Document QkwG8wL0ZLNoN0K3vBR3M1NM5

FILE NAME: National Safety Council (NSC) DATE: 1933 Jan DOC#: NSC167 DOCUMENT DESCRIPTION: NSC - Safety News - The Effects of Inhaled Mineral Dusts by Dr. Gardner The Effects f Inhaled Mineral Dusts By LEROY U. GARDNER, M. D.* A S LONG as ken have worked' not yet berin correlated with patho in stone it has been appreciated logical anatomy) chemical studies of that an unusually large propor the tissues and detailed analyses of much lower than thajt " normal" for the age group. As et corroborated experimental proof 4f protective ac tion of them suffer from disease of the industrial atmospheres. There is a tion of coa,i\ against tuberculous in- lungs. It was natural to assume that tendency to assume th at many of fection is lacking. . such disease would be caused by the these pulmonary changes are due to dust generated, and this belief was the action of silica perhaps modified : ' Silica and Tuberculosis strengthened by the discovery of by the Chemical components of the Not only the tubercle bacillus but black, grey ,or red pigments in the dust. We shall only be in a position other bacteria seem to develop with lungs, sometimes accompanied by the to speak with assurance about them special facility in the tissues pre formation of scar tissue. when the pure types of dust and viously damaged by silica. For ex The term pheumonokoniosik was introduced to describe the lung pig mented in this manner. With further observation pathologists at tempted to classify various forms of pneumonokoniosis on a basis of the type of dust inhaled and such names as anthracosis, siderosis, chalicosis and even byssinosis and tobaccosis made their appearance. It was rec ognized that some forms of the dis ease were attended by severe symp toms and resulted in death but there was no correlation between the clin ical and pathological pictures and their various combinations have been ample the pneumonia rate among studied in human beings or in ex silicotic native laborers of South perimental animals. Africa is many times that in non- For the sake Of clarity no mention silicotic natives living under similar has been made of the infections conditions. In coal miners, likewise, which so frequently complicate some pneumonia is a common and often forms of pneumonokoniosis. In the fatal complication. Case reports of prebacteriological era of medicine - fatal pneumonia in asbestosis are the use of such terms as " grinders' frequent but morbidity statistics consumption" 'a n d " miners' phthis from large groups of asbestos work is" reflects the popular association ers are lacking. For most other of pneumonokoniosis with tubercu dusts the data are even more frag losis. The names were justified both mentary. by clinical and pathological observa W hat has been said of the effects tion for it has been subsequently of inhaled inorganic dusts would in the causative dust. Filially statistical shown that, in silicosis at least, a dicate that the reaction of the tissues study demonstrated that of all kinds super-imposed tuberculosis may cause is not merely a response to mechan of industrial dusts silica generally death in perhaps 75 per cent of the ical irritation by particulate matter. produced a definite type of disease cases. Some observers even go so Today it is generally accepted that with a characteristic pathological far as to state that silicosis itself the injury is chemical in nature and lesion and complex of symptoms. does not develop unless the lungs Today the clinical entity known as are previously damaged by a latent silicosis is one form of pneumono tuberculous infection. This is prob koniosis which is quite clearly de fined. Moreover, within the last three or four years asbestos dust has also been shown to produce another ably an exaggeration, for typical sili cosis can be produced in the experi mental animal by the inhalation of silica without infection. specific type of reaction attended by Asbestos Dust symptoms differing in some respects ( The role of asbestos dust as an from those of silicosis. excitant of tuberculous infection is The other forms of pneumono riot as clear cut as that of pure silica. koniosis still lack complete defini While there are numerous reports of tion. The widespread use of radiog death in asbestosis due to a terminal raphy has brought together a mass tuberculosis, nevertheless surveys of of descriptive data from individuals living workers have failed to demon exposed to many kinds of occupa strate any excess of such infection. tional dusts but these findings have Simple anthracosis is said to prevent that only certain of the common types of industrial dusts possess properties capable of exciting reac tion. In the cases of silica and the silicate of magnesium or asbestos th slightly alkaline body fluids prob ably effect a slow solution of the dust particles liberating silica in col loidal form. This substance irritates the connective tissue cells which re spond by multiplying. The result is an overgrowth of the supporting framework elements at the expense of the more delicate cells specialized for specific functions. For these two types of dust the character and form of the patho logical changes has been carefully D irector, Saranac L aboratory for the S tu d y of T u b e rc u lo s is, S a r a n a c L a k e , N . Y. (A p atter p re se n te d before th e In d u stria l the progression of tuberculous in fection. Statistics from coal mining worked out. In siUcosis the essen tial tissue change,consists of nodules H ealth Section, T w enty-first A nnual Safety C ongress). districts do show a tuberculosis rate of connective tissue which develop 3 ' k ^ f ^ ^N A TIO N A L SAFETY NEWS first in the lymphoid tissues situated finf tubes and little of it is removed life-time to pigment considerable in the drainage apparatus of the by the lymphatic drainage system. areas of their lungs. Deposits of grey lungs. These nodules interfere with ,' Tissue reaction, probably initiated by or black dust will be found along the the physiological removal of foreign' the solution of the fibers, occurs in course of the lymphatic drainage sys ^bodies and subsequently inhaled par their immediate vicinity. As in the tem but this pigmentation is associ ticles accumulate in the framework case of silica this reaction consists of ated with little or no new growth of of the lung itself. Such reaction an overgrowth of the connective tis connective tissue. The coal miner's gradually decreases the normal elas sues which is later transformed into lung is much blacker but in most in ticity of the organ and encroaches leather-like scars. The arrangement stances it also develops no deforming upon its functional elements. As a : of the scar tissue in asbestosis is quite scars. When such reaction does occur result the cardinal symptom of the different from the nodular collections analysis usually reveals appreciable disease, dyspnoea or shortness of in silicosis because -of the difference amounts of silica itt the lungs. The breath develops. Because of the ex in localization o f the foreign particles. presence of excessive quantities of car cessive amounts of scar tissue formed In asbestosis the deposition long the bon dust apparently, influences the in the lungs the. right, side of the walls of fine tubes radiating from localization of moderate amounts of heart encounters increasing difficulty larger bronchi in all, planes through silica ,so that the latter is not depos in forcing blood into the organs. l o out the lung gives rise ,to a fin linear ited in nodules as in pure silicosis but an attempt to compensate the over fibrosis with little or no nodule forma in streaks along lymph vessels as pure worked heart muscle becomes thicker tion. coal would localize. and heavier and Unless infection in Aluminum oxide will serve admir Coal miners' fibrosis, due to rela tervenes the time eventually arrives ably as an example of a non-siliceous tively small amounts of silica, is there when the heart fails and death oc- dust Whose particles are as hard and fore different from that of the pure curs from this cause. sharp as those of crystalline silica. quartz worker. When the amount of When a measured quantity of such inhaled silica is excessive, the effect Obscure Causes / . particles, 1 to 3 miera in diameter, of the coal is negligible and the re The reasons for the prevalence of are injected into the ear vein of a action approximates that in pure sili infection in the silicotic lung are not altogether clear. I t is obvious that when the drainage system is so ob structed by nodules of scar tissue rabbit th majority of them come to cosis., There is said to be more reaerest in its liver and spleen. There tion to hard coal than to the bitu they remain, apparently harmless, minous variety but there is evidence collected in large phagocytic cells and to suggest that this is due to the that more dust particles can only be producing no reaction of the connec greater amount of siliceous rock removed with difficulty, the same tive tissues for at least two years. -which must be worked in mining an must he true of bacteria which may Injection of the same quantity of the thracite coal.,, . _ be inhaled. As a consequence they same sized quartz particles excites the Finally,; consider th silicosis jof remain in the lung and set up pro formation of so much scar tissue that granite octets. This develop some gressive infections. But this is not the functional elements are almost what more slowly than that of the the whole story. The silicotic tissue completely destroyed. pure quartz miner and it has been apparently offers a peculiarly favor Carborundum, the carbide of sili maintained that this is due to the able soil for the continued multipli con, when inhaled by guinea pigs for relatively small amount of uncom cation of tubercle bacilli and perhaps periods as long as four years, likewise bined silica in granite (25 to 40 per other bacteria. Experiment' has fails to excite significant overgrowth cent). But it is the w riter's belief shown that even attenuated organ of the connective tissues. It produces that other components of the glomer isms of this type will produce rap only a low grade inflammatory change ate granite may neutralize or at least idly fatal tuberculosis in a silicotic with no nodules. inhibit the effects of the silica so that guinea pig. Furthermore, inhaled Instances such as those cited con only after prolonged exposures to silica dust will cause a preexisting stitute the basis for believing that the high concentrations does significant latent tuberculous focus, harboring a cellular response to dust particles is reaction occur. While typical silicotic few attenuated bacilli, to become pro not due to their hardness arid sharp nodules develop in guinea pigs inhal gressive and spread. ness but to chemical substances liber- ing pure quartz for a year, not even The cause of this effect upon tuber ; afed by the action of the tissues upon the earliest suggestion of nodules has culous infection has ndt yet been as them; \(The ca for solubility has not appeared in the lungs of animals in certained but the writer believes that been proven directly, for the detection haling^ comparable concentrations of it is in some way associated with the of soluble silica in the tissues offers granite (40 per cent silica) for four death of tissue caused by the toxic technical difficulties which today,are ..years. silica. Associated with this factor is unsurmountable. Nevertheless this ; This very bri'fi discussion of some an increased activity of the "phago ' substance is known to be cell pison of the problems involved in pneu- cytes which are stimulated by the and in weak concentrations i t will pro monokoniosis draws attention to the irritating silica so that these cells tend , voke an overgrowth of the connective limitations of our present knowledge. to migrate rapidly and carry tubercle; tissues. , It indicates that the reaction to an bacilli into previously uninvolved por tions of the lung. - `Coal Dust inhaled dust Is determined by the eheinical and probably physical com Asbestos dust, perhaps because of < 'Mention should he made of the position of that dust. I t emphasized its fibrous structure, is not trans seffect of inhaled coal dust. Most city , ! the need to further study of different ported very far within the lung. I t dwellers breathe in sufficient quanti- , types of dust both in th pure state tends to lodge along the walls of the ties of this material during an average and in measured combinations. NATIONAL fctt n r NEWS