The Significance of Lung Function Changes in Asbestosis

Asbestos is the name given to a series of minerals composed of fibrous silicates of magnesium and iron which find widespread use in industry. Inhalation of the dust may cause asbestosis, a crippling form of pulmonary fibrosis, which usually does not appear until many years after the initial exposure. There is also an increased incidence of carcinoma of the lung in patients with asbestosis, and Doll (1955) estimated that the risk of lung cancer in asbestos workers was approximately 10 times greater than in the general population. The diagnosis of asbestosis at present depends on the history of exposure to the dust together with certain physical signs and radiological changes. The most characteristic features of the latter are a " ground-glass " mottling of the lower zones of the lung fields with a shaggy border to the heart. The physical signs are clubbing of the fingers and fine metallic crepitations on auscultation of the lung bases. Unfortunately many cases even with definite physical signs do not show the characteristic radiological changes, and the early diagnosis of the disease may be most difficult. The presence of "'asbestosis bodies" in the sputum simply proves that asbestos dust has been inhaled and does not necessarily imply that fibrosis is present. The purpose of the present work was to relate the changes in lung function in asbestosis to the clinical and radiological signs of the disease and to try and determine the value of lung function tests in assisting with its early diagnosis.