PROGRESSION OF PLEURAL AND PARENCHYMAL DISEASE ON CHEST RADIOGRAPHS OF WORKERS EXPOSED TO AMOSITE ASBESTOS

Objectives-To determine predictors of progression of pleural and paren chymal disease on the chest radiographs of workers exposed to a short term, intense exposure of amosite asbestos. Methods-The first and last of a series of chest radiographs of 887 workers exposed to amosite wa s interpreted and coded according to International Labour Organisation (ILO) standards by two physicians. Significant predictors of disease progression were found by a linear stepwise regression analysis from a mong such variables as smoking history, latency (time since first expo sure), duration and intensity of exposure, and cytology. Results-Altho ugh most radiographs remained normal, some showed progression of disea se with about twice as many patients with abnormalities on the last fi lm. Various combinations of age, intensity of exposure, and time betwe en films were significant predictors of pleural and parenchymal diseas e and progression of such disease. No predominance of one sided diseas e was noted. Cytology and smoking were unreliable predictors of diseas e. Most disease progression was minor, usually of less than two scorin g categories. Conclusion-An intense, yet short, exposure to amosite as bestos can produce pleural and parenchymal changes on chest radiograph s. The number of those affected roughly doubled over a period spanning 10 to 20 years after exposure. Age and intensity of exposure are the most important predictors of disease.