New research from Sweden has found that people who have been exposed to certain harmful environmental chemicals are more likely to develop multiple sclerosis (MS).
This large study looked at blood samples from over 1,800 people and found that those who had higher levels of two types of chemicals—PFAS and PCBs—were nearly twice as likely to be diagnosed with MS.
Multiple sclerosis is a disease where the body’s own immune system attacks the nervous system. This can cause problems with movement, balance, and thinking. Scientists believe both genetics and the environment play a role in causing MS, but the exact reasons are not fully understood.
In this study, researchers focused on two common groups of environmental toxins. PFAS are man-made chemicals used in products like non-stick cookware, water-repellent clothing, and firefighting foam.
PCBs were used in electrical equipment and building materials before being banned in many countries, but they still linger in the environment. When PCBs break down inside the body, they form other harmful substances called hydroxylated PCB metabolites.
The research team tested the blood of about 900 people who had recently been diagnosed with MS and compared them to 900 people without the disease. They measured 14 different PFAS chemicals and three types of PCB byproducts to see how much of these substances were in each person’s blood.
The results showed that people with the highest levels of certain chemicals—especially PFOS, a type of PFAS, and two types of PCB byproducts—had almost double the odds of having MS compared to those with the lowest levels. This clear pattern suggests that chemical exposure may play a stronger role in MS than previously thought.
The scientists also looked at the combined effects of all these chemicals. Since people are often exposed to many substances at once in real life, they tested what happened when all the chemical levels were added together.
They still found a higher risk of MS, even after accounting for known risk factors like lifestyle habits and genetic background. This shows that studying mixtures of chemicals gives a better picture of real-life health risks than looking at each one alone.
Another important finding involved genes. Some people carry a gene variant that usually gives some protection against MS. But in this study, even those people showed a higher risk if they had high levels of PFOS in their blood. This means that chemical exposure might cancel out the protective effects of certain genes.
The researchers say these results highlight a complicated connection between our genes, our environment, and our health. Understanding how toxic substances interact with genetic traits could help scientists better understand how MS begins—and how it might be prevented.
This study is one of the largest of its kind and offers strong evidence that long-lasting chemicals in our environment could be playing a hidden role in diseases like MS. It also shows the importance of reducing exposure to harmful substances and studying their long-term effects on the human body.
The study is published in Environment International.
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