Introduction Sarcoidosis is an inflammatory disease with unknown etiology that involves the formation of granulomas, mainly in the lungs and/or intrathoracic lymph nodes. Hypothesis about the etiology of sarcoidosis are combination of genetic and environmental factors. Previous studies have linked exposure to silica dust with increased risk of sarcoidosis.

Object A case-control study to investigate the silica exposure among Swedish sarcoidosis cases.

Methods The data was collected from the National non-primary outpatient care register kept by the Swedish National Board of Health and Welfare. All cases between the age of 20 and 65 with the diagnosis Sarkoidos-D86 according to the International Classification of Diseases, 10th Edition (ICD-10) was included in the study (11 772 cases). The information was matched towards the register for cause of death and the register for emigration.

For each case two controls were included matched for age, sex, was resident in the same county, should not be first degree relatives to cases and not have been diagnosed with the investigated disease using the Swedish Central Bureau of Statistics (SCB) multigeneration register. Cases and controls was matched against SCBs occupational registry for work profession. The levels of silica dust exposure were estimated using NOCCA-JEM (Nordic Occupational Cancer study job-exposure matrix) a modified version of the Finnish Information System on Occupational Exposure job-exposure matrix (FINJEM) which is a well-established method of estimating exposure.

Result Cases of sarcoidosis have an increased exposure to silica before diagnosis (1.19; 95%  CI 1.1 to 1.30).

Conclusion The increased exposure to silica among sarcoidosis cases suggest that silica can be an environmental factor that contribute to development of sarcoidosis.