A case-control study of occupational exposures and systemic sclerosis

Objectives. A case-control study was conducted in Verona, Italy, to assess the relationship between occupation, occupational exposures and systemic sclerosis (SSc). Methods. Fifty-five cases (46 female and nine male) and 171 controls were recruited. Interviews provided work histories, including job titles, industry and likelihood of occupational exposure to silica, hand-arm vibration, organic solvents, and other chemicals. Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated. Results. Female teachers (OR 3.4, 95% CI 1.2-10.1) and textile workers (OR 2.1, 95% CI 1.0-4.6) were at an increased risk of SSc. Compared with those never exposed, age-adjusted and gender-adjusted ORs were 2.3 (95% CI 1.0-5.4) among subjects exposed to organic solvents, 2.5 (95% CI 0.8-8.0) for exposure to selected chemicals, 1.7 (95% CI 0.4-7.6) for exposure to silica, and 1.5 (95% CI 0.5-4.8) for usage of vibrating tools. When data analysis was stratified according to gender, only men showed a significant increase in risk for exposure to solvents and selected chemicals. Conclusions. The findings of this study tend to support the role of organic solvents and certain chemicals in SSc causation. The association with teaching and working in the textile industry suggests that other exposures are involved in the aetiology of SSc among women. However, because of the small number of subjects, particularly in stratified analyses, chance cannot be ruled out as an explanation of some findings of this study.