Radiographic search for asbestos-related disease in a naval shipyard.

The Long Beach Shipyard underwent a chest x-ray survey of 6640 employees, or 88.6% of the total shipyard population, to determine the level of asbestotic changes. For computer classification purposes, the findings were divided into five groups: abnormal findings consistent with inhalation of asbestos fiber; normal; pulmonary fibrosis, nonspecific, questionable; and other findings not related to asbestosis. Asbestos-related abnormal findings, were encountered in 1061 workers, or 16.0%. No change was noted in 4806, or 72.4%. Pulmonary fibrosis was encountered in 140, or 2.1%. Other abnormalities not related to the inhalation of free asbestos fiber were encountered in 624, or 9.4%. The interpretation was questionable in nine individuals, or 0.1%. Of the male employees, 17.2% were positive for asbestos-related chest x-ray changes, and four women, or 0.8%, showed comparable findings. Of the men, 71.5% had normal chest x-rays, and 83.3% of the 402 women demonstrated normal films. Positive x-ray changes for asbestosis were encountered in a linear relationship when viewed by age of the worker. Employees aged 25--29 years exhibited 1.3% positive findings, and this level increased to a maximum of 38.2% positives among workers aged 65 years and over. Normal chest films descended, conversely, in a linear relationship. Similarly, the percentage of positive findings for asbestos-related disease increased in a linear configuration with length of service. Persons with 2--6 years of asbestos contact displayed 12.4% positive findings, while individuals with 22-26 years of work at the shipyard manifested 37.0% positive chest film findings. Although the shipyard was operational between 1943 and 1949, the system of allocation of badge numbers precludes the inclusion of these 7 years of work among persons who had had at least 26 years of service. When studied by work site, dividing the subjects into production and nonproduction personnel, it was found that production workers accounted for 74.5% of the asbestos-positive films. Overall, the 780 production workers manifested 11.8% of the positive findings of all persons studied, while nonproduction employees accounted for 4.1% of the positives out of the population studied. A figure that approximates the total finding of asbestos-related disease is 16.0%.