| Recent occupational studies link crystalline silica dust exposure to systemic lupus erythematosus (SLE). This study examines the association between silica exposure and SLE using data from a population-based case-control study of SLE in North Carolina and South Carolina. Cases were identified through community-based and university rheumatologists. Eligibility required fulfillment of the 1997 revised-American College of Rheumatology classification criteria for SLE and diagnosis between January 1, 1995 and July 30, 1999. Controls were identified through driver's license records and frequency matched to cases by age, sex, and state. The final sample consisted of 265 (93% of referred and eligible) cases and 355 (75% of screened and eligible) controls. Ninety-percent of the cases were women, 60% were African-American, and the median age at diagnosis was 39 years. In-person interviews collected a detailed lifetime job and farming history, and information on specific jobs and tasks with possible silica exposure. Follow-up telephone interviews collected additional data on potential high or medium-level silica exposure. I observed an association between SLE and silica for exposure from trades (odds ratio, OR = 3.1, 95% CI 1.4–7.0), farming (OR = 3.0, 95% CI 1.1–8.2), and trades and farming combined (medium exposure OR = 2.0, 95% CI 1.1–3.7; high exposure OR = 4.2, 95% CI 1.2–13.9). The association was seen in men and women, whites and blacks, and different education levels. As the first population-based study of silica and SLE, these results extend the literature on occupational silica exposure and SLE. The study also contributes to methods in exposure assessment through developing a protocol to retrospectively assess silica exposure from farm work. |
