Pulmonary fibrosis, carcinoma, and ferruginous body counts in amosite asbestos workers. A study of six cases.

The Tyler Asbestos Workers Program is a continuing study of 1,105 former amosite asbestos workers. This report includes a study of six former workers, five of whom died and had autopsies, and one who underwent a lobectomy. Five of these men were exposed to asbestos for three months or less. Four had lung cancer, and one a rectal carcinoma. All were cigarette smokers. Ferruginous (asbestos) body content of the upper and lower lobes of the lungs was quantitated by a digestion technic. Tissue sections from upper and lower lobes were independently quantitated for fibrosis and ferruginous bodies, and chest roentgenograms were examined for interstitial fibrosis. (Control lung tissue was obtained from consecutive autopsies of 52 adults who did not have a known occupational exposure to asbestos.) Relatively low ferruginous body counts (less than 700/g lung tissue) were associated with mild degrees of fibrosis, and higher counts (greater than 10,000/g) with moderate to severe fibrosis. Mild to moderate pulmonary fibrosis could be identified on tissue sections before interstitial changes were detectable by chest roentgenograms.