Non-malignant asbestos diseases in workers in an electrochemical plant.

The prevalence of non-malignant asbestos related disorders was studied in a group of men who had been subjected to different levels of asbestos exposure when working at an electrochemical plant producing nitric acid sometime between 1928 and 1970. There were 153 men eligible for an initial clinical examination in 1979-80 and that group has been followed up to 1985. Among the cohort members the "accumulated prevalence" of lung fibrosis alone or in combination with pleural plaques and of "pleural plaques only" was 24.2% and 24.8% respectively. The subgroup with the heaviest exposure had a total prevalence of asbestos related disorders of 82.5%. Only study subjects with lung fibrosis had statistically significant increased prevalences of respiratory symptoms. All subgroups from the study population, however, had mean spirometric values under the age, height, and smoking specific predicted means. Subjects with heavy asbestos exposure and current smoking had a prevalence of three or more respiratory symptoms of 28.8% compared with 5.6% among lightly exposed never smokers. Pleural crepitations at chest auscultation were more prevalent among subjects with radiologically visible asbestos related disorders than among study subjects with normal chest x ray films. During the follow up from 1980 to 1985, three cases of lung cancer, two of pleural malignant mesothelioma, and one of stomach cancer were found among the cohort members.