Swedish Study Links Environmental Chemicals to Multiple Sclerosis Risk

Researchers at Uppsala University in Sweden have discovered a concerning link between common environmental contaminants and multiple sclerosis (MS), potentially shedding new light on factors that may contribute to this debilitating autoimmune disease.

Published in the journal Environmental International, the study found that exposure to two types of environmental pollutants – PFAS (per- and polyfluoroalkyl substances) and PCBs (polychlorinated biphenyls) – could significantly increase the risk of developing MS.

The research examined blood samples from approximately 1,800 Swedish individuals, including about 900 who had recently been diagnosed with MS. Researchers analyzed 14 different PFAS contaminants and three substances that form when PCBs break down in the body, then investigated their relationship to MS diagnosis risk.

“We saw that several individual substances, such as PFOS and two hydroxylated PCBs, were linked to increased odds for MS,” explained lead study author Kim Kultima. “People with the highest concentrations of PFOS and PCBs had approximately twice the odds of being diagnosed with MS, compared to those with the lowest concentrations.”

PFAS, commonly known as “forever chemicals” due to their persistence in the environment, are widely used in household products including non-stick cookware, textiles and cleaning products. The U.S. Environmental Protection Agency has detected these chemicals in drinking water supplies throughout the United States. PCBs, though banned decades ago, were once widely used in electrical equipment and remain toxic environmental contaminants.

The researchers also examined the combined effects of these substances, finding that exposure to mixtures of these chemicals was likewise associated with increased MS risk. This finding is particularly significant because most people are exposed to multiple environmental contaminants simultaneously.

“Risk assessments should consider chemical mixtures, not just individual exposures,” noted researcher Aina Vaivade, highlighting the complex nature of environmental exposure in real-world settings.

The study also revealed an intriguing genetic component to the risk equation. Individuals who carry a certain gene variant actually showed a reduced risk of MS in general. However, when these same individuals had higher exposure to PFOS – a specific type of PFAS chemical – they unexpectedly demonstrated an increased risk of developing the disease.

“This indicates that there is a complex interaction between inheritance and environmental exposure linked to the odds of MS,” Kultima said. “We therefore think it is important to understand how environmental contaminants interact with hereditary factors, as this can provide new knowledge about the genesis of MS and could also be relevant for other diseases.”

Dr. Marc Siegel, a senior medical analyst not involved in the study, cautioned that while the research shows a correlation between these chemicals and MS, it doesn’t definitively prove causation.

“MS is a complex disease that is somewhat autoimmune and somewhat post-inflammatory,” Siegel noted. “Epstein-Barr virus infection greatly increases the risk of MS. There is every reason to believe that environmental triggers play a role, including microplastics, but this important study shows a correlation, not causation.”

The study authors acknowledged certain limitations, including that chemical exposure was measured only once at the time of blood sampling, which may not accurately represent participants’ long-term or past exposure levels relevant to MS development.

Multiple sclerosis affects approximately 2.8 million people worldwide and causes the immune system to attack the protective covering around nerve fibers. This can lead to a range of symptoms including numbness, weakness, difficulty walking, vision changes, and permanent neurological damage. While there is currently no cure for MS, treatments can help manage symptoms and modify disease progression.

In response to growing concerns about environmental chemicals, the EPA enacted a new federal rule in April 2024 that sets mandatory limits on certain PFAS chemicals in drinking water. The agency is also funding testing and treatment efforts to reduce public exposure to these substances.

The American Chemistry Council has stated that “manufacturers and many users of today’s PFAS are implementing a variety of practices and technologies to help minimize environmental emissions,” though concerns about these chemicals’ widespread presence in consumer products and the environment persist.

This research represents an important step in understanding the complex interplay between environmental factors and autoimmune disease development, potentially opening new avenues for prevention and treatment of MS and related conditions.