O2D.1 A follow-up study of occupational styrene exposure and risk of systemic sclerosis, rheumatoid arthritis, and other systemic autoimmune rheumatological diseases

Background Increased risk of systemic sclerosis, systemic lupus erythematosus, rheumatoid arthritis, primary systemic vasculitis, and systemic Sjogren’s syndrome has been suggested following occupational solvent exposure. The evidence for specific solvents is, however, limited and little is known about exposure and risk patterns. Aim Our aim is to examine the exposure response relation for systemic sclerosis, rheumatoid arthritis, systemic lupus erythematosus, primary systemic vasculitis, and systemic Sjogren’s syndrome following occupational styrene exposure. Methods We followed 72 467 styrene exposed workers of the Danish reinforced plastics industry from 1977–2012. We modelled styrene exposure from employment history, survey data and historical styrene exposure measurements. We identified cases in a national patient register, and investigated gender specific exposure response relations by cumulative styrene exposure for different exposure time windows adjusting for age, decade, educational level and a proxy for tobacco smoking. Results During 1,553,577 person-years, we identified 223 women and 453 men diagnosed with a systemic autoimmune rheumatological disease, of which three out of four were rheumatoid arthritis. When adjusting for potential confounders and comparing the highest with the lowest styrene exposure tertile, we observed a statistically non- significantly increased risk of systemic sclerosis among men (IRR=1.79; 95% CI 0.48–6.87) and women (IRR=2.58; 95% CI 0.51–12.94), based on 20 and 9 cases respectively. However, for women with systemic sclerosis, we saw a significantly increasing trend of 1.19 (1.01–1.40) pr. 100 mg/m3-years. Increased risks were also suggested for primary systemic vasculitis (IRR=2.32; 95% CI 0.63–8.52) and rheumatoid arthritis (IRR=1.26; 95% CI 0.95–1.67) among men. Analyses of exposure time windows suggest a latency period for rheumatoid arthritis of about 15 years. Conclusion This study might indicate that styrene exposure is associated with the occurrence of systemic sclerosis among men and women, and primary systemic vasculitis and rheumatoid arthritis among men.