You probably know the smell of engine oil on a mechanic's hands, or the slick residue cutting fluids leave on metalworking tools. For most of the shift it fades into the background, just part of the job.
A new study in the journal Neurology found that workers exposed to petroleum-derived lubricants had about 38 percent higher odds of multiple sclerosis than unexposed workers, according to NewsWise.
The fluids studied were engine oil, hydraulic oil, cutting fluids and concrete form oil.
The analysis compared 2,872 people newly diagnosed with MS to 6,122 people without the disease, matched on age, sex and location in Sweden. The average age was 35.
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These are odds from an observational study, so the result points to an association, not proof that the lubricants cause MS.
The strongest signal
The odds climbed with time on the job. Each extra year of exposure added about 2 percent to the odds, and so did each extra weekly hour of exposure.
When the researchers restricted the analysis to exposures that happened at least seven years before symptoms appeared, the link grew to 55 percent higher odds.
That timing argues against reverse causation, where early symptoms would push a person toward a different job.
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Two things seemed to amplify the risk. Smokers who were also exposed had higher odds than simply adding the two risks together would predict.
The pattern was starkest in people who smoked, carried a known MS risk gene and lacked a protective genetic variant. That group was tiny, only 16 MS cases and 2 controls, so the roughly 33-fold odds carry wide uncertainty.
Anna Karin Hedström of Karolinska Institutet, who led the study, said to NewsWise that the link was stronger "when combined with smoking or certain genetic characteristics."
Who meets these fluids every day?
The exposed occupations read like a map of blue-collar work. They include metalworking, construction, automotive repair and machinery maintenance.
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According to News-Medical, 251 of the MS patients, or 8.7 percent, had this type of exposure, compared with 6.5 percent of the comparison group.
Multiple sclerosis is a disease of the central nervous system in which the immune system attacks the protective coating around nerves. The causes are not fully understood.
About 727,000 US adults were estimated to be living with MS in 2010, according to a health-claims analysis led by the National Multiple Sclerosis Society.
Smoking, low vitamin D, obesity in adolescence and Epstein-Barr virus have already been tied to the risk.
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What the study cannot tell you
Workers reported their own exposure on questionnaires, which leaves room for recall errors.
Workplaces also carry other chemicals the survey did not capture, and the findings need to be confirmed in other populations.
The authors have called for more detailed exposure data in future research, including when and how much people were exposed on the job.
For workers in these industries, standard occupational advice applies. Use the workplace ventilation and gloves provided, and talk to a doctor about unexplained numbness, vision changes or balance problems.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.