Environmental exposures and rheumatoid arthritis risk.

In addition to rapidly burgeoning data regarding novel genetic risk factors, a growing list of environmental exposures have been implicated in rheumatoid arthritis (RA) susceptibility. Cigarette smoking is chief among the many environmental exposures implicated in disease risk, accounting for approximately one in six new cases of RA, with recent results underscoring the central importance of select gene-smoking interactions in RA development. In this review, we examine data linking several environmental exposures with RA risk, including cigarette smoking, other air pollutants and occupational exposures, reproductive/hormonal influences, alcohol consumption, select infections leading to periodontal disease, and dietary factors. Where applicable, we review the current understanding of biologic mechanisms linking these environmental factors to disease risk.