asbestos--amosite and Pleural-Diseases

To determine predictors of progression of pleural and parenchymal disease on the chest radiographs of workers exposed to a short term, intense exposure of amosite asbestos.. The first and last of a series of chest radiographs of 887 workers exposed to amosite was 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 among such variables as smoking history, latency (time since first exposure), duration and intensity of exposure, and cytology.. Although most radiographs remained normal, some showed progression of disease with about twice as many patients with abnormalities on the last film. Various combinations of age, intensity of exposure, and time between films were significant predictors of pleural and parenchymal disease and progression of such disease. No predominance of one sided disease was noted. Cytology and smoking were unreliable predictors of disease. Most disease progression was minor, usually of less than two scoring categories.. An intense, yet short, exposure to amosite asbestos can produce pleural and parenchymal changes on chest radiographs. 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.

Topics: Adult; Age Factors; Asbestos, Amosite; Calcinosis; Cohort Studies; Disease Progression; Female; Follow-Up Studies; Humans; Lung Diseases; Male; Occupational Exposure; Pleural Diseases; Radiography; Regression Analysis; Risk Factors; Severity of Illness Index; United States

The study aimed to evaluate the risk of pleural plaques according to the degree of past exposure to asbestos, type of amphibole asbestos, and smoking, as well as to estimate the aetiologic fraction of asbestos as a cause of plaques among urban men.. The occurrence and extent of pleural plaques were recorded at necropsies of 288 urban men aged 33 to 69 years. The pulmonary concentration of asbestos and other mineral fibres was analysed with scanning electron microscopy. The probability of past exposure was estimated from the last occupation.. Pleural plaques were detected in 58% of the cases and their frequency increased with age, probability of past occupational exposure to asbestos, pulmonary concentration of asbestos fibres, and smoking. The risk of both moderate and widespread plaques was raised among asbestos exposed cases, and the risk estimates were higher for widespread plaques than for moderate plaques. The age adjusted risk was higher for high concentrations of crocidolite/amosite fibres than for anthophyllite fibres. The aetiologic fraction of pulmonary concentration of asbestos fibres exceeding 0.1 million fibres/g was 43% for widespread plaques and 24% for all plaques. The median pulmonary concentrations of asbestos fibres were about threefold greater among cases with widespread plaques than among those without plaques. No increased risk of pleural plaques was associated with raised total concentrations of non-asbestos fibres.. The occurrence of pleural plaques correlated closely with past exposure to asbestos. The risk was dependent on the intensity of exposure. Due to methodological difficulties in detecting past exposures to chrysotile and such low exposures that may still pose a risk of plaques, the aetiologic fractions calculated in the study probably underestimate the role of asbestos.

Topics: Adult; Age Factors; Aged; Asbestos, Amosite; Asbestos, Amphibole; Asbestos, Crocidolite; Autopsy; Finland; Humans; Male; Middle Aged; Occupational Diseases; Occupational Exposure; Odds Ratio; Pleura; Pleural Diseases; Risk Factors; Smoking; Urban Population