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Researchers in Sweden find more evidence that exposure to lung irritants raises MS risk in those who carry the MS gene.
If you’re at risk of developing multiple sclerosis (MS), it may make sense to skip that next do-it-yourself project around the house — at least based on the findings of a new study published online July 3, 2018, in Neurology, the journal of the American Academy of Neurology.
Researchers from the Karolinska Institutet in Sweden, a leading research institution that since 1901 has selected the Nobel laureates in medicine, found that people who have been exposed to paint or other solvents are 50 percent more likely to develop the condition than those who haven’t.
Those who are genetically predisposed to MS are 7 times more likely to be diagnosed with the condition if they have been exposed to solvents than who don’t carry MS genes and haven’t been exposed to solvents.
Solvent Exposure Not a Guarantee of Disease
The authors of the study are quick to emphasize that if you’ve been exposed to chemicals found in household paints and cleaners, you won’t necessarily get MS.
“MS is a rare disease even if you carry the strongest genetic risk factor for the disease,” says Anna Hedstrom, MD, PhD, the study’s lead author, who works in the Institute of Environmental Medicine at Karolinska. “But what you can do to reduce the risk is avoid smoking and unnecessary exposure to organic solvents, and especially the combination of these exposures.”
Smoking Also a Risk Factor
Indeed, Dr. Hedstrom and her colleagues have published earlier research in 2017 in the European Journal of Epidemiology suggesting that if you carry the so-called MS gene — the human leukocyte antigen gene variant shown to increase risk — and you smoke, you’re increasing your risk of being diagnosed with the condition.
For their current study, they identified 2,042 Swedes who had recently been diagnosed with MS and matched them with 2,947 healthy adults the same age and gender. They used blood tests to confirm genetic risk.
Lung Irritation May Contribute to Immune Response
“Our hypothesis [for the smoking study] was that the chronic lung irritation caused by smoking contributes to an immune response that results in MS, primarily in those with a genetic susceptibility to the disease,” Hedstrom explains. “[For the new study], we wanted to investigate whether organic solvents, another source of lung irritation, also interact with MS risk genes to increase the disease risk. Identifying environmental exposures is important since these are preventable.”
All of the people in the study were then asked to respond to questionnaires regarding their exposure to organic solvents, painting products, or varnish, and whether they had history of smoking.
They found that within the group without the MS gene and no smoking or exposure to solvents, there were 139 people with MS and 525 people without the condition.
But within the group with the MS gene and exposure to solvents but no smoking, there were 34 people with MS and 19 people without the condition, and within the group with the MS gene and exposure to solvents and smoking, there were 40 people with MS and 5 people without the condition.
Based on these findings, they concluded that the MS gene and solvent exposure combined were responsible for roughly 60 percent of the risk of developing MS.
A Dose-Dependent Relationship
“For both, there’s a dose-dependent relationship,” Hedstrom notes. “Meaning: The risk of disease increases with increasing exposure. Overall, smoking a few cigarettes daily during a few years does not seem to influence disease risk. The same may be true for organic solvents, but we cannot yet clarify how much exposure that is needed for an association to occur.”