Reevaluation of silicosis and lung cancer in North Carolina dusty trades workers.
Amandus-HE; Castellan-RM; Shy-C; Heineman-EF; Blair-A
Am J Ind Med 1992 Aug; 22(2):147-153
A reexamination of data obtained in a study of the relationship between radiographic silicosis and the lung cancer risk of workers employed in dusty occupations was performed. The original study examined the mortality of 760 white males in 1983 who had been employed in dusty trades in North Carolina and who were diagnosed with silicosis between 1930 and 1983 on the basis of chest X-ray findings. The reanalysis was performed because of the possibility of misclassification of silicosis due to errors in reading the X- rays. Chest X-rays were reevaluated for silicosis by three experienced B-readers using 1980 International Labor Office (ILO) criteria. The lung cancer standardized mortality ratio (SMR) was recomputed. Of the 306 X-ray films from the silicotics, 104 were reclassified as ILO category 0, 160 as simple silicosis, and 83 as progressive massive fibrosis (PMF). Among the 107 radiographs from nonsilicotics, 104 were reclassified as ILO category 0, and one as simple silicosis. The recalculated SMRs for silicotics whose chest X-rays were reclassified as ILO category 0 and those who were judged as having simple silicosis were 1.0 and 2.5, respectively. The SMRs for subjects who had no exposure to other known carcinogens whose radiographs were reclassified as ILO category 0 or who had simple silicosis were 1.2 and 2.4, respectively. PMF was not associated with an increased risk for lung cancer. The authors conclude that lung cancer rates in North Carolina silicotics who were employed in dusty trades appear to be elevated. The reanalysis, which controls for possible errors in misclassifying silicosis, supports the hypothesis that silicosis is a risk factor for lung cancer.
NIOSH-Author; Epidemiology; Lung-cancer; Silica-dusts; Chest-X-rays; Occupational-exposure; Mortality-data; Respiratory-system-disorders; Risk-factors;
Author Keywords: cancer; PMF; pneumoconiosis; dusty trades; silica exposures
American Journal of Industrial Medicine