Occupational exposure to mineral oil, primarily motor or hydraulic oil, is associated with an increased risk of Rheumatoid Arthritis (RA), new research indicates. This supports findings from animal studies showing that these oils induce arthritis.

In the study, published in the medical journal Arthritis Research & Therapy, investigators compared the level of oil exposure between 1,419 individuals with RA and 1,674 individuals matched for age, sex and residential area who did not have RA (control subjects). All of the study participants lived in the southern part of Sweden from 1996 to 2003.

As it turned out, only men reported high levels of exposure to mineral oils, so the study focused on 135 men with RA and 132 controls, lead author Dr. Berit Sverdrup, from the Karolinska Hospital in Stockholm, and colleagues note.

In the overall analysis, mineral oil exposure raised the risk of RA among men by 30 percent. Further analysis revealed that this exposure only increased the risk of RA in subjects positive for rheumatoid factor and anti-citrulline, blood tests used to help diagnose RA.

Genetic analysis showed no relationship between the subjects’ genetic profile and the elevated RA risk associated with mineral oil exposure, the authors note.

Further exploration of the relationship between mineral oils and RA may help to establish if other types of exposure - to microbial or other occupational agents - can also induce arthritis, the researchers conclude.

SOURCE: Arthritis Research & Therapy, September 23, 2005.