People who regularly work with petroleum-based lubricants such as engine oil and metalworking fluids may have a higher likelihood of developing multiple sclerosis, according to a large Swedish study.
Researchers compared 2,872 people with newly diagnosed multiple sclerosis with 6,122 people without the disease and examined their occupational histories.
The study published in Neurology found that participants who reported workplace exposure to petroleum-derived oils and lubricants had 38% higher adjusted odds of MS than those who reported no such exposure.
The association became stronger when researchers excluded exposures occurring during the seven years immediately before the first MS symptoms, suggesting the relationship was not easily explained by early disease changing a person’s work history.
However, the study does not show that engine oil or industrial lubricants directly cause multiple sclerosis.
Table of Contents
Nearly 9,000 People Were Included
The population-based study was conducted in Sweden and included people participating in a large epidemiological investigation of MS risk.
Researchers studied:
| Study Detail | Finding |
|---|---|
| People with MS | 2,872 |
| Controls without MS | 6,122 |
| Average age | About 35 years |
| Exposed MS cases | 251 |
| Exposed controls | 399 |
| Overall adjusted association | 38% higher MS odds |
| 7-year lag analysis | 55% higher MS odds |
| Journal | Neurology |
| Published online | 4 November 2026 |
Among people with MS, 8.7% reported occupational exposure to petroleum-based lubricants, compared with 6.5% of participants without MS.
Researchers accounted for multiple established MS risk factors before calculating the association.
Which Workplace Products Were Included?
The study considered occupational contact with several petroleum-derived lubricants commonly used in industrial and mechanical environments.
These included:
- cutting oils and metalworking fluids;
- engine oil;
- hydraulic oil;
- concrete form oil.
Common occupations among exposed participants included:
- metalworking;
- construction;
- automotive repair;
- machinery maintenance.
The American Academy of Neurology report on the findings notes that these materials can expose workers to oil mists, aerosols and volatile compounds, particularly when they are heated, sprayed or used during machining.
Workers With Exposure Had 38% Higher Odds of MS
After adjusting for factors including age, sex, smoking, residential area and other known MS-related characteristics, occupational exposure was associated with an adjusted odds ratio of 1.38.
In practical terms, that means the exposed group had about 38% higher odds of MS than the unexposed group.
This should not be interpreted as meaning 38% of exposed workers will develop MS.
Multiple sclerosis remains relatively uncommon, and an odds ratio describes a statistical difference between groups rather than an individual’s absolute probability of disease.
Longer Exposure Was Linked to Greater Risk
The researchers also found evidence of a dose-response pattern.
For every additional year of occupational exposure, MS odds increased by approximately 2%.
The odds also increased by around 2% for each additional hour of exposure per week.
Duration and intensity both remained associated with MS when researchers included them in the same statistical model.
Dose-response patterns can strengthen an epidemiological finding because they suggest greater exposure corresponds with greater risk.
But they do not prove causation on their own.
Association Strengthened When Recent Exposure Was Removed
MS can begin biologically years before neurological symptoms become obvious.
That creates a problem for occupational research because early, undiagnosed illness might influence where a person works or how much exposure they receive.
Researchers addressed this by performing a seven-year lag analysis.
They counted only lubricant exposure that occurred at least seven years before the first MS symptom.
The association became stronger.
Workers with earlier exposure had 55% higher odds of MS compared with unexposed participants.
The adjusted odds ratio was 1.55.
This result makes reverse causation less likely, although it cannot eliminate every possible explanation.
Smoking Appeared to Make the Association Stronger
Smoking is already a well-established environmental risk factor for multiple sclerosis.
The new study found that tobacco smoking and lubricant exposure appeared to interact.
People who both smoked and had occupational petroleum-lubricant exposure had roughly 2.5 times the odds of MS compared with people who had neither exposure.
The statistical pattern suggested that the combined association was greater than would be expected simply by adding the individual effects of smoking and lubricant exposure.
This finding supports a broader hypothesis that repeated exposure to substances irritating the lungs may contribute to immune processes involved in MS.
Why the Lungs Could Matter in Multiple Sclerosis
Multiple sclerosis is an autoimmune disease in which the immune system attacks structures in the brain and spinal cord.
Scientists still do not fully understand why the disease begins.
Both genetics and environmental exposures are important.
Previous research has associated MS risk with lung irritants including:
- cigarette smoke;
- organic solvents;
- air pollution.
Petroleum-based lubricants can generate fine aerosols and volatile compounds that workers may inhale.
The study authors propose that repeated respiratory exposure could contribute to:
- airway inflammation;
- oxidative stress;
- inflammatory immune signaling.
In genetically susceptible individuals, that inflammatory environment could theoretically help activate immune cells involved in autoimmunity.
This remains a biological hypothesis rather than a proven mechanism.
Genetic Susceptibility Also Influenced Risk
Researchers examined two HLA genetic variants that are strongly associated with MS susceptibility.
HLA-DRB1*15:01 increases MS risk.
HLA-A*02:01 is associated with lower risk.
The researchers found evidence that lubricant exposure interacted particularly with the absence of the protective HLA-A*02:01 variant.
This follows a broader pattern already seen with smoking and solvent exposure: environmental risk factors can have stronger effects in people with particular genetic backgrounds.
The Dramatic ‘33 Times Higher’ Figure Needs Context
One subgroup in the study attracted attention because participants who:
- were exposed to petroleum-based lubricants;
- smoked;
- carried HLA-DRB1*15:01;
- lacked HLA-A*02:01
had more than 33 times the odds of MS compared with people who had none of those risk factors.
However, this estimate came from only 16 MS cases and two controls.
That is a very small group and produces substantial statistical uncertainty.
For that reason, the 33-fold figure should not be treated as the study’s main result.
The 38% overall association is considerably more robust.
Individual Lubricants Did Not All Show the Same Result
Researchers also analyzed lubricant categories separately.
Significant associations were observed for several products, including cutting fluids and engine oil.
Hydraulic oil showed a weaker association that did not reach conventional statistical significance after adjustment.
This is another reason not to treat every petroleum lubricant as carrying identical potential risk.
Different products can vary in:
- chemical composition;
- additives;
- aerosol formation;
- exposure intensity;
- workplace ventilation.
Researchers Adjusted for Solvent Exposure
Industrial workers exposed to lubricants may also encounter organic solvents, which have independently been linked to MS risk.
To address that possible confounding, researchers adjusted their models for solvent exposure.
The petroleum-lubricant association remained.
The adjusted odds ratio remained around 1.37 after accounting for solvents.
That suggests solvent exposure alone does not explain the observed relationship.
The Study Does Not Show That Occasional Engine-Oil Contact Causes MS
The findings specifically concern occupational exposure.
They should not be extended automatically to occasional household contact with engine oil or lubricants.
Industrial workers can experience much more frequent and intense exposure through:
- aerosols;
- mists;
- skin contact;
- repeated handling;
- poorly ventilated workplaces.
The research does not define a threshold below which exposure is safe or above which MS will develop.
Nor does it show that everyone exposed to these products faces a substantial risk.
Self-Reported Exposure Is an Important Limitation
Participants reported their employment histories and lubricant exposure through questionnaires.
That creates the possibility of recall bias or exposure misclassification.
Some people may not accurately remember:
- which products they used;
- how often they used them;
- exact exposure duration;
- workplace concentrations.
Researchers also could not completely account for every chemical or occupational exposure occurring in the same workplaces.
These limitations are particularly important because observational studies can identify associations without proving the exposure itself is responsible.
The Study Was Conducted in Sweden
The findings also come from one national population.
Workplace practices, lubricant formulations, safety regulations and ventilation standards can differ substantially between countries.
The results therefore need replication in other occupational populations.
Future research using direct workplace exposure measurements could provide stronger evidence than retrospective questionnaires.
What Does This Mean for Workers?
The study does not suggest that people working with engine oils or cutting fluids should stop working with them.
It reinforces the importance of established occupational-safety measures designed to reduce unnecessary exposure.
These can include:
- adequate workplace ventilation;
- controlling oil mist and aerosols;
- appropriate protective equipment;
- reducing direct skin contact;
- following product-specific safety procedures.
Workers should rely on occupational-health guidance appropriate to the specific materials used in their workplace rather than making medical or employment decisions from one observational study.
Why the Findings Matter
The research fits into a larger change in how scientists think about multiple sclerosis.
Genetics clearly matter, but environmental exposures also appear to influence whether disease develops in susceptible people.
The lungs are increasingly being studied as one possible site where those environmental and genetic factors interact.
Cigarette smoke, organic solvents and air pollution have already been associated with increased MS risk.
The new study adds petroleum-derived occupational lubricants to that list of exposures requiring closer investigation.
What the Research Really Shows
The evidence does not establish that petroleum lubricants cause multiple sclerosis.
What it shows is that Swedish workers who reported occupational exposure had 38% higher adjusted odds of MS, and that the association strengthened with longer exposure and remained when recent exposures were excluded.
The association was also more pronounced when combined with smoking and certain genetic risk profiles.
Those patterns make the finding scientifically important.
They also justify further studies using objective exposure measurements and different populations to determine whether petroleum-derived workplace aerosols genuinely contribute to MS development, and whether reducing exposure could lower that risk.
