Document e85oG7290kjOoVYddkZRJdK4

I:: DL'STSIAL D US 7 S j , or Ferruginous Bodies. E. .A. Caensler and W. '.V. .Addington. Med.' -IdO'. 4a-4~T(Feb. 27, 17691. i to'T.Bcaocs earth, graphite ar.d carborundum have been Identified as the core of typical bodies" in man. Substances believed to be biologically inert, Including fibrous "rr.inum silicate, fibrous glass, silicon carbide and forsterite have caused ferruginous bodies '"'hamsters and guinea pigs. Evan fragments of the lung's own elastic tissue may produce inlastosis bodies" that lock similar. Technics are now available for analysis of the core fibers, -t v include electron beam and x-ray diffraction, iaser microprobes, ultrasonic disintegration * d mass spectroscopy. The electron-beam diffraction patterns of ferruginous bodies from 22 fr` a ol "unexposed'1 persons did not coincide with that of chrysotile. Since 95 per cent of :ung os used in the United States is of this type, it was concluded that the vast majority of Srruginus bodies found at random autopsies are not from asbestos. Obviously, the diagnosis f asbestosis, based on the finding of ferruginous bodies in an apparently unexposed person, --ust jje made with caution. However, one must be equally cautious in making a diagnosis of ^'ons pacific Interstitial pneumonitis" in a person with known exposure because there is no Nation between the number of bodies and the severity of asbestos pneumoconiosis. On the contrary, we and others have`noted an Inverse relation. In persons with prolonged but distant aosure, often retired because of respiratory Impairment, the lungs frequently show severe b*osis with only rare asbestos bodies whereas in patients with more recent exposure, lung Aoosy reveals alveoli filled with bodies and debris-laden macrophages but little or no fibrosis, "his paradox can be explained in a number of ways. The small number of asbestos bodies in workers with fibrosis who were exposed long ago may be the result of clearing of the intra- j'veolar material. This clearing occurs most rapidly in areas of supple alveolar walls whereas it is delayed In the more noncompllant regions near the thickened pleura and around larger vessels ar.d bronchi. Therefore, the distribution of asbestos bodies is uneven, and their number n any section need not be representative. The relation between the number of visible asbestos Adies and the degree of fibrosis is also poor because only a very small and variable fraction of ':hers become coated. Probably the tiniest, uncoated particles, which are Invisible by light -icroscooy. are most fibrogenic because they have the Largest aggregate surface area. This U important because at some stage a chemical reaction must initiate the process of fibrosis. The visible asbestos bodies, therefore, are best considered as markers, rather than as tmsortant causative agents. In 1929 W. E. Cooke Wld that "curious bodies have been found in ivery necropsy In pulmonary asbestosis, and the problems we have to decide are, first, what :he bodies are, and second, whether they are diagnostic of asbestosis." Although at first anj-wers seemed deceptively simple, new information Increasingly has raised new questions. That asbestos bodies may contain asbestos is clear. It is equally clear that structures appar ent.y indistinguishable from asbestos bodies may have as their core other materials. Unfor tunately, the methods of Identification are exceedingly complex, and, even In the best hands, results remain tentative. Nevertheless, recent animal exposure and analytical work suggests ".at. until asbestos has been identified as the core of an "asbestos body, " It is best to use the ".re general term "ferruginous body." There are 27 references. -Cond. from text ribrosis of Lungs due to inhalation of asbestos dust. Brit. M. J. 2:147, 1924 The Community Hazards of Asbestos. J. Cuthbert. l:.-.ch. med. Wochschr. 109, 1369-1372 (April-June, 1967). German. e inhalation of asbestos is far more dangerous than is generally recognized by the public, ",ce even a transient period of exposure can lead to disease (interstitial fibrosis of the lung, cancer, mesothelioma, endothelioma of the pleura and the peritoneum, painful dermal 'rest md death many years later. Electron microscopic studies have shown that for every ',:,s fiber recognizable under an ordinary (light! microscope, there are hundreds of tiny ' ir.iced particles, which dust experiments with guinea pigs have shown to be just as i: ' is the larger fibers. '.S'hiie the asbestos industry has taken energetic measures toward _ r*vsnt,.on of classical forms of asbestosis by dust elimination in its plants (vacuum removal ' '-St, use of gas masks, automation of manufacturing processes), such prophylactic . ``res have not prevented the gradual long-term development of cancer in persons who come Ssional, slight, cr temporary contact with as bescos. This group certainly includes -soestos workers ar.d all persons .i-.-ir.g within 1. 5 km of an asbestos plant; these persons