Silica and lung cancer: a proportionate mortality study.
Case studies in occupational epidemiology. Steenland K, ed. New York: Oxford University Press, 1993 Jan; :92-102
NIOSH investigators sought a cohort of granite cutters exposed primarily to silica (14808607) in an effort to determine whether silica exposed humans were at an increased risk of lung cancer and whether those who have silicosis were at increased risk of lung cancer. This study was described as part of a text book and took the reader through the same steps that the investigator took when conducting the actual study to allow the student to solve the same problems that the investigator solved in the course of the study. The men in the cohort worked in granite sheds near quarries and cut granite to make gravestones, building materials, and other products. Historical levels of exposure were approximately 20 to 50 million particles per cubic foot (mppcf) through the 1940s, but were lowered to about 3 to 5mppcf thereafter. Union records identified 2,274 deaths. Analysis of 1,905 deaths revealed that the majority died in Vermont (36%), followed by New York (17%), and Massachusetts (14%). The average age at death was 69 years. Much of the large tuberculosis excess found was due to silicotuberculosis. The problem of competing causes, typical of proportionate mortality studies, was particularly pronounced here not only because of the deficit in heart disease but also because of the counterbalancing excesses in tuberculosis and nonmalignant respiratory disease. A proportionate cause of mortality ratio was calculated, which for lung cancer was 1.09. The excess of silicosis increased with duration of union membership.
Lung-cancer; Silica-dusts; Occupational-exposure; Cancer-rates; Epidemiology; Risk-factors; Mineral-dusts; Dust-exposure; Respiratory-system-disorders; Bacterial-infections
Case studies in occupational epidemiology