Radiographic evidence of asbestos effects in American marine engineers

Marine engineers undergoing routine annual chest roentgenography showed an unusual prevalence of pleural abnormalities including plaques suggestive of past asbestos exposure. A pilot survey, and a subsequent comprehensive study of the films of more than 5,000 men, showed an overall prevalence of 12% with pleural abnormality (typical calcification or plaque, or diffuse thickening). Prevalence of films classifiable for pneumoconiotic small opacities was negligible--1.2% in the pilot study. Prevalences of pleural abnormality were significantly higher among men with longer union membership, after controlling for age. Older merchant ships contain substantial amounts of asbestos-containing thermal insulation. Marine engineers often remove and reapply insulation, operations known to produce high airborne fiber concentrations. These roentgenographic survey results indicate significant past asbestos exposures of ships' engineering department personnel.