Paul Smith, a former nurse anesthetist, has been battling chronic lymphocytic leukemia since 2012, and his doctors suspect he has a tumor forming in his pituitary gland. But despite concerns about his health, a well-known cholesterol management drug is giving him some hope.

Mr. Smith lives in Barnstable, Massachusetts in an area called Centerville. The local firefighter training school and nearby airport are located here. contaminated the water supply For decades. The facility allowed an environmental leak of firefighting foam containing per- and polyfluoroalkyl substances, also known as PFAS or “forever chemicals.”

Smith continued to drink the contaminated water for years until he learned that the water had spiked levels of certain PFAS. In 2022, the Silent Spring Institute will Commissioned by a non-profit health research organization Research involving center buildings.

Through that research, Smith learned exactly how much PFAS was circulating in his blood. In other words, his level was high. For one chemical, perfluorohexane sulfonic acid (PFHxS), his blood levels were 14 times higher. National average (PDF). “I felt pretty bad” after getting the results, he says.

And he’s not alone. After heavy exposure, it can take decades for PFAS levels to return to baseline. People like Smith often feel like they’re carrying these toxic substances, which have been linked to health problems ranging from high cholesterol to cancer. Shiwen Lee, an epidemiologist at the University of Hawai’i at Mānoa who studies the health effects of PFAS, said many people “hope for some kind of medical solution.”

That may be the case with cholestyramine, a cholesterol management drug approved in the United States more than 50 years ago. In the past four years, 3 studies have Cholestyramine was suggested. can Eliminate PFAS from the body.

Lee cautioned that all three studies are preliminary and are not implicating any of them. In his opinion, it’s too early to celebrate. “We shouldn’t be touting this as a solution without large-scale clinical trials.” At the same time, he says, based on knowledge of biochemistry, the mechanism of how the drug removes PFAS makes sense.

Smith sought out cholestyramine after finding publications in the scientific literature about its potential benefits for people with high PFAS exposure. Smith’s gastroenterologist was familiar with cholestyramine and believed it to be safe, so he agreed to give Smith a prescription.

After taking cholestyramine for about eight months, Smith saw her PFAS levels drop dramatically. Two fluorinated chemicals are almost undetectable in his blood, and his PFHxS is about 30% of what it once was. “It was definitely a mental boost,” he says.

Cholestyramine is a powdered resin taken orally that lingers in the intestine for some time and is thought to reduce PFAS levels in the same way that it lowers cholesterol: by interrupting the round trip of bile acids from the liver to the intestine and back again.

Bile acids are normally made in the liver and then travel to the intestines, where they bind to fats and help the body digest them. Some fats can slow down the breakdown of cholesterol in the body, so lowering the levels of these fats can lower cholesterol. Cholestyramine accomplishes this by binding to bile acid and fat complexes in the intestines, creating an insoluble matrix that remains outside the body in the feces. In the absence of cholestyramine, bile acids are processed in the intestines and then returned to the liver where they can be recycled by the body.

But PFAS can also be caught up in this cycle. Because some PFASs share structural features with fats—both have long, neutrally charged tails and negatively charged heads—PFASs also bind bile acids, allowing them to travel along as they circulate between the liver and intestines. By breaking this cycle, cholestyramine can capture PFAS and flush them out of the body and into the toilet.

At least since the 1980s Researchers suspect that cholestyramine may lower PFAS. But only recently have scientists begun to rigorously test this idea. Alan Ducatman, a longtime PFAS researcher at West Virginia University, said in a 2021 publication: We followed up on the cholestyramine theory by reanalyzing the data from Original research links PFAS levels to many health issues. He found that 36 of the 56,175 participants in the study happened to be taking cholestyramine, and their specific PFAS levels were reduced compared to levels in the rest of the population (environment. Toxic. Pharmacology. 2021, DOI: 10.1016/j.etap.2021.103650). One PFAS in particular, perfluorooctane sulfonic acid (PFOS), “really disappeared,” Ducatman says.

Meanwhile, in Denmark, Morten Lindhardt, a nephrologist and internist at the University of Copenhagen, and his colleagues We tested cholestyramine in a group of 45 people highly exposed to PFAS.. Permanent chemicals entered their bodies after they ate meat from cows raised near the fire academy. Half of the participants took cholestyramine for 12 weeks, the other half received no treatment, and then switched between the two groups (environment. internal. 2024, DOI: 10.1016/j.envint.2024.108497).

When study participants took cholestyramine, levels of various PFAS decreased by about 20-60%. Levels in the untreated group fell by only about 3%, or in some cases rose slightly. “The effects of the treatment were astronomical and enormous.” It works,” Lindhardt said.

Around the same time, Australian firefighters were becoming aware of the extent to which firefighting foam could pose a risk to their health. In response, the South Australian Metropolitan Fire Service launched a voluntary program in early 2018 to identify and provide treatment to highly exposed firefighters. Twelve firefighters chose to take cholestyramine. PFOS and PFHxS levels appear to have decreased by about a third The same level as those who did not receive treatment for one year (environment. internal. 2025, DOI: 10.1016/j.envint.2025.109609).

However, it is important to note that the Australian study was designed around the aspirations of those affected, rather than aiming to produce solid scientific findings, said study author Ian Delair, a toxicologist and director of toxicology consultancy Expotox. Because of this design decision, the study is small and has many caveats.

For example, participants may have avoided PFAS in their daily lives because they knew they had higher levels of cholestyramine and that cholestyramine appeared to be more effective than it actually was, Lee says. But when you look at the results side by side with other recent studies, “they all seem to point in the same direction,” Delair said.

Cholestyramine often causes gastrointestinal upset side effects Symptoms such as nausea and diarrhea may occur, and fat-soluble vitamins may be flushed from the body. “It’s not incredibly comfortable, but it’s not particularly dangerous either,” Ducatman said. Lindhardt believes that adjusting the dose and duration of cholestyramine treatment could reduce the likelihood of side effects and limit how long users have to endure them.

However, other experts warn that cholestyramine’s initial effects on lowering blood PFAS levels may be deceptive. Just because PFAS levels in a person’s blood are reduced doesn’t necessarily mean they will be reduced in all tissues, Lee said. Over time, PFAS can leach from fat and other tissues into the blood, causing levels to rise again.

Whether lowering PFAS levels after high-dose exposure provides long-term health benefits is a topic of debate within the research community. When a chemical enters a person’s body, damage has already occurred, and removing the chemical may have little effect.

Lindhardt believes those claiming health benefits of using cholestyramine to accelerate PFAS removal are on “thin ice” at this early stage of the research. He compares the situation to smoking, saying, “The risk of lung cancer doesn’t go away the day after you quit smoking.” But by the same logic, telling someone not to use cholestyramine to lower PFAS levels is like telling a smoker that there are no health benefits to quitting, which is clearly not true, Dr. Delaire counters.

there are some signs “Your body will slowly heal itself” After clearing PFASsays Lee. So far, the evidence centers around cholesterol levels rising in response to exposure to PFAS. As PFAS levels decrease, cholesterol levels also appear to return to normal.

Smith hopes the same applies to her health issues. “If my levels go down, other issues I have may improve,” he says. And even if cholestyramine doesn’t deliver on its promise, he and his friends are already battling serious health problems, so “what do we have to lose?” he asks.

Saima Siddique A science writer based in Somerville, Massachusetts, who covers climate, environmental science, and biomedicine. A version of this story first appeared in ACS Central Science: cenm.ag/cholestyramine.