Could plastic byproducts and forever chemicals found in drinking water cause your body to attack your own nervous system? New research from Sweden links higher levels of per- and polyfluoroalkyl substances, or PFAS, and polychlorinated biphenyls, or PCBs, with a higher risk for developing multiple sclerosis.

“We saw that several individual substances, such as PFOS and two hydroxylated PCBs, were linked to an increased odds for MS,” lead author and clinical chemist Kim Kultima from Uppsala University in Sweden told the science news website Science Alert. “People with the highest concentrations of PFOS and PCBs had approximately twice as high odds of being diagnosed with MS, compared with those with the lowest concentrations.”

Although PCBs have been banned in the United States since 1979, and Maryland banned most uses of PFAS since 2024, the chemicals persist for a long time in the environment and in human bodies. The Maryland Department of the Environment identified PFAS in state drinking water supplies as recently as 2022.

The Swedish research team tested for 24 variants of PFAS and seven byproducts of PCBs in the blood of 907 patients recently diagnosed with multiple sclerosis and 907 healthy control subjects. Those testing high for multiple compounds were mostly in the diagnosed group.

They published their work in the journal Nature Communications in 2025.

Multiple sclerosis is the most common autoimmune nerve disease among young adults, affecting more than 2.9 million people worldwide, according to the National Institutes of Health.

The disease causes inflammation and an immune response attacking the central nervous system. It has no single identified cause and no cure, although risk factors previously identified include smoking, adolescent obesity and low Vitamin D. Women are more likely than men to develop multiple sclerosis.

The disease is usually diagnosed between the ages of 20 and 40, with symptoms including double vision, muscle weakness, muscle stiffness and spasms, tingling or numbness, clumsiness, bladder control and dizziness.

While there is no cure, treatments like steroid injections can offer a reprieve and delay the long-term progression of the disease.

PFAS also have been linked to high cholesterol, high blood pressure, decreased vaccine response and cancers, according to the Centers for Disease Control and Prevention.

PFAS have been found in 16% of Maryland water utilities, according to the Maryland Department of the Environment. Another 15% of households draw water from wells and are responsible for their own testing. A list of labs that test drinking water can be found on the MDE website.

PCBs have been associated with a higher risk for cancer, liver damage, skin problems, and negative effects on immune, reproductive, nervous and endocrine systems, according to the Environmental Protection Agency.

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