Saturday, October 1, 2022

A new way to smash the ‘forever’ out of ‘forever chemicals’

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“Forever chemicals” have a reputation for being indestructible, persistent, and just about everywhere — including many places where they shouldn’t be, like our drinking water.

But now, there’s excitement about a new way to essentially smash these molecules to bits so that they don’t cause environmental and health problems. It’s described in research published today in the journal Science. There are caveats to the process, but to many experts’ delight, it’s surprisingly simple for such a tough substance.

“It truly goes against everything I’ve known for the past 10 years. And that’s really cool because someone else can then take this information and exploit it and adapt it to technologies that we need,” says Shira Joudan, an environmental chemist and postdoctoral researcher at York University who is one of the authors of an accompanying perspective on the new research in Science.

The pervasive chemicals are per- and polyfluoroalkyl substances, more commonly known as PFAS. They were once believed to be so harmless that they’ve gone into everything from fast food wrappers to non-stick pans, but lately, there’s growing concern about how those chemicals might harm people and the environment. There are many different kinds of PFAS, but their defining trait is that they don’t break down easily — not in the environment and not even in tough conditions like very high temperatures. That resilience has made PFAS sought-after for all kinds of applications since the 1950s, like making things water and stain resistant or to quelch blazes when applied in a firefighting foam.

PFAS get their molecular strength from the particularly hardy bond between carbon and fluorine within the chemical structure of all 9,000 or so different kinds of the chemical. That’s what essentially puts the “forever” in “forever chemicals.” To get rid of PFAS, researchers are trying to figure out how to break those bonds. But it typically takes a lot of effort — like incinerating them at above 700 degrees Celsius (1,292 degrees Fahrenheit).

What’s so surprising about the new research is that it found a way to use a fraction of that energy to rip those bonds apart. The authors of the new study found that by adding a commonly used industrial solvent and sodium hydroxide (the chemical found in lye) to a certain class of PFAS, the molecules start to fall apart when heated to between 80 to 120 degrees Celsius (176 to 248 degrees Fahrenheit). That doesn’t take much more energy than boiling a pot of water.

The process breaks down the PFAS into six different byproducts that experts tell The Verge are relatively benign. Five of those are found in nature and might even be ingredients you’d see in toothpaste and face wash. The sixth leftover product, trifluoroacetate, still has those pesky carbon-fluorine bonds, but it’s not as risky as PFAS. Ultimately, all those broken down pieces could be turned into rock or otherwise disposed of safely — unlike PFAS, which has the tendency to leak out of landfills and potentially even persist in the air after being incinerated.

It’s no wonder then that forever chemicals easily found their way from food packaging, Teflon pans, dental floss, and tap water into human bodies. By the 1990s, national blood sampling performed by the CDC had discovered PFAS in more than 98 percent of Americans tested. It’s also been found in water sources, fish, and soil across the US. And while that pollution is often found in low levels, it’s also more concentrated in many areas around military bases and factories that used PFAS heavily (in firefighting foam and manufacturing).

Despite evidence of what the CDC describes as “widespread chemical exposure,” research on what that exposure does to human health and environment has lagged. So have efforts to regulate the use of forever chemicals. The EPA just issued health advisories in June on how much PFAS it considers to be safe in drinking water, after years of environmental and health advocates pushing for more regulation. Those advisories are essentially still just non-binding recommendations to federal, state, and local officials. But they’ve already sparked a legal challenge by industry.

Scientists are still trying to better understand how widespread PFAS are and what threats the chemicals might pose. But high levels of PFAS have been linked to a higher risk of certain kinds of cancer, liver damage, increased cholesterol, as well as reproductive health risks like higher blood pressure in pregnant women and lower infant birth weights. As a result, some companies have already turned away from using the most common types of PFAS, but now there are similar concerns about replacement chemicals called GenX.

“The [forever] chemicals we already have released will be with us for millennia. This is a mistake that we’ve made that will linger for generations already,” says Rolf Halden, director of the Biodesign Center for Environmental Health Engineering at Arizona State University. “So it is not too late and certainly not too soon to consider how much we put out and how we capture and destroy these chemicals.”

While the new research published in Science today is promising, there’s still a long way to go from research to real-world action. For starters, the forever chemicals need to be filtered out of water, soil, or otherwise taken out of wherever they’ve wound up before they can go through this kind of destructive chemical reaction.

Plus, this newly found process for degrading forever chemicals doesn’t successfully destroy every kind of PFAS. (Bear with me here — we’re about to get into a bunch of annoyingly similar acronyms.) The new process attacks what are known as perfluoroalkyl carboxylic acids (PFCAs). Thankfully, that does include one of the most commonly found kind of forever chemical: perfluorooctanoic acid (PFOA). Many other types of forever chemicals do eventually break down into a kind of PFCA over time, and then this new research could apply to them.

The other neat thing about this research is that it gives other scientists looking for ways to destroy PFAS a better understanding of how to tear them apart. “If you had a Lego and you smashed it to bits, you could do kind of a structural analysis of how it fell apart,” says Brittany Trang, lead author of the new Science paper.

“We cannot ask for one single paper to solve everything. But I will say that the [study] will be very helpful to teach or guide so many of PFAS degradation technology researchers to think about how they can further improve their system because mechanistic understanding is very, very important,” says Jinyong Liu, an assistant professor at the University of California, Riverside who published a paper with other researchers earlier this year on another potential method for destroying PFAS that uses ultraviolet light and sulfite.

“I would say [the new study] adds another tool to the arsenal that’s emerging to be able to destroy [PFAS],” says Timothy Strathmann, a professor at the Colorado School of Mines who has researched using hydrothermal technology to degrade PFAS. Ultimately, an entire armory of methods might have to be mobilized to clean up the big mess PFAS has left behind.

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