Objective: To quantify silicosis and lung cancer risks among porcelain workers occupationally exposed to respirable crystalline silica.
Methods: We reread historical radiographs to identify silicosis and estimated exposure on the basis of detailed work history and about 8000 industrial hygiene measurements. Cox proportional hazards models estimated risks by cumulative and average exposure.
Results: Adjusted silicosis hazards ratios were 5.3 (95% confidence interval [CI], 1.6 to 17.3); 7.3 (95% CI, 2.6 to 20.8); and 6.8 (95% CI, 3.0 to 15.3) for cumulative exposures >4 to 5; >5 to 6; and >6 mg/m3-years, and 3.3 (95% CI, 0.8 to 14.7), 13.6 (95% CI, 4.2 to 44.4) and 23.2 (95% CI, 8.2 to 65.8) for average exposures >0.1 to 0.15; >0.15 to 0.2 and >0.2 mg/m3, respectively. Exposure was not associated with any cause of death including lung cancer.
Conclusions: Respirable crystalline silica exposure more than 4 mg/m3-years (cumulative) or more than 0.15 mg/m3 (average) were strongly associated with silicosis, but unrelated to lung cancer risks.
From the ENVIRON International Corporation (Dr Mundt, Mr Parsons, Dr Heavner), Amherst, Mass; ENVIRON Germany, GmbH (Mr Birk), Essen, Germany; Institute of Occupational and Social Medicine (Dr Borsch-Galetke, Dr Siegmund), Heinrich Heine University, Düsseldorf, Germany; and Verwaltungs-Berufsgenossenschaft (Dr Guldner), Würzburg, Germany.
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Address correspondence to: Kenneth A. Mundt, PhD, ENVIRON International Corporation, 28 Amity St, Ste 2A, Amherst, Massachusetts; E-mail: email@example.com.