Slilica, Silicosis, and Lung Cancer in Diatomite Workers

摘要

The project served to update a cohort mortality study of workers exposed tocrystalline silica (14808607), primarily as cristobalite (14464461). Exposure occurred during the mining and processing of diatomaceous-earth in two facilities located in California. There were 2,961 workers in the cohort who had at least 12 months of cumulative service at either facility. This update extended an earlier study by 7 years. Mortality was followed up for 1942 through 1994. Chest radiographs were obtained for 2,520 workers. As expected, radiographcally determined silicosis was strongly related to cumulative exposure to crystalline silica. Compared to national rates, mortality rates from both nonmalignant respiratory disease and lung cancer were elevated among these workers. A strong dose response association was noted for cumulative exposure to crystalline silica and mortality from nonmalignant respiratory diseases. Lung cancer mortality was also associated with cumulative exposure to crystalline silica, but the association was not as strong as that from nonmalignant respiratory disease. Confounding by either smoking or by occupational asbestos (1332214) exposure was not likely to account for the observed exposure/response relations with nonmalignant respiratory disease and lung cancer mortality.