"Forever chemicals" are everywhere—from your non-stick frying pans to your raincoat, your makeup bag, and even your popcorn bag. These chemicals, known as PFAS (short for per- and polyfluoroalkyl substances), have been used in everyday products since the 1940s. They're loved by manufacturers because they resist heat, water, grease, and stains. But there's a big problem: once these chemicals are made, they don't go away. That's why they're called forever chemicals.
PFAS are incredibly hard to break down. They're made of carbon and fluorine atoms bonded tightly together, which makes them extremely durable. This durability also means they stick around in the environment—and in our bodies. Nearly everyone in the U.S. has PFAS in their blood. They've been found in drinking water, food, farmland, polar bears, and even in the middle of the ocean.
While a few PFAS chemicals have been studied and linked to serious health problems like cancer, liver damage, and lower birthweight, there are over 14,000 known types—and most haven't been tested at all. That's a big problem, especially since these chemicals are still found in older products and even in newer, replacement ones.
So how do we figure out which of these many chemicals are harmful, and which arent?
A team of researchers at Duke University thinks the answer may lie in a surprising place: tiny worms.
The Worms on the Frontline
In biologist Ryan Baugh's lab at Duke, thousands of microscopic worms called C. elegans are helping researchers better understand PFAS. These worms are barely the size of an eyelash, but they're playing a big role in chemical safety testing. Postdoctoral researcher Tess Leuthner explains that these worms are perfect for the job because they grow quickly, are easy to study, and share many biological processes with humans.
In their experiment, the researchers fed the worms bacteria mixed with different PFAS chemicals. They then measured how the chemicals affected the worms' growth.
The results? Every chemical tested harmed the worms in some way—but some were much worse than others. One particular chemical, PFOSA, was found to be a thousand times more toxic than another chemical, PFBA. Even more interestingly, not all worms reacted the same way. Some strains were more sensitive than others, depending on their genes.
A Faster, Cheaper Way to Study Chemicals
Why use worms instead of mice or other lab animals? Time and cost. Testing chemical toxicity in animals like mice can take more than a year. But the same tests in C. elegans take less than a week. Their small size means researchers can test thousands of worms at once, giving them quick and clear results.
The idea is to use these worms to identify which PFAS chemicals are most dangerous and which genes are responsible for different reactions. If those genes have human versions—and many do—this could help scientists figure out which people might be more at risk from certain chemicals.
"This is the first evidence that genetic variation contributes to susceptibility to PFAS toxicity," Leuthner said. In simple terms, not everyone reacts the same way to the same chemical, and part of that comes down to genetics.
Why It Matters
Understanding which PFAS are most dangerous, and who might be most vulnerable—could help governments and regulators act faster. Instead of spending years and millions of dollars testing every chemical one by one, researchers could use these tiny worms to quickly flag the most harmful ones for deeper investigation. It could also help doctors and public health officials identify communities or individuals who may be more at risk due to their genetic makeup.
"This could really speed up testing and regulation," Leuthner said. And that's the real hope: to get ahead of the problem, not just react to it. Because right now, we're all living in a world where invisible chemicals surround us—on our skin, in our food, even in the water we drink. We may not be able to see them, but their effects could be shaping our health in ways we don't yet understand.
Thanks to the help of some humble little worms, we might finally start to crack the code on which forever chemicals pose the greatest danger—and who among us needs the most protection.
Sometimes, it turns out, the smallest creatures can help answer the biggest questions.