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 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.
This man spent over 70 years in an iron lung. What he was able to accomplish is amazing.
It’s a sight we don’t normally see these days: A man lying prone in a big, metal tube with his head sticking out of one end. But it wasn’t so long ago that this sight was unfortunately much more common.
In the first half of the 20th century, tens of thousands of people each year were infected by polio—a highly contagious virus that attacks nerves in the spinal cord and brainstem. Many people survived polio, but a small percentage of people who did were left permanently paralyzed from the virus, requiring support to help them breathe. This support, known as an “iron lung,” manually pulled oxygen in and out of a person’s lungs by changing the pressure inside the machine.
Paul Alexander was one of several thousand who were infected and paralyzed by polio in 1952. That year, a polio epidemic swept the United States, forcing businesses to close and polio wards in hospitals all over the country to fill up with sick children. When Paul caught polio in the summer of 1952, doctors urged his parents to let him rest and recover at home, since the hospital in his home suburb of Dallas, Texas was already overrun with polio patients.
Paul rested in bed for a few days with aching limbs and a fever. But his condition quickly got worse. Within a week, Paul could no longer speak or swallow, and his parents rushed him to the local hospital where the doctors performed an emergency procedure to help him breathe. Paul woke from the surgery three days later, and found himself unable to move and lying inside an iron lung in the polio ward, surrounded by rows of other paralyzed children.
Hospitals were commonly filled with polio patients who had been paralyzed by the virus before a vaccine became widely available in 1955. Associated Press
Paul struggled inside the polio ward for the next 18 months, bored and restless and needing to hold his breath when the nurses opened the iron lung to help him bathe. The doctors on the ward frequently told his parents that Paul was going to die.But against all odds, Paul lived. And with help from a physical therapist, Paul was able to thrive—sometimes for small periods outside the iron lung.
The way Paul did this was to practice glossopharyngeal breathing (or as Paul called it, “frog breathing”), where he would trap air in his mouth and force it down his throat and into his lungs by flattening his tongue. This breathing technique, taught to him by his physical therapist, would allow Paul to leave the iron lung for increasing periods of time.
With help from his iron lung (and for small periods of time without it), Paul managed to live a full, happy, and sometimes record-breaking life. At 21, Paul became the first person in Dallas, Texas to graduate high school without attending class in person, owing his success to memorization rather than taking notes. After high school, Paul received a scholarship to Southern Methodist University and pursued his dream of becoming a trial lawyer and successfully represented clients in court.
Paul Alexander, pictured here in his early 20s, mastered a type of breathing technique that allowed him to spend short amounts of time outside his iron lung. Paul Alexander
Paul practiced law in North Texas for more than 30 years, using a modified wheelchair that held his body upright. During his career, Paul even represented members of the biker gang Hells Angels—and became so close with them he was named an honorary member.Throughout his long life, Paul was also able to fly on a plane, visit the beach, adopt a dog, fall in love, and write a memoir using a plastic stick to tap out a draft on a keyboard. In recent years, Paul joined TikTok and became a viral sensation with more than 330,000 followers. In one of his first videos, Paul advocated for vaccination and warned against another polio epidemic.
Paul was reportedly hospitalized with COVID-19 at the end of February and died on March 11th, 2024. He currently holds the Guiness World Record for longest survival inside an iron lung—71 years.
Polio thankfully no longer circulates in the United States, or in most of the world, thanks to vaccines. But Paul continues to serve as a reminder of the importance of vaccination—and the power of the human spirit.
““I’ve got some big dreams. I’m not going to accept from anybody their limitations,” he said in a 2022 interview with CNN. “My life is incredible.”
When doctors couldn’t stop her daughter’s seizures, this mom earned a PhD and found a treatment herself.
Twenty-eight years ago, Tracy Dixon-Salazaar woke to the sound of her daughter, two-year-old Savannah, in the midst of a medical emergency.
“I entered [Savannah’s room] to see her tiny little body jerking about violently in her bed,” Tracy said in an interview. “I thought she was choking.” When she and her husband frantically called 911, the paramedic told them it was likely that Savannah had had a seizure—a term neither Tracy nor her husband had ever heard before.
Over the next several years, Savannah’s seizures continued and worsened. By age five Savannah was having seizures dozens of times each day, and her parents noticed significant developmental delays. Savannah was unable to use the restroom and functioned more like a toddler than a five-year-old.
Doctors were mystified: Tracy and her husband had no family history of seizures, and there was no event—such as an injury or infection—that could have caused them. Doctors were also confused as to why Savannah’s seizures were happening so frequently despite trying different seizure medications.
Doctors eventually diagnosed Savannah with Lennox-Gaustaut Syndrome, or LGS, an epilepsy disorder with no cure and a poor prognosis. People with LGS are often resistant to several kinds of anti-seizure medications, and often suffer from developmental delays and behavioral problems. People with LGS also have a higher chance of injury as well as a higher chance of sudden unexpected death (SUDEP) due to the frequent seizures. In about 70 percent of cases, LGS has an identifiable cause such as a brain injury or genetic syndrome. In about 30 percent of cases, however, the cause is unknown.
Watching her daughter struggle through repeated seizures was devastating to Tracy and the rest of the family.
“This disease, it comes into your life. It’s uninvited. It’s unannounced and it takes over every aspect of your daily life,” said Tracy in an interview with Today.com. “Plus it’s attacking the thing that is most precious to you—your kid.”
Desperate to find some answers, Tracy began combing the medical literature for information about epilepsy and LGS. She enrolled in college courses to better understand the papers she was reading.
“Ironically, I thought I needed to go to college to take English classes to understand these papers—but soon learned it wasn’t English classes I needed, It was science,” Tracy said. When she took her first college science course, Tracy says, she “fell in love with the subject.”
Tracy was now a caregiver to Savannah, who continued to have hundreds of seizures a month, as well as a full-time student, studying late into the night and while her kids were at school, using classwork as “an outlet for the pain.”
“I couldn’t help my daughter,” Tracy said. “Studying was something I could do.”
Twelve years later, Tracy had earned a PhD in neurobiology.
After her post-doctoral training, Tracy started working at a lab that explored the genetics of epilepsy. Savannah’s doctors hadn’t found a genetic cause for her seizures, so Tracy decided to sequence her genome again to check for other abnormalities—and what she found was life-changing.
Tracy discovered that Savannah had a calcium channel mutation, meaning that too much calcium was passing through Savannah’s neural pathways, leading to seizures. The information made sense to Tracy: Anti-seizure medications often leech calcium from a person’s bones. When doctors had prescribed Savannah calcium supplements in the past to counteract these effects, her seizures had gotten worse every time she took the medication. Tracy took her discovery to Savannah’s doctor, who agreed to prescribe her a calcium blocker.
The change in Savannah was almost immediate.
Within two weeks, Savannah’s seizures had decreased by 95 percent. Once on a daily seven-drug regimen, she was soon weaned to just four, and then three. Amazingly, Tracy started to notice changes in Savannah’s personality and development, too.
“She just exploded in her personality and her talking and her walking and her potty training and oh my gosh she is just so sassy,” Tracy said in an interview.
Since starting the calcium blocker eleven years ago, Savannah has continued to make enormous strides. Though still unable to read or write, Savannah enjoys puzzles and social media. She’s “obsessed” with boys, says Tracy. And while Tracy suspects she’ll never be able to live independently, she and her daughter can now share more “normal” moments—something she never anticipated at the start of Savannah’s journey with LGS. While preparing for an event, Savannah helped Tracy get ready.
“We picked out a dress and it was the first time in our lives that we did something normal as a mother and a daughter,” she said. “It was pretty cool.”