RETENTION OF ASBESTOS FIBERS IN LUNGS OF WORKERS WITH ASBESTOSIS, ASBESTOSIS AND LUNG-CANCER, AND MESOTHELIOMA IN ASBESTOS TOWNSHIP

Objective-To conduct a mineralogical study on the particles retained i n the necropsied lungs of a homogenous group of asbestos miners and mi llers from Asbestos township (and a local reference population) and to consider the hypothesis that there is a difference in size between fi bres retained in the lungs of patients with asbestosis with and withou t lung cancer. Methods-Samples of lung tissue were obtained from 38 pa tients with asbestosis without lung cancer, 25 with asbestosis and lun g cancer, and 12 with mesothelioma, from necropsied Quebec chrysotile miners and millers from Asbestos township. Fibre concentrations in the lungs of these patients were compared with those in tissue from necro psies carried out on a local reference population: men who had died of either accidental death or acute myocardial infarction between 1990 a nd 1992. 23 were born before 1940 and 26 after 1940. Results-Geometric mean (GM) concentrations were higher in cases than in the controls fo r chrysotile fibres 5 to 10 mu m long in patients with asbestosis with or without lung cancer; for tremolite fibres 5 to 10 mu m long in all patients; for crocidolite, talc, or anthophyllite fibres 5 to 10 mu m long in patients with mesothelioma; for chrysotile and tremolite fibr es greater than or equal to 10 mu m long in patients with asbestosis; and crocidolite, talc, or anthophyllite fibres greater than or equal t o 10 mu m long in patients with mesothelioma. However, median concentr ations of each type of fibre in the lungs did not show any significant differences between the three disease groups. Average length to diame ter ratios of the fibres were calculated to be larger in patients with asbestosis and lung cancer than in those without lung cancer for croc idolite fibres greater than or equal to 10 mu m long, for chrysotile, amosite, and tremolite fibres 5 to 10 mu m long, and for chrysotile an d crocidolite fibres < 5 mu m long. However, there was no statistical difference in the median length to diameter ratios for any type of fib res across the disease groups when they were calculated in each patien t. Cumulative smoking index (pack-years) was higher in the group with asbestosis and lung cancer but was not statistically different from th e two other disease groups. Conclusion-Lung cancers occurred in worker s with asbestosis from Asbestos township who had an equal concentratio n of retained fibres but a tendency to a higher length to diameter rat io of amphiboles. These workers had a 29% higher average cumulative sm oking index.