Study links PFAS “forever chemicals” to higher multiple sclerosis risk in women

• Women with higher blood levels of PFAS chemicals had up to 63% greater odds of having multiple sclerosis, according to a new study published in Environmental Research
• The chemical PFHxS showed the strongest association, with each increase in levels raising MS odds by 56% in women
• PFAS were detectable in more than 99.5% of all 439 study participants, regardless of health status
• The Trump administration recently removed Biden-era regulations on four PFAS chemicals, including PFHxS
• Researchers caution the findings do not prove causation but add to growing evidence linking PFAS to autoimmune disease

What happened: PFAS exposure tied to multiple sclerosis

Women with higher blood levels of per- and polyfluoroalkyl substances—known as PFAS or “forever chemicals”—may face up to 60% greater odds of having multiple sclerosis, according to a study published June 2026 in the journal Environmental Research. Researchers at the University of Miami Miller School of Medicine analyzed blood samples from 439 U.S. participants, comparing those with MS to healthy controls and individuals with other autoimmune diseases. The findings come as the Trump administration recently rescinded Biden-era drinking water regulations for four PFAS chemicals, including PFHxS, the compound most strongly linked to MS in the study.

PFHxS emerges as primary driver

Among the three PFAS chemicals measured—PFHxS, PFOA and PFOS—PFHxS showed the strongest and most consistent association with MS. For each increase in PFHxS levels, the odds of having MS rose by about 53% overall and 56% among women. People with the highest PFHxS levels were more than 3.5 times as likely to have MS as those with the lowest levels. PFHxS has an exceptionally long half-life of up to 35 years in the human body, meaning past exposures continue affecting health for decades.

PFOA showed a similar but less uniform pattern, with those at the highest levels about 2.6 times as likely to have MS. PFOS showed the weakest links. All three chemicals were detectable in more than 99.5% of study participants, underscoring the near-ubiquitous nature of PFAS exposure in the U.S. population.

Why this matters for women’s health

Multiple sclerosis affects about 2.8 million people worldwide, with women accounting for roughly two-thirds of diagnoses. The study found that women with MS consistently had higher PFHxS levels compared to healthy women and women with two other autoimmune diseases that can resemble MS: MOGAD and NMOSD. This pattern suggests PFHxS may act through pathways unique to MS rather than general immune system disruption.

The findings build on two Swedish studies published in 2025 that linked PFAS exposure to MS, particularly among women. Those studies analyzed blood samples from more than 1,800 people and found that higher combined exposure to PFAS and PCB-related chemicals was linked to greater odds of MS, suggesting chemical mixtures may play a larger role than individual compounds.

Regulatory rollback raises concerns

The study’s publication coincides with a significant shift in federal PFAS policy. On May 18, 2026, the Trump administration removed Biden-era regulations on four PFAS chemicals, including PFHxS, PFNA and GenX chemicals. The administration also eliminated restrictions on mixtures of these compounds, which experts say are even more dangerous to health. While regulations on PFOA and PFOS remain, drinking water systems can now petition for an additional two years to comply, moving deadlines from 2029 to 2031.

The EPA previously set a non-binding health advisory limit of 70 parts per trillion for PFOA and PFOS, while independent scientists recommend a safe level of about 1 ppt. The Biden administration had set enforceable limits of 4 ppt for PFOA and PFOS and 10 ppt for PFNA, PFHxS and GenX. Environmental groups argue the rollback violates the Safe Drinking Water Act’s anti-backsliding provision, which requires any revision to maintain or increase health protections.

What remains unknown

The study has several limitations. Blood measurements captured PFAS levels at a single point in time, and samples were taken after participants had already developed MS. However, because PFHxS and PFOA remain in the body for years, researchers said a single sample likely reflects long-term exposure rather than recent disease activity. The study included only non-Hispanic white participants, limiting how broadly findings can be generalized. Some analyses involved small numbers of participants, particularly men and those with other neurological conditions.

Researchers emphasized this individual study does not prove PFAS cause multiple sclerosis. But it advances what Haleigh Cavalier, a research scientist at Columbia University Mailman School of Public Health, called “a plausible and concerning hypothesis that a near-ubiquitous environmental exposure may be contributing to one of the most common serious neurological diseases in young adults.”

The bottom line: A growing crisis

The evidence linking PFAS to human disease continues to accumulate, even as federal protections weaken. PFAS are called “forever chemicals” because they never break down in the environment, contaminating drinking water, food, food packaging and personal care products. They are found in the blood of virtually everyone on Earth, including newborn babies. Very low doses have been linked to suppressed immune systems, elevated cancer risk, reproductive harms and developmental problems.

With states establishing their own varying limits for PFAS—New Jersey set standards as low as 13 ppt for some compounds, while Michigan covers seven different PFAS—the regulatory landscape remains fragmented. The PFAS Action Act, passed by the House, would set deadlines for limiting industrial PFAS releases, establish a two-year deadline for a national drinking water standard, and designate PFAS as hazardous substances under Superfund law. But the Senate has refused to act.

For consumers, experts recommend using water filters certified to remove PFAS and reducing exposure through avoiding nonstick cookware, stain-resistant fabrics and food packaging labeled as grease-resistant. As the science grows clearer about the health risks, the policy response remains uncertain—leaving millions of Americans exposed to chemicals that persist in their bodies and the environment for decades.

Sources for this article include:

ChildrensHealthDefense.org

ScienceDirect.com

CNN.com