Are cleaning activities a source of exposure to crystalline silica in women with rheumatoid arthritis? A case–control study

INTRODUCTION: Inhalation of crystalline silica (silicon dioxide, SiO(2)) is associated with a wide range of acute and chronic diseases, including rheumatoid arthritis (RA). The objectives of this work were to identify the main sources of exposure to SiO(2) in a series of patients with RA not selected on the basis of their professional activity, compared with a representative sample of the French general population, and to assess the association between silica exposure and disease features. METHODS: The Dust Exposure Life-Course Questionnaire (DELCQ) is a tool that enables retrospective quantification of both occupational and non-occupational lifetime exposure to SiO(2). DELCQ—previously validated in a large representative sample of the French general population—was administered to 97 consecutive RA patients, and exposure scores were compared between cases and age, gender and smoking status-matched controls (1:4). The main sources of SiO(2) exposure were identified in cases and controls, and source-specific exposure levels were compared. The association between DELCQ scores and disease variables in cases was tested via univariable and multivariable analyses. RESULTS: In women with RA, the main sources of SiO(2) exposure were cleaning activities and dusty clothes laundry, with higher exposure levels from these sources versus the general population (p<0.005). Across the whole series of RA patients, high SiO(2) exposure was independently associated with mediastinal lymphadenopathy (OR 6.3, 95% CI 1.4 to 27.7). CONCLUSION: Cleaning activities and dusty clothes laundry may be underestimated sources of SiO(2) exposure in women with RA.