PFAS and PCB Exposure Linked to Increased Multiple Sclerosis Risk
Exposure to a mixture of PFAS and PCBs is associated with higher odds of being diagnosed with MS.
People exposed to PFAS and polychlorinated biphenyls (PCBs) are more likely to be diagnosed with multiple sclerosis (MS), a new study suggests.
The research, published in Environment International, draws on data from more than 900 individuals who had recently been diagnosed with MS and an equal number of matched controls.
Using blood tests and data from the Swedish Epidemiological Investigation of Multiple Sclerosis (EIMS) cohort, the researchers investigated the link between concentrations of common environmental contaminants in the blood and the odds of being diagnosed with MS.
They found that, even after adjusting for lifestyle factors, those exposed to a mixture of PFAS and PCBs had higher odds of being diagnosed with MS.
Environmental pollutants and MS
Worldwide, the number of people living with MS or other chronic autoimmune disorders is on the rise. While some of this rise may be due to improved diagnosis and treatment pathways enabling those with MS to live longer than before, increasing incidence rates suggest that the number of new cases is also growing.
“Global incidence rates [for MS] have risen substantially, by an estimated 5-10% per year according to recent analyses. Since our genetic background cannot change rapidly enough to account for this trend, the rise must be primarily driven by environmental factors. These include pollution, chemical exposures, infections, dietary shifts, stress, and other lifestyle-related influences,” lead study author Dr. Kim Kultima, associate professor and senior lecturer in experimental clinical chemistry at Uppsala University, told Technology Networks.
“In this study, we sought to test the hypothesis that environmental pollutants – specifically PFAS and PCBs – may contribute, at least in part, to the increasing incidence of MS,” Kultima said.
What are PFAS?
Per- and polyfluoroalkyl substances (PFAS) are a family of synthetic chemicals that were previously widely used in non-stick coatings for cookware and as an ingredient in firefighting foams. Due to the presence of many strong carbon–fluorine bonds in their structure, they do not degrade easily in the environment, making them a persistent pollutant.
What are PCBs?
Polychlorinated biphenyls (PCBs) are synthetic chemicals that were once commonly used in electrical equipment, paints, and plastics to impart stability and non-flammability. The manufacturing of PCBs in the United States was banned in 1979; however, they persist as environmental pollutants. The most common route of exposure to PCBs is by eating contaminated fatty foods, such as fish, dairy products, or eggs, where PCBs can bioaccumulate.
Exposure to PFAS and PCBs linked to higher odds of MS
In the first phase of the study, the research team studied the incidence of 14 different PFAS compounds, as well as 3 compounds that are formed when PCBs are broken down by the body, known as hydroxylated PCB metabolites. For each substance, the researchers measured its concentration in the participants’ blood and used statistical methods to evaluate any links between this and the odds of being diagnosed with MS.
“We were able to adjust for lifestyle factors because the EIMS cohort is specifically designed to collect detailed information on MS-related behaviors and exposures. These variables were included as covariates in our regression and mixture models,” Kultima explained. “In practice, this meant accounting for key lifestyle factors such as smoking and snus use, body mass index, sun exposure habits, diet, physical activity, and alcohol consumption. By adjusting for these well-known MS risk factors, we could better isolate the association between chemical exposures and MS risk, rather than differences driven by lifestyle.”
They found that several substances – including the prominent PFAS compound perfluorooctane sulfonate (PFOS) and two hydroxylated PCBs – were linked to increased odds of MS diagnosis. People with the highest blood concentration of PFOS and hydroxylated PCBs were found to have approximately double the odds of being diagnosed with MS, compared to those with the lowest blood concentrations.
“People are rarely exposed to one compound at a time. PFAS and PCB-related compounds tend to co-occur and be correlated, so focusing on single chemicals can miss the real-world exposure pattern,” Kultima added.
To better reflect this reality, the second phase of the study investigated how the odds of MS diagnosis were affected when these substances occurred together as a mixture.
“The mixture approach lets us estimate the combined effect of multiple PFAS and hydroxylated PCB metabolites on MS odds, instead of assuming each acts independently. We found that higher total co-exposure was associated with higher odds of MS, even when some individual chemicals showed weak or no association on their own, suggesting that the overall burden, and potentially additive or interactive effects, matter,” said Kultima.
PFOS exposure may weaken genetic protection against MS
In addition to accounting for lifestyle factors, genetics can also play a key role in MS; individuals who carry certain gene variants have a reduced risk of developing MS over their lifetimes.
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“MS has a strong genetic component, and in our study, we accounted for this by adjusting for known MS-related HLA genes. We also examined whether genetics influenced how PFOS exposure related to MS risk,” Kultima said.
“We found that the association between PFOS and MS differed by genetic background: in people carrying a gene variant that is usually protective against MS, higher PFOS exposure was linked to higher odds of developing the disease.”
“This suggests that environmental exposures, such as PFOS, may weaken genetic protection, highlighting the complexity of associations between environmental contaminants, lifestyle, and genetic risk factors.”
While the observational nature of the study prevents the researchers from proving causality, the team is planning additional studies to replicate these findings in additional cohorts and in prospective studies.
“Like most epidemiological studies, ours has limitations. First, the study is observational, which means we can identify associations but cannot definitively prove that chemical exposures cause MS. Additionally, PFAS and PCB exposures were measured at a single time point near diagnosis, which may not fully capture long-term or early-life exposures that could be particularly important for MS development. Although we adjusted for a wide range of lifestyle factors and known MS-related genetic risk variants using the rich data available in the EIMS cohort, some residual confounding cannot be completely ruled out. The study population is also Swedish, and we focused on a defined set of PFAS and PCB metabolites; therefore, the findings may not fully represent other populations or the broader spectrum of environmental chemicals to which people are exposed,” Kultima explained.
“Our following steps are to replicate these findings in independent cohorts and, ideally, in prospective studies where exposures are measured before MS onset,” Kultima continued. “We also need mechanistic studies to better understand how these chemicals may interact with the immune system and how genetic susceptibility influences MS risk. Together, we hope this clarifies whether environmental pollutants play a causal role and identifies which individuals are most vulnerable to these exposures.”
Alexander Beadle, science writer and editor for Technology Networks, was speaking with Dr. Kim Kultima, associate professor and senior lecturer in experimental clinical chemistry at Uppsala University.
Reference: Vaivade A, Sreenivasan AP, Erngren I, et al. Co-exposure to PFAS and hydroxylated PCBs is associated with increased odds of multiple sclerosis. Environ Int. 2026;207:109993. doi: 10.1016/j.envint.2025.109993
