Solvent Exposure May Be Linked to Significantly Greater Risk of MS

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Multiple sclerosis risk increased significantly in individuals with occupational exposure to organic solvents.

Exposure to organic solvents and cigarette smoking, in addition to having certain multiple sclerosis (MS) susceptibility genes, may create a 30-fold increased risk of developing the disease, according to a new study published in Neurology.

According to the study, environmental factors and MS susceptibility genes may interact and significantly increase the risk of MS beyond the individual factors alone. Factors such as cigarette smoking, adolescent obesity, vitamin D deficiency, and Epstein-Barr virus infection have been linked to disease occurrence.

The researchers sought to determine whether occupational exposure to organic solvents affects MS risk. Organic solvents can be found in products such as paints, varnishes, lacquers, adhesives, glues, and degreasing/cleaning agents, as well as in the production of dyes, polymers, plastics, textiles, printing inks, agricultural products, and pharmaceuticals.

The study evaluated MS development based on factors such as genes, environmental exposures, and lifestyle factors. For the study, the researchers recruited 2042 individuals who had recently been diagnosed with MS in Sweden and 2947 individuals without MS.

The researchers used blood tests to determine whether the patients had the HLA-DR15 gene, which is linked to an increased risk of developing MS, or lacked the protective HLA-A02 gene. Additionally, they collected information on occupational solvent exposure, painting products, and/or varnish, as well as current and previous smoking habits.

The findings showed that MS risk increased significantly in individuals with occupational exposure to organic solvents compared with those with no exposure. Individuals who had both MS risk genes and exposure to solvents were nearly 7 times as likely to develop MS as those without MS genes and solvent exposure. Individuals who had been smokers, in addition to having the genes and solvent exposure, were 30 times more likely to develop MS than those who have never smoked or been exposed to solvents and did not have the MS gene.

According to the researchers, MS genes and exposure to the solvents combined were responsible for an estimated 60% of the risk for developing MS.

Exposure to these solvents may elicit lung irritation and inflammation that leads to an immune reaction, subsequently contributing to the development of MS in individuals with genetic susceptibility to the disease, the researchers indicated.

“How this cocktail of MS genes, organic solvents, and smoking contributes so significantly to MS risk warrants an investigation,” Gabriele C. DeLuca, MD, PhD, of the University of Oxford in the United Kingdom, said in an accompanying editorial.

The researchers concluded that individuals with a family history of the disease can take steps to reduce their risk through lifestyle changes, such as avoiding cigarette smoke and unnecessary exposure to solvents, particularly in combination with each other.

References

Hedström AK, Hössjer O, Katsoulis M, et al. Organic solvents and MS susceptibility: Interaction with MS risk HLA genes. Neurology. 2018. Doi: https://doi.org/10.1212/WNL.0000000000005906

Exposure to paint, varnish, other solvents linked to increased risk of MS [news release]. Minneapolis. AAN’s website. https://www.aan.com/PressRoom/Home/PressRelease/1658. Accessed July 5, 2018.