Trends in pleural radiographic findings in the Navy Asbestos Medical Surveillance Program (1990-1999)

The U.S. Navy Asbestos Medical Surveillance Program is a comprehensive effort to decrease exposure to asbestos, a known health hazard. This study was part of a programmatic review of the Asbestos Medical Surveillance Program database, which included 233,353 radiographic examinations from 1990 to 1999. The initial review focused on incidental findings recorded by B-readers for 23,460 radiographs. Abnormalities reported included bullae (0.68%), cancer (0.56%), cardiac size/shape abnormalities (1.36%), emphysema (0.74%), subpleural fat (2.62%), fractured ribs (1.24%), hilar adenopathy (0.13%), ill-defined diaphragm (0.46%), ill-defined heart border (0.29%), Kerley lines (0.06%), pleural thickening (2.35%), and tuberculosis (0.27%). The rates by age cohort for pleural abnormalities decreased significantly (30-39 years, χ² for trend = 23.49, df = 1; 40-49 years, χ² for trend = 176.21; 50-59 years, χ² for trend = 401.87), but findings were not significantly different for those ≥60 years of age. This suggests that sequential age cohorts in the program are developing fewer pleural abnormalities; pleural abnormalities have historically been associated with asbestos exposure.