Document npz1N7wERJJ4pbzeQ9LDVLyG8

368 0. A. SANDER In 1556, in De re metallica, Agricola17 stated: Oa the other hand, some mines are so dry that they are entirely devoid of water, aril this dryness causes the workman even greater harm for the dust which is stirred and beatf: up by digging penetrates into the windpipe and lungs and produces difficulty in breathing.; .r The best of the early writings on silicosis is that of Ramazzini,18 translated 1 1705 in A Treatise of the Diseases of Tradesmen, in which he stated: For in hewing marble or stones out of the rock, in polishing and cutting them, the oftentimes suck in by inspiration the sharp, rough and cornered small splinters or particf that fly off; so that they are usually troubled with a cough, and some of them turn asthmatic' and consumptive. . . . And in dissecting the corps of Buch artificers, the lungs have been foun'd stuffed with little stones. Diemerbrock gives a curious relation of several stone cutters that dyfd asthmatick, and were opened by him; in whose lungs he found such heaps of sand that running the knife through the pulmonary vesicles he thought he was cutting some sand boL He adds that he was informed by a master stone cutter that in cutting stones there rises sue a subtile dust, as is able to penetrate through ox bladders hung in the shop. . . . And this ve ` dust he took to be the cause of the death of many unwary workmen. In recent years the contributions to knowledge of silicosis have been suffi ciently substantial, numerous, and varied to make this perhaps the most widel discussed occupational disease. Silicosis is of particular interest to students of pre ventive medicine not only because of its general distribution in industry but mdr particularly because of its tendency to increase susceptibility to tuberculosis-^ characteristic inherent in the disease. The limited space of this chapter does no permit reference to many sound contributions which have led to our present undef standing-ofdust-diseaser-An-exceedingly-interesting-and'somewhfftrdetaited' of the history of diseases caused by dust may be found in the work of Lanza.19 ' * 2. Exposure to Silica in Industry Since siliceous material makes up the bulk of the earth's crust, it is not surpris ing to find silica exposures in industry, where raw materials from the earth are usA to make many of the commodities necessary to our daily lives. Rocks and miner-a are often intimately associated with free silica and it is obvious that those occupa tions concerned with mining, rock grinding, or drilling may constitute silicosf hazards, as well as occupations concerned with the processing and industrial use d siliceous products._______ _ common forms of free silica used industriMf are massive crystalline quartz, quartzite, sandstone, flint, tripoli, diatomaceoffi earths and silica sand. Table...!.,.from Ladoo,21 illustrates the great variety of uses', to which silica is put in industry and indicates the kind of silica adapted to eacf; -purpose.----------------------------------------- ;------- :___:.................................... ............ " - Ramazzini, A Treatise of the Diseases of Tradesmen, English trans., 1705. " A. J. Lanza, ed., Silicosis and Asbestosis. Oxford Univ. Press, New York 1938. " A. Knopf, V. S. Pub. Health Bull. No. 187, 1929. nR. B. Ladoo, Silica, NonmetaUic Minerals. McGraw-Hill, New York, 1925, p. 525. PULMONARY DUST DISEASES 369 S. Etiology of Silicosis Silicosis has been defined by the Committee on Pneumoconiosis of the Indusal Hygiene Section of the American Public Health Association22 as: A disease due to breathing air containing silica (SiOi), characterized anatomically by genilized fibrotic changes and the development of military nodulation in both lungs and clin- by shortness of breath, decreased chest expansion, lessened capacity for work, absence T fever, increased susceptibility to tuberculosis (some or all of whioh symptoms may be pfesent) and by characteristic x-ray findings. The definition adopted at the Intel-national Silicosis Conference in 1930 and Affirmed at the 1939 conference is generally accepted and is somewhat simpler 'an the above. If is as follows: Silicosis is a pathological condition of the lungs due to inhalation of silicon dioxide. It , be produced experimentally in animals. Lanza28 in "Etiology of Silicosis," as printed in the National Silicosis Confer ee Report on Medical Control, states: Simple of uncomplicated silicosis is a chronic, fibrotic disease of the lungs, due to the assive invasion of the pulmonary tissue by silica (SiO), inhaled in the form of dust. In itB itly stages silicosis may be symptom free; in its later stages shortness of breath, decreased Ifst .expansion, lessened capacity for work, may--one or more--be present, together with an creased susceptibility to tuberculosis. The disease presents the characteristic x-ray appearance "jfnodulation, without which a clinical diagnosis may not be made. The production of silicosis depends upon the following factors: the composij of inhaled dust, the number of particles'"ofinhaled dusfc,` the size of the particles 1`inhaled dust, the length of time during which particles are inhaled, and Jiividual susceptibility. a. Composition of Dust in Relation to Production of Fibrosis. The fact that ilicosis is caused by free silica (SiOj) is attested by the great mass of clinical xperience as well as by experimental observations. Gye and Kettle24 have shown '-ft silica in solution, or in noncrystalline form, stimulates the proliferation of |roblasts in tissues. Gardner28 produced a reaction in the lungs of animals in a . as short as two years by exposure to extremely high concentrations of dust, "tiler and Sayers29 developed an intraperitoneal injection technique for testing the le response to dust, and their method has been used extensively 'by the United JiTPubiic Health ServiceTD'nTHe'Basis of this procedure it' has been found that lusts behave in one of three ways in the body tissues; they may disappear (be fSsorbed), cause cellular proliferation, or remain inert in the tissues. "R, R. Sayers, Am, Pub. Health Assoc. Yearbook, 1932-33. LA-j-LaQza>-R&pQFt-OQ-m6dical:coatr:ol,-NatiQnaLSilicQais,CQaferQflC&,J7i-au.fle^.Ll^.q^ _v, Labor Standards, Bull. No. 21, Pt. 1 (1938). i>f * W. E. Gye and E. H. Kettle, Brit. J. Expl. Pathol., 3, 241 (1922). BL. U. Gardner, in A. J. Lanza, ed., Silicosis and Asbestosis. Oxford "Univ. Press, New >k, 1038. ,^ 8 J. W. Miller and R. R. Sayers, TJ. S. Pub. Health Repts., 56, 264 (1941), Reprint 2234.