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

Abstract

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.