Tracing the path of toxic ‘forever chemicals’ inside the bodyPlay
Stacks of boxes line the front hall of Wendy Thomas’ house in Merrimack, New Hampshire, not far from the Massachusetts border. Inside each box are jugs of water that she relies on daily.
Thomas, age 64, uses the bottled water for cooking and drinking because her well water is contaminated with high levels of PFAS.
Technically called per- and polyfluorinated substances, this class of thousands of chemicals has been linked to numerous health risks. The chemicals are added to a variety of products — from hand lotion and dental floss to nonstick pans, outdoor gear and industrial fabrics — because of their ability to repel water, oil and grease.
After attending a community meeting about PFAS contamination, Thomas learned that unsafe levels of the chemicals had been found in local drinking water. New Hampshire environmental officials largely attributed the pollution to emissions from a factory owned by the company Saint-Gobain. Thomas got her well tested. Then, she got her blood tested.
Use of PFAS is so widespread that nearly every American has detectable levels of these human-made chemicals in their blood. So Thomas knew some PFAS would show up in her test. Still, she was unprepared for the results.
“The only word I can come up with is gobsmacked,” she said, recalling her reaction when she opened the lab report. “Numb. Raw.”
The testing showed her level of PFOA, one type of PFAS, was higher than in 99% of Americans.
“My blood is toxic,” Thomas remembered thinking. “What does that mean?”
She also wondered about her six adult children, who are coping with health problems like high cholesterol and autoimmune disorders.
The intruders inside
Researchers are racing to learn more about PFAS. They are just beginning to understand what these chemicals do once they enter the body. Unlike many other toxins that harm one organ or system, PFAS seem to interfere with a wide range of internal functions.
“I'm not sure I know a tissue or an organ system where effects haven't been reported.”Linda Birnbaum, former director of the National Toxicology Program
According to the federal Centers for Disease Control and Prevention, high levels of PFAS may increase the risk of testicular and kidney cancers. They may lead to high cholesterol and lower birth weights. They may also decrease how effective vaccines are in children. And, even at low levels, scientists are linking PFAS to a number of other health concerns.
“It's pretty remarkable, in my opinion, that PFAS chemicals can affect so many parts of the body in adverse ways,” said Patrick Breysse, the former director of the Agency for Toxic Substances and Disease Registry at the CDC, during a presentation to a Massachusetts task force on PFAS. “Not many chemicals have such a breadth of effect.”
While some PFAS chemicals are thought to be more harmful than others, researchers are looking into a broad spectrum of potential concerns.
“I'm not sure I know a tissue or an organ system where effects haven't been reported,” said Linda Birnbaum, former director of the National Institute of Environmental Health Sciences and the National Toxicology Program.
What about PFAS give them this remarkable reach inside the body?
Imagine Thomas takes a gulp of her PFAS-laden well water. Or a person catches bass from a contaminated river and fries it up for dinner. Or, perhaps, someone eats a sandwich that's been wrapped in paper lined with PFAS.
Scientists understand the first thing that happens. The chemicals in the food or water work their way from your mouth to your stomach and into your intestines.
“And in the small intestine, they'll basically be completely absorbed into the body,” said Angela Slitt, a professor at the University of Rhode Island College of Pharmacy. Studies in rodents have shown that PFAS are “within a couple of days, 100% absorbed,” Slitt said, “which is not the case for every chemical or drug.”
Once absorbed, scientists compare PFAS to obnoxious house guests: They overstay their welcome, they spread out inside the body, and they impersonate friendlier substances.
They don’t leave
PFAS move in, and they stick around.
This is partly because of the molecular structure of these compounds. The chemical bond is super strong and super stable, so much so that PFAS chemicals have earned the nickname “forever chemicals.”
“They are just virtually indestructible,” Slitt said. In nature, it takes high temperatures to break down the carbon fluorine bonds in PFAS. “And a problem is that the body doesn't break them down either,” she added.
The strength of this bond is useful when it comes to consumer products, like nonstick pots and pans.
“Think about how hot cookware gets," Slitt explained. "So to have something that can stay coated and be resistant to temperature, that's valuable."
But when it comes to the body or the environment, the chemicals' ability to stick around is less ideal. Substances like caffeine, Tylenol and BPA, a chemical in plastics, leave the body in a matter of hours. Lead leaves the blood in a couple months. For the most prevalent PFAS chemicals, it can take years to exit the body. For at least one type of PFAS, it can top a decade.
This longevity is what makes PFAS more worrisome to many experts than other harmful chemicals.
“I think BPA is bad. I think phthalates are, in general, bad. I think some of the benzophenones — the ones that are killing the coral — are bad. But they're not persistent,” Birnbaum said. “They break down in the environment, and then you don't have them anymore. PFAS are going to be with us forever, and they're going to build up in the environment, and they're going to build up in us, too.”
A chemical in the body is measured by its half-life, or how long it takes for 50% of the substance to leave the body. Caffeine has a half-life of about six hours (0.25 days).
Lead, which can damage the brain and nervous system, has a half-life of up to two months (60 days) in the blood.
But some PFAS chemicals have a half-life of up to eight years. This — and their persistence in the environment — is why some refer to them as "forever chemicals."
They spread out
Once PFAS pass through the digestive system, those chemicals find their way to the liver and from there, some get into the bloodstream.
“They bind to small proteins in our blood,” said Megan Romano, an epidemiologist at Dartmouth’s Geisel School of Medicine. “And what that means is it's a really excellent delivery system to get all sorts of places in our body.”
PFAS ride along in our blood, reaching all over the body. Researchers believe this is part of the reason why such a wide variety of ailments are associated with PFAS.
A skilled impersonator
Once PFAS are circulating around our bodies, they have the ability to infiltrate a number of organs and body systems.
“We're seeing a lot of changes in how things function,” said Birnbaum.
One of the best understood mechanisms for how PFAS — especially PFOA — interrupt body functions is by impersonating another substance the body has grown to expect and welcome. On a molecular level, PFOA resembles fatty acids, and this allows it to click into certain receptors — called nuclear receptors — in the cell.
Essentially, the molecule fools the cell "into thinking it knows the secret handshake, and that's how it gets in the door," Romano said.
This is problematic because fatty acids are essential to the body’s functioning, playing a key role in energy storage, and influencing cell metabolism and how the body responds to hormones.
By impersonating fatty acids, scientists believe PFOA has the potential to alter how our bodies store and use fat. Studies also suggest it can affect hormones like those involved in breastfeeding.
Birnbuam said this is just one of the mechanisms that seems to be at play with PFAS chemicals.
“There's evidence that at least 14 different nuclear receptors can be targeted by PFAS,” she said. “It’s complicated, but it explains why you can have different things going on in different tissues.”
Evicting the intruder
So far, scientists don’t know a good way to remove PFAS from the body. A little leaves in the urine and bile but not much and not quickly.
Scientists have seen PFAS decrease when a parent passes them along to a child through the placenta or by nursing.
“Let's say she breastfeeds for six months, she can actually eliminate half of her body burden [of PFAS] to the child,” said Philippe Grandjean, an adjunct professor at Harvard’s School of Public Health.
Studies also suggest donating blood can reduce PFAS levels. But there, too, the substances are simply being passed on to another person.
Grandjean said there is one way to reduce PFAS levels without directly giving them to another person. “You might have thought that menstruation was a bother, but hey, it's an important excretion mechanism for PFAS,” he said.
'It’s just overwhelming'
Scientists have a lot of unanswered questions about PFAS. Only a few of the chemicals, mainly PFOA and PFOS, have been well studied.
“This is a huge data gap,” said Birnbaum. “We know that PFOA and PFOS are predominantly in our liver, our kidney and our blood. We really don't have the data for any of the [thousands of other PFAS] chemicals on where they go in our body.”
She pointed to one study of pilot whales that looked at 20 different PFAS chemicals. “What they found was depending upon the specific PFAS, where they went [in the body] was very different,” she said.
In the U.S., manufacturers stopped producing PFOS and PFOA in 2002 and 2015, respectively. Since then, the overall concentration of these chemicals in blood sampling has declined, according to national data. However, they remain in some consumer and industrial products, inside people’s bodies and in the environment.
“We know that PFOA and PFOS are predominantly in our liver, our kidney and our blood. We really don't have the data for any of the [thousands of other PFAS] chemicals on where they go in our body.”Linda Birnbaum
Another problem, many scientists say, is that PFOS and PFOA have largely been replaced by other, newer PFAS chemicals, and little is known about them. Slitt, of the University of Rhode Island, said many of these chemicals can’t easily be tested in the lab. Academics have tools to identify them, she said, but they don’t have the pure chemicals to run experiments with.
“We don’t have purified, standardized, vetted chemicals to study,” she said. “It’s just overwhelming.”
The American Chemistry Council, which represents chemical manufacturers, casts doubt on some of the research that has been carried out. It declined interview requests but said in a statement that there are significant differences among PFAS chemicals, and they shouldn't be treated as a monolith, especially when it comes to state and federal regulations.
“All PFAS are not the same and they should not be regulated the same way,” the statement said, although the group added it supports “science-based regulation of PFAS.” The group also pointed out that these chemicals have many important uses, including for renewable energy, medical devices, transportation and air travel.
Still, some politicians are working to outlaw PFAS in food packaging and some consumer products. A bill to do that, among other things, was filed last month in Massachusetts. The lawmakers behind it say they don’t want to invite more PFAS into our environment or our bodies.
'It’s too late for me'
When Wendy Thomas learned of her PFAS blood levels, she began to advocate for better awareness about the chemicals and stricter regulations, even becoming a state representative in New Hampshire.
Then, last spring, Thomas was diagnosed with breast cancer, despite no family history of it.
She may never know what role — if any — PFAS played in her cancer and her family’s other health problems.
“I don't know if this is all related to PFAS, but it's beginning to look like a duck and it's beginning to quack like a duck,” Thomas said.
At least one study suggested the area where she lives has unusually high rates of certain cancers. Thomas and other residents have sued Saint-Gobain, the company whose factory allegedly spewed PFAS into the air.
Saint-Gobain declined interview requests but said in a statement, “Saint-Gobain is not the only source of PFOA in the area,” and it is “committed to ongoing remedial work.”
Under a new agreement with the state, Saint-Gobain has offered to pay for Thomas' home — and others — to be connected to a municipal water system. But she still feels stuck in a house that can't be sold — since the property has known PFAS contamination — and in a body teeming with toxic chemicals.
“It's too late for me. It might even be too late for our adult children," she said. "But we have to fight for the future.”
This segment aired on February 16, 2023.