Emerging research suggests that individuals subjected to specific types of persistent organic pollutants, commonly referred to as “forever chemicals,” may face an elevated susceptibility to developing multiple sclerosis (MS), a neuroinflammatory condition.
The precise mechanisms behind this potential link remain unclear. However, this finding could offer insight into the observed phenomenon of MS prevalence escalating by an average of 26 percent globally over the last three decades. In certain countries, the incidence of new cases has more than doubled since 1990.
Multiple sclerosis is characterized as an autoimmune disorder affecting the central nervous system. Currently, there is no identified single causative agent nor a definitive cure for this complex disease.
This recent investigation, originating from Sweden, posits that these enduring chemical compounds might represent a previously underestimated contributing factor to MS development.
Over many years, prior studies have established correlations between MS risk and particular genetic predispositions, as well as specific environmental triggers, such as exposure to the Epstein-Barr virus.
A segment of scientific inquiry has explored the potential involvement of these pervasive chemical agents, more technically christened as per- and polyfluoroalkyl substances (PFAS).
Leveraging comprehensive Swedish health records, investigators quantified the presence of 24 distinct PFAS compounds in the bloodstreams of 907 individuals recently diagnosed with MS, contrasted with 907 healthy participants serving as controls. Additionally, the study examined seven derivative compounds of other persistent chemicals, known as polychlorinated biphenyls (PCBs).
The findings indicated that individuals exhibiting higher concentrations of these substances in their blood presented with a statistically significant augmentation in their risk of developing MS.
Notably, some of the most pronounced associations emerged from the synergistic effect of combined PFAS compounds and/or their byproducts, rather than the impact of any single chemical in isolation.
This concept of “toxic synergy” among persistent chemicals is a phenomenon that scientific experts have previously cautioned against.
“Our findings underscore the necessity of considering chemical mixtures when evaluating the effects of PFAS and related compounds on human health, rather than focusing solely on individual substances. This is because individuals are typically exposed to a multiplicity of agents concurrently,” stated first author and medical researcher Aina Vaivade, affiliated with Uppsala University in Sweden.
Since the mid-20th century, forever chemicals, including PFAS, have been extensively utilized in a broad spectrum of consumer and industrial products, ranging from non-stick cookware and stain-resistant textiles to fire suppression agents and a wide array of cosmetic formulations.
Presently, these persistent chemicals are ubiquitous: they are detected in potable water supplies, packaged beverages, foodstuffs, within the human gastrointestinal tract, circulating in our blood, and even within our cerebral matter. Furthermore, dermal absorption can occur through the use of cosmetic products.
Compounding these concerns, an increasing volume of research is revealing adverse health associations linked to specific chemical exposures at particular concentrations.
Among the vast array of over 12,000 identified PFAS chemicals, only two, namely PFOA and PFOS, have established clear connections to carcinogenic effects and congenital abnormalities. Although both of these substances have been phased out of production in numerous countries, including the United States, their exceptionally slow natural degradation rate in the environment renders them enduring hazards.
In the context of the current investigation, participants who had elevated levels of PFOS or one of two specific PCB metabolites (4-OH-CB187 and 3-OH-CB153) demonstrated particularly heightened probabilities of developing MS.
“We observed that several individual compounds, such as PFOS and two hydroxylated PCBs, were correlated with an increased likelihood of MS,” explained lead author and clinical chemist Kim Kultima from Uppsala University.
“Individuals with the highest concentrations of PFOS and PCBs faced approximately double the risk of an MS diagnosis compared to those with the lowest concentrations.”
Both PFOS and OH-PCBs possess the capacity to traverse the blood-brain barrier, potentially impacting immune cells within the central nervous system.
Should these chemicals induce oxidative stress, researchers hypothesize that they could compromise the brain’s intrinsic antioxidant defense mechanisms. This disruption may contribute to the motor deficits, sensory disturbances, or visual impairments frequently characteristic of MS.
Intriguingly, Kultima and his colleagues discovered that individuals carrying a genetic variant typically associated with a reduced risk of MS exhibited a significantly elevated likelihood of developing the disease if they had been exposed to higher PFOS levels.
Indeed, with increasing PFOS exposure, participants possessing this specific gene variant faced a more than fourfold increased risk of MS development.
“This observation suggests a complex interplay between inherited genetic factors and environmental exposures that influences the probability of developing MS,” commented Kultima.
“Consequently, we believe it is crucial to elucidate how environmental contaminants interact with hereditary predispositions. Such understanding could yield novel insights into the etiology of MS and may also hold relevance for other diseases.”
This research was disseminated in the scientific journal Environment International.
