The epidemiology of scleroderma among women: assessment of risk from exposure to silicone and silica.

OBJECTIVE: To investigate the relationship between exposure to silicone (including breast implants) and silica and the development of scleroderma (systemic sclerosis, SSc) among women. METHODS: A population based case-control study was conducted among women in Michigan. 274 confirmed cases of SSc diagnosed between 1985 and 1991 were identified by contacting rheumatologists, hospitals, and a scleroderma support group. These cases and 1184 controls were interviewed by telephone to ascertain past exposures to silicone or silica. RESULTS: Silicone in the form of breast implants was not associated with significantly increased risk of SSc (adjusted odds ratio, 1.30; 95% confidence interval, 0.27 to 6.23). Among 20 other potential silicone exposure surveyed, self-reported exposure to silicone based glues, sealants, and caulks, manufacture or repair of windows or windshields, repairing or frequently using photocopy machines, consumption of simethicone-containing antacids, and implanted medication delivery pumps were significantly associated with SSc. However, blinded assessment of all job and hobby descriptions in terms of their potential for silicone exposure failed to support the first 3 associations, antacid consumption may have been confounded by esophageal dysmotility before the diagnosis of SSc, and other silicone containing device categories (pacemakers, central nervous system shunts, other shunts and catheters) were not significantly associated with SSc. Surgically implanted metallic fixation devices were associated with significantly reduced risk for SSc. No association was detected between SSc and silica dust exposure. CONCLUSION: Consistent with other studies, we found no increased risk of SSc among women with silicone breast implants, equivocal evidence of risk from other silicone exposures, and no evidence of risk from silica exposure.