Document zz4gXLxvv7z78BQb0LYBzLXBg

14 not have been successful in every instance, due to inadequate recall of the worker or because an asbestos exposure may have occurred without his knowledge. The large number of workers with identified exposures suggests the possible scope of the problem. Such unidentified expo sures would, however, contribute proportionately to the abnormalities found in both the exposed (brake workers) and unexposed groups under study. In the analysis that follows workers will be classified accord ing to their asbestos exposure irrespective of their union affiliation or job classification at recruitment. * It is striking that 8.9% of all participants had previous employment in the shipbuilding and ship repair industry. As approximately 45% of the study participants were over age 55, many had opportunity for employ ment in one of the several New York area shipyards that operated during and after World War II (Brooklyn Navy Yard, the Hoboken yards of Todd and Bethlehem Steel). [Approximately 4,500,000 men (and women) were employed in ship construction and repair during World War II (Nicholson, Perkel, and Selikoff, 1982).,.This constituted 9.4% of the non-agricultural national male work force in 1943, but a much smaller percentage was employed after World War II (0.2%-0.5%) (Bureau of Labor Statis tics, 1979). Thus, the finding of such a large number with shipyard employment in this study is understandable and provides an opportunity to evaluate the effects of past short-term shipyard work as well as that of garage employment. Tables 6 and 7 display the distributions, by work activity, of those for whom interpretable X-rays are available and for whom valid pul monary function tests were obtained. As can be seen, lower percentages of readable X-rays were available for DC 37 and SEIU 246 members be cause of the previously mentioned loss of 30 X-rays. The individuals involved, however, were randomly scattered among the different exposure categories. The percentage of individuals with valid pulmonary func tion tests (96.4%) compares favorably with other surveys. Again, those with- missing tests are randomly distributed among all occupational categories.