Systemic sclerosis and occupational risk factors: a case-control study

Aims: A case-control study was carried out between 1998 and 2000 to investigate the relation between systemic sclerosis and occupational exposure. Methods: Eighty cases of systemic sclerosis admitted consecutively to the Department of Internal Medicine at the University Hospital of Tours from 1998 to 2000 were included. For each case, two age, gender, and smoking habits matched controls hospitalised during the same period in the same department were selected. A committee of experts was set up retrospectively to assess occupational exposure. Exposure to silica dust and organic solvents (such as trichlorethylene and other chlorinated solvents, and benzene and other aromatic solvents) was investigated using semiquantitative estimates of exposure. An exposure score was calculated for each subject based on probability, intensity, daily frequency, and duration of exposure for each period of employment. The final cumulative exposure score was obtained, taking into account all periods of employment. Results: Significant associations with SS were observed for crystalline silica, trichlorethyiene, chlorinated solvents, toluene, aromatic solvents, ketones, white spirit, epoxy resins, and welding fumes. Risk of SS was significantly associated with a high final cumulative exposure score of occupational exposure to crystalline silica, trichlorethylene, chlorinated solvents, welding fumes, and any types of solvents. Conclusion: Results confirm the influence of occupational risk factors in the occurrence of SS in both men and women. The link is not only with silica but also with other compounds such as solvents.