Exposure to PFAS and PCBs linked to increased risk of multiple sclerosis

Using blood tests and data from the Swedish Epidemiological Study of Multiple Sclerosis (EIMS) cohort, the researchers examined the association between concentrations of these common pollutants and the likelihood of receiving an MS diagnosis. The results showed that even after controlling for lifestyle factors, people exposed to a mixture of PFAS and PCBs had a higher risk of developing multiple sclerosis.

Around the world, the number of people suffering from multiple sclerosis and other chronic autoimmune diseases is increasing. Some of this increase is due to improved diagnosis and treatment allowing patients to live longer, but the rise in incidence also reflects an increase in the number of new cases. Recent estimates indicate that the global incidence of multiple sclerosis is increasing annually by approximately 5-10%. Since genetics cannot change as quickly, environmental factors such as pollution, chemical exposure, infections, dietary changes, stress and other lifestyle aspects are believed to be the main cause of this increase.

At the first stage of the study, scientists analyzed the content of 14 different PFAS compounds and 3 hydroxylated PCB metabolites – substances formed during the breakdown of PCBs in the body. For each compound, they measured concentrations in the participants’ blood and used statistical methods to estimate the relationship between levels of these substances and the likelihood of being diagnosed with multiple sclerosis.

The results showed that several substances, including the common PFAS perfluorooctanesulfonate (PFOS), as well as two hydroxylated PCBs, were associated with an increased risk of developing multiple sclerosis. People with the highest concentrations of PFOS and hydroxylated PCBs were about twice as likely to be diagnosed with MS as participants with the lowest levels of these substances.

In a second step, the researchers examined how the risk of multiple sclerosis changed when exposed to these substances in combination. The mixture analysis method allowed us to assess the impact of the entire group of PFAS and hydroxylated PCB metabolites on the risk of developing multiple sclerosis, rather than considering each substance separately. The researchers found that higher total concentrations of PFAS were associated with an increased likelihood of illness, even if the individual substances themselves showed little or no association. This indicates that the total load and possible additive or interactive effects of the chemicals are important.