Study: Motor oil may promote rheumatoid arthritis

Exposure to mineral oils such as motor and hydraulic oils can raise your risk of developing rheumatoid arthritis, research shows.

In a study in the journal Arthritis Research & Therapy, Swedish researchers report that occupational exposure to these oils can increase the risk of developing rheumatoid arthritis by as much as 60%. Rheumatoid arthritis is a potentially debilitating autoimmune disorder that causes the joints and other tissues to become painfully inflamed. It affects about 1% of Canadians.

Noting that both genetic and environmental factors appear to play a role in the development of rheumatoid arthritis and that experiments have shown that mineral oils can induce arthritis in rats, the researchers compared exposure to mineral oils among people who had been diagnosed with rheumatoid arthritis and control subjects who had not.

The study included 1,419 people who had recently been diagnosed with rheumatoid arthritis and 1,674 people who did not have arthritis but were selected on the basis of similarity of age, gender and residential. All participants completed questionnaires containing specific questions about lifestyle, personal health, occupational data, and socioeconomic and demographic information. Participants were also asked specific questions relating to exposure to cutting oil, motor oil, form oil, hydraulic oil and asphalt.

Only men were found to have had occupational exposure to mineral oils, with motor and hydraulic oil exposure being the most common. After analyzing the data, the researchers found that men who were exposed to mineral oils had a 30% greater risk of developing rheumatoid arthritis, though a significant link was found only with rheumatoid-factor-positive rheumatoid arthritis. Furthermore, the researchers found that mineral oil exposure was linked to a 60% greater chance of developing another type of rheumatoid arthritis, called anticitrulline-positive rheumatoid arthritis.

Genetic analysis on the subjects showed no interaction between genetic profile and mineral oil exposure when it comes to rheumatoid arthritis risk.

While the reason behind the increased rheumatoid arthritis risk associated with mineral oil exposure is unclear, the researchers speculate that the oils could trigger immune activity in the lymph nodes, eventually leading to inflammation in the joints.

They say further research could help to determine whether other environmental or occupational agents could also increase the risk of developing rheumatoid arthritis.