Objectives The aim was to find out occupational differences in the incidence of rheumatoid arthritis (RA) in the Finnish population and to detect exposures in occupations with a high risk of RA.

Methods The employed persons of 15–64 years of age receiving specially compensated medicines because of RA for the period of 1971–2000 were linked with the 5-year periodical census data. The incidence rates were calculated by sex, occupation and region. Occupational and exposure history, and confounding factors were studied via a questionnaire sent to a sample of 5 000 RA patients and 5 000 matched referents with hypertension.

Results The highest age- and region-adjusted incidence rate ratios (RR; 95% CI; reference administrative work) were observed for men in mining and quarrying work (2.1; 1.6–2.8), textile work (1.7; 1.3–2.2), iron and metalware work (1.4; 1.3–1.5), road transport work (1.3; 1.2–1.4), and for women in agricultural and horticultural work, animal husbandry (1.4; 1.3–1.5), postal work (1.3; 1.2–1.5), iron and metalware work (1.3; 1.1–1.5), laundering, and pressing work (1.3; 1.1–1.6). The RA patients noticed cold, humidity, draft (p<0.001), and vibration (p<0.01) more often in their work than the referents. Also different dusts: clay minerals, synthetic mineral fibres, carbonate minerals (p>0.01), and concrete (p<0.001) were reported by the RA patients more frequently. As other harmful exposures were mentioned, for example, insects, animal epithelium, and strenuous work.

Conclusions The variation in occupational incidences of RA cannot be explained by regional factor. The results indicate that occupational exposures have contributed to RA.