New study finds association between eternal chemicals and multiple sclerosis

New research has found that people most exposed to PFAS have twice the risk of developing multiple sclerosis.

Exposure to so-called “forever chemicals” can increase the risk of developing multiple sclerosis (EM), according to a new published in Environment International

Research suggests that per- and polyfluoroalkylated substances (PFAS) — widely used synthetic chemicals that accumulate in the environment and the human body — may be an underexplored contributing factor to MS, an autoimmune disease of the central nervous system with no known cure. The findings may help explain why the global prevalence of MS increased by an average of 26% over the last three decadeswith cases more than doubling in some countries since 1990.

Using data from the Swedish health register, researchers analyzed blood samples from 907 patients recently diagnosed with MS and compared them with samples from 907 healthy individuals. The team measured levels of 24 PFAS compounds different types, as well as seven byproducts of polychlorinated biphenyls (PCBs), another class of long-lasting industrial chemicals.

Participants with higher concentrations of these chemicals in their blood had a significantly higher risk of developing multiple sclerosis. The strongest associations arose not from individual substances alone, but from combinations of chemicals, evidencing what scientists describe as a “toxic synergy” effect.

“The results show that we need to take into account mixtures of chemicals, not just individual substances,” said Aina Vaivade, first author of the study and medical researcher at Uppsala University. “People are generally exposed to several substances at the same time.”

PFAS have been used since the mid-20th century in products such as nonstick cookware, stain-resistant fabrics, firefighting foams and cosmetics. Although only a small number of PFAS — namely PFOS and PFOA — have been proven associated with cancer and birth defects, thousands of related compounds remain poorly studied. Even chemicals that are no longer produced persist in the environment for decades.

The study found strong links between multiple sclerosis (MS) and high levels of PFOS, as well as two PCB byproducts that can cross the blood-brain barrier. People with the highest concentrations of these substances showed approximately twice the probability of developing MS compared to those with the lowest levels.

Researchers have also identified a complex interaction between genetics and environmental exposure. Individuals with a genetic variant typically associated with a lower risk of MS had four times higher risk when exposed to high levels of PFOS.

“These findings suggest a complex interplay between heredity and environmental exposure,” said lead author Kim Kultima, a clinical chemist at Uppsala University.