Crystalline silica exposure in patients with rheumatoid arthritis and systemic sclerosis: a nationwide cross-sectional survey.

OBJECTIVES
Develop and validate a thorough exposure questionnaire to comprehensively explore crystalline silica (SiO2) exposure in the general population (gender-specific, occupational and non-occupational) and in patients with autoimmune diseases (Rheumatoid arthritis (RA), Systemic sclerosis (SSc)).


METHODS
Lifetime exposures to SiO2 in occupational and non-occupational settings were assessed using a thorough exposure questionnaire. The questionnaire was applied to a general population panel (N = 2,911) sampled from the French rolling census, and to unselected patients with SSc (N = 100) and RA (N = 97). Global (GES), occupational (OES) and non-occupational (NOES) exposure scores were assessed in SSc and RA patients, and compared with up to 4 controls from the general population, matched by age group, sex and tobacco consumption.


RESULTS
Patients had higher GES than their matched controls (SSc: p= 0.001; RA: p< 0.0001) due to higher OES (p< 0.0001 for SSc and RA). Men had higher GES than women (SSc: p< 0.0001; RA: p= 0.002) due to higher OES (p< 0.0001 for SSc and RA). The NOES did not differ between men and women. In SSc patients: Men had higher GES than controls (p< 0.0001). Men and women with SSc had higher OES than controls (p< 0.0001). In RA patients: GES and OES were higher in both men (p= 0.00521; p< 0.0001) and women (p< 0.0001; p< 0.0001) than in their respective controls. Women had higher NOES than controls (p= 0.045).


CONCLUSION
The lifetime SiO2 exposure gap between RA and SSc patients and controls was substantially due to occupational exposure. In both diseases, men had higher exposure scores than women.