ASBESTOS-RELATED RADIOGRAPHIC CHANGES BY ILO CLASSIFICATION OF 10 X 10 CM CHEST X-RAYS IN A SCREENING OF THE GENERAL-POPULATION

A sample of 1388 10 x 10 cm chest X-rays from a previous population sc reening of males aged 40+ years were reevaluated by use of the ILO cla ssification. There were 1036 films of subjects from an industrialized town, and 352 from a rural community. The observed rates of parenchyma l changes (profusion greater-than-or-equal-to 1/0) at the reevaluation were 1.3% in the urban community and 3.4% in the rural community. The corresponding figures for pleural changes were 5.0% and 6.0%, respect ively. Based on additional questionnaire information on asbestos expos ure, it was found that the radiographic changes were probably related to past asbestos exposure for 2.3% of the subjects from the urban comm unity and 0.6% from the rural community. In cases of asbestos-related illnesses the mean time since first exposure to asbestos was 35.9 year s, whereas the mean duration of the exposures was 11.4 years. The resu lts seem to indicate that the ILO reassessment of the radiographs was more sensitive in detecting pleural changes than the previous clinical screening of both small and large films.