Scientists discover the Achilles' heel (or head) of PFAS, cancer-causing chemicals
Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.
Brittany Trang led research on a new way to destroy "forever chemicals," which cause a litany of health problems, while working in William Dichtel’s chemistry lab at Northwestern University.
Brittany Trang was staring at her glass test tube, which suddenly turned opaque white. At first, she had thought that the chemical reaction she tested left behind some residue, but when she couldn’t clean it off, she realized that the reaction produced corrosive compounds that ate at the glass. That, however, was a good sign. It meant that the reaction, which she didn’t necessarily expect to work, was in fact, working. And Trang, who in 2020 was a Ph.D. researcher in chemistry at Northwestern University, had reasons to be skeptical. She was trying to break down the nearly indestructible molecules of per- and polyfluoroalkyl substances or PFAS—the forever chemicals called so because they resist heat, oil, stains, grease, and water, and thus don’t react or break down in the environment.
“The first time I ran this, I was like, oh, like there's a bunch of stuff stuck to the glass, but when I tried to clean it, it wasn’t coming off,” Trang says, recalling her original experiment and her almost-disbelief at the fact she managed to crack the notoriously stubborn and problematic molecules. “I was mostly just surprised that it worked in general.”
In the recent past, the world has been growing increasingly concerned about PFAS, the pollutants that even at low levels are associated with a litany of adverse health effects, including liver damage, thyroid disease, high cholesterol, pregnancy complications and several cancers. Used for decades in manufacturing and in various products such as fire retardant foam, water-repellant clothes, furniture fabrics, Teflon-coated pans, disposable plates, lunch containers and shoes, these super-stable compounds don’t degrade in the environment. The forever chemicals are now everywhere: in the water, in soil, in milk, and in produce.
As of June 2022, the Environmental Working Group, a nonprofit watchdog organization, found 2,858 locations in 50 states and two territories to be heavily contaminated with PFAS while many farmers had been forced to dump their milk or spinach because the levels of these compounds were in some cases up to 400 times greater than what’s considered safe. And because PFAS are so pervasive in the environment and the food we eat, they are in our bodies too. One study found some levels of PFAS in 97 to 100 percent of participants tested.
Because these compounds were made to be very stable, they are hard to destroy. So far, the only known way to break down PFAS has been to “cook” them under very harsh conditions. The process, known as pyrolysis, requires upwards of 500 degrees Centigrade, high pressure and absence of oxygen, which is energy expensive. It involves sophisticated equipment and the burning of fossil fuels. Trang, who worked in the laboratory of William Dichtel, managed to break PFAS at 120 degrees Centigrade (248 F) without using strong pressure. After she examined the results of her process with various techniques that help quantify the resulting compounds and confirmed that PFAS had indeed degraded into carbon and the corrosive fluorine that clouded her glass, she was thrilled that it worked in such simple conditions.
“That's really what differentiates our finding from everything else that's out there,” Dichtel said about their discovery at a press conference announcing the study last month. “When we're talking about low temperatures, we're at 120 degrees Celsius and sometimes even quite a bit lower than that, and especially ambient pressure.”
The process used by Trang’s team was the exact opposite of the typical organic synthesis method.
Trang’s journey into PFAS degradation began with a paper she read about the nuances of the chemicals’ molecular structure. A long molecule comprised primarily of carbon and fluorine atoms, along with oxygen and hydrogen, it has what Trang describes as a head and a tail. At the head sits a compound called carboxylic acid while the fluorine atoms make up the tail portion, with the atomic bonds so strong they aren’t possible to break without harsh treatment. But in early 2020, Trang read that a solvent called dimethylsulfoxide, or DMSO, commonly used in labs and industry, can make the carboxylic acid “pop off” its place. The DMSO doesn’t react with carboxylic acid but sort of displaces it, leaving the rest of the typically indestructible PFAS molecule vulnerable.
Trang found that its exposed fluorine tail would react with another common chemical compound, sodium hydroxide, causing a cascade of reactions that ultimately unravel the rest. “After you have decarboxylated the head, the hydroxide is able to react with the tail,” Trang says. “That's what sets off a cascade of reactions that degrades the rest of the molecule.”
That pathway took time to figure out. Trang was able to determine that the molecule carboxylic acid head popped off, but before she was able to figure out the rest, her lab and the entire Northwestern University went into lockdown in early March of 2020. “I was able to do three experiments before the shutdown,” she recalls. For the next few months, she sat at home, reading scientific literature to understand how to continue the degradation process. “I had read a bunch of literature and had a bunch of ideas for what may or may not work,” she says. By the time she could return to work, she had a plan. “I added sodium hydroxide in my batch of experiments when the lab reopened.”
The process used by Trang’s team was the exact opposite of the typical organic synthesis method. “Most organic chemists take two molecules and squish them together to make one big molecule. It’s like taking two Legos and putting them together to make one thing that was larger,” she says. “What we are doing is kind of smashing the Lego with two bits and looking at what was left to figure out how it fell apart.” The team published their discovery in the journal Science.
Although very promising, the process isn’t quite ready for industrial applications, and will take time to adapt, Trang says. For starters, it would have to be scaled up to continuously clean large quantities of water, sewage or other substances that can be contaminated with PFAS. The process will also have to be modified, particularly when it comes to removing PFAS from drinking water because as an industrial chemical, DMSO is not suitable for that. Water companies typically use activated carbon to filter out PFAS and other pollutants, so once that concentrated waste is accumulated, it would be removed and then treated with DMSO and hydroxide to break down the molecules. “That is what our method would likely be applied to,” Trang says—the concentrated waste rather than a reservoir because “you wouldn't want to mix DMSO with your drinking water.”
There are some additional limitations to the method. It only breaks down one class of forever chemicals, but there are others. For example, the molecules of perfluoroalkane sulfonic acids, or PFSA, don’t have a carboxylic head that DMSO can displace. Instead, PFSA have a sulphonic acid as their molecular head, which would require a different solvent that still needs to be discovered. “There is certainly the possibility of activating sulphonates in similar ways [to what] we've done [with] carboxylates,” Dichtel said, and he hopes this will happen in the future. Other forever chemical types may have their own Achilles’ heels, waiting to be discovered. “If we can knock that sulphonated headgroup off the molecule and get to the same intermediates we get to in this study,” Dichtel added, “it's very reasonable to assume that they'll degrade by very similar pathways.” Perhaps another team of inquisitive chemists will take on the challenge.
Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.
Here's how one doctor overcame extraordinary odds to help create the birth control pill
Dr. Percy Julian had so many personal and professional obstacles throughout his life, it’s amazing he was able to accomplish anything at all. But this hidden figure not only overcame these incredible obstacles, he also laid the foundation for the creation of the birth control pill.
Julian’s first obstacle was growing up in the Jim Crow-era south in the early part of the twentieth century, where racial segregation kept many African-Americans out of schools, libraries, parks, restaurants, and more. Despite limited opportunities and education, Julian was accepted to DePauw University in Indiana, where he majored in chemistry. But in college, Julian encountered another obstacle: he wasn’t allowed to stay in DePauw’s student housing because of segregation. Julian found lodging in an off-campus boarding house that refused to serve him meals. To pay for his room, board, and food, Julian waited tables and fired furnaces while he studied chemistry full-time. Incredibly, he graduated in 1920 as valedictorian of his class.
After graduation, Julian landed a fellowship at Harvard University to study chemistry—but here, Julian ran into yet another obstacle. Harvard thought that white students would resent being taught by Julian, an African-American man, so they withdrew his teaching assistantship. Julian instead decided to complete his PhD at the University of Vienna in Austria. When he did, he became one of the first African Americans to ever receive a PhD in chemistry.
Julian received offers for professorships, fellowships, and jobs throughout the 1930s, due to his impressive qualifications—but these offers were almost always revoked when schools or potential employers found out Julian was black. In one instance, Julian was offered a job at the Institute of Paper Chemistory in Appleton, Wisconsin—but Appleton, like many cities in the United States at the time, was known as a “sundown town,” which meant that black people weren’t allowed to be there after dark. As a result, Julian lost the job.
During this time, Julian became an expert at synthesis, which is the process of turning one substance into another through a series of planned chemical reactions. Julian synthesized a plant compound called physostigmine, which would later become a treatment for an eye disease called glaucoma.
In 1936, Julian was finally able to land—and keep—a job at Glidden, and there he found a way to extract soybean protein. This was used to produce a fire-retardant foam used in fire extinguishers to smother oil and gasoline fires aboard ships and aircraft carriers, and it ended up saving the lives of thousands of soldiers during World War II.
At Glidden, Julian found a way to synthesize human sex hormones such as progesterone, estrogen, and testosterone, from plants. This was a hugely profitable discovery for his company—but it also meant that clinicians now had huge quantities of these hormones, making hormone therapy cheaper and easier to come by. His work also laid the foundation for the creation of hormonal birth control: Without the ability to synthesize these hormones, hormonal birth control would not exist.
Julian left Glidden in the 1950s and formed his own company, called Julian Laboratories, outside of Chicago, where he manufactured steroids and conducted his own research. The company turned profitable within a year, but even so Julian’s obstacles weren’t over. In 1950 and 1951, Julian’s home was firebombed and attacked with dynamite, with his family inside. Julian often had to sit out on the front porch of his home with a shotgun to protect his family from violence.
But despite years of racism and violence, Julian’s story has a happy ending. Julian’s family was eventually welcomed into the neighborhood and protected from future attacks (Julian’s daughter lives there to this day). Julian then became one of the country’s first black millionaires when he sold his company in the 1960s.
When Julian passed away at the age of 76, he had more than 130 chemical patents to his name and left behind a body of work that benefits people to this day.
Therapies for Healthy Aging with Dr. Alexandra Bause
My guest today is Dr. Alexandra Bause, a biologist who has dedicated her career to advancing health, medicine and healthier human lifespans. Dr. Bause co-founded a company called Apollo Health Ventures in 2017. Currently a venture partner at Apollo, she's immersed in the discoveries underway in Apollo’s Venture Lab while the company focuses on assembling a team of investors to support progress. Dr. Bause and Apollo Health Ventures say that biotech is at “an inflection point” and is set to become a driver of important change and economic value.
Previously, Dr. Bause worked at the Boston Consulting Group in its healthcare practice specializing in biopharma strategy, among other priorities
She did her PhD studies at Harvard Medical School focusing on molecular mechanisms that contribute to cellular aging, and she’s also a trained pharmacist
In the episode, we talk about the present and future of therapeutics that could increase people’s spans of health, the benefits of certain lifestyle practice, the best use of electronic wearables for these purposes, and much more.
Dr. Bause is at the forefront of developing interventions that target the aging process with the aim of ensuring that all of us can have healthier, more productive lifespans.
