Document EdVQOzJYyjYLooX2b68KyBg6j

360 0. A. SANDER Valle1 has pointed out that more than 50 per cent of industrial dusts are grea| than 1 p in size while in atmospheric dust the median size is approximately 0.Bloomfield8 found that only 20 per cent of the particles found in air in fifty ind tries were smaller than 1 p and that the median size was 1.3 p; he suggested tjr most of the particles of smaller size found in industrial atmospheres were th.p normally present in air. In certain industries, however, such as pneumatic rot drilling, large numbers of particles well below 1 p in size are produced.4 II. Classification of Dust Based on Its Effect in the Body The industrial hygienist is interested in dust because of its effect on:i!f human body. Therefore, a limited classification of dust from this viewpoint nj form a basis for relating the chemical composition of dust to the anatomical a physiological reactions that occur. Pneumoconiosis is defined as: Any dust particles retained in the lympha depots oj the lungs. The term generically carries no implication of fibrosis or ot' reaction and no implication of disturbed function of the lungs. Nor is it epeci with relation to the type of dust. I If we accept this generic definition of "Pneumonokoniosis," which Zen coined in 1866 (the term was shortened by the International Labor Office in 19. then all humans have some degree of pneumoconiosis. In city dwellers it is;]|S' anthracotic pigmentation from air pollution and in farmers the dust from the fiel and from the grains. The only reason such deposits are not generally thought p, pneumoconioses is that they usually are not visualized by x-rav. Even where/' soil is fairly high in free silica, insufficient silicotic nodulation results to be seeiif x-ray. Also, most dusts in the general atmosphere have a low grade of radiopaci| so that such deposits in the lungs do not cast direct shadows. Therefore, our ctf roentgenograms are read as showing "healthy lungs," even though we know,'!" we all have-some degree of retained dust or pneumoconiosis. $ There are those who, for medical-legal reasons, would limit the meaning "pneumoconiosis" to the fibroses resulting from industrial dust exposure. Tne; argue that ordinary dust retention should not be dignified with such a wijf In addition, a number of state compensation laws list "pneumoconiosis" "as. compensable occupational disease. However, there are others who feel that su| strict limitation of meaning of the, term is artificial-and that it. A'mrRgar* occupational ddst tlegpsits.which are benign and do not cause fibrosis ..(the spfcS "benign pneumpcdnioses"). To the authors it seems more sound scientifica'l think in terms of the generic definition and to consider that all humans hi? pneumoconiosis. When a doctor says that so-and-so has pneumoconiosis, -reply-dugK't'to-Bef^We-al'l-ha-ver-Please-specif'y--Is-it-occupatioha'H-Wha'tdi; dust?" Certainly the word has no place in occupational disease laws where! compensable diseases should be carefully and specifically defined. J. J. Bloomfield, U. S. Pub. Health Repts., 48, 961 (1933). 4 T. Hatch and C. L. Pool, J. Ind. Hyg., 16, 177 (1934). ' PULMONARY DUST DISEASES 361 STuseful classification of the pneumoconioses, based on the effect of dust in the fis as follows: %Jnert Dusts ("benign pneumoconioses"). Little or no fibrous tissue reacfTprmant deposits in pulmonary lymphatics and root lymph nodes, which are aflzed by x-ray when the material is radiopaque. They do not appear to have a Ifiosing effect on tuberculosis or other infection and do not cause impaired function. HjGarbon (smoke, soot): Most anthracosis due to coal deposits also benign, excessive deposition over many years may lead to disabling emphysema (see *$&< %0alcium (cement, marble, gypsum): Generally not visualized by x-ray. flailed "calcicosis" in past probably were endogenous calcification due to igis diseases such as histoplasmosis. Iron (confined welding, grinding, steel cutting, and burning): Radiopaque fits visualized by x-ray as discrete nodulation. "Siderosis" is a perfectly 'j^term for such iron pigmentation, but there should be no implication of sis in the term. $ Artificial abrasives (carborundum, emery, aluminum oxide): Have re{$ sandstone in grinding wheels. (.Aluminum (or hydrated aluminum): Used in some areas in prevention and "ent of silicosis. ./Barium and tin (radiopaque deposits): Baritosis and stannosis. rolHerative Dusts ("fibrotic pneumoconioses"). |Silica (crystalline free silica, SiOs, as quartz, flint, etc.): Typical fibrous s spread throughout both lungs and visualized by x-ray.'Usually normal Ir walls. Simple silicosis, (a) Most silicosis today modified by other com||in dust, such as Ca, Al, Fe, and C. (b) No disability unless conglomerate implicated with tuberculosis or advanced emphysema, (c) Relationship of ffiand tuberculosis: Primarily reactivation and spread of pre-existing tuber(`loci. Combined lesions frequently result in chronic massive progressive Jp'Cd) Relationship with heart disease: Right heart strain (cor pulmonale) ,with advanced stages of silicosis, silicotuberculosis, and emphysema. 2||Asbestos (hydrated magnesium silicate): Mechanical plugging'of bronchi- vllong fibers and peribronchiolar fibrosis. Fibrosis may result from breakdSaibestos bodies. Asbestosis. -|fBther silicates? (talc, kaolin, soapstone, mica, feldspar): Reported fibrosis "Some silicates may be due to quartz impurities. . /Bauxite processing (Shaver's disease): Diffuse fibrosis with marked ^sema-and-frequeht-spbntaheous-pneumofehoraxr-Due-to-siiica-fume-modified Ipminum fume? fjDiatomaceous earth: Amorphous and only slightly reactive before calcin- ten crystobalite formed, causing diffuse fibrosis. /Coal dust (coal workers' pneumoconiosis): Focal emphysema and,minimal