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Scientists Achieve the Impossible, Safely Destroy Toxic ‘Forever Chemicals’

They’re flowing through our kitchen faucets, buried in our soil, and embedded in the food we eat every day. Anywhere you look, we’re drowning in so-called forever chemicals, or PFAS (per- and polyfluoroalkyl substances). 

These substances were originally developed in the 1940s to make life easier by creating non-stick cookware, waterproof clothing, and stain resistant furniture. Yet the same tough chemistry that made these feats possible also made it nearly impossible for these chemicals to degrade naturally after they were used up. Worse yet, research in the decades since the introduction of PFAS to our daily life has found that even low-level exposure to the chemicals over a sustained amount of time can lead to serious health effects, including thyroid disease, reduced immune response, and several cancers

Existing approaches to destroying these chemicals can be harsh—for example, incineration—and require a lot of energy to carry out and may even spread PFAS across communities. In a new paper published Thursday in the journal Science, a team of researchers have uncovered a new way to dispose of a class of these chemicals under comparatively mild conditions, including ambient pressure and temperatures as low as 176 degrees Fahrenheit.

William Dichtel is a lead author on the paper and a professor of chemistry at Northwestern University. He said in a press conference about the work on Tuesday that one of the exciting benefits of this discovery is that the reaction leaves no damaging products in its wake.

“We were pleased to find a relatively low temperature, low energy input method where the one specific portion of these molecules falls off and sets off a cascade of reactions that ultimately breaks these PFAS compounds down to relatively benign products including fluoride ions… that are in many cases found in nature already and do not pose serious health concerns.”

In particular, Dichtel and colleagues focused on a class of PFAS called PFCAs, which is a final form that many other PFAS degrade into over time.

Brittany Trang is the first author on the new paper and carried out a majority of the experiments. She said at the press conference that in order to understand how to break down these chemicals, she and colleagues needed to use unconventional techniques to study them. 

“Most synthetic organic chemists are taking two molecules and squishing them together to make one big molecule, like taking two Legos and putting them together to make one larger thing,” Trang said. “But instead, what we were doing was smashing the Legos to bits and looking at what was left to figure out how it fell apart.”

For Trang and colleagues, studying the destruction of these chemical “Legos” meant studying the concentration of ions and magnetic resonance of their resulting samples. Through experimentation and computational analysis done by colleagues at the University of California, Los Angeles, the team determined that the chemical breakdown was started by the decarboxylation of acids groups when the PFCAs were exposed to a common solvent called DMSO (dimethyl sulfoxide). They also found that a secondary solvent, sodium hydroxide or lye, helped complete the reaction by breaking down secondary compounds into non-harmful, organic molecules. 

It is still unknown whether other PFAS will have similar pathways to degradation, but Ditchel told Motherboard that they’re currently working to understand what those differences might be. 

For now, this approach is not yet ready to be put into action against PFAS worldwide, but the team said that when that time comes it would likely be part of a collaborative approach to degrading PFAS that first starts with collecting them in a concentrated amount before applying their solvents. Regardless of the role this method ultimately plays in the eradication of PFAS, Dichtel says he’s excited to contribute to solving such an important problem.

“It feels very meaningful to work on such an important problem that faces society,” Dichtel said. “Even though I don’t pretend that this is the final solution, it is why I do science—to have a positive impact on the world.” 

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