People with multiple sclerosis (MS) were more likely than people without the disease to report that they had been exposed to petroleum-based lubricants at work. This is shown by a new study from Karolinska Institutet, published in the journal Neurology.
MS is a chronic disease in which the immune system attacks the central nervous system. Previous research has linked smoking, organic solvents and air pollution to a higher risk of MS. In the new study, researchers investigated exposure to substances including engine oil, hydraulic oil and cutting fluids used for cooling and lubrication in metalworking.
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“In metalworking, for example, tiny droplets of lubricant can spread through the air and be inhaled. Just like cigarette smoke, it can irritate the lungs. Our hypothesis is that irritation in the lungs can trigger immune reactions that contribute to the development of MS”, says Anna Hedström , researcher at the Department of Clinical Neuroscience , Karolinska Institutet.
The study included 2,872 people with newly diagnosed MS and 6,122 people without MS in Sweden. Participants answered questions about their work history and any contact with substances including cutting fluids, engine oil and hydraulic oil. Exposure was common in areas such as metalworking, construction, vehicle repairs and machinery maintenance.
Higher odds of MS after exposure
Among people with MS, 8.7 per cent said they had been exposed to petroleum-based lubricants at work, compared with 6.5 per cent in the control group. After the researchers accounted for several other factors, exposure was linked to 38 per cent higher odds of MS. The odds rose slightly with more years of exposure and more hours per week.
The association remained when the researchers only counted exposure that had occurred at least seven years before the first MS symptoms. In that analysis, exposure was linked to 55 per cent higher odds of MS.
Among people who smoked, the association was stronger. In the subgroup for which genetic data were available, the researchers also saw a stronger association in people who lacked a gene variant previously linked to a lower risk of MS.
One limitation is that participants reported their exposure themselves and may therefore have remembered or classified it incorrectly. Other exposures in the work environment may also have affected the results. The study therefore does not show that petroleum-based lubricants cause MS.
“The next step is to see whether the association is seen again in other studies. To understand whether the lubricants themselves contribute to the risk of MS, we need more detailed information about which products were used and how often and for how long people were exposed”, says Anna Hedström.
The study was funded by the Swedish Research Council, Forte, the Swedish Brain Foundation and the Margaretha af Ugglas Foundation. See the study for information about any reported conflicts of interest.
Publication
” Occupational Exposure to Petroleum-Derived Lubricants and Risk of Multiple Sclerosis “, Hedström Anna Karin, Olsson Tomas, Alfredsson Lars, Neurology, online 4 November 2026, doi:10.1212/WNL.0000000000218718
