Am I At Increased Risk to Develop Rheumatoid Arthritis Because I’m Car Mechanic?
By Nathan Wei
A recent Swedish study seems to indicate that people who have occupational exposure to mineral oils, in particular hydraulic or motor oil, have an increased risk of developing rheumatoid arthritis by about 30%.
Berit Sverdrup and fellow researchers from the Karolinska Institute in Stockholm, Sweden, selected a group of patients diagnosed with rheumatoid arthritis (RA) between May 1996 and December 2003. They matched these patients with people of the same age, gender and residential area, who acted as controls. Shortly after they had been diagnosed with RA, the patients were asked to complete a questionnaire regarding occupational exposure to different types of mineral oils, such as cutting oil, motor oil, form oil, hydraulic oil and asphalt. The same questionnaire was sent to controls.
In total, the study included 1419 cases and 1674 controls. Only males reported high occupational exposure to oil, mostly motor and hydraulic oil. A group of 135 men diagnosed with RA and reporting high exposure, as well as 132 matching controls, was retained for further study. The research results showed that men highly exposed to motor or hydraulic oil have a 30% higher risk of developing RA than unexposed men.
Exposure only increased the risk of developing ‘rheumatoid factor positive’ (RF+) rheumatoid arthritis, a generally more severe form of RA. It didn’t increase the risk of developing rheumatoid factor negative (RF-) rheumatoid arthritis. Exposure to oil is also linked to a 60% increased risk of developing ‘ anti-cyclic citrullinated peptide antibody positive’ (anti-CCP+) rheumatoid arthritis. Anti-CCP is a more specific marker for RA than RF is. It may also represent a disease with greater severity.
This study confirms results found in animals – exposure to mineral oil had been shown to induce arthritis in rats — and raises questions regarding exposure to other environmental or occupational agents. Exposure to environmental toxins may be linked to the development of certain kinds of arthritis. (Sverdrup B, Kallberg H, Bengtsson C, Lundberg I, Padyukov L, Alfredsson L, Klareskog L. Association between occupational exposure to mineral oil and rheumatoid arthritis. Results from the Swedish EIRA case-control study. Arthritis Research & Therapy 2005, 7:R1296-R1303)
Authors note: We still don’t know what causes RA. However, studies like this are very intriguing.
Nathan Wei, MD, FACP, FACR is a rheumatologist and Director of the Arthritis and Osteoporosis Center of Maryland (http://www.aocm.org). He is a Clinical Assistant Professor of Medicine at the University of Maryland School of Medicine and consultant to the National Institutes of Health. For more info: Arthritis Treatment