major fires, Dichtel said.

"And especially jet fuel fires. So PFAS are often found contaminating communities around airports, military bases and other places with a lot of industrial activity," Dichtel explained.

Chemicals can enter the environment through water runoff, industrial waste and sewage. Some PFAS bioaccumulate, or build up, in an organism. This means fish and other food sources living in contaminated water could have dangerous levels of these chemicals.

In Dupont’s role as a scientist with USU’s Water Research Laboratory, he studies wastewater contaminants in Cache Valley.

"We don't have a lot of industry. Our setting is common to a lot of places, particularly in the Intermountain West," Dupont said. "And so we're interested in how our levels of exposure, the levels of contaminants in our water and biosolids, compare to other places that have much, much higher concentrations because of firefighting foams and heavy industrial processes that use these compounds."

Dupont said concentrations of PFAS found in wastewater around Cache Valley are comparable to concentrations found in large cities like San Francisco or Chicago.

"So we're getting exposed to these things from all different kinds of settings, whether we're in a highly industrialized area or not," Dupont warned. "Most of what we're seeing in wastewater is actually from just personal use consumer products."

A broken regulatory system

Chronic exposure to low levels of PFAS has been linked to many adverse health effects, including thyroid disease, liver damage, high cholesterol, reduced immune responses, low birth weights and several cancers. Dichtel said this is no surprise.

"PFAS manufacturers have known or strongly suspected that exposure to these chemicals would cause major harm in humans and many animals. And they hid that knowledge from the public for decades," Dichtel explained. "And unfortunately, they did that because they were making so much money selling them, that they did not want to stop doing them."

Dupont said PFAS levels in water are not regulated yet, but the suggested allowable levels would be minuscule.

"It's like parts per trillion. … So the concentrations of these materials that are considered to be potentially harmful are extremely low," Dupont said.

Dichtel said that the way chemicals are used and introduced to the U.S. market is fundamentally broken.

"Because the burden of proof of safety is really on the regulatory side, not on the manufacturer. … Even today, if you introduce a new PFAS compound, and there are many thousands of them, there's no real burden of proof that that particular substance is safe," Dichtel said.

He said instead what happens is when a certain PFAS is close to regulation, manufacturers replace it with a different one.

"So it's this game of Whack-a-Mole, where really the burden of proof should be on the manufacturer that wants to use a new PFAS, to show that it's safe. And unfortunately, I don't believe that any of them are really definitively proven to be safe," Dichtel said.

A partial solution?

Dichtel and his collaborators discovered a way to break down PFAS under relatively mild conditions. They combined DMSO, a common solvent used in organic chemistry, and sodium hydroxide or lye, which is used to make soap. When these chemicals are mixed with PFAS, the strong carbon-fluorine bonds break down and the atoms are released in forms that are safe for the environment. Dichtel said this is a promising development but not a complete solution to the problem.

"First, this method, and other PFAS destruction methods are very unlikely to be applied to all of our drinking water," Dichtel said. "There's promising aspects in that we're using inexpensive chemicals, we're doing this reaction at low temperatures. … So all of those things bode well, for it being eventually scaled up. But there are also limitations that still would need to be overcome."

While Dupont said Utah’s drinking water is not contaminated with PFAS, the accumulation of these chemicals in wastewater is a cause for concern.

"There's a competing concern here because we want to try to reuse that water as much as possible, right?" Dupont said. "But we have to be careful about all of these chemicals that we discharge into that sewer, just from human waste, because of the things that we use and get exposed to."

Dichtel said the use of PFAS should be limited to only the most necessary applications.

"Is it worth destroying our environment and giving others cancer so that we can have a slightly better pizza box?"
William Dichtel, Professor of Chemistry at Northwestern University

"These things do not need to be in pizza boxes, they do not need to be in microwave popcorn bags, they do not need to be in makeup, they do not need to be in dental floss, they do not need to be in you know all of these products where we like their properties and it's convenient. But at what cost, right?" Dichtel asked. "Is it worth destroying our environment and giving others cancer so that we can have a slightly better pizza box?"

Dupont agrees that the only solution is to stop using PFAS wherever possible.

"Because once they're produced, they move around in the environment, we get exposed to them and then we potentially have problems," Dupont said.

Dichtel and his collaborators published their discovery in the journal Science on August 18, 2022. While Dichtel is optimistic about the implications of their research, he said environmental contamination from chemicals like PFAS is a global issue.

Caroline Long is a science reporter at UPR. She is curious about the natural world and passionate about communicating her findings with others. As a PhD student in Biology at Utah State University, she spends most of her time in the lab or at the coyote facility, studying social behavior. In her free time, she enjoys making art, listening to music, and hiking.