Silica exposure and rheumatoid arthritis: a follow up study of granite workers 1940-81.

The incidence and prevalence of subjects awarded disability pensions and the prevalence of subjects receiving free medicines because of rheumatoid arthritis were studied in a Finnish cohort of 1026 granite workers hired between 1940 and 1971 and followed up until 31 December 1981. The incidence of awards of disability pensions because of rheumatoid arthritis during 1969-81, the prevalence of rheumatoid arthritis on 31 December 1981, and the prevalence of subjects receiving free medicines for rheumatoid arthritis at the end of 1981 were significantly higher among the granite workers than in the general male population of the same age. Retrospective analysis of the records of all patients with rheumatoid arthritis in the cohort showed a predominance of a severe, serologically positive and erosive form of rheumatoid arthritis, usually with an age at onset of 50 or over. The possible aetiological or pathophysiological role of granite dust in rheumatoid arthritis may be based on the effects of quartz on the immune system.