ANGULAR AND FIBROUS PARTICLES IN LUNG IN RELATION TO SILICA-INDUCED DISEASES

Introduction: The lung concentration of angular and fibrous particles was measured in cases of lung fibrosis only, in cases of lung fibrosis and lung cancer, and in cases of lung cancer only. These patients wor ked in different trades (mining, foundries, construction and were not a homogeneous group of exposed workers. Material and methods: Particle s, both angular and fibrous, were extracted from lung parenchyma by a bleach digestion method, mounted on copper microscopic grids by a carb on replica technique, and analyzed by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). The quartz concentrat ion was also determined by X-ray diffraction (XRD) on a silver membran e filter after extraction from the lung parenchyma. Results: (1) Lung cancer and lung fibrosis cases retained more metal-rich particles (P = 0.02) and more angular particles of all sorts (P = 0.009) than did lu ng fibrosis cases only, and the differences were statistically signifi cant. (2) However, more quartz was retained in the lungs in lung fibro sis cases than in lung fibrosis or lung cancer cases, but the differen ce in the concentrations was not statistically significant. (3) More f erruginous bodies were retained in the lungs in lung cancer and lung f ibrosis cases than in cases of lung fibrosis only, and the difference in the concentrations was statistically significant (P = 0.02). Conclu sion: Results obtained from lung tissue must always be interpreted cau tiously. However, these results are consistent with the hypothesis tha t workers in some trades such as foundries; were exposed not only to q uartz but also to asbestos, ceramic fibers, metal-rich non fibrous par ticles, and other likely carcinogenic chemicals. The wide range of par ticle types identified in the lungs of these workers illustrates the c omplexity of trying to determine disease origins in these work environ ments. Epidemiology studies have to control for the exposure to these carcinogens as well as for smoking habits.