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FILE NAME: Mine Safety Appliances (MSA) DATE: 1944 DOC#: MSA017 DOCUMENT DESCRIPTION: Book - Dust & Fumes SC 030793 Dusts and Fumes in Industry (Sources, Effects and Control) ' I n t r o d u c t o r y St a t e m e n t In dealing with occupational diseases and their effects, the attending physician should keep in mind that the etiology o f these conditions is present in the industrial environment -- i f the conditions are to be considered truly industrial in origin. I t is likewise important to understand that rational diagnosis and treatment rests upon a fairly accurate knowledge o f the etiology o f the disturbances; this is especially true o f occupational diseases and allied disorders. Moreover, employers, industrial hygiene and medical depart ments are greatly interested in the prevention o f various maladies ' which ordinarily affect employees; this clinical and economic interest on the part o f industrial management further emphasizes the need for understanding the etiological factors in the working environment, so that they m ay be properly controlled. T h is booklet on industrial dusts and fumes is the second of a series o f which the purpose is to show the most important effects o f occupations, show how these occur, give measures for treatment, diagnosis, and prevention, meanwhile considering the source 'or cause o f such conditions. I t is hoped that these simple and brief expositions will be o f considerable help to industrial physicians, and to private practitioners who have among their patients employees o f industrial plants subject to such exposure. D efin itions . Dusts m ay be defined as soEd particles o f m atter which are ordinarily produced b y grinding, crusiing, drilling or blasting < J i D- Dusts and Fumes in Industry processes, the composition o f the particles being the same as that of the parent materials. These materials m ay be rock, metals, ores, or such products, for example, as coal, grains, or wood. T h e size o f the particles varies from w hat is called ultra-micro scopic to those which are visible. Authorities now agree that the hygienic significant particle size o f dust ranges from a Fraction of a micron to 10 microns. (A micron is 1/25,000 o f an inch). T h e most frequently encountered dasts in industrial processes are mainly those from inorganic minerals, and a few organic dusts, such as wood and Hour. Fumes m ay be defined as solid particles which are formed b y processes similar to combustion, condensation and sublima tion. T h e most common types o f fumes encountered in industry are usually caused b y the oxidation o f a metal, o f which typical examples are the oxides o f lead or zinc. Particle size is usually smaller than dust and ranges below one micron. In contrast to dusts, fumes tend to flocculate very easily. M a n y people erron eously speak o f fumes when they mean vapors o f liquid materials, such as acid solutions, organic solvents, and the like. Incidence an d E tio lo g y Dusts are the most common type o f air contaminants en countered in industrial processes, and can occur whenever various' materials, as -mentioned before, are subjected to processes which break them up in to fine particles; or where powdered or pulver ized materials are handled or transported- Inorganic dusts are the prevailing typ e so far as frequency is concerned, b u t organic dusts are also found in different industrial operations. Fumes are usually found wherever there are molten metals such as lead, zinc, and ralmium being processed or used in indus trial operations. W elding is an operation which has greatly in creased in frequency o f use and it m a y give rise to fumes o f the metals which are welded or to fumes and gases from the variegated coatings o f welding rods. . <3 a t> Incidence and Etiology I t is to be borne in mind th at metals m ay produce both dusts and Fumes, according to the nature o f the operation and the state o f the materials when processed. For example, among the heavy metals such as lead, dust m ay be o f equal or greater etiologic importance with fumes -- other mineral dusts and metallic dusts also are considered o f etiological importance, as the following outline will show: I. Organic dusts: 1. Non-living organic dusts: (a) Toxic and/or irritant dusts; ' ` {Various organic compounds such as trinitrotoluene, mercury ful minate, tetryl)." (b) allergy-producing dusts (woods, pollens, and the . like). 2. L ivin g organic dusts: (a) bacteria (b) fungi II. Inorganic dusts: (mineral dusts) (a) toxic and/or irritant dusts; (mainly the dusts from heavy metals and their salts, such as arsenic, lead, manganese.) (b) fibrosis-producing dusts, (examples are free silica and asbestos). (c) non-fibrosis-producing dusts; (die so-called inert dusts, such as alundum, corundum, emery, lime stone, magnesite, marble, plaster-of-paris, and polisher's rouge).*" T h e most important o f the non-metallic, inorganic mineral dusts is free silica, which produces silicosis, i f breathed in suffi cient quantities over a long period o f time. Free silica dust and This cUusficatfon li a accordance ti(V cite k m o f knowledge. F e t m cod*** aod cxptvtcoc wO probably thaw n o t o f tba w ccK ed iocre or e e a t a a dt*re to k lu iafw L <3> SC 030796 Dusts and Fumes in Industry asbestos dust are the tw o kinds o f mineral dusts which produce disease entities corresponding to the names o f the dusts -- sili cosis and asbestosis. M ixed dusts o f various kinds, such as various ores which contain different amounts o f free silica, can produce different types o f reactions, according to the kind o f minerals which are in the ores. Where, for example, there are mixtures o f iron, and various calcium-containing compounds such as gypsum, with free silica, a protective influence is exerted against the action o f free silica on the lungs. Other modifications o f free silica action occur according to the types o f minerals present some o f which tend to inhibit or restrain the action o f free silica. Another important conception with reference to the etiology o f dust and fame diseases which m a y result from exposure to these classes o f materials, is the use o f the terms exposure and hazard: they are not synonymous -- exposure merely means contact w ith some substance which is a potential health hazard; whether it is an actual health hazard can only be determined by an industrial hygiene engineering survey, in which the amount and kind o f exposure is rated, according to accepted standards o f concentration, size, and q u ality o f dusts and fumes. M an y persons erroneously therefore state that there is a lead hazard, for example, when it is only known that contact is being made with lead; and when there are no data to support the contention th at there is an actual hazard present in the working environ ment. M ethods for the determination o f dusts and fumes in the air, also with reference to the types o f devices used for such determinations, will be mentioned later. T h e importance o f air contamination will be realized when it is stated th a t the patho logic effects produced b y dusts and fumes are brought about almost entirely b y the inhalation o f these compounds and m a terials. There is only one outstanding example, for instance, of the possibility o f absorption o f lead through the skin, namely tetraethyl lead, and this occurs in the form o f a fluid. N o dusts, so far as is known, produce an y systemic pathological condi- < 4> General Diagnostic Methods dons from skin absorption, and it is doubtful that any kind o f tru fume is absorbed b y the skin. From the etiologic point o f view, particularly w ith reference to pathologic effects, the following outline shows how different types o f substances (among the dusts and fumes) act on various systems in the body to produce pathological effects: 1. General system ic poisoning: Examples: Arsenic, lead, manganese, mercury. 2. Substances acting on the circulatory system: Examples; Arsenic, lead, mercury, vanadium. 3. Substances acting on the respiratory system: Exam ples: 'Asbestos, free silica. 4. Substances acting on the gastro-inteslinal system: Examples: Antim ony, cadmium, lead, mercury, zinc. J. Substances acting on the skeleton andjoin ts: Exam ples: Lead, mercury, mesothorium, phosphorus, radium. 6. Substances acting on organs o f special sense; Examples: Arsenic, lead, manganese, mercury. 7. Substances acting asfe ta l poisons: Examples: Lead, mercury. 8. Substances acting on the genito-urinary system: Examples: Arsenic, lead, mercury, vanadium. 9. Substances acting on the brain and nervous system: Examples: Arsenic, lead, manganese. G en eral D iag n ostic M ethods T h e accurate diagnosis 0/ pathological conditions arising from the inhalation o f industrial dusts and fumes has tremendous economic significance and also it is o f medicolegal importance. Moreover, it is impossible to understand how proper and effica- < s> SC 030798 Dusts and Fumes in Industry ceous treatment m ay be rendered unless a scientific diagnosis is made. I f a claim results from the pathological condition alleged, it is evident th a t the disease sustained m ust be directly related to the employment and further, must produce disability to entitle the individual concerned to compensation. D iagnostic methods w ith reference to dust and fam e diseases need not differ w idely, i f a t all, from those used as routine pro cedures in general scientific medicine, although there are specific j M methods as in any other application of general medical diagnostic principles to- an y special group o f persons. N ew discoveries occur relative to diagnostic methods in occupational disease work and for the m ost part, reliance must be placed on information which is scattered throughout the current literature in addition to available textbook material which is better now than it was even five years ago. Emphasis has already been placed upon the vita! part played b y etiology; it is wise to repeat th a t etiology forms the bulwark 1 o f the diagnostic and therapeutic background. Am ong the methods which are used to m ake a fairly accurate diagnosis w ith reference to occupational diseases, is the tak in g o f a thorough industrial history; consideration o f sym ptom atology, I 4 the physical findings, the results o f air examination; and finally, H la st bu t not least, a differential diagnosis, ruling out diseases of ordinary life which have no relation to occupation. * t T h e industrial history m a y be o f very great assistance in arriving a t an opinion. M o s t industrial physicians o f considerable 1 experience believe that it is desirable to include a complete >J resume o f the kinds o f occupations which have been experienced ;-j b y the individual being examined, dating from the first jo b to the la s t one. I t is o f course d ea r th a t d ie details o f actual occupa tional exposure cannot be evaluated b y this method, but im portant information bearing on the diagnosis m ay thus be obtained. I t is the present practice, therefore, to list the occupa tions w ith the dates o f occurrence, in the industrial history. I t is SC 030799 General Diagnostic Methods furthermore advisable to get more detailed information relative to the performance o f the occupation, if that can be obtained. T h is will a t least give information relative to the kind o f exposure in industry, although lt will g iv e no idea o f the severity o f ex posure. T h e sym ptom atology in m any kinds o f occupational disease is likely to be confusing rather than useful, because in m any instances it so closely simulates that of non-industrial disease that it is quite commonly not characteristic. Especial attention should be given, however, to the recording o f the sym ptom atology and critical attempts made o f its proper evaluation. Here again, distinction must be made between symptoms which may be due to non-occupational disease and those symptoms which are specific for occupational diseases -- this is where the difficulty arises in adequately assessing sym ptom atology. T h e physical findings, on the whole, are more reliable than the sym ptom atology, although in certain instances they too arc not characteristic and are, therefore, liable to be somewhat puzzling. Where only one portion o f the body is affected, as in silicosis, for example, it m ight be assumed that the physical findings would be more characteristic, but the opposite o f this is usually true. In ocher instances, for example lead poisoning, where different organs and system s are pathologically affected, the picture is liable to be one which demands expert evaluation to differentiate from non-occupational conditions. Clinical laboratory d ata, including X -r a y findings, are frequently found to be decisive, although here again intelligent appraisal means proper interpretation o f the data. When they are decisive, such tests are b y the Very specificity o f their nature, o f great value as diagnostic aids, although they should be defi nitely correlated w ith other findings. Differential diagnosis presents perhaps the m ost difficult problem o f all in the realm o f diagnosis o f occupational diseases. There is good reason to believe th at differential diagnosis will <t 7 t> SC 030800 B u lls and Fumes in Industry continue to be one o f the most difficult phases o f the medical ramifications o f the medicolegal problems of occupational dis eases. T h e reason which has already been indicated is th a t the sym ptom atology and frequently the physical findings .im itate so closely the sym ptom atology and physical findings o f non industrial diseases, that one must make use o f specific procedures which are designed especially as diagnostic guideposts. Frequently such specific procedures are not used to a n y great extent, except b y those w ho are highly specialized in the field and whose work takes them into a review o f the current literature containing these developments. For example, one m a y believe that an industrial employee has lead poisoning, largely because o f second hand knowledge that lead was used in his occupation, more easily than one could demonstrate adequate etiology and the existence o f lead poisoning b y scientific methods. Because o f all o f these obvious and other difficulties, it seems wise to adapt specifically certain examination procedures to industrial problems arising out o f occupational or suspected occupational diseases. M o st authorities now agree th a t the examining physician can be o f greater service and give more effi cient ad vice regarding either acceptability for employment, continuance in it, opinion on the diagnosis o f systemic pathologic conditions and the estimation o f disability, i f he is conversant with the following points: I. T h e nature and extent o f the industrial exposure into which the employee will go or where he has been. T h is can be determined only by scientific methods which w ill be referred to later. a. T h e effect o f this specific exposure upon normal and abnormal physical states o f employees, as interpreted by the physical status o f each individual on examination. (T h is refers specifically to etiology in the industrial en vironment and the effects which such etiology m ay or could produce.) ' <1 8 > SC 030801 Clinical Examples 3. T h e nature o f the protective devices supplied b y the em ployer, if a hazardous exposure cannot be otherwise con trolled, and as to whether these devices are functioning efficiently. (Reference will be made later to these devices, especially designed for protection against dust and fume exposures.) I t is realized that these procedures arc somewhat removed from the usual program o f physical examinations, particularly with reference to d ie work o f part-tim e industrial physicians, but it is also expected that the physician will be called upon increas ingly to know and appreciate such information so that he may function better as a diagnostic medium. Because the most frequent and m ost significant exposures in industrial processes are free silica du st and lead and its com pounds, it seems advisable to include in the next secdon some clinical examples, namely silicosis and lead poisoning; there will also be included a brief discussion o f m etal fume fever. C lin ical E xam ples Sim ply stated, silicosis is a disease o f the lungs, caused b y the continuous inhalation over a lon g period o f rime o f very finely divided, microscopic, particles o f free silica dust. There have been various standards set up by different agencies, based upon studies o f silicotic workmen and their exposure to free silica dust. T h e National Silicosis Conference R eport on M edical Control o f Silicosis says: " There is evidence th at for prolonged exposure a concentration o f more than five million p arad es per cubic foot o f a highly siliceous dust is dangerous. Therefore, it is now con sidered good practice to hold concentrations o f high ly siliceous dust at 5 million particles per cubic foot, or less." Because o f die fact th at industrial exposures, involving high free silica content in which the concentration o f dust should be restricted to five million particles per cubic foot, are relatively infrequent in industry, and also because the opposite usually < 9> SC 030802 Dusts and Fumes in Industry occurs (an exposure to " mixed" dusts which contain appreciable amounts o f free silica b u t also contain considerable amounts o f Other types o f material) it is believed wise to refer to the form ula* developed b y the N ation al Silicosis Conference with reference to a working criterion w ith respect to satisfactory or unsatisfactory conditions, when exposure to `mixed' dusts occurs. I t is to be borne in mind, however, th a t any unprotected industrial operation, which involves the production o f a lo t o f fine dust particles o f material containing a relatively large percentage o f free silica, offers a potential silicosis hazard. T h e incidence o f silicosis is not known w ith any degree o f accuracy, although various estimates have been made. O ne of these made some time ago b y the American Institute o f M ining and Metallurgical Engineers indicated that in the United States the number o f industrial workers exposed to the silica dust hazard is in excess o f a half million. Figures quoted by the Com mittee Reports of the N ational Silicosis Conference disclosed estimates that approximately 1% o f the working population of the U nited States or about one million workers are exposed in some w a y to the potential hazard o f silicosis, and that perhaps h alf o f this number, 500,000, or 1 % o f the total, ate exposed to a serious hazard. It is furthermore believed th a t approximately 110,000, or 0.2 o f l % o f the total, have silioosis to some degree, b u t likely o n ly 4000 to 5000 (a small fraction o f 1 % o f th e total) suffer a n y degree o f disability from the disease. (These figures are based upon prewar estimates.) I t can readily be seen th a t silicosis, although not a rare disease, is not common and furthermore not as common as may ordinarily have been supposed b y many persons. R ecen t conceptions w ith regard to the contraction o f silicosis have established the belief that approximately 2 5 % of those i exposed to a real silica hazard will eventually develop silicosis. * FO RM ULA A : "M u ltip ly th e p e rc ta rif at irtc u C o b y ifcc to ta l use co u n t. I f tb e resu lt it codec 5 Bslboa* m e condition m ay be to tm d trtd pcrmiiwbiei the result u over 5 mtHioa, the c o o d nion m ay be cenudered toe High F o r evatopl* tO p er cent free n lie a w*d* en average to ta l d us*, concentration o r 30 omIIkw parrxele* per m bae foor would fiv e 0.10 tim es 50 oilloo. w hich equals 5 cnDton (food practice): 50 p er c e n t with an a re c a s t eof*l d o s t tonem ra u ao of SO m dlton, vaW qua! 0 5 iim JO, o r 15 (nM teficW tr). T h u b r a e la U n i applicable to any dut c. t a is m j tea th a n S pet cent free aiRcs.** < 10 > : < ! SC 030803 > Clinical Examples W ith respect to the occurrence o f silicosis in the foundry industry, a prewar survey b y th Division o f Industrial H ygiene o f the N ew Y o rk State Department o f Labor, based on a study o f 31 x foundries, o f which 80 plants included X -r a y examinations in volving 4,754 employees, provides some interesting figures: the X -ray summary showed th at 3,259 or 80.2% were negative; 185 or 4 .5 % showed fibrosis; n o or 2 .7 % showed silicosis with and w ithout infection; 485 or 1 1 .9 % showed healed primary and re infection types o f tuberculosis; 27 or 0.07% showed clinically significant tuberculosis. I t was concluded, as stated in the report, th a t it would appear th at the silicosis hazard in the foundry industry in N ew Y o r k S ta te, while existent, is o f mild degree o f severity and m ay be expected to yield satisfactorily to appropriate measures o f control. T h e report further indicated th a t tuber culosis as manifested b y X -r a y films o f the chest w as found to be more prevalent am ong silicones than am ong non-silioorics in fouadrym en. T h e occupational history, as previously indicated, is o f con siderable importance. Forms for the recording o f occupational records have been devised b y various organizations and groups and b y physicians and insurance companies. One o f the most com plete an d longer forms has been devised and used b y the Saranac Laboratory, Saranac Lake, N . Y ., in connection with silicosis studies and sym posia on silicosis which have been held b y this group. I t is suggested th at the physician, i f interested, should contact the industrial hygiene bureau o f his state health departm ent through which detailed forms m ay be secured or information relative to them. T h e sym ptom s and physical signs are not characteristic; they m ay be confused even b y skilled diagnosticians in other diseases, with the sym ptom s and signs which com m only occur in both minor and the more serious types o f die well-known respiratory infections. Characteristically, shortness o f breath on exertion and decreased chest expansion frequendy occur in advanced cases o f silicosis, b u t these findings must also be differentiated as <3 I I > SC 030804 Dusts and Fumes in Industry co their casual relationships and their possible association with other diseases. T h e dinical confirmation o f the diagnosis o f silicosis rests mainly on the characteristic X -ra y appearance o f the chest. This shows the typical lesions o f silicosis, hyaline fibrous nodules which are scattered as opaque bodies throughout both lung fields, the density o f these nodules being somewhat less than calcified bodies, but discrete in outline, all about the same size in the early stage (so-called millet-seed size) and evenly dis tributed throughout both lung fields. These nodules appear as the first indication o f silicosis, later become somewhat confluent and in the U tter stages, there are large masses o f opaque material found near the periphery o f the lu n g fields. In the later stages o f silioosis, the disease is frequently com plicated b y infection, usually tuberculous in nature. A s an aid to interpretation o f the X -r a y films o f the chest where silicosis m ay be suspected, it is suggested th at the physician refer to a tabulation o f the X -r a y changes in silicosis, w ith the underlying histological conditions which cause them, published in the transcript of the Second Silicosis Symposium, Saranac Lake, N . Y ., 1935. Diagnosis rests upon proof o f occupational dust exposure sufficient to produce the disease, and the presence o f character istic nodular lesions in the X -r a y film o f the chest. T h e mere mention o f occupation is not sufficient for diagnostic purposes -- adequate knowledge concerning the qu ality and quantity o f dust exposure, as well as the length o f the employment period, is necessary to establish a distinct causal relationship. Although considerable diagnostic reliance is usually and properly placed upon the history o f adequate occupational dust exposure and the characteristic chest X -r a y appearance, a thor ough physical examination with appropriate clinical laboratory examinations should be done, especially w ith reference to the .ruling out o f other respiratory diseases. Diagnosis becomes essentially a differential diagnosis, as before explained, one which is likely to be difficult, necessitating special experience Clinical Examples and knowledge. Some o f the conditions requiring differential consideration here are miliary tuberculosis, multiple calcifications o f healed tuberculosis, cancer o f the lungs, and fungous growths o f the lungs. W ithin recent years, superimposed infection has come to be the accepted cause for disability. T h e outlook in simple silicosis, therefore, (that is, w ithout infection) is more favorable than was formerly believed. I t is obvious th at the chief problem for the silicotic is to avoid superimposed infection, which is usually tuberculous. There is no one specific, efficacious treatment for silicosis, although in recent years, the inhalation o f metallic aluminum powder has shown some promise. In cases where tuberculosis complicates the picture, it is obviously to be treated b y the best known methods for that disease. There is some recent evidence that surgical therapy as used in ordinary forms o f tuberculosis is also a help in the type o f tuberculosis which follows silicosis. T h e evidence for this is not conclusive, but there are good results on record. In general, recommendations for the treatm ent o f cases o f silicosis vary with experience and w ith the findings o f each case. I t is believed, for example, that no treatment is necessary in the case o f an individual without sym ptom s, whose X -r a y film o f the chest (taken perhaps in a routine industrial survey) shows on ly widespread discrete nodulation w ithout localized shadows indi cating infection. However, the employee should have serial X -r a y examinations with physical examinations o f the chest at least once a year and should be removed from further silica exposure to some other jo b , since the disease is very slowly progressive and there is at this stage no disability which precludes co n tin u e non in employment. A person w ith localized conglomerate lesions m ay have symptoms and usually cannot do as h eavy work as formerly; therefore, a lighter jo b should be found. In the presence o f active infection where there are sym ptom s or incapacitation, the individual cannot obviously continue in his <J 13 > Dusts and Fumes in Industry former employment. I f the case Is one o f open tuberculosis with \ positive sputum, it is evident that such an employee is a source 1 o f danger to his fellow workmen and should be placed in a sani tarium or hospital. In cases o f inacti re infection wi rh no incapaci- j ration, lighter work should be provided, without further dust ' exposure. j Dusts containing silica in combined form do not cause silicosis; j however, one such dust, asbestos, a magnesium silicate, will : produce a characteristic fibrosis which is called asbestosis. T h is ] i disease is quite different in its pathology from silicosis, and has j < a characteristic `ground-glass' appearance on the X -ra y films o f the chest. Animal experimentation indicates that the action of asbestos is probably mechanical, since it cannot be produced in other than die pulmonary tissue. Asbestosis may cause disability and a few Fatal cases haw: been recorded, bu t in those cases show ing marked disability, other organic disease is usually also present. T h e sym ptom atology and physical findings include {i cough, dyspnea, pallor, clubbing o f fingers, and diminished chest 1 expansion, with a characteristic X -ra y appearance as previously mentioned. . Lead Poisoning Lead poisoning offers a good example o f an Industrial poisoning which is contracted b y the inhalation either o f a toxic dust or fume, and has been stated to be one o f the most frequent and im portant types o f metallic poisoning in industry, on account o f the wide spread use o f lead and its compounds. Although there are no reliable statistics available with respect to the national incidence o flea d poisoning, it is believed th at lead poisoning is very prevalent and th at most o f it is mild. T h e incidence o f severe types o f cases, particularly lead encephalo pathy and the more severe types of nervous system involvement are not seen with as great frequency as in former years. M a n y physicians who are used to handling industrial cases now rarely see a case of wrist drop due to lead poisoning, whereas ao to 2J U Years ago it was a rather common phenomenon, in cases o f lead intoxication. < 14 > .m a i buiuuh f u iu 1 t JP SC 030807 Clinical Examples T h e industrial history is o f great importance, as previously indicated, and a thorough consideration o f the nature and extent o f the exposure to lead and its compounds is an essential point in the etiology. I t is now generally accepted that the standard o f the U. S. Public Health Service and the American Standards Association o f 1.5 milligrams o f lead per ten cubic meters o f air, is the maximum allowable concentration. Because it is now con ceded that practically all industrial lead poisoning is contracted b y the breathing o f lead dust and fumes, it becomes o f con siderable importance in working out the etiology to ascertain the am ount and quality o f lead dust and fumes in the air, during the occupation o f the involved individual. T h is point will be dis cussed later with reference to prevention. Form erly, the nature and variety o f non-industrial sources o f lead intake made it particularly difficult to establish industrial etiology on a sound and competent basis. M ore recently, how ever, non-industrial lead intake has been measured b y scientific methods and with die exception o f an occasional difficulty with . various types o f homemade beverages stored in utensils glazed w ith a lead compound, the non-industrial lead intake is not believed to be a considerable factor in the production o f lead poisoning in adults. There are, however, some exceptions and these should be taken into account, as indicated. T h e diagnosis o f industrial lead poisoning is not a simple m atter on account o f the fact that clinical sym ptom s and signs are protean and are liable therefore to simulate other diseases. G reat increase in our knowledge, however, has occurred within the past ten to fifteen years, and it is now known that there is a close relationship between the action o f lead and its compounds within the body and the calcium metabolism, and further, normal and abnormal excretion o flead has been worked out on a scientific basis. I t is now an accepted fact that persons w ithout industrial exposure normally excrete a certain am ount o f lead in the urine. I t has been stated th at definite clinical findings o f lead poisoning are practically always associated with abnormal urinary lead <3 15 > Dusts and Fumes in Industry excretion -- the reverse, however, is not true -- th a t abnormal urinary excretion o f lead in the absence o f characteristic clinical findings indicates lead poisoning. Other laboratory findings are im portant, particularly the examination o f the blood, some investigators and clinicians using the increase in basophilic stippled red cells as an indication of positive findings and others using w hat is known as the basophilic i i aggregation test. Both are found to be successful, the former more adaptable in cases o f frank poisoning, the latter more useful in cases o f lead absorption and suspected incipient poisoning. r Although as indicated, the clinical symptoms and signs of i-. lead poisoning are protean, the principal effects are expressed in the blood, the gastrointestinal system, and the nervous system , named in order o f their usual chronological occurrence. In brief, the most consistent findings are changes in the color and form o f the red cells o f the blood, colic and constipation, and weakness , i and atrophy o f the extensors and flexors o f the muscles o f the wrists, with partial paralysis in the more advanced types o f cases. T h e differential diagnosis, as m a y be obvious, has to do mainly with differentiating industrial lead poisoning from non industrial diseases which m ay involve the blood, the gastro intestinal system , and the central and peripheral nervous systems, producing changes which are similar to those observed in frank lead poisoning. Such non-industrial diseases show a considerable variety o f pathological processes affecting the above-named r systems. T h e treatm ent o f lead poisoning has undergone considerable change within the past ten to fifteen years. In general, the treat m ent consists m ainly o f appropriate therapy for the toxic episodes and the mobilization o f stored lead in the long bones. I t is usually agreed th a t it is wise to facilitate the storage o f lead b y an excess calcium intake rather than to set lead free in the blood stream ; after die passihg o f acute toxic episodes, the elimination o f lead may be assisted b y means o f low calcium in take, the administra- <116 > SC 030809 Clinical Examples tion o f w eak organic adds and ammonium salts, sodium bicarbo nate, an d potassium iodide. Care should be exerdsed in using such forms o f treatment on patients who have nephritis. T w o schools o f thought w ith widely divergent views exist w ith reference to deleading the bod y: there are chose w ho fed that in the m ajority o f instances deleading will accomplish good results, while there are others w ho adopt a conservative attitude and because o f the possibility o f precipitating acute symptoms, feel that it is safer to produce artificial deleading b y slow- methods, or to resort to the natural process o f lettin g the b od y delead itself over a period o f time. T h e choice in the m atter depends upon the individual case and the previous results which have been achieved a t the hands o f the physician in charge o f the case. i Storage o f lead m ay be facilitated in acute cases b y a high calcium diet or b y the slow intravenous injection o f io ce o f 20% calcium gluconate; variations w ith relationship to this form o f i treatment have been devised b y various physicians. In the delead ing process, low calcium diet together with oral administration o f ammonium chloride has been found to be effective, whereas h in certain cases parathyroid extract and sodium bicarbonate also have been useful. W ithin recent years it has been established that i*l. large doses o f viosterol have been instrumental in increasing the excretion o f lead. O ther investigators have found th at an adequate phosphorus intake is essential for the depositing o f lead in the bones and for the removal from the bones o f the excess cations, as the insoluble phosphate salts in the feces; it has therefore been recommended that deleading m ay be accomplished b y giving a diet low in calcium and relatively high in phosphorus, using viosterol 20 minims daily. There are also variations o f treatment w ith reference to the amount o f intoxication, and where there has been high, medium or low lead intake in industrial occupations. In all these types o f treatment, deleading should be done in the hospital where the patient m ay be closely supervised. Some investigators advise < 17 > SC 030810 Dusts and Fumes in Industry against deleading more often than once in four weeks and the course should not be prolonged for more than three or four d ays; some physicians believe that it m a y tak e from six to fifteen courses o f deleading to free the individual o f his most looselycombined lead, which o f course is the m ost dangerous ty p e o f lead. I t is again warned that deleading should not be undertaken in the presence o f acute sym ptom s; it is further agreed b y all in vestigators that calcium therapy is considered to be the m ost specific at the present time. T h e outlook in cases o f lead poisoning is much better now than formerly because o f the occurrence o f moderate types of effects, the severer forms being a great deal less frequent than in former years. M etal Fum e Fever . T h is name is applied to the condition w hich results from breathing fairly heavy concentrations o f freshly formed metallic oxide fumes, principally zinc and one o f its alloys, brass; although the condition may result from the inhalation o f other m etallic oxide fumes. M etal fume fever is not a system ic poisoning, but it should be borne in mind that some o f the m etallic fumes that can cause it, such as lead, cadmium, mercury, and manganese, m a y also cause systemic poisoning. T h e sym ptom s come on some hours after exposure, usually after leaving work, a dryness o f the throat b a n g first noticed, which m a y he followed b y a dry cough and a feeling o f heaviness in the chest. Rise o f temperature, accompanied b y sweating, and leucocyte sis and elevation o f the pulse rate and th e blood pressure usually follow, sometimes with chills. T h e sym ptom s ordinarily pass off in 12 to 24 hours and the usual experience is th a t the employee returns to work the following day. A natural im m unity is conferred in certain types o f workers, which seems to be lost rapidly after removal from continuous exposure. Diagnosis is made usually on a clear history o f industrial exposure to metallic oxide fumes. I t m ust be remembered that < 18 > Other Dusts and Fumes the effects and sym ptom s o f metal fume fever are very similar to those o f influenza and that the m alady is more often noticed in the fall and winter, when influenza usually occurs. T h e in dustrial history is, therefore, important in diagnosis, particularly w ith reference to a causative exposure to metallic oxide fumes. T h e outlook is good for complete recovery in a short time and usually there is no time lost from work, alchough there m ay be temporary incapacity in terms o f hours. ! Th e treatment is symptomatic and especially directed toward comfort because the patient usually recovers within a relatively short time in all events. R est in bed w ith adequate warmth and protection from drafts are recommended. However, all suspected cases o f metal fume fever should be attended b y a physician because the symptoms m a y closely simulate influenza which makes the differential diagnosis important. O t h e r D usts an d F umes It m ust not be concluded that although clinical examples were given o f silicosis, lead poisoning, and metal fume fever, there are not other examples which are o f importance. These subjects were selected because o f their frequency o f occurrence and because o f the fact th at they are commonly encountered as examples o f dust alone, dust and fumes, and fumes. ' A m ong the other metals which m a y be mentioned are arsenic, antim ony, cadmium, manganese, mercury, radium, selenium, silver, tellurium, thallium, and vanadium. N o t all o f these are eq u ally important w ith reference to toxic effects. Probably the most important o f these from a toxic point o f view are arsenic, mercury, manganese, and cadmium. Arsenic pro duces chronic poisoning chiefly from breathing over a long period o f thin air containing dusts, or sprays o f arsenic compounds. T h e compounds o f arsenic such as lead arsenate, paris-green, arsenic oxide and arsenic sulphide are among the more dangerous forms. d 1 9 1> SC 030812 Dusts and Fumes in Industry W here dusts o f mercury are present, th ey will be in the form o f either mercurous or mercuric, compounds, where metallic mercury is used in the manufacture o f such items as thermometers, mercury switches, mercury vapor lamps, m ercury boilers, etc., i the hazard is from the vapor since mercury has a considerable -1 vapor pressure even a t normal temperatures. Mercurialism is characterized b y three features: inflammation o f the mouth, muscular tremors, and psychic irritability -- sometimes all of ' i these are encountered and sometimes only tw o or on ly one. In the more chronic or slaw form o f poisoning, a characteristic tremor is the commonest sym ptom , com ing on late, and has been noted to occur particularly among mercury miners. Manganese poisoning is an old industrial poisoning, having been described more than lo o years ago, b u t has receded in incidence in American industry. Characteristically it produces a peculiar slapping gait w ith phenomena o f retropulsion and pro pulsion; masklike faces; monotonous voice with economical speech; muscular twitching varying from a fine tremor to gross rhythm ical movements o f the extremities; languor and sleepiness; cramps in the calves o f the legs w ith stiffness; slight increase in the tendon reflexes without an y disturbance o f the deep or super ficial sensation. Studies within the past five years indicate th at dust is the most important type o f exposure. Cadm ium is encountered in the smelting o f ores, the handling o f socalled ` blue powder' compounds, the spraying o f pigments, the welding o f alloys, and the melting o f cadmium metal itself, as well as certain non-industrial exposures where utensils have -been plated with this metal. In recent years there have been several outbreaks o f cadmium poisoning among non-industrial users o f such utensils. T h e use o f the m etal has increased tremen dously and therefore, there is more industrial exposure. T w o types o f effects have been observed, those with, reference to the lungs and also those w ith reference to the gastrointestinal tract, the former being more important a n d more frequent. Pulm onary involvem ent is characterized b y a feeling o f constriction in the <3 20 > i i || .... SC 030813 Prevention chest, edema and congestion o f the lungs, sometimes with hemorrhage, proliferative interstitial pneumonitis; while the latter is characterized b y nausea and vom iting an d a general irritative reaction o f the gastro-intestinal tract, w ith diarrhea, hiccough, and oliguria. I f further details are desired on the clinical aspects o f the metals mentioned, standard works on industrial hygiene and occupational diseases should be consulted. P revention T h e general principles o f prevention involve first the identi fication o f industrial exposures and the evaluation o f such ex posures b y proper scientific methods to determine whether or not they represent actual health hazards. T h is is done b y sampling the air and determining the amount o f air contaminants and the quality o f them in each type o f occupation or problem involved, and comparing the results with the accepted standards o f maxi mum allowable concentration th a t have been adopted b y official bodies. Second, after it has been determined th a t there is an actual health hazard represented b y the occupation, control measures, both engineering and medical, are instituted to control the hazard, providing it cannot be entirely eliminated. In discussing the methods o f engineering control, we are con cerned w ith three basic principles: 1. Investigation of occupational conditions. 2. T h e measurement o f the occupational exposure and the raring of the hazard, if one oasts. 3. P utting into effect the specific measures o f protection which have been indicated b y information secured under (1) and (2). A m ong the methods o f approach for engineering control measures m a y be mentioned: . 1. Physical and hygienic survey o f plant conditions. <3 21 > SC 030814 Dusts and Fumes in Industry 2. Occupational history and analysis. 3. Adequate information concerning materials and processes used. 4 . Atmospheric and gross sampling o f materials, combined with quantitative physical and chemical determinations. ;! 5. T h e rating o f the hazard by comparing the findings in the given instance with accepted standards. 6. An appraisal o f the efficiency o f protective apparatus and a detrices. 7. An adequate and proper interpretation o f the information so th a t it can be applied practically to the industrial .* I problem involved. When the foregoing methods o f approach to engineering control have been carried ou t and information secured from them, the information can indicate the necessity for using specific methods o f protection which have been found useful in different combinations: 1. T he use o f mechanical devices, such as exhaust ventilating systems, respirators, masks, and the like. 2. T h e changing o f processes (segregation, enclosure, wetting, etc.). 3. Substitution o f nontoxic materials for those o f proved toxicity. s 4 . Educational programs for management, workers, engineers, and physicians. t J. Continuous maintenance and checking o f the efficiency o f protective equipment. u A tm osph eric Sa m plin g T h e best method for collecting a sample o f a dust or fume A from the air will depend somewhat upon the typ e o f contaminants {t to be sampled. H ie degree o f hazard o f fibrosis-producing dusts is measured in terms o f particles per unit volume o f air (example: < 22 > SC 030815 /itm osphtric Sam pling 10 million particles o f silica dust per cubic foot o f air) while toxic dusts and fumes which m ay cause system ic poisoning are usually measured in terms o f weight per unit volum e o f air. (Exam ple: lead dust 1.5 milligrams per 10 cubic meters o f air.) Since results m ay vary with the type o f air sampling device used, it is im portant to select a typ e accepted through general usage in the practice o f industrial hygiene. T h e larger Impinger which samples one cubic foot o f air per m inute b y im pinging the air containing the du st particles from a nozzle submerged in water or alcohol against a plate or bottom o f the flask w as used in all o f the original studies in the United States on fibrosis-producing dusts. T h e large Impinger, however, has the disadvantage o f being bulky and requiring electric current or compressed air for operation o f the motor-driven air pump, which produces the suction stream for air sampling. A portable M id g e t Impinger has been developed which has been proven to g iv e results as reliable as the large Impinger. T h is apparatus samples a t the rate o f i/io th o f a cubic foot per minute and is operated b y a hand cranked, positive action, four cylinder pump, in conjunction w ith a vacuum regulator which maintains an unfluctuating suction regardless o f minor variations in rate or smoothness o f cranking. A fter the sample has been collected in the Im pinger flask, a portion is placed in a special dust counting cell and counted under a microscope with an eyepiece having a special ruling similar to a blood count ruling. Further analyses are necessary with reference to the amount o f free silica in the du st and this is accomplished b y the use o f specific chemical, petrographic and X -r a y diffraction methods. T h e Im pinger m ethod o f sampling is not entirely suitable for collecting fumes or dusts of toxic materials such as lead, cadmium, and others because the efficiency o f the Impinger is not adequate when sampling the very fine fume particles and since the am ount < 23 > Dusts and Fumes in Industry or concentration o f such materials in air which m ay be injurious is much smaller than the safe amounts o f fibrosis-producing dusts, a correspondingly large air sample should be taken for reliable results. T h e Electrostatic Precipitator is w idely used in the collection . o f toxic dusts and fumes, particularly o f m etals and their com pounds. A Portable Electrostatic Precipitator has been developed which operates from n o volts, 60 cycle current; and b y high voltage electrical precipitation collects the sample o f the particu late m atter d ry on the inside o f aluminum or glass cylinders. T h is device samples at the rate o f 2 cubic feet per minute. After the sample is collected, a quantitative chemical analysis is made in th laboratory. T his type o f apparatus permits determinations o f v e r y low concentrations o f m any different kinds o f atmospheric particulate matter. W here equipment or personnel is nor available for atmospheric sampling, state industrial hygiene bureaus or private testing laboratories m ay be engaged. M a n y insurance companies also h a ve fa c iliti for such work. T h e Industrial H ygiene Foundation in Pittsburgh, Pa., an association o f industries for the advance m ent o f healthful working conditions, also have an excellent staff o f technicians for industrial hygiene surveys or consultations in this field. R e spir ato r y P r o te ctiv e E qu ipm ent I t frequently happens that because o f the nature o f the operation or process in an industry, it is not possible to thoroughly control a hazardous exposure resulting from the evolution o f dusts and fumes. In such instances, it is considered wise to pro vide employees with personal respiratory protective devices. These va ry with the kind o f exposure and with the am ount of materials in the air. F or ordinary conditions in which o n ly dusts and fumes are present, simple filter typ e respirators are available which will Respiratory Protective Equipm ent protect the worker against the hazards of breathing these dusts and fumes. Such respirators normally consist o f a facepiece covering the nose and mouth, made o f some pliable materia] such as rubber which will conform to the face and provide a comfortable and dust-tight fit, and to which is attached a filter made o f treated paper or felt through which the air is inhaled. I f the filtering material is o f the correct ty p e and density, it will effectively filter particles down to less than a micron in size from the air. I Com fort is a most im portant consideration in a device o f this type. Since a high breathing resistance will materially affect the i com fort o f the wearer, the filters should be o f large area so that \ the inhalation resistance will be as low as possible. V alves should be provided which open on exhalation and further lessen the exhalation breathing resistance. T h e particular type o f filter employed will depend upon the kind o f contaminant present in the air. Since the amounts o f such, toxic materials as lead which will affect the wearer are much smaller than the harmful amounts o f fibrosis-producing dusts, a filter will have to be more effective when used against toxic dusts than against fibrosis-producing and nuisance dusts. F o r special operations such as sandblasting, a mechanical filter type respirator is n ot practical because o f the extremely high concentrations o f dusts present. In such conditions, special airsupplied masks or respirators should be used in which air from a compressed air line is supplied through a hose to the facepiece for breathing. Such devices m ay also be employed if desired as protection in less severe and hazardous operations. T h e advantage o f an air-supplied respirator is that there is no breathing resistance and the wearer is protected against an y and all dusts and fumes in the surrounding atmosphere. H owever, the restriction b y the air hose which must be attached to the wearer at all times be tween his facepiece and the air supply, prevents the use o f this device in m any operations w h o the worker must m ove freely 4 25 > SC 030818 Dusts m d Fumes in industry over a considerable area. Furthermore, caution must be taken to see that the air supplied to such devices is free from all in jurious or objectionable odors and contaminants and that the humidity and temperature o f the air is such as to provide reason able comfort. T h e United States Bureau o f Mines (Department o f the Interior) tests respiratory protective devices against various air contaminants under carefully controlled conditions. Devices meeting its tests receive that Bureau's official approval, and this is indicated b y approval numbers on the device and a reproduction ` o f the certificate on the package. Equipm ent approved b y the U. S . Bureau o f Mines for the particular contaminant or class o f contaminants in the air should be used. P M ED ICAL CONTROL ' I I t is o f course obvious that medical control measures arc futile after a disease has been contracted because o f the exposure to dusts or fumes except when the information is adapted to prevent ' f additional cases. However, before the diseases are contracted, there are a number o f things that can be done b y physicians to prevent such occupational diseases, which m ay be summarized | as follows: ' i . The intelligent use o f preemployment physical examina Si tions, including chest X -ra y films, and appropriate clinical laboratory tests as indicated. ijM 2. Similar use o f periodic physical examinations, chest X -ra y films, and clinical laboratory tests on employees in occu pations where typical hazards have been proved to exist, b y industrial hygiene investigations. 3. Responsibility for seeing th at hazardous exposures are properly taken care of, b y various efficient methods of protection, including the supplying o f personal respiratory il protection, where industrial conditions make i t impossible to control the hazard b y other means. < 26> . : 1 SC 030819 . M edical Control 4. Prom pt transference to non-hazardous occupations of employees found to have sym ptom s o f an occupational disease associated with their exposure. 5. Prom pt removal from work o f all persons suffering from active occupational diseases, when such persons are a menace to themselves, their fellow workmen or the em ployer. 6. Adequate provision for treatment, rehabilitation, and prom pt return to work, o f employees having disability resulting from occupational diseases. Sum m ary In this brief discussion o f dusts and fumes in industry, the sources, effects, and control have been considered under the following headings: 1. Definitions. 2. Incidence and etiology. ' 3. General diagnostic methods. . 4. Clinical examples. 5. Prevention -- general principles, including specific methods o f air sampling and apparatus for this purpose; specific methods o f protection, including mention o f respiratory protective equipment available; and other general methods. I t should again be emphasized that industrial managers are ` interested in the prevention o f trouble that m ay arise from exposure to dusts and fumes in industry, and th at this principle is particularly important nowadays because of the need for every perron in active production, and in addition, because so m any physicians are being used in the armed services. I t is believed that if the suggestions made in the foregoing pages are followed, the problems arising from dusts and fumes in industry can be successfully managed. <3 27 > SC 030820 M .S .A an d In d u stry Throughout the many types o f American Industry are the products o f this Company -- the largest commercial manufacturer of approved safety equip ment in the world today. In 1914, Mine Safety Appliances Company was formed (as its name would indicate), to serve the mining industry. T oday, the Company has far outgrown its original field, to include the design and manufacture o f approved safety equipment for every major industry and the public protective services. The Company's program is founded squarely upon Research -- research which is concerned with all industrial hazards to the life and safety o f the worker, conducted in M .S A .'s extensive laboratories, by scientists of national reputation, laboratories for chemical research, dust research, and experimental research join with the engineering departments in translating safety require ments o f industry into equipment meeting the highest demands o f efficiency, comfort, and practicality. An important adjunct o f M .S.A. Research is its nation-wide network ot fidd representatives, attached to M .S A . district offices in approximately JO principal cities. In intimate contact with industrial Health and safety problems, these trained men work in effective liaison with industry and J-LS.A. A dose contact is maintained with the many official bureaus and agendes devoted to furthering the cause o f industrial safety. - The broad institutional work o f M-S.A.-- exampled, in small part, b y this particular publication -- is undertaken with the fullest sense of responsibility. M ine Safety Appliances Company r SRADDOCX, THOMAS AND MEADE STREETS I P it t s b u r g h ( 8 ), P e n n sy l v a n ia *i < 28 t> P ri J Id U.S.A. SC 030821 APPROVED M S A EQUIPMENT fo r DUST and FUME PROTECTION * * * M.5 -A- Protection for men and women industrial workers against harmful dusts is the result of many years of research into all phases of industry's respiratory protective problems. In a wellequipped Dust Research Laboratory, which is a special division of our Research Department, continual study of dust hazards is maintained, and from this research group have come many of the most important improvements in dust protection -- dating from the first U. S. Bureau of Mi no-approved dost respirator, the famous M.S.A. "Comfo." The M.S-iV trademark on rhe products you recommend is a solid assurance of excellence in design, manufacture and performance. PEBBtSSBLE BBnBJUm ns oasts *** Miff ttfETT ISfttMCCf tt. MqM 6.&JL "SwKsr AH M.S.A. personal protective equipment against harmful dusts or fumes is approved by the high, est authority -- the United States Bureau of Mines, official testing agency of the United States Gov ernment for safety equipment. The approval certificate o f the Bureau signifies that each product has passed the most stringent im partial tests -- fit for the mosc exacting service in industry. We will be glad to send you, upon request, descriptive bulletins o f any or all of the products mentioned in this folder -- without obligation. M-S-A Dustfoe RESPIRATOR M-S-A Comfo RESPIRATOR The Duttfoc Reptcr The Comfo Respirator These widefy-used respirators for protection against harmful dusts offer maximum breathing comfort and wearing ease. Both answer ail respiratory protective require ments against pneumoconiosisproducing,nuisance or toxic dusts, and selection is a matter of per sonal preference. The compact and light-weight Dustfoe Respirator is built of transparent plastic -- durable, odorless, non-corrosive, non-con ductive of electricity or heat. A molded sponge rubber face, cushion assures comfortable fit; the filter is easily replaceable; the entire unit can be sterilized without harm, and its transparent con struction enables checking o f in terior condition at a glance with out disassembly. The original U .S. Bureau o f Mines -approved Comfo Dust Respira tor features twin side-placed filters o f large area, offering nrinimuiT! breathing resistance; the thin-edged filter containers of strong, maided plastic do not obstruct downward or sidewise vision, and there is nointerference with wearing protective hats or goggles on the job. T h e flexible rubber face piece fits the face snugly; the respirator is e a s ily cleaned and sterilized. SC 030823 M-S-A Comfo METAL FUME RESPIRATOR Of basic "Comfo" design, this reapU rater with a special Seer affords respiratory protectionCo workers ex. i posed to toxic fumes given off by metals in molten condition --such as alloys or materials containing lead, tin e , cadm ium , m anganese, chromium,arsenic,etc. -- fumes bom which may arise in burning, welding, melting, pouring, or cutting opera tions. The filters are quickly replace able as required. M S A A ir Line RESPIRATOR Gives complete respiratory pro . tecdon against many hazardous classes o f air contaminants by employing air from the shop compressed air line for breath ing. The half-coask type rubber facepiece is equipped with twin exhalation valves and an air- deflector tube. The complete assembly includes a corrugated supply tube, quick release con nection, ``bump-proof" air con trol valve and an air hose with couplings. Where protection to the face and eyes ta an additional requirement, an All-Vision gas mask type facepiece can be supplied. - SC 030824 M S A ABRASIVE MASK This stm dy assembly weighs less than 4 pounds, yet gives complete pro- I tection to the wearer from heavy concentrations o f fine dust present in I shot or sandblast rooms. Using supplied air, the M .S.A. Abrasive Mask - I comprises a facepiece and connecting tube, air flow control valve with . "bump-proof" adjustment, quick release connection and optional air > filter, web belt to carry valve and fitter, and air hose with couplings. j A lightweight, yer long-wearing hood covers the head and shoulders of ) the operator and fastens to the waist, cushioning the impact of abrasives. The facepiece has a wide-viskm safety glass lens with a tilting screen cover of alloy stccL Both lens and screen are quickly removable and re placeable. The operator can immediately detach himself from the air- , line in the event of supply failure -- breathing through the filter on j rfce free end of the inhalation tube as he leaves the confined space. ! I I I SC 030825 M S A MIDGET IMPINGER A portable instrument for quick and dependable dtzsr sampling che Midget Irapingcr is cntrrdy sel&coatained and hand operated, yet weighs less than so lbs. T he Impinger samples at the rate o f i /io cu. ft. per minute, with pump main taining an unfluctuating suction regardless of minor variations in cranking rate. The apparatus is contained in a convenient carrying case, complete with nine Impinger flasks and nozzles. M'S-A Electrostatic DUST and FUME SAMPLER T his instraracnt provides highest precision in the quantitative sampling of dusts, fumes (in cluding metal fumes) and mist) -- utilizing the principle of pre ionization with electrostatic pre cipitation of air-borne particles apon a collecting cylinder, for determination by weight, count or chemical analysis. Accurate determination is enabled o f very low concentracin! o f atmos pheric particulate matter. *===3 - . D SC 030826 M-S-A D u st Counting MICROSCOPE This is an instrument low in cost, yet o f high grade workmanship and performance -- specialty equipped and adjusted for dust determination. The fine adjust ment is by micrometer screw; coarse adjustment is by diagonal rad: and pinion. Equipment in cludes bakelite stage with builtin mechanical stage; fork type substage divisible Abbe con denser, nosepiecc adapter, ro-X eyepiece fin e d . with Whipple disc, io-X objective, and other accessories. A special set of aux iliary laboratory dusf counting equipment is available. DUST COUNTING CELL A new cell for counting impinger samples, with an accurate depth o f 1 mm. Absence of comets makes cell easier to clean and prevents leaks and air bubbles. *** MINE SAFETY APPLIANCES BaADOOCX, THOMAS AHO MEADE STREETS P ittsbu rg h 8, P a . CO. IN CANADA MINE SAFETY APPLIANCES COMPANY OF CANADA, LTD. H eadquarters, T oronto, C anada 4*9 L>tbo to U.S A. SC 030827 SC 030828 Dusts and Fumes in Industry (Sources, Effects and Control) I n t r o d u c t o r y St a t e m e n t In dealing with occupational diseases and their effects, the attending physician should keep in mind that the etiology of these conditions is present in the industrial environment-- i f the conditions are to be considered truly industrial in origin. I t is likewise important to understand that rational diagnosis and treatment rests upon a fairly accurate knowledge o f the etiology o f the disturbances; this is especially true o f occupational diseases and allied disorders. Moreover, employers, industrial hygiene and medical depart ments are grcady interested in the prevention of various maladies which ordinarily affect employees; this clinical and economic interest on the part o f industrial management further emphasizes the need for understanding the' etiological factors in the working environment, so that they m ay be properly controlled. T h is booklet on' industrial dusts and fumes is the second o f a series o f which the purpose is to show the m ost important effects o f occupations, show how these occur, give measures for treatment, diagnosis, and prevention, meanwhile considering the source or cause o f such conditions. I t is hoped that these simple and brief expositions will be o f considerable help to industrial physicians, and to private practitioners who have among their patients employees o f industrial plants subject to such exposure. D efinitions Dusts m ay be defined as solid particles o f matter which are ordinarily produced by grinding, crushing, drilling or blasting I > SC 030829 Dusts and Fumes in Industry processes, the composition o f the particles being the same as that o f the parent materials. These materials m ay be rock, metals, ores, or such products, for example, as coal, grains, or wood. T he size o f the particles varies from what is called ultra^micro scopic to those which are visible. Authorities now agree that the hygienic significant particle size o f dust ranges from a fraction o f a micron to to microns. (A micron is 1/25,000 o f an inch). The most frequently encountered dusts in industrial processes are mainly those from inorganic minerals, and a few organic dusts, such as wood .and Hour. Fum es m ay be defined as solid parades which are formed b y processes similar to combustion, condensation and sublima tion..TJte most common types o f fumes encountered in industry are usually caused b y the oxidation o f a metal, o f winch typical examples are the oxides o f lead or zinc. Particle size is usually smaller than dust and ranges below one micron. In contrast to dusts, fumes tend to flocculate very easily. M a n y people erron eously speak o f fumes when they mean vapors o f liquid materials, such as ad d solutions, organic solvents, and the like. Incidence and E tio lo g y D usts are the most common type o f air contaminants en countered in industrial processes, and can occur whenever various' materials, as mentioned before, are subjected to processes which break them up into fine parades; or where powdered or pulver ized materials are handled or transported. Inorganic dusts are the prevailing type so far as frequency is concerned, b a t organic dusts are also found in different industrial operations. Fumes are usually found wherever there are molten metals such as lead, zinc, and caimium b o n g processed or used in indus trial operations. Welding is an operation which has gready in creased in frequency o f use and it may give rise to fumes o f the metals which are welded or to fumes and gases from the variegated coatings o f welding rods. . < 2> Incidence and Etiology I t is to be borne in mind that metals m ay produce both dusts and fumes, according to the nature o f the operation and the state o f the materials when processed. For example, among the heavy metals such as lead, dust m ay be o f equal or greater etiologic importance with fu m e -- other mineral dusts and metallic dusts also are considered o f etiological importance, as the following - outline will show: " I. Organic dusts: i . N ondiving organic du3ts: (a) Toxic and/or irritant dusts; " (Various organic compounds such as trinitrotoluene, mercury fulminate, tetryl)." (b) allergy-producing dusts (woods, pollens, and the like). 2. Living organic dusts: (a) bacteria (b) fongi . ' . II. Inorganic dusts: (mineral dusts) (a) toxic and/or irritant dusts; (mainly the dusts from heavy metals and their salts, such as arsenic, lead, manganese.) (b) fibrosis-producing dusts, (examples are free silica and asbestos). (c) non-fibrosis-producing dusts; (the so-called inert dusts, such as alundum, corundum, emery, lime stone, magnesite, marble, plastcr-of-paris, and polisher's rouge).* . 'j T h e most important o f the non-metallic, inorganic mineral dusts is free silica, which produces silicosis, i f breathed in sufH- c e n t quantities over a long period o f time. Free silica dust and T U i d u t& c a n m U I ccor&cc* -wtfc t U p te m t t t n t o f keowledcc. F o r a r a m ^ in u il x p a ja m *iD probably A w i b m of tW po-oHod low* M i n a f i u u b ia m b L <13 > . A mi , , - t -t o j k t y ju jjj* * .V M X H U U m M ^ -K V t*^ P R )W -.! w m 'S B tR - -iHVTH. I SC 030831 \ 1 I 1 l l \ \ \ I . i 5 n FJ < I Dusts and Fumes in Industry asbestos dust are the two kinds o f mineral dusts which produce disease entities corresponding to the names o f the dusts -- sili cosis and asbestosis. Mixed dusts o f various kinds, such as various ores which contain different amounts o f free silica, can produce different types o f reactions, according to the kind o f minerals which are in the ores. Where, for example, there are mixtures o f iron, and various calcium-contaimng compounds such as gypsum, with free silica, a protective influence is exerted against the action o f free silica on the lungs. Other modifications o f free silica action occur according to the types o f minerals present some o f which tend to inhibit or restrain the action o f free silica. Another important conception w ith reference to the etiology o f dust and fume diseases which m a y result from exposure to these cla s s o f materials, is the use o f the terms exposure and hazard: they are not synonymous -- exposure merely means contact w ith some substance which is a potential health hazard; whether i t is an actual health hazard can only be determined by an industrial hygiene engineering survey, in which the amount and kind o f exposure is rated, according to accepted standards o f concentration, size, and quality o f dusts and fumes. M a n y persons erroneously therefore state that there is a lead hazard, for example, when it is only known that contact is being made with lead; and when there are no data to support the contention th at there is an actual hazard present in the working environ ment. M ethods for the determination o f dusts and fumes in the air, also w ith reference to the types o f devices used for such determinations, will be mentioned later. T h e importance o f air contamination will be realized when it is stated th at the patho logic effects produced b y dusts and fumes are brought about almost entirely b y the inhalation o f these compounds and m a terials. There is on ly one outstanding example, for instance, o f the possibility o f absorption o f lead through the skin, nam ely tetraethyl lead, and this occurs in rite form o f a fluid. N o dusts, so .far as is .known, produce any systemic pathological oondi- SC 030832 General Diagnostic Methods dons from skin absorption, and it is doubtful that any kind of true fume is absorbed b y the skin. From the etiologic point o f view, particularly with reference to pathologic effects, the following outline shows how different types o f substances (among the dusts and fumes) act on various systems in the body to produce pathological effects: r. General systemic poisoning: Examples: Arsenic, lead, manganese, mercury. 2. Substances acting on the circulatory system: Examples: Arsenic, lead, mercury, vanadium. 3. Substances acting on the respiratory system: Examples: 'Asbestos, free silica. 4. Substances acting on the gastro-mtestinal system: Examples: Antim ony, cadmium, lead, mercury, zinc. f . Substances acting on the skeleton andjoin ts: Exam ples: Lead, mercury, mesothorium, phosphorus, radium. 6. Substances acting on organs o f special sense: Examples: Arsenic, lead, manganese, mercury. 7. Substances acting asfe ta l poisons: Examples: Lead, mercury. 8. Substances acting on the genito-urinary system: Examples: Arsenic, lead, mercury, vanadium. 9. Substances acting on the brain and nervous system: Examples: Arsenic, lead, manganese. G en eral D iagn ostic M ethods T h e accurate diagnosis o f pathological conditions arising from the inhalation o f industrial dusts and fumes has tremendous economic significance and also it is o f medicolegal importance. Moreover, it is impossible to understand how proper and effica- <5 $l> SC 030833 : ! i t . I [ ' 1 1< Dusts and Fumes in Industry ceous treatment m ay be rendered unless a scientific diagnosis is made. I f a claim results from the pathological condition alleged, it is evident that the disease sustained must be directly ; related to the employment and further, must produce disability I to entitle the individual concerned to compensation. Diagnostic methods with reference to dust and fume diseases need not differ widely, if at all, from those used as routine pro cedures in general scientific medicine, although there are specific methods as in any other application o f general medical diagnostic j principles to any special group o f persons. N ew discoveries occur relative to diagnostic methods in occupational disease work and - for the most part, reliance must be placed on information which is scattered throughout the current literature in addition to available textbook material which is better now than it w as even five years ago. Emphasis has already been placed upon the vital part played ; b y etiology; it is wise to repeat that etiology forms the bulwark o f the diagnostic and therapeutic background. Am ong the methods which are used to make a fairly accurate diagnosis with reference to occupational diseases, is the taking o f a thorough industrial history; consideration o f sym ptom atology, the physical findings, the results o f air examination; and finally, last but not least, a differential diagnosis, ruling ou t diseases of ordinary life which have no relation to occupation. T h e industrial history m ay be o f very great assistance in arriving at an opinion. M ost industrial physicians o f considerable experience believe th at it is desirable to indude a complete resume o f the kinds o f occupations which have been experienced b y the individual being examined, daring from the first jo b to the last one. I t is o f course d ear th at the details o f actual occupa tional exposure cannot be evaluated b y this method, b u t im portant information bearing an the diagnosis m ay thus be obtained. I t is the present practice, therefore, to list the occupa- ; tions with the dates o f occurrence, in the industrial history. I t is ; 1 < lfi> :! : ......................... SC 030834 General Diagnostic Methods furthermore advisable to get more detailed information relative. to the performance o f the occupation, if that can be obtained. T h is will at least give information relative to the kind o f exposure in industry, although it will give no idea o f the severity o f ex posure. T h e sym ptom atology in many kinds o f occupational disease is likely to be confusing rather than useful, because in many instances it so closely simulates that of non-industrial disease that it is quite commonly not characteristic. Especial attention should be given, however, to the recording o f the symptomatology and critical attempts made of its proper evaluation. H ere again, distinction must be made between symptoms which m ay be due to non-occupational disease and those symptoms which arespedfic for occupational diseases -- this is where the difficulty arises in adequately assessing symptomatology. T h e physical findings, on the whole, are more reliable than the sym ptom atology, although in certain instances they too are not characteristic and are, therefore, liable to be somewhat puzzling. Where only one portion o f the body is affected, as in silicosis, for example, it. might be assumed drat the physical findings would be more characteristic, but the opposite o f this is usually true. In other instances, for example lead poisoning, where different organs and systems are pathologically affected, die picture is liable to be one which demands expert evaluation to differentiate from non-occupational conditions. Clinical laboratory data, including X -ra y findings, are frequendy found to be derisive, although here again intelligent appraisal means proper interpretation o f the data. W hen they are decisive, such tests are b y the very specificity o f their nature, o f great value as diagnostic aids, although they should be defi nitely correlated w ith other findings. Differential diagnosis presents perhaps the m ost difficult problem o f all in die realm o f diagnosis o f occupational diseases. There is good reason to believe that differential diagnosis will < 7 > Dusts and Fum es in Industry continue to be one o f the most difficult phases o f the medical ramifications o f the medicolegal problems o f occupational dis eases. T h e reason which has already been indicated is that the sym ptom atology and frequently the physical findings .imitate so closely the sym ptom atology and physical findings o f non industrial diseases, that one must make use o f specific procedures which are designed especially as diagnostic guideposts. Frequently such specific procedures are not used to any great extent, except b y those who are highly specialized in the field and whose work takes them into a review o f the current literature containing these developments. For example, one m a y believe th at an industrial employee has lead poisoning, largely because o f second hand knowledge that lead was used in his occupation, more easily than one could demonstrate adequate etiology and the existence o f lead poisoning b y scientific methods. Because o f all of these obvious and other difficulties, it seems wise to adapt specifically certain examination procedures to industrial problems arising out o f occupational- or suspected occupational diseases. M o st authorities now agree th at the exam ining physician can be of greater service and give more effi cien t advice regarding either acceptability for employment, continuance in it, opinion on the diagnosis o f system ic pathologic conditions and the estimation o f disability, i f he is conversant w ith the following points: I. T h e nature and extent o f the industrial exposure into which the employee will go or where he has been. T his can be determined only b y scientific methods which will be referred to later. ' a. T h e effect o f this specific exposure upon normal and abnormal physical states o f employees, as interpreted b y die physical status o f each individual on examination. (This refers specifically to etiology in die industrial en vironment and the effects which such etiology m ay or could produce.) <J 8 > SC 030836 C lin ical Examples j . T h e nature o f the protective devices supplied b y the em ployer, If a hazardous exposure cannot be otherwise con trolled, and as to whether these devices are functioning efficiently. (Reference will be made later to these devices, . especially designed for protection against dust and fume exposures.) I t is realized that these procedures are somewhat removed from d ie usual program o f physical examinations, particularly with reference to the work o f part-time industrial physicians, but it is also expected that the physician will be called upon increas ingly to know and appreciate such information so th at he m ay function better as a diagnostic medium. Because the most frequent and most significant exposures in industrial processes ate free silica dust and lead and its com pounds, ic seems advisable to include in the next section some clinical examples, namely silicosis and lead poisoning; there will also be included a brief discussion o f metal fume fever. C lin ical E xam ples .Simply stated, silicosis is a disease o f the lungs, caused b y the continuous inhalation over a long period o f time o f very finely divided, microscopic, particles o f free silica dust. There have been various standards set up b y different agencies, based upon studies o f silicotic workmen and their exposure to fixe silica dust. T h e National Silicosis Conference Report an M edical Control o f Silicosis sayst " There is evidence that for prolonged exposure a concentration o f more than five million particles per cubic foot o f a highly siliceous dust is dangerous. Therefore, it is now con sidered good practice to hold concentrations o f highly siliceous dust at 5 million particles per cubic foot, or less." Because o f the fact that industrial exposures, involving high free silica content in which die concentration o f d u st should be restricted to five milfion partides per cubic foot, are relatively infrequent in industry, and also because the opposite usually 9 > SC 030837  *p.i-|S*+** S 9 I ' I i f i! i VI n N [i N i 1 Dusts and Fum es in Industry occurs (an exposure to ``mixed" dusts which contain appreciable amounts o f free silica but also contain considerable amounts of other types o f material) it is believed wise to refer to the formula* developed b y the N ation al Silicosis Conference w ith reference to a working criterion w ith respect to satisfactory or unsatisfactory conditions, when exposure to `mixed' dusts occurs. It is to be borne in mind, however, th at a n y unprotected industrial operation, which involves the production o f a lot o f fine dust particles of material containing a relatively large percentage o f free silica, offers a potential silicosis hazard. T he incidence o f silicosis is not known with any degree o f accuracy, although various estimates have been made. One of these made some rime ago b y the American Institute o f M ining and Metallurgical' Engineers indicated that in the United States the number o f industrial workers exposed to the silica dust hazard is in excess o f a h alf million. Figures quoted b y the Com mittee Reports o f the N ational Silicosis Conference disclosed estimates that approximately i % o f the working population of the United States or about one million workers are exposed in some w ay to the potential hazard o f silicosis, and that perhaps half o f this number, 500,000, or 1 % o f the total, are exposed to a serious hazard. I t is furthermore believed th a t approximately 110,000, or 0.2 o f 1 % o f the total, have silicosis to some degree, b u t likely only 4000 to 5000 (a small fraction 0/ x % o f the total) suffer an y degree o f disability from the disease. (These figures are based upon prewar estimates.) It can readily be seen th at silicosis, although not a rare disease, is not common and furthermore not as common as m ay ordinarily have been supposed b y many persons. R ecent conceptions with regard to the contraction o f silicosis have established the belief that approximately 2 5 % o f those t exposed to a real silica hazard will eventually develop silicosis. FORM(FLA A: "Multiply tbt pmcanit of rmoSta by the total Is caatt ITibt rtnU u tiade S otfliaa, ch*eoadttie aty it esiti^tnl ptrmssaiblo. If the iw h t** 5 oattlroft, tbe mi* it ouy bo mntlmd too For cvampU, 10 pr CDocsnasnonof SOmillion pasocle* porruble foot all cetu free diet c 0,10 aim* w h ivott rota! dtut JO mllbe, mk*cb equal* 1 mill (food ymtite): per mat wivfc an i w i h total du*e a fu 'w n of SOHim, w a ll cqn^j 0S dm 50or 15 miOioa (aanewfeetery). This formal i* trot applicabto any 4 oarcon* cowsnp lea* host 5 p e r ease fam u R ee," < to > " SC 030838 I C lin ical Exam ples , ' ' i . , j : | ` 1 | . | | / W ith respect to the occurrence o f silicosis in the foundry industry, a prewar survey b y the Division o f Industrial Hygiene o f the N ew York State Department o f Labor, based on a study o f 31 i foundries, o f which 80 plants included X -ra y examinations involving 4,754 employees, provides some interesting figures: the X -ray summary showed that 3,259 or 80.2% were negative; 185 or 4 .5 % showed fibrosis; 110 or 2 .7 % showed silicosis with and without infection; 485 or 1 1 .9 % showed heated primary and re infection types o f tuberculosis; 27 or 0 .0 7% showed clinically significant tuberculosis. I t w as concluded, as stated in the report, that it would appear that the silicosis hazard in the foundry industry in N ew York State, while existent, is o f mild degree o f severi t y and m ay be expected to yield satisfactorily to appropriate measures o f control. T h e report further indicated th a t tuber culosis as manifested b y X -r a y films o f the chest was found to be more prevalent am ong silicotics than among non-silicodcs in foundrymen. T h e occupational history, as previously indicated, is o f con siderable importance. Forms for the recording o f occupational records have been devised b y various organizations and groups and b y physicians and insurance companies. One o f the most complete and longer forms has been devised and used b y the Saranac Laboratory, Saranac Lake, N . Y ., in connection with silicosis studies and symposia on silicosis which have been held b y this group. I t is suggested that the physician, i f interested, should contact the industrial hygiene bureau o f his state health department through which detailed forms m ay be secured or information relative to them. T h e symptoms and physical signs are not charac teristic; they m ay be confused eves b y skilled diagnosticians in other diseases, w ith the symptoms and signs which com monly occur in both minor and the more serious types o f the well-known respiratory infections. Characteristically, shortness o f breath on exertion and decreased chest expansion frequently occur in advanced cases o f silicosis, bu t these findings must also be differentiated as < II > SC 030839 Dusts and Fum es in Industry to their casual relationships and their possible association with other diseases. T h e clinical confirmation o f the diagnosis o f silicosis rests mainly on the characteristic X -ray appearance of the chest. This shows the typical lesions o f silicosis, hyaline fibrous nodules which are scattered as opaque bodies throughout both lung fields, the density o f these nodnles being somewhat less than calcified bodies, bu t discrete in outline, all about the same size in the early stage (so-called millet-seed size) and evenly dis tributed throughout both lung fields. These nodules appear as the first indication o f siScosis, later become somewhat confluent and in the latter stages, there are large masses o f opaque material found near the periphery o f the lung fields. In the later stages of silicosis, the disease is frequently complicated b y infection, usually tuberculous in nature. As an aid to interpretation o f the X -r a y films o f die chest where silicosis may be suspected, it is suggested that the physician refer to a tabulation o f the X -r a y changes in silicosis, with the underlying histological conditions which cause them, published in the transcript o f the Second Silicosis Symposium, Saranac Lake, N . Y ., 1935. Diagnosis rests upon proof o f occupational dust exposure sufficient to produce the disease, and the presence o f character istic nodular lesions m the X -r a y film o f the chest. T h e mere mention o f occupation is not sufficient for diagnostic purposes -- adequate knowledge concerning the q u ality and quantity o f dust exposure, as wed as the length o f the employment period, is necessary to establish a distinct causal relationship. Although considerable diagnostic reliance is usually and properly placed upon the history o f adequate occupational dust exposure and the characteristic chest X -ra y appearance, a thor ough physical examination w ith appropriate clinical laboratory examinations should be done, especially with reference to the ruling out o f other respiratory diseases. Diagnosis becomes essentially a differential diagnosis, as before explained, one which is likely to be difficult, necessitating special experience C lin ical Examples and knowledge. Some o f the conditions requiring differential consideration here are miliary tuberculosis, multiple calcifications o f healed tuberculosis, cancer o f the lungs, and fungous growths o f the lungs. W ithin recent years, superimposed infection has come to be die accepted cause far disability. T he outlook in simple silicosis, therefore, (that is, without infection) is more favorable than was formerly believed. I t is obvious that the chief problem for the silicotic is to avoid superimposed infection, which is usually tuberculous. There is no one specific, efficacious treatment for silicosis, although in recent years, the inhalation o f metallic aluminum powder has shown some promise. In cases where tuberculosis complicates the picture, it is obviously to be treated by the best known methods for that disease. There is some recent evidence that surgical therapy as used in ordinary forms o f tuberculosis is also a help in the type o f tuberculosis which follows silicosis. T he evidence for this is not conclusive, bu t there are good results on record. . In genera], recommendations for the treatment o f cases o f silicosis vary w ith experience and with the findings o f each case. I t is believed, for example, that no treatment is necessary in the case o f an individual without symptoms, whose X -r a y film o f the chest (taken perhaps in a routine industrial survey) shows only widespread discrete nodularion without localized shadows indi cating infection. However, the employee should have serial X -ray examinations w ith physical examinations o f the chest at least once a year and should be removed from further silica exposure to some other jo b , on ce the disease is very slowly progressive and there is a t this stage no disability which precludes continua tion in employment. A person with localized conglomerare lesions m ay have symptoms and usually cannot do as heavy work as formerly; therefore, a lighter jo b should be found. In the presence o f active infection where there are symptoms or incapacitation, the individual cannot obviously continue in his Dusts and Fumes in Industry former employment. I f the case is one o f open tuberculosis w ith ' positive sputum, it is evident that such an employee is a source o f danger to his fellow workmen and should be placed in a sani tarium or hospital. In cases o f inactive infection with no incapaci tation, lighter work should be provided, without further dust exposure. Dusts containing silica in combined form do not cause silicosis; ' however, one such dust, asbestos, a magnesium silicate, will produce a characteristic fibrosis which is called asbestosis. This disease is quite different in its pathology from silicosis, and has a characteristic `ground-glass' appearance on die X -ray films o f dm chest. Animal experimentation indicates th at the action o f asbestos is probably mechanical, since it cannot be produced in . other than the pulmonary tissue. Asbestosis m ay cause disability and a few fatal cases have been recorded, but in those cases show ing marked disability, other organic disease is usually also present. T he symptomatology and physical findings include cough, dyspnea, pallor, clubbing of fingers, and diminished chest expansion, with a characteristic X -ra y appearance as previously mendoned. . Lead Poisoning Lead poisoning offers a good example of an industrial poisoning which contracted by the inhalation either o f a toxic dust or fume, and has been stated to be one o f the most frequent and important types o f metallic poisoning in industry, on account o f the wide spread use o f lead and its compounds. Although there are no reliable statistics available with respect to the national incidence o f lead poisoning, it is believed that lead poisoning is very prevalent and that most o f i t is mild. T h e incidence o f severe types o f cases, particularly lead encephalo pathy and the more severe types o f nervous system involvement are not seen with as great frequency as in former years. M a n y physicians who are used to handling industrial cases now rarely see a case o f wrist drop due to lead poisoning, whereas 20 to 25 years ago it was a rather common phenomenon, in cases o f lead intoxication. 3 14 > i SC 030842 I C lin ical Examples T h e industrial history is o f great importance, as previously indicated, and a thorough consideration o f the nature and extent o f the exposure to lead and its compounds is an essential point in the etiology. I t is now generally accepted that the standard o f the U . S. Public Health Service and the American Standards Association o f 1.5 milligrams o f lead per ten cubic meters o f air, is the maximum allowable concentration. Because it is now con ceded that practically all industrial lead poisoning is contracted b y the breathing o f lead dust and fumes, it becomes o f con siderable importance in working out the etiology to ascertain the amount and quality o f lead dust and fumes in the air, during die occupation o f the involved individual. This point w3 i be dis cussed later with reference to prevention. Formerly, the nature and variety o f non-industrial sources o f lead intake made it particularly difficult to establish industrial etiology on a sound and competent basis. More recently, how ever, non-industrial lead intake has been measured b y scientific methods and with the exception o f an occasional difficulty with . various types o f homemade beverages stored in utensils glazed with a lead compound, the non-industrial lead intake is not believed to be a considerable factor in the production o f lead poisoning in adults. There are, however, some exceptions and these should he taken into account, as indicated. T h e diagnosis o f industrial lead poisoning is not a am ple m atter on account o f the fa ct th at clinical symptoms and signs are protean and are liable therefore to simulate other diseases. G reat increase in our knowledge, however, has occurred within the past ten to fifteen years, and it is now known that there is a d ose relationship between the action o f lead and its compound s within the body and the calcium metabolism, and further, normal and abnormal excretion o f lead has been worked ou t on a scientific basis- I t is now an accepted fact that persons without industrial exposure normally excrete a certain amount o f lead in the urine. I t has been stated that definite clinical findings o f lead poisoning are practically always associated with abnormal urinary lead < ij > SC 030843 Dusts and Fumes in Industry ceredon -- the reverse, however, is not true -- that abnormal urinary excretion o f lead in the absence o f characteristic clinical findings indicates lead poisoning. ' Other laboratory findings are important, particularly the examination o f the blood, some investigators and clinicians using the increase i s basophilic srippled red cells as an indication o f positive findings and others using w hat is known as the basophilic aggregation test. Both are found to be successful, the former more adaptable in cases o f frank poisoning, the latter more useful is cases o f lead absorption and suspected incipient poisoning. ' Although as indicated, the clinical symptoms and signs o f lead poisoning are protean, the principal effects are expressed in the blood, the gastrointestinal system, and the nervous system , named in order o f their usual chronological occurrence. In brief, the m ost consistent findings are changes in the ctdor and form o f the red cells o f the blood, colic and constipation, and weakness and atrophy o f the extensors and flexors of the muscles o f the wrists, with partial paralysis in the more advanced types o f cases. T h e'differen tial diagnosis,' as m ay be obvious, has to do mainly with differentiating industrial lead poisoning from non industrial diseases which m ay involve the blood, the gastro in testinal system , and the central and peripheral nervous systems, producing changes which are similar to those observed in frank lead poisoning. Such non-industrial diseases show a considerable variety o f pathological processes affecting the above-named systems. T h e treatment o f lead poisoning has undergone considerable change within the past ten to fifteen years. In general, the treat ment consists mainly o f appropriate therapy for the toxic episodes and the mobilization o f stored lead in the long bones. I t is usually agreed th a t it is wise to facilitate the storage o f lead b y an excess calcium intake rather than to set lead free in the blood stream; after the passihg o f acute toxic episodes, the elimination o f lead m ay be assisted b y means o f low calcium intake, the administra- < 16 > 1 Clinical Examples Don o f w eak organic ad d s and ammonium salts, sodium bicarho- n a n , and potassium iodide. Care should be exercised in using such forms o f treatment on patients who have nephritis. T w o schools o f thought with widely divergent views exist with reference to deleading the body: there are those who feel that in the m ajority o f instances deleading will accomplish good results, while there are others who adopt a conservative attitude and because o f the possibility o f predpitaring acute symptoms, feel that it is safer to produce artificial deleading b y slow methods, or to resort to the natural process o f letting the bod y delead itself over a period o f time. T h e choice in the m atter depends upon the individual case and the previous results which have been achieved at the hands o f the physidan in chaige o f the case. Storage o f lead m a y be facilitated in acuta cases b y a high calcium diet or b y the slow intravenous injection o f 10 cc o f 2 0 % calcium gluconate; variations w ith relationship to this form o f treatment have been devised b y various physicians. In the delead in g process, low calcium diet together with oral administration o f ammonium chloride has been found to be effective, whereas in certain cases parathyroid extract and sodium bicarbonate also have been useful. W ithin recent years it has been established that large doses o f viosterol have been instrumental in increasing the excretion o f lead. O ther investigators have found that an adequate phosphorus intake is essential for the depositing o f lead in the bones and for the removal from the bones o f the excess cations, as the insoluble phosphate salts in the feces; it has therefore been recommended that deleading m ay be accomplished b y giving a diet low in calcium and relatively high in phosphorus, using viosterol 20 minims daily. ' There are also variations o f treatment with reference to die amount o f intoxication, and where there has been high, medium or low lead intake in industrial occupations. In all these types o f treatment, deleading should be done in the hospital where the patient m ay be- closely supervised. Some investigators advise 4 I7 > - : . ' ' SC 030845 ... ri 1 II I l ' I f i : i * l! li ' \ ! ft li H Dusts and Fumes in Industry against deleading more often than once in four weeks and the course should not be prolonged for more than three or four cl^ys; some physicians believe that it m ay take from sax to fifteen courses o f deleading to free the individual o f his most looselycombined lead, which o f course is the most dangerous type of lead. I t is again warned that deleading should not be undertaken in the presence o f acute symptoms; it Is further agreed by all in vestigators that calcium therapy is considered to be the most specific at the present time. T h e outlook in cases o f lead poisoning is much better now than formerly because o f the occurrence o f moderate types of effects, the severer forms being a great deal less frequent than in former years. M etal Fum e Freer T h is name is applied to the condition which results from breathing fairly heavy concentrations o f freshly formed metallic oxide fumes, principally zinc and one o f its alloys, brass; although the condition m ay result from the inhalation o f other metallic oxide fumes. M etal fume fever is not a systemic poisoning, but it should be borne in mind that some o f the metallic fumes that can cause it, such as lead, cadmium, mercury, and manganese, m a y also cause systemic poisoning. T h e symptoms come on some hours after exposure, usually after leaving work, a dryness o f the throat being first noticed, which m ay be followed b y a d ry cough and a feeling o f heaviness in the chest. Rise o f temperature, accompanied b y sweating, and leucocy tnsis and elevation o f the pulse rate and the blood pressure usually follow, sometimes w ith chills. T h e symptoms ordinarily pass off in ia to 24 hours and the usual experience is th at the employee returns to work the following day; A natural im munity is conferred in certain types o f workers, which seems to be lost rapidly after removal from continuous exposure. Diagnosis is m ade usually on a d ear history o f industrial exposure to metallic oxide fumes. I t m ust be remembered that < 18 > SC 030846 I i i Other Dusts and Fum es the effects and sym ptom s o f metal fume fever are very similar to those' o f influenza, and that the malady is more often noticed in the fall and winter, when influenza usually occurs. T h e in dustrial history is, therefore, important in diagnosis, particularly with reference to a causative exposure to metallic oxide fumes. T h e outlook is good for complete recovery in a short time and usually there is no rime lost from work, although there m ay be temporary incapacity in terms o f hours. The treatment is symptomatic and especially directed w a rd comfort because the patient usually recovers within a relatively short rime in all events. Rest in bed with adequate warmth and protection from drafts are recommended. However, all suspected cases o f metal fume fever should be attended b y a physician because the sym ptom s m ay closely simulate influenza which makes the differential diagnosis important. O t h e r D usts and F umes I t must not be concluded that although clinical examplea were given o f silicosis, lead poisoning, and metal fume fever, there are not other examples which are o f importance. These subjects were selected because o f their frequency o f occurrence and because o f the fact that th ey are commonly encountered as examples o f dust alone, dust and fumes, and fumes. ' Among the other metals which m ay be mentioned are arsenic, antimony, cadmium, manganese, mercury, radium, selenium, silver, tellurium, thallium, and vanadium. N o t all o f these are equally important w ith reference to toxic effects. Probably the m ost important o f these from a to n e point o f view are arsenic, mercury, manganese, and cadmium. Arsenic pro duces chronic poisoning chiefly from breathing overa longperiod o f dun air containing dusts, or sprays o f arsenic compounds. T h e compounds o f arsenic arch as lead arsenate, paris-green, arsenic oxide and arsenic sulphide are among the more dangerous forms. <3 19 > SC 030847 1 --------- I 1 i I a ` Dusts and Fumes in Industry Where dusts o f mercury are present, they "will be in the form o f either mercurous or mercuric compounds, where metallic mercury is used in the manufacture o f such items as thermometers, mercury switches, mercury vapor lamps, mercury boilers, etc., the hazard is from the vapor since mercury has a considerable vapor pressure even ac normal temperatures. Mercurialism is characterized b y three features: inflammation o f the mouth, muscular tremors, and psychic irritability-- sometimes all o f these are encountered and sometimes only two or only one. In the more chronic or slow form o f poisoning, a characteristic tremor is the commonest symptom, coming on late, and has been noted to occur particularly among mercury miners. Manganese poisoning is an old industrial poisoning, having been described more than io o years ago, bu t has receded in incidence in American industry. Characteristically it produces a peculiar slapping gait with phenomena o f retropulsion and pro* pulsion; masklike faces; monotonous voice w ith economical speech; muscular twitching varying from a fine tremor to gross rhythmical movements o f die extremities; languor and sleepiness; cramps in die calves o f the legs with stiffness; slight increase in the tendon reflexes without an y disturbance o f the deep or super ficial sensation. Studies within the past five years indicate that dust is the most important type o f exposure. Cadm ium is encountered in the smelting o f ores, the handling o f socalled ` blue powder* compounds, the spraying o f pigments, the welding o f alloys, and the melting of cadmium metal itself, as well as certain non-industrial exposures where utensils have .been plated with this meeaL In recent years there have been several outbreaks o f cadmium poisoning among non-industrial users o f such utensils. T h e use o f die metal has increased tremen dously and therefore, there is more industrial exposure. T w o types o f effects have been observed, those w ith reference to the lungs and also those with reference to the gastrointestinal tract, the former being more important and more frequent. Pulmonary involvement is characterized by a feeling o f constriction in the <i zo > SC 030848 Pretention chest, edema and congestion o f the hings, sometimes with hemorrhage, proliferative interstitial pneumonitis; while the latter is characterized b y nausea and vom iting and a general irritative reaction o f the gastro-intestinal tract, with diarrhea, hiccough, and oliguria. I f further details are desired on the clinical aspects o f the metals mentioned, standard works on industrial hygiene and occupational diseases should be consulted. P revention T h e general principles o f prevention involve first the identi fication o f industrial exposures and the evaluation o f such ex posures b y proper scientific methods to determine whether or not they represent actual health hazards. T h is is done b y sampling the air and determining the amount o f air contaminants and the quality o f them in each type o f occupation or problem involved, and comparing the results with the accepted standards o f maxi mum allowable concentration th at have been adopted b y official i bodies. Second, after it has been determined that there is an actual health hazard represented b y the occupation, control measures, both engineering and medical, are instituted to control the hazard, providing it cannot be entirely eliminated. In discussing the methods o f engineering control, w e are con cerned w ith three basic principles: 1. Investigation o f occupational conditions. 2. T h e measurement o f the occupational exposure and the racing o f the hazard, if one exists. 3. P u ttin g into effect the specific measures o f protection which have been indicated b y information secured under (1) and (2). Am ong the methods o f approach for engineering control -measures m ay be mentioned: 1. Physical and hygienic survey o f plant conditions. < 21 O SC 030849 *1 Dusts and Fumes in Industry ci 2. Occupational history and analysis. 3. Adequate information concerning materials and processes used. 4. A t mospheric and gross sampling o f materials, combined with quantitative physical and chemical determinations. 5. T h e rating o f the hazard b y comparing the findings in the given instance with accepted standards. 6. A n appraisal o f the efficiency o f protective apparatus and devices. 7. A n adequate and proper interpretation o f the information so that it can be applied practically to the industriai problem involved. When the foregoing methods o f approach to engineering control have been carried out and information secured from them, the information can indicate the necessity for using specific methods o f protection which have been found useful in different combinations: 1. T h e use o f mechanical devices, such as exhaust ventilating systems, respirators, masks, and the like. 2. T h e changing o f processes (segregation, enclosure, wetting, etc.). 3. Substitution of nontoxic materials for those o f proved toxicity. 4. Educational programs for management, workers, engineers, and physicians. 5. Continuous maintenance and checking o f the efficiency o f protective equipment. A tm o sph eric Sa m plin g T h e best method for collecting a sample o f a du st or fume from the air will depend somewhat upon the type o f contaminants to be sampled. T h e degree o f hazard o f fibrosis-producing dusts is measured in terms o f particles per unit volume o f air (example: < 22 > I Atmospheric Sam pling 10 million particles o f silica dust per cubic foot o f air) while tome dusts and fumes which m ay cause systemic poisoning are usually measured in terms o f weight per unit volume o f air. (Example: lead d u st 1.5 milligrams per 10 cubic meters o f air.) Since results m ay va r y with the typ e o f air sampling device used, it is im portant to select a ty p e accepted through genera] usage in the practice o f industrial hygiene. T h e larger Impinger which samples one cubic foot o f air per minute b y impinging the air containing the dust particles from a nozzle submerged in water or alcohol against a plate or bottom o f the flask w as used in all o f the original studies in the United States on fibrosis-producing dusts. T h e large Impinger, however, has the disadvantage, o f being b a lk y and requiring electric current or compressed air for operation o f the motor-driven air pump, which produces rite suction stream for air sampling. A portable M id get Impinger has been developed which has been proven to give results as reliable as the large Impinger. T h is apparatus samples a t the rate o f i/ io th o f a cubic foot per minute and is operated b y a hand cranked, positive action, four cylinder pump, in conjunction with a vacuum regulator which . maintains an unfluctuating suction regardless o f minor variations in rate or smoothness o f cranking. A fter the sample has been collected in the Impinger* flask, a portion is placed in a special dust counting cell and counted under a microscope w ith an eyepiece having a special ruling similar to a blood count ruling. Further analyses are necessary w ith reference to the amount o f free silica in th e d u st and this is accomplished-by the use o f specific chemical, petrographic .and X -r a y diffraction methods. H ie Im pinger method o f sampling is not entirely suitable for collecting fumes or dusts o f toxic materials such as lead, cadmium, and others because the efficiency o f the Impinger is not adequate when sampling the very fine fume particles and since the amount <323 > SC 030851 Dusts and Fumes in industry or concentration o f such materials in air which m ay be injurious is much smaller than the safe amounts o f fibrosis-producing dusts, a correspondingly large air sample should be taken for reliable results. T h e Electrostatic Precipitator is widely used in the co lla tio n o f toxic dusts and fumes, particularly o f metals and their com pounds. A Portable Electrostatic Precipitator has been developed which operates from n o volts, 60 cycle current, and b y high voltage electrical precipitation collects the sample o f the particu late matter dry on the inside o f aluminum or glass cylinders. This device samples at the rate o f i cubic feet per minute. A fter the sample is collected, a quantitative chemical analysis is made in the laboratory. This type o f apparatus permits determinations o f very low concentrations o f many different kinds o f atmospheric particulate matter. Where equipment or personnel is not available for atmospheric . i sampling, state industrial hygiene bureaus or private testing laboratories m ay be engaged. M a n y insurance companies also have facilities for such work. T h e Industrial Hygiene Foundation in Pittsburgh, Pa., an association o f industries for the advance ment o f healthful working conditions, also have an excellent staff o f technicians for industrial hygiene surveys or consultations in this field. R espiratory P r o tectiv e E quipm ent le frequently happens that because o f tbe nature o f the operation or process in an industry, i t is not possible to thoroughly control a hazardous exposure resulting from the evolution o f dusts and fumes. In such instances, it is considered wise to pro vide employees with personal respiratory protective devices. These vary with the kind o f exposure and with the amount o f materials in the air. For ordinary condirions in which only dusts and fumes are present, simple filter type respirators are available which will !? <3 24 > I SC 030852 Respiratory Protective Equipment protect the worker against the hazards o f breathing these dusts and fumes. Such respirators normally consist o f a facepiece covering the nose and mouth, made o f some pliable material such as rubber which, will conform to the face and provide a comfortable and dust-dght fit, and to which is attached a filter made o f treated paper or felt through which the air is inhaled. I f the filtering material is o f the correct typ e and density, it will effectively filter particles down to less than a micron in size from the air. Comfort is a most important consideration in a device o f this type. Since a high breathing resistance will materially affect the comfort o f the wearer, the filters should be o f large area so that the inhalation resistance will be as low as possible. Valves should be provided which open on exhalation and further lessen the exhalation breathing resistance. T h e particular type o f filter employed will depend upon the kin d o f contaminant present in the air. Since the amounts o f such toxic materials as lead which will affect the wearer are much smaller than the harmful amounts o f fibrosis-producing dusts, a filter will have to be more effective when used against toxic dusts than against fibrosis-produdng and nuisance dusts. For special operations such as sandblasting, a mechanical filter type respirator is not practical because o f the extremely high concentrations o f dusts present. In such conditions, special airsupplied masks or respirators should be used in which air from a compressed air line is supplied through a hose to the facepiece for breathing. Such devices m ay also be employed if desired as protection in less severe and hazardous operations. T h e advantage o f an air-supplied respirator is that there is no breathing resistance and the wearer is protected against a n y and all dusts and fumes in the surrounding atmosphere. However, the restriction b y the air hose which must be attached to the wearer a t all times be tween his facepiece and the air supply, prevents the use o f this device in m any operations where the worker must m ove freely  i . i i ! ! 1 Dusts and Fumas in Industry over a considerable area. Furthermore, caution m ust be taken : to see that the air supplied to such devices is free from all in - \ jurious or objectionable odors and contaminants and that the i humidity and temperature o f the air is such as to provide reason- . able comfort. j T h e United S tates. Bureau o f Mines (Department o f the Interior) tests respiratory protective devices against various air contaminants under carefully controlled conditions. Devices j meeting its tests receive that Bureau's official approval, and this , is indicated b y approval numbers on the device and a reproduction o f the certificate on the package. Equipment approved b y die U . S. Bureau o f Mines for the particular contaminant or class o f contaminants in the air should be used. M EDICAL CONTROL I t is o f course obvious that medical control measures are futile after a disease has been contracted because o f the exposure to dusts or fumes except when the information is adapted to prevent additional cases. However, before the diseases are contracted, there are a number o f things that can be done b y physicians to prevent such occupational diseases, which m ay be summarized as follows: i . T h e intelligent use o f preemployment physical examina tions, including chest X -ray films, and appropriate clinical laboratory tests as indicated. a. Similar use o f periodic physical examinations, chest X -ray films, and clinical laboratory tests on employees in occu pations where typical hazards have been proved to exist, b y industrial hygiene investigations. 3. Responsibility for seeing that hazardous exposures are properly taken care of, b y various efficient methods o f protection, including the supplying o f personal respiratory protection, where industrial conditions m ake it impossible to control the hazard by other means. < z6 t> SC 030854  f 1 . --l I M edical Control 4 . Prom pt transference to non-hazardous occupations o f employees found to have symptoms o f an occupational disease associated w ith their exposure. j . Prompt removal from work o f all persons suffering from active occupational diseases, when such persons are a menace themselves, their fellow workmen or the em ployer. 6. Adequate provision for treatment, rehabilitation, and prom pt return to work, o f employees having disability resulting from occupational diseases. Su m m ary In this brief discussion o f dusts and femes in industry, the sources, effects, and control have been considered under the following headings: - 1. Definitions. 2. Incidence and etiology. 3. General diagnostic methods. I - _ 4 . Clinical examples. _ 5. Prevention -- general principles, including specific methods o f air sampling and apparatus fer this purpose; specific methods o f protection, including mention o f respiratory protective equipment available; and other general methods. I t should again be emphasized th at industrial managers are interested in die prevention o f trouble that m ay arise from exposure to dusts and femes in industry, and that this principle is particularly important nowadays because o f the need for every person in active production, and in addition, because so m any physicians are being used in the armed services. I t is believed th a t i f the suggestions made in the foregoing pages are followed, the problems arising from dusts and femes in industry can be successfully managed. I < 2 7 1> l ! SC 030855 3 1 M .S .A . . . . and In d u s t r y Throughout the many types of American Industry ore die products of this Company -- the largest commercial manufacturer o f approved safety equip mentjn the world today. In 1914, Mine Safety Appliances Company was formed (as its name would Indicate), to serve the mining industry. Today, the Company has fir outgrown its original field, to include the design and manufacture of approved safety equipment for every major industry and die public protective serv ices. The Company's program is founded squarely upon Research -- research which is concerned with all industrial hazards to the life and safety o f the worker, conducted in M.Sj L '8 extensive laboratories, by scientists o f national reputation. Laboratories for chemical research, dost research, and experimental research join with the engineering departments in translating safety require ments o f industry into equipment meeting the highest demands o f efficiency, comfort, and practicality. An important adjunct o f M S .A . Research is its nation-wide network ot field representatives, attached to M-S.A. district offices in approximately 50 principal dries. In intimate contact with industrial health and safety problems, these trained men work in effective liaison with industry and M.S.A. A dose contact is maintained with the many official bureaus and agendes devoted to furthering the cause o f industrial safety. . The broad institutional work of M .S.A--- erampler!, in small part, by das particular publication -- is undertaken with the fullest sense of responsibility. Mine Safety Appliances Company H A S S O C K , THOMAS ANO M U S E STXEETS PlTTSSOSGH (II), P U B T O T A S U <1 28 > r i t n a la O A A . i SC 030856 ZS80S0 OS a f/jP y ri? ' * t,/ C # s 7 M-S-A,' ; a n d I n d u s t r y - ... ,r.: v" t'- *-. T h roughout the many types o f American Industry are rite products o f :, this.Company-- the largest commercial.manufacturer o f approved'safety*: . '.yi'equipm ent ur th e world, today. Jo 1914, M ine Safety Appliances C om p an y.^ .' ' * : Was- formed/(asr its name w ould indicate) to serve the mining industry: 1 .' '"iTodayv the'.Company has- fa r outgrown, its original, field*. rt> in d u d e .th e '; .*' '.' ' ` ' design and' manufacture, o f approved safety equipment fo r every m ajor . I 7 ` "ndiutiy acid R e p u b lic p ro te ctiv e se rv ia i.v ^ ;^ -' - .' 7 yi'. } ` T fie Company's program is founded squarely upon Research-- research . ^which s concerned with all industrial hazards to the life and-safety o f the-',. .' / '4 ` worktri'.conducted. in sM SA 's exrensive' laboratories, b y -sd e n tis o o.". j { ' ' national reputation. Laboratories for chemical research dust research, and ' ` . experimental research join with che engineering departments in translating . - '.' s a fe t y requirements-of Industry. into equipment m eeting'the highest de-':"-.' - ; maods o f efficiency, comfort, and practicality. ' . ... 7 ' . -A it im portant adjunct of. M S A Research- is its nation-wide network o f . , ' field representatives, attached to M S A district offices in approximately 76 ^ ', principal,'dries-. In. intimate contact w ith industrial health aod safety 7 problems, H-- . trained men. w ork in effective- liaison w ith industry and - ' M -S-A. A i d o s e contact is. m ain tain ed'w iththe many official bureaus and ; ;,\ .'-` agendes-devoted t o furthering th e cause b f'industrial safe^ .*. 7 \y--L A i . ' The broad insricurianal work o f M SA-- exampled, in small part, by this PublisbttL By M INE SAFETY APPLIANCES CO M PAN Y 201 N o rth Brad dock A venue ' Pittsburgh 8, Pennsylvania C opyright 19J7 SC 030858 stss^B essessB ^ Dusts and Fumes in Industry (Sources, Effects and Control) I n t r o d u c t o r y St a t e m e n t In dealing with occupational diseases and their effects, the attending physician should keep in mind that the etiology of these conditions is present in the industrial environm ent-- if the conditions are to' be considered truly industrial in origin. I t is likewise important to understand that rational diagnosis and treatment rests upon a fairly accurate knowledge o f the etiology o f the disturbances; this is especially true o f occupational ' diseases and allied disorders. Moreover, employers, industrial hygiene and medical depart ments are greatly interested in the prevention o f various maladies * which ordinarily affecc employees; this clinical and economic interest on the part o f industrial management further emphasizes the need for understanding die etiological factors in the working environment, so that they may be properly controlled. T h is booklet on industrial dusts and fumes is the second of a series o f which the purpose is to show the most important effects o f occupations, show how these occur, give measures for treatment, diagnosis, and prevention, meanwhile considering the source or cause o f such conditions. It is hoped that these simple and brief expositions will be o f considerable help to industrial physicians, and to private practitioners who have among their patients employees o f industrial plants subject to such exposure. D efinitions Dusts m ay be defined as solid particles o f m atter which are ordinarily produced by grinding, crushing, drilling or blasting 1 SC 030859 Dusts and Fumes in Industry processes, the composition of the particles being the same as that o f the parent materials. These materials m ay be rock, metals, ores, or such products, for example, as coal, grains, or wood. Tire size of the particles varies from w hat is .called ultra-micro scopic to those which are visible. Authorities now agree that the hygienic significant particle size o f dust ranges from a fraction of a micron to 10 microns. (A micron is 1/25,000 o f an inch). T he most frequently encountered dusts in industrial processes are mainly those from inorganic minerals, and a few organic dusts, such as wood and flour. Fumes may be defined as solid particles which are formed by processes similar to combustion, condensation and sublima tion. The most common types o f fumes encountered in industry are usually caused b y the oxidation o f a metal, o f which typical examples are the oxides o f lead or zinc. Particle size is usually smaller than dust and ranges below one micron. In contrast to dusts, fumes tend to flocculate very easily. M any people erron eously speak of fumes when they mean vapors o f liquid materials, such as acid solutions, organic solvents, and the like. Incidence and Etiology Dusts are the most common type o f air contaminants en countered in industrial processes, and can occur whenever various materials, as mentioned before, are subjected to processes which break them up into fine particles; or where powdered or pulver ized materials are handled or transported. Inorganic dusts are the prevailing type so far as frequency is concerned, but organic dusts are also found in different industrial operations. Fumes are usually found wherever there are molten metals such as lead, zinc, and calmium being processed or used in indus trial operations. Welding is an operation which has greatly in creased in frequency o f use and it may give rise to fumes of the metals which are welded or to fumes and gases from the variegated coatings o f welding rods. Incidence and Etiology It is to be borne in mind that metals may produce both dusts and lames, according to the nature o f the operation and the state of the materials when processed. For example, among the heavy metals such as lead, dust may be of equal or greater etiologic importance with fumes -- other mineral dusts and metallic dusts also are considered o f etiological importance, as the following outline will show: ' I. Organic dusts: - 1. N on-living organic dusts: (a) Toxic and/or irritant dusts; " (Various organic compounds such as trinitrotoluene, mercury ful minate, tetryl)." (b) allergy-producing dusts (woods, pollens, and the like). 2. Living organic dusts: (a) bacteria (b) fungi I I . Inorganic dusts: (mineral dusts) (a) toxic and/or irritant dusts; (mainly the dusts from heavy metals and their salts, such as arsenic, lead, manganese.) (b) fibrosis-producing dusts, (examples are free silica and asbestos). (c) non-fibrosis-producing dusts; (the so-called inert dusts, such as nlundum, corundum, emery, lime stone, magnesite, marble, plaster-of-paris, and polisher's rouge).* T h e most important of the non-metallic, inorganic mineral dusts is free silica, which produces silicosis, if breathed in suffi cient quantities over a long period o f time. Free silica dust and * T W d u i i f i c y t B a 4 te K<eordar*cv w tth riw p r t i e n t tie r o f k n o w led c c. Kotor od r s p e n e n c i will p ro b a b ly show i o t s r o f th e io><*Qd i n or a u u t c e 4ot* to h e harm faL 3 V SC 030861 Dusts and Fumes in Industry asbestos dust are the two kinds of mineral dusts which produce disease entities corresponding to the names o f the dusts -- sili cosis and asbestosis. Mixed dusts of various kinds, such as various ores which contain different amounts of free silica, can produce different types of reactions, according to the kind o f minerals which are in the ores. Where, for example, there are mixtures of iron, and various calcium-containing compounds such as gypsum, with free silica, a protective influence is exerted against the action o f free silica on the lungs. Other modifications o f free silica action occur according to the types o f minerals present some o f which tend to inhibit or restrain the action of free silica. Another important conception with reference to the etiology o f dust and fume diseases which may result from exposure to these classes of materials, is the use o f the terms exposure and hazard; they are not synonymous -- exposure merely means contact with some substance which is a potential health hazard', whether it is an actual health hazard can only be determined by an industrial hygiene engineering survey, in which the amount and kind o f exposure is rated, according to accepted standards o f concentration, size, and quality o f dusts and fumes. Many persons erroneously therefore state that there is a lead hazard, for example, when it is only known that contact is being made with lead-, and when there are no data to support the contention that there is an actual hazard present in the working environ ment. Methods for the determination o f dusts and fumes in the air, also with reference to the types o f devices used for such determinations, will be mentioned later. T h e importance of air contamination will be realized when it is stated that the patho logic effects produced b y dusts and fumes are brought about almost entirely by the inhalation of these compounds and ma terials. There is only one outstanding example, for instance, o f the possibility o f absorption of lead through the skin, namely tetraethyl lead, and this occurs in the form of a fluid. N o dusts, so far as is known, produce any systemic pathological condi- i General Diagnostic Methods tions from skin absorption, and it is doubtful that any kind of true fume is absorbed by the skin. From the tiologie point o f view, particularly with reference to pathologic effects, the following outline shows how different types o f substances (among the dusts and fumes) act on various systems in the body to produce pathological effects: 1. General systemic poisoning: Examples: Arsenic, lead, manganese, mercury. 2. Substances acting on the circulatory system: Examples: Arsenic, lead, mercury, vanadium. 3. Substances acting on the respiratory system: Examples: Asbestos, free silica. 4. Substances acting on the gastro-intcstinal system: Examples: Antimony, cadmium, lead, mercury, zinc. 5. Substances acting on ike skeleton andjoints: Examples: Lead, mercury, mesochorium, radium. phosphorus, 6. Substances acting on organs of special sense: Examples: Arsenic, lead, manganese, mercury. 7. Substances acting asfetal poisons: Examples: Lead, mercury. 8. Substances acting on ike genito-urinary system: Examples: Arsenic, lead, mercury, vanadium. 9. Substances acting on the brain and nersous system: Examples: Arsenic, lead, manganese. G eneral D iagnostic M ethods T h e accurate diagnosis o f pathological conditions arising from the inhalation o f industrial dusts and fumes has tremendous economic significance and also it is o f medicolegal importance. Moreover, it is impossible to understand how proper and effica- 5 i Hi? t SC 030863 Dusts and Fumes in Industry ceous treatment may be rendered unless a scientific diagnosis is made. I f a claim results from the pathological condition alleged, it is evident that the disease sustained must be directly related to the employment and further, must produce disability to entitle the individual concerned to compensation. Diagnostic methods with reference to dust and fume diseases need not differ widely, if at all, from those used as routine pro cedures in general scientific medicine, although there are specific methods as in any other application of general medical diagnostic principles to any special group of persons. N ew discoveries occur relative to diagnostic methods in occupational disease work and for the most part, reliance must be placed on information which is scattered throughout the current literature in addition to available textbook material which is better now than it was even five years ago. Emphasis has already been placed upon the vital part played b y etiology; it is wise to repeat that etiology forms the bulwark o f the diagnostic and therapeutic background. Among the methods which are used to make a fairly accurate diagnosis with reference to occupational diseases, is the taking of a thorough industrial history; consideration of symptomatology, the physical findings, the results o f air examination; and finally, last but not least, a differential diagnosis, ruling out diseases of ordinary life which have no relation to occupation. T he industrial history m ay be o f very great assistance in arriving at an opinion. M ost industrial physicians of considerable experience believe that it is desirable to include a complete resume o f the kinds o f occupations which have been experienced b y the individual being examined, dating from the first jo b to the last one. It is o f course clear that the details o f actual occupa tional exposure cannot be evaluated b y this method, but im portant information bearing on the diagnosis may thus be obtained. I t is the present practice, therefore, to list the occupa tions with the dates o f occurrence, in the industrial history. I t is 6 SC 030864 -- ... u-rJ r r General Diagnostic Methods furthermore advisable to get more detailed information relative to the performance of the occupation, if that can be obtained. This will a t least give information relative to the kind o f exposure in industry, although it will give no idea of the seven ty o f ex posure. T h e symptomatology in many kinds o f occupational disease is likely to be confusing rather than useful, because in many instances it so d osely simulates that o f non-industrial disease that it is quite commonly not characteristics Especial attention should be given, however, to the recording of the symptomatology and critical attempts made o f its proper evaluation. Here again, distinction must be made between symptoms which may be due to nan-occupational disease and those symptoms which are specific for occupational diseases -- this is where the difficulty arises in adequately assessing symptomatology. T h e physical findings, on the whole, are more reliable than the symptomatology, although in certain instances they too are not characteristic and are, therefore, liable to be somewhat ' puzzling. Where only one portion o f the body is affected, as in silicosis, for example, it might be assumed that the physical findings would be more characteristic, but the opposite o f this is usually true. In other instances, for example lead poisoning, where different organs and systems are pathologically affected, the picture is liable to be one which demands expert evaluation ro differentiate from non-occupational conditions. Clinical laboratory data, including X -ray findings, are frequently found to be decisive, although here again intelligent appraisal means proper interpretation o f the data. When they are decisive, such tests are by the very specificity o f their nature, o f great value as diagnostic aids, although they should be defi nitely correlated with other findings. Differential diagnosis presents perhaps the most difficult problem o f all in the realm o f diagnosis of occupational diseases. There is good reason to believe that differentia! diagnosis will 7 *41 Hgkilll-l!!!L8!!UIUMl SC 030865 ^ Dusts and Fumes in Industry continue to be one o f the most difficult phases o f the medical ramifications o f the medicolegal problems of occupational dis eases. The reason which has already been indicated is that the symptomatology and frequently the physical findings imitate so closely the symptomatology and physical findings of non industrial diseases, that one must make use o f specific procedures which are designed especially as diagnostic guidepo3t3. Frequently such specific procedures are not used to any great extent, except b y those who are highly specialized in the field and whose work takes them into a review o f the current literature containing these developments. For example, one may believe that an industrial employee has lead poisoning, largely because of second hand knowledge that lead was used in his occupation, more easily than one could demonstrate adequate etiology and the existence o f lead poisoning by scientific methods. Because o f all o f these obvious and other difficulties, it seems wise to adapt specifically certain examination procedures tn industrial problems arising out o f occupational or suspected occupational diseases. M ost authorities now agree that the examining physician can be o f greater service and give more effi cient advice regarding either acceptability for employment, continuance in it, opinion on the diagnosis o f systemic pathologic conditions and the estimation o f disability, if he is conversant with the following points: i. T he nature and extent o f the industrial exposure into which the employee will go or where he has beat. This can be determined only by scientific methods which will be referred to later. a. T he effect o f this specific exposure upon normal and abnormal physical states o f employees, as interpreted by the physical status o f each individual on examination. (This refers specifically to etiology in the industrial en vironment and the effects which such etiology may or could produce.) 8 Clinical Examples 3, The nature o f the protective devices supplied by the em ployer, if a hazardous exposure cannot be otherwise con trolled, and as to whether these devices are functioning efficiently. (Reference will be made later to these devices, especially designed for protection against dust and fume exposures.) It is realized that these procedures are somewhat removed from the usual program o f physical examinations, particularly with reference to the work o f part-time industrial physicians, but it is also expected that the physician will be called upon increas ingly to know and appreciate such information so that he may function better as a diagnostic medium. Because the most frequent and most significant exposures in industrial processes are free silica dust and lead and its com pounds, it seems advisable to include in the next section some clinical examples, namely silicosis and lead poisoning; there will also be included a brief discussion o f metal fume fever. C linical Examples Simply stated, silicosis is a disease o f the lungs, caused by the continuous inhalation over a long period o f time o f very finely divided, microscopic, particles o f free silica dust. There have been various standards set up b y different agencies, based upon studies o f silicotic workmen and their exposure to free silica dust. T he National Silicosis Conference Report on Medical Control o f Silicosis says: "There is evidence that for prolonged exposure a concentration o f more than five million particles per cubic foot o f a highly siliceous dust is dangerous. Therefore, it is now con sidered good practice to hold concentrations of highly siliceous dust at 5 million particles per cubic foot, or less." Because o f the fact that industrial exposures, involving high free silica content in which the concentration o f dust should be restricted to five million particles per cubic foot, are relatively infrequent in industry, and also because the opposite usually S> SC 030867 fAlP Dusts and Fumes in Industry occurs (an exposure to "mixed" dusts which contain appreciable amounts of free silica but also contain considerable amounts of other types of material) it is believed wise to refer to the formula* developed by the National Silicosis Conference wich reference to a working criterion with respect to satisfactory or unsatisfactory conditions, when exposure to ` mixed' dusts occurs. It is to be borne in mind, however, that any unprotected industrial operation, which involves the production o f a lot o f fine dust particles o f material containing a relatively large percentage of free silica, offers a potential silicosis hazard. The incidence o f silicosis is not known with any degree of accuracy, although various estimates have been made. One of these made some rime ago by the American Institute of Mining and Metallurgical Engineers indicated that in the United States the number o f industrial workers exposed to the silica dust hazard is in excess o f a half million. Figures quoted by the Com mittee Reports o f the National Silicosis Conference disclosed estimates that approximately i % o f the working population of the United States or about one million workers are exposed in some way to the potential hazard o f silicosis, and that perhaps half of this number, 500,000, or 1 % o f the total, are exposed to a serious hazard. It is furthermore believed chat approximately 1io,oao, or 0.2. o f 1 % o f the total, have silicosis to some degree, but likely only 4000 to 5000 (a small fraction o f 1 % o f the total) suffer any degree o f disability from the diseases (These figures are based upon prewar estimates.) It can readily be seen that silicosis, although not a rare disease, is not common and furthermore not as common as may ordinarily have been supposed b y many persons. Recent conceptions wich regard to the contraction o f silicosis have established the belief that approximately 25% o f those exposed to a real silica hazard will eventually develop silicosis. * F O R M U L A A: " M u ltip ly t b * p e r c e n ta g e o f ffc e s x E c * b y t b c t * a l a i r t w i t IF tir e r e s a le it u j e t S m iS to n , r iw c o n d itio n m a p b e m w d t r i d p r r i m a l b V . I f t i n m u l e r* o v e r > th e con i i n e * m a p b e e o n o d r r H too h f fc F o t c r u m p le . 10 p ee c e n t f r e e l i e s * * t h * * frv c r* g e t o t a l H e a t c flttc c n tra o o A o f JO n U tt * c a tta d e * p f r a b n - f o o t o i d d r r r e C U C tim e * JO m iB io a . * W b e q u a ls i oM&wfi ( r o o d p f e n c e }- W p e r c e n t w ith * n a v e r * r e t o o l d o t e c o o c c ittr a r io n o f >0 m illio n , w e a ld e q u a l 0 J ttm e a SO, o r I S m r f b a a ( M i t w f a e t e i y ) . T h i s b r m i i l a 11 n o t a p p l i c a b l e t o k e y d u s t coo* i* t3 c le u th a n S p er c u t free wftc*." 10 SC 030868 Clinical Example! _ W ith respect to the occurrence o f silicosis in the foundry industry, a prewar survey by the Division of Industrial Hygiene of the New York State Department o f Labor, based on a study o f 3 1 1 foundries, o f which 80 plants included X -ray examinations involving 4,754 employees, provides some interesting figures: the X-ray summary showed that 3,259 or 80.2% were negative; 185 or 4 .5 % showed fibrosis; n o or 2 .7% showed silicosis with and without infection; 485 or 11.9 % showed healed primary and re infection types of tuberculosis; 27 or 0.07% showed clinically significant tuberculosis. I t was concluded, as stated in the report, that it would appear that the silicosis hazard in the foundry industry in New York State, while existent, is o f mild degree of severity and may be expected to yield satisfactorily to appropriate measures o f control. T h e Teport further indicated that tuber culosis as manifested by X -ray films o f the chest was found to be more prevalent among silicotics than among non-siiicotics in foundrymen- T h e occupational history, as previously indicated, ts o f con siderable importance. Forms for the recording o f occupational records have been devised by various organizations and groups and by physicians and insurance companies. One of the most complete and longer forms has been devised and used by the Saranac Laboratory, Saranac Lake, N . Y ., in connection with silicosis studies and symposia on silicosis which have been held b y this group. It is suggested that the physician, if interested, should contact the industrial hygiene bureau of his state health department through which detailed forms may be secured or information relative to thetn. T he symptoms and physical signs are not characteristic; they may be confused even by skilled diagnosticians in other diseases, with the symptoms and signs which commonly occur in both minor and the more serious types o f the well-known respiratory infections. Characteristically, shortness o f breath on exertion and decreased chest expansion frequently occur in advanced cases o f silicosis, but these findings must also be differentiated as a Dustj and Fumes in Industry to their casual' relationships and their possible association with other diseases. T h e clinical confirmation of the diagnosis o f silicosis rests mainly on the characteristic X -ray appearance o f the chest. This shows the typical lesions of silicosis, hyaline fibrous nodules which are scattered as opaque bodies throughout both lung fields, the density of these nodules being somewhat less than calcified bodies, but discrete in outline, all about the same size in the early stage (so-called millet-seed size) and evenly dis tributed throughout both lung fields. These nodutes appear as the first indication o f silicosis, later become somewhat confluent and in the latter stages, there are large masses o f opaque material found near the periphery of the lung fields. In the later stages of silicosis, the disease is frequently complicated b y infection, usually tuberculous in nature. As an aid to interpretation o f the X -ray films o f the chest where silicosis may be suspected, it is suggested that the physician refer to a tabulation o f the X -ray changes in silicosis, with the underlying histological conditions which cause them, published in the transcript o f the Second Silicosis Symposium, Saranac Lake, N . Y ., 1935. Diagnosis rests upon proof o f occupational dust exposure sufficient to produce the disease, and the presence o f character istic nodular lesions in the X -ray film of the chest. T h e mere mention o f occupation is not sufficient for diagnostic purposes -- adequate knowledge concerning the quality and quantity o f dust exposure, as well as the length o f the employment period, is necessary to establish a distinct causal relationship. Although considerable diagnostic reliance is usually and properly placed upon the history o f adequate occupational dust exposure and the characteristic chest X -ra y appearance, a thor ough physical examination with appropriate clinical laboratory examinations should be done, especially with reference to the ruling out o f other respiratory diseases. Diagnosis becomes essentially a differential diagnosis, as before explained, one which is Likely to he difficult, necessitating special experience . 12 nrrrriita*aiiii SC 030870 Clinical Examples and knowledge. Some of die conditions requiring differential consideration here are miliary tuberculosis, multiple calcifications o f healed tuberculosis, cancer of the lungs, and fungous growths o f the lungs. Within recent years, superimposed infection has come to be the accepted cause for disability. T h e outlook in simple silicosis, therefore, (that is, without infection) is more favorable than was formerly believed. It is obvious that the chief problem for the silicotic is to avoid superimposed infection, which is usually tuberculous. There is no one specific, efficacious treatment for silicosis, although in recent years, the inhalation o f metallic aiuminum powder has shown some promise. In cases where tuberculosis complicates the picture, it is obviously to be treated b y the best known methods for that disease. There is some recent evidence that surgical therapy as used in ordinary forms o f tuberculosis is also a help in the type o f tuberculosis which follows silicosis. T he evidence for this is not conclusive, but there are good results on record. In general, recommendations for the treatment o f cases of silicosis vary with experience and with the findings o f each case. It is believed, for example, that no treatment is necessary in the case o f an individual without symptoms, whose X -r a y film o f the chest (taken perhaps in a routine industrial survey) shows only widespread discrete nodulation without localized shadows indi cating infection. However, the employee should have serial X-ray examinations with physical examinations o f the chest at least once a year and should be removed from further silica exposure to some other jo b , since the disease is very slowly progressive and there is at this stage no disability which precludes continua tion in employment. A person with localized conglomerate lesions m ay have symptoms and usually cannot do as heavy work as formerly; therefore, a lighter job should be found. In the presence o f active infection where there are symptoms or incapacitation, th e .individual cannot obviously continue in his 13 Dusts and Fumes in Industry former employment. If the case is one o f open tuberculosis with positive sputum, it is evident that such an employee is a source o f danger to his fellow workmen and should be placed in a sani tarium or hospital. In cases of inactive infection with no incapaci tation, lighter work should be provided, without further dust exposure. Dusts containing silica in combined form do not cause silicosis; however, one such dust, asbestos, a magnesium silicate, will produce a characteristic fibrosis which is called asbestosis. This disease is quite different in its pathology from silicosis, and has a characteristic 'ground-glass' appearance on the X -ray films of the chest. Animal experimentation indicates that the action of asbestos is probably mechanical, since it cannot be produced in other chan the pulmonary tissue. Asbestosis may cause disability and a few fatal cases have been recorded, but in those cases show ing marked disability, other organic disease Is usually also present. The symptomatology and physical findings include cough, dyspnea, pallor, clubbing o f fingers, and diminished chest expansion, with a characteristic X-ray appearance as previously mentioned. Lead Poisoning Lead poisoning offers a good example o f an industrial poisoning which is contracted by the inhalarion either o f a toxic dust or fume, and has been stated to be one o f the most frequent and important types of metallic poisoning in industry, on account o f the wide spread use o f lead and its compounds. Although there are no reliable statistics available with respect to the national incidence o f lead poisoning, it is believed that lead poisoning is very prevalent and that most o f it is mild- T h e incidence o f severe types o f cases, particularly lead encephalo pathy and the more severe types o f nervous system involvement are not seen with as great frequency os in former years. M any physicians who are used to handling industrial cases now rarely see a case o f wrist drop due to lead poisoning, whereas 20 to 25 1 years ago it was a rather common phenomenon, in cases of lead f intoxication. 14 SC 030872 Clinical Examples The industrial history is o f great importance, as previously indicated, and a thorough consideration o f the nature and extent o f the exposure to lead and its compounds is an essentia] point in the etiology. Ir is now generally accepted that the standard of the CJ. S. Public Health Service and the American Standards Association o f 1.5 milligrams o f lead per ten cubic meters o f air, is the maximum allowable concentration. Because it is now con ceded that practically all industrial lead poisoning is contracted by the breaching of lead dust and fumes, it becomes of con siderable importance in working out the etiology to ascertain the amount and quality oflead dust and fumes in the air, during the occupation o f the involved individual. This point will be dis cussed later with reference to prevention. Formerly, the nature and variety o f non-industrial sources of lead intake made it particularly difficult to establish industrial i etiology on a sound and competent basis. More recently, how ever, non-industrial lead intake has been measured b y scientific methods and with the exception of an occasional difficulty with various types o f homemade beverages stored in utensils glazed with a lead compound, the non-industrial lead intake is not 1 I I believed to be a considerable factor in the production o f lead l i poisoning in adults. There are, however, some exceptions and these should be taken into account, as indicated. T he diagnosis o f industrial lead poisoning is not a simple matter on account o f the fact that clinical symptoms and signs are protean and are liable therefore to simulate other diseases. Great increase in our knowledge, however, has occurred within the past ten to fifteen years, and it is now known that there is a dose relationship between the action o f lead and its compounds within the body and the calcium metabolism, and further, normal and abnormal excretion o f lead has been worked out on a scientific bads. I t is now an accepted fact that persons without industrial exposure normally excrete a certain amount o f lead in the urine. It has been stated that definite dtnical findings o flea d poisoning are practically always associated with abnormal urinary lead is SC 030873 Dusts and Fumes in Industry excretion -- the reverse, however, is not true -- that abnormal urinary excretion o f lead in the absence of characteristic clinical findings indicates lead poisoning. Other laboratory findings are important, particularly the examination o f the blood, some investigators and clinicians using the increase in basophilic stippled red cells as an indication of positive findings and others using what is known as the basophilic aggregation test.' Both are found to be successful, the former more adaptable in cases of frank poisoning, the latter more useful in cases o f lead absorption and suspected incipient poisoning. Although as indicated, the clinical symptoms and signs of lead poisoning are protean, the principal effects are expressed in the blood, the gastrointestinal system, and the nervous system, named in order of their usual chronological occurrence. In brief, the most consistent findings are changes in the color and form of the red cells o f the blood, colic and constipation, and weakness and atrophy o f the extensors and flexors of the muscles o f the wrists, with partial paralysis in the more advanced types o f cases. T h e differential diagnosis, as m ay be obvious, has to do mainly with differentiating industrial lead poisoning from non industrial diseases which may involve the blood, the gastro intestinal system, and the central and peripheral nervous systems, producing changes which are similar to those observed in frank lead poisoning. Such non-industrial diseases show a considerable variety o f pathological processes affecting the above-named systems. T h e treatment o f lead poisoning has undergone considerable change within the past ten to fifteen years. In general, the treat ment consists m ainly o f appropriate therapy for the toxic episodes and the mobilization o f stored lead in the long bones. It is usually agreed that it is wise to facilitate the storage o f lead b y an excess calcium intake rather than to set lead free in the blood stream; after the passing o f acute toxic episodes, the elimination o f lead may be assisted b y means o f low calcium intake, the administra te SC 030874 lematti r r -r\ Clinical Examples j < ' . I I tion o f weak organic acids and ammonium sales, sodium bicarbonate, and potassium iodide. Care should be exercised in using such forms of treatment on patients who have nephritis. T w o schools of thought with widely divergent views exist with reference to deleading the body: there are those who feel that in the majority o f instances deleading will accomplish good results, while there are others who adopt a conservative attitude and because o f the possibility o f precipitating acute symptoms, feel that it is safer to produce artificial deleading b y slow methods, or to resort to the natural process of letting the body delead itself over a period o f rime. T he choice in the matter depends upon the individual case and the previous results which have been achieved at the hands o f the physician in charge o f the case. Storage o f lead may be facilitated in acute cases b y a high calcium diet or b y the slow intravenous injection o f 10 cc o f 20% calcium gluconate; variations with relationship to this form of treatment have been devised b y various physicians. In the deleading process, low calcium diet together with oral administration o f ammonium chloride has been found to be effective, whereas in certain cases parathyroid extract and sodium bicarbonate also have been useful. Within recent years it has been established that large doses o f viosrerol have been instrumental in increasing the excretion o f lead. Other investigators have found that an adequate phosphorus intake is essential for the depositing o f lead in the bones and for the removal from the bones o f the excess cations, as the insoluble phosphate salts in the feces; it has therefore been recommended that deleading may be accomplished b y giving a diet low in calcium and relatively high in phosphorus, using viosterol 20 minims daily. There are also variations o f treatment with reference to the amount o f intoxication, and where there has been high, medium or low lead intake in industrial occupations. In all these types of treatment, deltaJing should be done in the hospital where che patient may be closely supervised. Some investigators advise 37 j j j ( " ' . .1 \ \ : ' ' : ' SC 030875 Dusts and Fumet in Industry against deleading more often than once in four weeks and rite course should not be prolonged for more than three or four days; some physicians believe that ic m ay take from six to fifteen courses of deleading to free the individual o f his most looselycombined lead, which o f course is che most dangerous type of lead. It is again warned that deleading should not be undertaken in rhe presence o f acute symptoms; it is further agreed b y all in vestigators that calcium therapy is considered to be the most specific at the present time. The outlook in cases of lead poisoning is much better now than formerly because o f the occurrence o f moderate types of effects, che severer forms being a great deal less frequent than in former years. Metal Fume Fetter This name is applied to the condition which results from breathing fairly heavy concentrations o f freshly formed metallic oxide fumes, principally zinc and one o f its alloys, brass; although the condition may result from the inhalation of other metallic oxide fumes. M etal fume fever is not a systemic poisoning, but it should be borne in mind that some o f the metallic fumes that I can cause it, such as lead, cadmium, mercury, and manganese, may also cause systemic poisoning. T h e symptoms come on some hours after exposure, usually after leaving work, a dryness o f the throat being first noticed, which may be followed b y a dry cough and a feeling o f heaviness in the chest. Rise o f temperature, accompanied b y sweating, and leucocy tosis and elevation o f the pulse rate and the blood pressure I1 usually follow, sometimes with chills. The symptoms ordinarily ' pass off in i z to 14 hours and the usual experience is that rite employee returns to work the following day. A natural immunity is conferred in certain types o f workers, which seems to be lost rapidly after removal from continuous exposure. Diagnosis is made usually on a clear history o f industrial exposure to metallic oxide fumes. It must be remembered that 18 SC 030876 Other Dusts and Fumes the effects and symptoms o f metal fume fever arc very similar to those o f influenza and that the malady is more often noticed in the fall and winter, when influenza usually occurs. T he in dustrial history is, therefore, important in diagnosis, particularly with reference to a causative exposure to metallic oxide fumes. T h e outlook is good for complete recovery in a short time and usually there is no time lost from work, although there may be temporary incapacity in terms o f hours. T h e treatment is symptomatic and especially directed toward comfort because the patient usually recovers within a relatively short time in ail events. Rest in bed with adequate warmth and protection from drafts are recommended. However, all suspected ! cases o f metal fume fever should be attended by a physician because the symptoms may closely simulate influenza which makes the differential diagnosis important. i 1 O th er D usts an d F um es ' It must not be concluded that although clinical examples were > given o f silicosis, lead poisoning, and metal fume fever, there are ' not other examples which are o f importance. These subjects were ; selected because o f their frequency of occurrence and because o f the fact that they are commonly encountered as examples of dust alone, dust and fumes, and fumes. { Am ong the other metals which m ay be mentioned are arsenic, antimony, cadmium, manganese, mercury, radium, selenium, i silver, tellurium, thallium, and vanadium. N o t all o f these are l equally Important with reference to toxic effects. t i Probably the most important o f these from a toxic point o f ' view are arsenic, mercury, manganese, and cadmium. Arsenic pro. duces chronic poisoning chiefly from breathing over a long period o f thin air containing dusts or sprays o f arsenic compounds. The compounds o f arsenic such as lead arsenate, paris-green, arsenic oxide and arsenic sulphide are among the more dangerous forms. 19 ~td- SC 030877 Dusts and Fumes in Industry Where dusts o f mercury are present, they will be in the form of either mercurous or mercuric compounds, where metallic mercury is used in die manufacture o f such items as thermometers, mercury swicches, mercury vapor lamps, mercury boilers, etc., the hazard is from the vapor since mercury has a considerable vapor pressure even at norma) temperatures. Mercurialism is characterized by three features: inflammation o f the mouth, muscular tremors,'and psychic irritability -- sometimes all of these are encountered and sometimes only two or only one. In the more chronic or slow form o f poisoning, a characteristic tremor is the commonest symptom, coming on late, and has been noted to occur particularly among mercury miners. Manganese poisoning is an old industrial poisoning, having been described more than too years ago, but has receded in incidence in American industry. Characteristically it produces a peculiar slapping gait with phenomena o f retropulsion and pro pulsion; masklike faces; monotonous voice with economical speech; muscular twitching varying from a fine tremor to gross rhythmical movements o f the extremities; languor and sleepiness; cramps in the calves of the legs with stiffness; slight increase in the tendon reflexes without any disturbance o f the deep or super ficial sensation. Studies within the past five years indicate that dust is the most important type o f exposure. Cadmium is encountered in the smelting of ores, the handling of socalled ` blue powder' compounds, the spraying o f pigments, the welding o f alloys, and the melting of cadmium metal itself, as well as certain non-industrial exposures where utensils have been plated with this metal. In recent years there have been several outbreaks o f cadmium poisoning among non-industrial users o f such utensils. T he use o f the metal has increased tremen dously and therefore, there is more industrial exposure. T w o types o f effects have been observed, those with reference to the lungs and also those with reference to the gastro-intestinal tract, the former being more important and more frequent. Pulmonary involvemenc is characterized by a feeling of constriction in the 20 ' SC 030878 Prevention KHWii iH'Mt'.W umw n.iia!im;)inBai..nw J u m S Ka1 chesr, edema and congestion o f the lungs, sometimes with hemorrhage, proliferative interstitial pneumonitis; while the latter is characterized by nausea and vomiting and a general irritative reaction of the gastro-intestinal tract, with diarrhea, hiccough, and oliguria. I f further details are desired on the clinical aspects o f the metals mentioned, standard works on industrial hygiene and occupational diseases should be consulted. P r e v e n t io n The general principles of prevention involve first the identi fication o f industrial exposures and the evaluation o f such ex posures by proper scientific methods to determine whether or not they represent actual health hazards. This is done by sampling the air and determining the amount o f air contaminants and the quality o f them in each type o f occupation or problem involved, and comparing the results with the accepted standards o f maxi mum allowable concentration that have been adopted by official bodies. Second, after it has been determined that there is an I actual health hazard represented b y the occupation, control measures, both engineering and medical, are instituted to control the hazard, providing it cannot be entirely eliminated. In discussing the methods of engineering control, we are con cerned with three basic principles: I. Investigation o f occupational conditions. z. T h e measurement o f the occupational exposure and the raring o f the hazard, if one exists. 3. Putting into effect the specific measures o f protection which have been indicated by information secured under (1) and (2). Among the methods o f approach for engineering control measures may be mentioned: 1. Physical and hygienic survey o f plant conditions. 21 SC 030879 f \ i V. y .A . Dusts and Fumes in Industry 2. Occupational history and analysis. 3. Adequate information concerning materials and processes used. 4. Atmospheric and gross sampling o f materials, combined with quantitative physical and chemical determinations. 5. The rating of the hazard by comparing the findings in the given instance with accepted standards. 6. An appraisal o f the efficiency o f protective apparatus and devices. 7. An adequate and proper interpretation o f the information so that it can be applied practically to the industrial problem involved. " When the foregoing methods o f approach to engineering control have been carried out and information secured from them, the information can indicate the necessity for using specific methods o f protection which have been found useful in different combinations: 1. The use o f mechanical devices, such as exhaust ventilating systems, respirators, masks, and the like. 2. The changing of processes {segregation, enclosure, wetting, etc.). 3. Substitution o f non toxic materials for those o f proved toxicity. 4. Educational programs for management, workers, engineers, and physicians. 5. Continuous maintenance and checking o f the efficiency of protective equipment. A tm ospheric Sam pling T h e best method for collecting a sample o f a dust or fume from the air will depend somewhat upon the type o f contaminants to be sampled. T he degree o f hazard o f fibrosis-producing dusts is measured in terms o f particles per unit volume o f air (example: >> . ' " T i n n iiTurn " - - r -- SC 030880 Atmospheric Sampling 10 million particles o f silica dust per cubic foot of air) while toxic dusts and fumes which, may cause systemic poisoning are usually measured in terms of weight per unit volume o f air. (Example: lead dust 1.5 milligrams per 10 cubic meters o f air.) Since results may vary with the type of air sampling device used, it is important to select a type accepted through genera! usage in the practice o f industrial hygiene. The larger Impinger which samples one cubic foot o f air per minute by impinging the air containing the dust particles from a nozzle submerged in water or alcohol against a plate or bottom o f the flask was used in all of the original studies in the United States on fibrosis-producing dusts. T he large Impinger, however, has the disadvantage o f being bulky and requiring electric current or compressed air for operation o f the motor-driven air pump, which produces the suction stream for air sampling. A portable Midget Impinger has been developed which has been proven to give results as reliable as the large Impinger. This apparatus samples at the rate o f r/ioth o f a cubic foot per minute and is operated by a hand cranked, positive action, four cylinder pump, in conjunction with a vacuum regulator which maintains an unfluctuating suction regardless o f minor variations in rate or smoothness o f cranking. After the sample has been collected in the Impinger flask, a portion is placed in a special dust counting cell and counted under a microscope with an eyepiece having a special ruling similar to a blood count ruling. Further analyses arc necessary with reference to the amount o f free silica in the dust and this is accomplished by the use of specific chemical, petrographic and X -ray diffraction methods. The Impinger method of sampling is not entirely statable for collecting fumes or dusts o f toxic materials such as lead, cadmium, and others because the efficiency o f the Impinger is not adequate when sampling the very fine fume particles and since the amount Dusts and Fumes in Industry or concentration of such materials in air which m ay be injurious is much smaller than the safe amounts o f fibrosis-producing dusts, a correspondingly large air sample should be taken for reliable results. T he Electrostatic Precipitator is widely used in the collection o f toxic dusts and fumes, particularly o f metals and their com pounds. A Portable Electrostatic Precipitator has been developed which operates from I lo volts, 60 cycle current, and by high voltage electrical precipitation collects the sample o f the particu late matter dry on the inside of aluminum or glass cylinders. T h is device samples at the rate o f 2 cubic feet per minute. After the sample is collected, a quantitative chemical analysis is made in the laboratory. This type o f apparatus permits determinations o f very low concentrations o f many different kinds o f atmospheric particulate matter. - Where equipment or personnel is not available for atmospheric sampling, sta te industrial hygiene bureaus or private testing laboratories may be engaged. M any insurance companies also have facilities for such work. T h e Industrial Hygiene Foundation in Pittsburgh, Pa., an association o f industries for the advance ment o f healthful working conditions, also have an excellent staff o f technicians for industrial hygiene surveys or consultations in this field. R espiratory P rotective E quipm ent - ..It frequently happens that- because o f the nature - o f the operation or process in an industry, it is not possible to thoroughly control a hazardous exposure resulting from the evolution of dusts and fumes. In such instances, it is considered wise to pro vide employees with personal respiratory protective devices. These vary with the kind o f exposure and with the amount of materials in the air. For ordinary conditions in which only dusts and fumes are present, simple filter type respirators are available which will 2i Respiratory Protective Equipment protect the worker against the hazards o f breathing these dusts and fumes. Such respirators normally consist o f a facepiece covering the nose and mouth, made of some pliable material such as rubber which will conform to the face and provide a comfortable and dust-tight fit, and to which is attached a filter made o f treated paper or felt through which the air is inhaled- If the filtering material is o f the correct type and density, it will effectively filter particles down to less than a micron in size from the air. Comfort is a most important consideration in a device o f this type. Since a high breathing resistance will materially affect the comforc o f the wearer, the filters should be o f large area so that the inhalation resistance will be as low as possible. Valves should be provided which open on exhalation and further lessen the exhalation breathing resistance. The particular type of filter employed tvill depend upon the kind o f contaminant present in the air. Since the amounts of such toxic materials as lead which will affect the wearer are much smaller chan the harmful amounts o f fibrosis-producing dusts, a filter will have to be more effective when used against toxic dusts than against fibrosis-producing and nuisance dusts. For special operations such as sandblasting, a mechanical filter type respirator is not practical because o f the extremely high concentrations o f dusts present. In such conditions, special airsupplied masks or respirators should be used in which air from a compressed air line is supplied through a hose to the facepiece for breathing. Such devices may also be employed i f desired as protection in less severe and hazardous operations. T h e advantage o f an air-supplied respirator is that there is no breathing resistance and the wearer is protected against any and all dusts and fumes in the surrounding atmosphere. However, the restriction b y the air hose which must be attached to the wearer at all times be tween his facepiece and the air supply, prevents the use of this device in m any operations where the worker must move freely 25 SC 030883 .mrc-v.ivvii Dusts and Fumes in Industry over a considerable area. Furthermore, caution must be taken ! to see that the air supplied to such devices is free from all in- . jurtous or objectionable odors and contaminants and that the ; humidity and temperature of the air is such as to provide reason- ; able comfort. The United States Bureau o f Mines (Department o f the : Interior) tests respiratory protective devices against various air contaminants under carefully controlled conditions. Devices meeting its tests receive that Bureau's official approval, and this is indicated by approval numbers on the device and a reproduction o f the certificate on the package. Equipment approved by the U. S. Bureau o f Mines for the particular contaminant or class of contaminants in the air should be used. M EDICAL CONTROL It is o f course obvious that medical control measures are futile after a disease has been contracted because o f the exposure to dusts or fumes except when the information is adapted to prevent additional cases. However, before the diseases are contracted, there are a number o f things that can be done b y physicians to prevent such occupational diseases, which may be summarized as follows: i . The intelligent use o f preemployment physical exsminations, including chest X -ray films, and appropriate clinical laboratory tests as indicated. i . Simitar use o f periodic physical examinations, chest X -ray films, and clinical laboratory tests on employees in occupations where typical hazards have been proved to exist, by industrial hygiene investigations. g. Responsibility for seeing that hazardous exposures are properly taken care of, b y various efficient methods of protection, including the supplying of personal respiratory protection, where industrial conditions make ic impossible to control the hazard b y other means. : i ; j : SC 030884 Medicai Control 4* Prompt transference to non-hazardous occupations of employees found to have symptoms o f an occupational , disease associated with their exposure. i 5. Prompt removal from work o f all persons suffering from . active occupational diseases, when such persons are a menace to themselves, their fellow workmen or the em- . ployer. ' 6. Adequate provision for treatment, rehabilitation, and prompt return to work, o f employees having disability ; resulting from occupational diseases. Su m m a r y In this brief discussion o f dusts and fumes in industry, the > sources, effects, and control have been considered under the following headings: 1. Definitions. 2. Incidence and etiology. 3. General diagnostic methods. 4. Clinical examples. . j. Prevention -- general principles, including specific methods o f air sampling and apparatus for this purpose; specific methods of protection, including mention o f respirator)' protective equipment available; and other general methods. It should again be emphasized that industrial managers are interested in the prevention of trouble that m ay arise from exposure to dusts and fumes in industry, and that this principle is particularly important nowadays because o f the need for every 1 person in active production, and in addition, because so many ; physicians are being used in the armed services. ` It is believed that if the suggestions made in the foregoing pages are followed, the problems arising from dusts and fumes in industry can be successfully managed. 27 SC 030885 A pproved M-S-A E q u ip m e n t for D u st a n d Fum e Protection M SA Protection for men and women workers against harmful dusts is the result o f many years of research into all phases o f every in dustry's respiratory protective prob lems. In a well-equipped Dust Re search Laboratory, which is a special division o f our Research Department, continual study of dust hazards is maintained, and from this research group have goitre many o f the most important improvements in dust pro tection-- dating from che first U. S. Bureau o f Mines-approved dust respi rator, the famous M-S-A "C om fo." The M-S-A trademark on the pro ducts you recommend is a solid assur ance o f excellence in design, manu facture and performance. A il applicable M-S-A personal pro tective equipment against harmful dusts or futhes is approved by the highest authority-- the United States Bureau o f Mines, official testing agency o f che United States Govern ment for safety equipment. The ap proval certificate o f the Bureau signifies that each product has passed the must stringent Impartial tests-- fit for the most exacting service in industry. W e w ill be glad to send you, upon request, descriptive bulletins on any or all o f the products mentioned in this booklet-- without obligation. SC 030886 M -S-A* Filter R e s p ir a t o r s D o w n ed for protection against harm* iu l du*t> and fumes bv the use of imerch.ingcat>fe filters. Each u f these Hfjpi- ratori answers <11 ro p ird to ri pnK caivc requirements against pneumocuni\r>t>produccng, nuisance or to x k duis. M-S-A* D ustfoe <56 Bureau of Mines Approved. An improved compact and lightweight Respirator with larger exhalation valves reducing rn iu a m v to a minimum. These spring-retatned valve elim i nate disturbing variation in breathing resistance' and prevent accidental removal of valves. Face* piece cushion td neoprene sponge is contoured to provide automatic lit, great wearing comfort, and alt'iijtht seal without adjustment. Qecuo* statically charged resin-created filterv voppleroent mechanical holding a n io n of biter's fibers. Simple cunstrucitun assures quick and cosy filter ihanging and cleaning of Respirator. Weight, including headband: 5 ounces. M -S -A D ustfoe uunt-FOter R espirator This compact and lightw eight Kevpsrator of aluminum is designed fur unusually toxic dusts and extremal) fine particles. Its filter holder allows for good field of vuinn and freedom of head movement. Facepiece forms to contour of wearer's foce. Neoprene sponge cushion assure* air-tight seal with minimum adjustment and maximum Comfort. N eoprene stays oft and pliable : will nut harden with age. M-S-A Type H Ultra-Filler protects against toxic aerosols, radim ettve dusts and fine particle smoke; also effective against airborne bacteria and certain viioies. Construction is simple for easy filter changing and cleaning. M - S - A C om fo Filter R espirator - M ost versatile of the M-S-A Respirators, facepiece is made of a special new soft com pound for improved wearing comfort and greater durability. Provides dependable air-tight sea] w ith wearer'a face, and will not harden or crack with age. Positive-action exhalation valve offer Hide resistance to air. T he C onfo features interchangeability of three filters: Type F (Bureau of Mines Approved) for dusts not significami) more toxic than lead; Type $ (B ureau of M ines A pproved) for du*c. misrs and metal fumes; and Type H Ultra-Filters for toxic aerosols, exiremcly fine particles, radio active dusis, bacteria and certain viruses. 1'J SC 030887 M-S-A* A ir Line R espirators IkMCOed for .ojnpiete ruspirmurv pro tection in cnncaminaceii atraovphercv diar are not immediately harmful iu life, Each M-S-A A ir Ltn Respirator Feflturtr lig h t ness in weight. comfortable lit. and free* dura of head movement. M-S-A D ustfoe A ir Lin e R espirator For Constant Flow Only Bureau of Mines Approved* Thi* Du>cfr>e Respirator i a supplied-air protective unit with a formable aluminum facepiece. Its streamlined nylon fitting at the bottom o f the facepiece serves 2 a um nector for the flexible c o r n i c e d air supply hose. D ual exhalation valves offer rain- mum breathing resistance, and an air diffuser prevents air Masts on the face. A standard chemi cal cartridge filter unit gives effective filtering of delivered air. Assembly includes aluminum Constant flow Control Valve with automatic shut-off and trigger release. M-S-A A ir Line R espirator 1 with Ctitnfu*' Cushion Facepiece For Constant Flow o r Demand Flow Bureau of M ines Approved* This Comfo Cushion Type R espirator is ideal protection from such hazardous classes of air contaminants as welding and cutring fumes, toxic dusts, paint >pray vapors, and fumes from molten metals. The special shape of the facepiece with its floating chin cup and soft tolled edge assures gas-right seat on the face. Double exhalation valves provide low resistance to air fow . A huilt-in a ir deflector assures proper circulation. i Complete assembly includes either Constant i Flow C ontrol Valve or Demand Flow Regulator, with qukk-disconrteCt coupling. ) M-S-A A ir L in e R espir ato r with All-Vision Facepiece For Constant Flow o r Demand Flow Bureau of M ines Approved. This MAU-Vi-*i*n" Type Respirator has been exclusively developed by MSA fnr use in contaminated areas w here protection fur face and eye is nccenvaiy. The full facepiece assures greater w orking etfiriency. The large tense for u'id*-anpfe vision are fogpruuf. The molded rubber body* o f the fa te p c ie has an airtight *eal w iiith doe not hind. Aftrubber headstraps have swivel buckles fur quick adjusting, Complete assembly includes cith e r Constant Flow Control Valve o r Demand How Regulator with qukk-diw-onnect coupling. For additional information no M-S-A Air Line Respirators and AiGCssories w rite for Bulletin N. ItitW-H. 30 SC 030888 M-S-A A brasive M ask Designed for respiratory protection against heavy umccntrnthtn of harmful du-t encountered in shot ami sand blasting operation* Durabilit) of [his air line respirator has been tested under tcnpacr of high Telocity abrasives. Bureau of Mines Approved. The comfortable, I lightweight, gas-mask cvpe face-piece is dust- tigbr and adjusts to fit all facial shapes and sues. Fresh air feeds into the mask through a corru gated tube, and is deflected From the wearer* e ) to (he lens to prevent fogging. Twin exhala tion valves circulate ate under the hood ami form an air-cushion against the impact nf abrasive*. W jde-riian, safety-glass itfn> with protective screen can be removed frrtm its hinged rubber frame. Flow control valve has replaceable char coal cartridge filter to remove nbjecthtnabfc odors, "1 and dirt. Abrasive mask assembly in cludes choice of lightweight o r heavy duty hntxl. cartridge filter, web belt and a ir hose. fo r additional information on M-S-A Abrasive Masks and auxiliary equipment write for Bul letin No. 1009*2. V. f M-S-A Ele c tr o static D ust a n d Fume Sam pler I A modern precision instrument for quantita tive sampling of airborne particulates including dusts and fumes in the ceramic, steel and rhemi* Val process industries, and (hose industries en gaged in the produ&tfon and u*e o f radioactive materials. The M-S-A Electrostatic Sampler is a portable unit used extensively by industrial hygienists, heallb physicists, ventilation engineer, chem ists and those engineers concerned with atr pollutkm. It works on the principle of preiunt- cation with electrostatic precipitation of airborne particles upon a cnllettng cylinder for deter- minstiim by w eight, count o r chemical analysis. * Accurate detertmnatiun is enabled of very low concentrations o f atmospheric paniculate matter. 7ttv.iivt't' The Sampler includes a portable sampling head consisting of ionizing electrode, collecting tube sod motnr-bliywer assembly; a power pack transformer rectifier assembly; retractable stand, stripling and collecting tubes, cables and part*, Jmed in a sturdy carrying cae_ l'o r additional infuroutw R on the M-S-A U leu to su tic Sam pler and AtoeM>ry equipment, w rite for Bulletin No. CT-9- 31 .*! ............ tt *. . . SC 030889 M-S-A M idget Impinger A portable tend^iperaied im m unent fir quick and dependable dust >nplio{[ in any location. LKed in the du* \ur\ey* conducted b$ the U . 5. Public Health Senicc and (he U. S. bureau of M inn 1 The M-S-A Midget Impinger > iJeai for col lecting ample of dur In ijnJated location and confined pace w tthnai die u>e of awnprewed air o r electrical current. This instrument employs the impinger meihod nf drawing a ir at a rela tively high velocity through a mail gia> nozzle ism a liquid, causing (he dur partnie to he **wetted** The welted triples are then available for accurate dust panicle count under mtcro- sc o p t The impinger is operated by a hand- cranked +<>finder pump in conjunction w iih a vacuum regulator for unftuctu&tioj* flow at 1/10 cu. ft. per minute. The apparatu* iv contained in a convenient cw rjing case with boulder strap, complete wtih Had and mizzles. W eight iv less I (ban 10 pounds. For additional ufirmmii on the M-S-A Midget impln.cer write fur Bulletin O&ilM. M-S-A D u st Co u n t in g M icroscope A lightweight, durably-built micrometer screw type instrument especially equipped and pr<i* sk>n.adjueed and double-checked at M-S-A laboratories for dut determination. AH machani- cal part are of high-grade workcaanainp and performance. The M-S-A D u x Grouting Micruope is a ; fow-coC lightweight instrument with optic j identical to those offered in more expensive microscopes. lr is finished in jet black satin enamel with rhodium-plated bright metal parts. The coarse adjustment is motivated by diagonal rack and pinion, with bearing surfaces provided w ith oil grooves. Adjustable draw robe fixed at correct tube length give* proper size field for d u x counting. Magnification iv lob times. Housed in leatherette carrying cue. M-S-A D ust C o u n t in g C ell ! A new cell for counting impinger samples with an accurate depth of 1 mm. Absence of comers makes cell easier to clean sod prevent leaks and bubble. For additional information on die M-S-A Dust Counting Mnrovcopc (he M-S-A D u x C*Minting Ceil and auxilwry laboratory equipment, write fur Bulletin No. UK2V-1. a SC 030890 SC 030891 0 4 . //0 ?s 7 *.*. M-S-A--'..; . a n d In d u s t r y T hroughout the many type o f Am erican Industry are the products of this Com pany-- the largest commercial, manufacturer o f approved safety i v i , equipm ent in th e w orld today. In 1 9 1 4 , M ine Safety Appliances Com pany _ was formed (as its name would indicate) to serve the mining industry. Today;, th e Com pany h as-far outgtown.-its origin al field ,.to include- th e -: >,1 design and manufacture o f approved safety equipment for every m ajor < M ^industry and the-public p r o te c t iv e - s e r v ic e * .* i . <'>.. . vV - a ,|- 1 T h e Com pany's program is founded squarely upon Research-- research which is concerned with all industrial hazards to the life and safety o f the >: i V-i w orker;.-conducted in - M S A 's extensive''laboratories,' b y scientists of.'-, national reputation. Laboratories fo r chemical research, dust research, and ' experimental research join with the engineering departments in translating . safety requirements o f industry into equipment m eeting the highest de mands o f efficiency, comfort, and practicality. , .- ' . , ' * 1* 1 < ." A n im portant ad ju n ct o f M S A Research is its nation-wide network o f . held representatives, attached to M SA district offices in approximately 7 6 . principal, cine*.. In intimate contact w ith industrial health and safety-; problems, these trained men. w ork in effective liaison with industty and .' M -S-A. A. d o se contact is maintained w ith the m any official bureaus and .V agencies devoted to furthering the cause o f industrial safety. . ' ` T he broad institutional w ork of M SA -- exampted, in small part, by this particular publication-- is undertaken w ith th e fnliesr sense o f respoosi- b ility .. ' . ..'**.* -.' '' i -1 i - ;A - s '.; ;* t VV- - Published- B y M INE SAFETY APPLIANCES CO M PA N Y 20 1 North Braddodc Avenue Pittsburgh 8, Pennsylvania ' Copyright Ip57 SC 030892 T' . I l i l F i B B B g f f l g f f i g k Dusts and Fumes in Industry (Sources, Effects and Control) In tr o d u cto r y St a t e m e n t In dealing with occupational diseases and their effects, the attending physician should keep in mind th a t the etiology of these conditions is present in the industrial environment -- if the conditions are to be considered tru ly industrial in origin. I t is likewise important to understand that rational diagnosis and treatment rests upon a fairly accurate knowledge o f the etiology o f the disturbances; this is especially true o f occupational diseases and allied disorders. Moreover, employers, industrial hygiene and medical depart ments are greatly interested in the prevention o f various maladies which ordinarily affect employees; this clinical and economic interest on the part o f industrial m anagem ent further emphasizes the need for understanding the etiological factors in the working environment, so that they m ay be properly controlled. T h is booklet on industrial dusts and fumes is the second oi a series o f which the purpose is to show the most important effects o f occupations, show how these occur, give measures for treatment, diagnosis, and prevention, meanwhile considering the source or cause o f such conditions. I t is hoped that these simple and brief expositions will be o f considerable help to industrial physicians, and to private practitioners w ho have am ong their patients employees o f industrial plants subject to such exposure. D efinitions Dusts m a y be defined as solid particles o f m atter which are ordinarily produced by grinding, crushing, drilling or blasting 1 SC 030893 Dusts and Fumes in Industry processes, the composition o f the particles ba n g the same as that o f the parent materials. These materials may be rock, metals, ores, or such products, for example, as coal, grains, or wood. T he size o f the particles varies from what is called ultra-micro scopic to those which are visible. Authorities now agree that the hygienic significant particle size o f dust ranges from a fraction o f a micron to 10 microns. {A micron is 1/25,000 o f an inch). T h e most frequently encountered dusts in industrial processes are mainly those from inorganic minerals, and a few organic dusts, such as wood and flour. Fumes may be defined as solid particles which are formed by processes similar to combustion, condensation and sublima tion. T he most common types o f fumes encountered in industry are usually caused b y the oxidation o f a metal, o f which typical examples are the oxides o f lead or zinc. Particle size is usually smaller than dust and ranges below one micron. In contrast to dusts, fumes tend to flocculate very easily. M any people erron eously speak o f fumes when they mean vapors o f liquid materials, such as acid solutions, organic solvents, and the like. Incidence an d E tio lo g y O usts are the most common type o f air contaminants en countered in industrial processes, and can occur whenever various materials, as mentioned before, are subjected to processes which break them up into fine particles; or where powdered or pulver ized materials are handled or transported. Inorganic dusts arc the prevailing type so far as frequency is concerned, but organic dusts are also found in different industrial operations. Fumes are usually found wherever there are molten metals such as lead, zinc, and catmium being processed or used in indus trial operations. W elding is an operation which has greatly in creased in frequency o f use and it m ay give rise to fumes o f the metals which are welded or to fumes and gases from the variegated coatings o f welding rods. z Incidence and Etiology It is to be borne in mind that metals m ay produce both dusts ' and fumes, according to the nature o f the operation and the state o f the materials when processed. For example, among the h ea vy metals such as lead, dust may be o f equal or greater etiologic importance with fumes -- other mineral dusts and metallic dusts also are considered o f etiological importance, as the following outline will show: ' I. Organic dusts: 1. Non-living organic dusts: (a) T o x ic and/or irritant dusts; " (Various organic compounds such as trinitrotoluene, mercury ful minate, terry!)." (b) allergy-producing dusts (woods, pollens, and the like). 2. Living organic dusts: (a) bacteria (b) fungi I I . Inorganic dusts: (mineral dusts) (a) toxic and/or irritant dusts; (mainly the dusts from heavy metals and their salts, such as arsenic, lead, manganese.) (b) fibrosis-producing dusts, (examples are free silica and asbestos). (c) non-fibrosis-producing dusts; (the so-called inert dusts, such as alundum, corundum, emery, lime stone, magnesite, marble, plaster-of-paris, and polisher's rouge).* T h e most important o f the non-metallic, inorganic mineral dusts is free silica, which produces silicosis, if breathed in suffi cient quantities over a long period o f time. Free silica dust and * T im it in accordance wirti th e present a t e o f Inow tedc*- fu ro r* studies and experience wit! probably show sror o f rb< so-called inert or truuance dusts to be harm ful. Dusts and Fumes in Industry asbestos dust are the two kinds o f mineral dusts which produce disease entities corresponding to the names o f the dusts -- sili cosis and asbestosis- Mixed dusts o f various kinds, such as various ores which contain different amounts of free silica, can produce different types o f reactions, according to the kind o f minerals which are in the ores. Where, for example, there are mixtures of iron, and various calcium-containing compounds such as gypsum, with free silica, a protective influence is exerted against the action o f free silica on the lungs. Other modifications o f free silica action occur according to the types o f minerals present some o f which tend to inhibit or restrain the action o f free silica. Another important conception with reference to the etiology o f dust and fume diseases which m ay result from exposure to these classes o f materials, is the use o f the terms exposure and hazard: they are not synonymous -- exposure merely means contact with some substance which is a potential health hazard; whether it is an actual health hazard can only be determined by an industrial hygiene engineering survey, in which the amount and kind o f exposure is rated, according to accepted standards o f concentration, size, and quality o f dusts and fumes. M any persons erroneously therefore state that there is a lead hazard, for example, when it is only known that contact is being made with lead; and when there are no data to support the contention that there is an actual hazard present in the working environ ment. M ethods for the determination o f dusts and fumes in the air, also with reference to the types o f devices used for such determinations, will be mentioned later. T h e importance o f air contamination will be realized when it is stated that the patho logic effects produced by dusts and fumes are brought about almost entirely b y the inhalation o f these compounds and ma terials. There is only one outstanding example, for instance, of the possibility o f absorption of lead through the slrin, namely tetraethyl lead, and this occars in the form o f a fluid. N o dusts, so far as is known, produce any systemic pathological condi- 4 General Diagnostic Methods dons from skin absorption, and it is doubtful that any kind of true fume is absorbed b y the skin. From the etiologic point o f view, particularly with reference to pathologic effects, the following outline shows how different types o f substances (among the dusts and fumes) act on various systems in the body to produce pathological effects: [. General systemic poisoning: Examples: Arsenic, lead, manganese, mercury. 2. Substances acting on the circulatory system: Examples: Arsenic, lead, mercury, vanadium. 3. Substances acting on the respiratory system: Examples: Asbestos, free silica. 4. Substances acting on the gastro-inleslinal system: Exam ples: Antim ony, cadmium, lead, mercury, zinc. 5. Substances acting on the skeleton and joints: Exam ples: Lead, mercury, mesothorium, radium. phosphorus, 6. Substances acting on organs of special sense: Examples: Arsenic, lead, manganese, mercury. 7. Substances acting as fetal poisons: Examples: Lead, mercury. 8. Substances acting on the genito-urinary system: Examples: Arsenic, lead, mercury, vanadium. 9. Substances acting on the brain and nervous system: Examples: Arsenic, lead, manganese. G eneral D iagnostic M ethods T h e accurate diagnosis o f pathological conditions arising from the inhalation o f industrial dusts and fumes has tremendous economic significance and also it is o f medicolegal importance. Moreover, it is impossible to understand how proper and effica- 5 SC 030897 Dusts and Fumes in Industry ceous treatment m ay be rendered unless a scientific diagnosis is made. I f a claim results from the pathological condition alleged, it is evident that the disease sustained m ust be directly related to the employment and further, must produce disability to entitle the individual concerned to compensation. Diagnostic methods with reference to dust and fume diseases need not differ widely, i f at all, from those used as routine pro cedures in general scientific medicine, although there are specific methods as in any other application o f general medical diagnostic principles to any special group o f persons. N ew discoveries occur relative to diagnostic methods In occupational disease work and for the most part, reliance must be placed on information which is scattered throughout the current literature in addition ro available textbook materia] which is better now than it was even five years ago. Emphasis has already been placed upon the vital part played b y etiology; it is wise to repeat that etiology forms the bulwark o f the diagnostic and therapeutic background. Among the methods which are used to make a fairly accurate diagnosis w ith reference to occupational diseases, is the taking of a thorough industrial history; consideration o f sym ptom atology, the physical findings, the results o f air examination; and finally, last but not least, a differential diagnosis, ruling out diseases o f ordinary life which have no relation to occupation. T h e industrial history m ay be o f very great assistance in arriving a t an opinion. M o st industrial physicians o f considerable experience believe th at it is desirable to include a complete resume o f the kinds o f occupations which have been experienced b y the individual bring examined, daring from the first jo b to the last one. I t is o f course clear that the details o f actual occupa tional exposure cannot be evaluated b y this method, but im portant information bearing on the diagnosis m ay thus be obtained. I t is the present practice, therefore, to list the occupa tions with the dates o f occurrence, in the industrial history. I t is 6 General Diagnostic Methods furthermore advisable to get more detailed information relative to the performance o f the occupation i f that can be obtained. This will at least give information relative to the kind o f exposure in industry, although it will give no idea o f the severity o f ex posure. T h e sym ptom atology in many kinds o f occupational disease is likely to be confusing rather than useful, because in many instances it so closely simulates that o f non-industrial disease that it is quite commonly not characteristic. Especial attention should be given, however, to the recording o f the symptomatology and critical attem pts made of its proper evaluation. Here again, distinction m ust be made between sym ptom s which may be due to non-occupational disease and those sym ptom s which are specific for occupational diseases -- this is where the difficulty arises in adequately assessing symptomatology. T h e physical findings, on the whole, are more reliable than the sym ptom atology, although in certain instances they too are not characteristic and are, therefore, liable to be somewhat puzzling. Where on ly one portion o f the body is affected, as in silicosis, for example, it might be assumed that the physical findings would be more characteristic, b u t the opposite o f this is usually true. In other instances, for example lead poisoning, where different organs and systems are pathologically affected, the picture is liable to be one which demands expert evaluation to differentiate from non-occupational conditions. Q in tcal laboratory data, including X -r a y findings, are frequently found to be decisive, although here again intelligent appraisal means proper interpretation o f the data. When they are decisive, such tests are b y the very specificity o f their nature, o f great value as diagnostic aids, although they should be defi nitely correlated with other findings. Differential diagnosis presents perhaps the m ost difficult problem o f all in the realm o f diagnosis o f occupational diseases. There is good reason to believe that differential diagnosis will 7 Dusts and fum es in Industry continue to be one o f the most difficult phases o f the medical ramifications o f the medicolegal problems of occupational dis eases. T h e reason which has already been indicated is that the symptomatology and frequently the physical findings imitate so closely the symptomatology and physical findings o f non industrial diseases, that one m ust make use o f specific procedures which are designed especially as diagnostic guideposts. Frequently such specific procedures are not used to any great extent, except b y those who are highly specialized in the field and whose work takes them into a review o f the current literature containing these developments. For example, one may believe that an industrial employee has lead poisoning, largely because o f second hand knowledge that lead was used in his occupation, more easily than one could demonstrate adequate etiology and the existence o f lead poisoning b y scientific methods. Because o f all o f these obvious and other difficulties, it seems wise to adapt specifically certain examination procedures to industrial problems arising out o f occupational or suspected occupational diseases. M ost authorities now agree that the examining physician can be o f greater service and give more effi cient advice regarding either acceptability for employment, continuance in it, opinion on the diagnosis o f systemic pathologic conditions and the estimation o f disability, if he is conversant with the following points: 1. T h e nature and extent o f the industrial exposure into which the employee will go or where he has been. T h is can be determined only b y scientific methods which will be referred to later. 2. T he effect o f this specific exposure upon normal and abnormal physical states o f employees, as interpreted by the physical status o f each individual on examination. (This refers specifically to etiology in the industrial en vironment and the effects which such etiology m ay or could produce.) 8 Clinical Examples 3. T h e nature o f the protective devices supplied bv the em ployer, if a hazardous exposure cannot be otherwise con trolled, and as to whether these devices are functioning efficiently. (Reference will be made later to these devices, especially designed for protection against dust and fume exposures.) I t is realized that these procedures are somewhat removed from the usual program o f physical examinations, particularly with reference to the work o f part-time industrial physicians, but it is also expected th at the physician will be called upon increas ingly to know and appreciate such information so that he may function better as a diagnostic medium. Because the most frequent and most significant exposures in industrial processes are free silica dust and lead and its com pounds, it seems advisable to include in the next section some clinical examples, namely silicosis and lead poisoning; there will also be included a brief discussion o f metal fume fever. C linical Examples Sim ply stated, silicosis is a disease o f the lungs, caused by the continuous inhalation over a long period o f time o f very finely divided, microscopic, particles o f free silica dust. There have been various standards set up b y different agencies, based upon studies o f silicotic workmen and their exposure to free silica dust. The National Silicosis Conference Report on Medical Control o f Silicosis says: "T h ere is evidence that for prolonged exposure a concentration o f more than five million particles per cubic foot o f a highly siliceous dust is dangerous. Therefore, it is now con sidered good practice to hold concentrations of highly siliceous dust a t 5 mitlion particles per cubic foot, or less." Because o f the fact that industrial exposures, involving high free silica content in which the concentration o f dust should be restricted to five million particles per cubic foot, are relatively infrequent in industry, and also because the opposite usually 9 Dusts and Fumes iu Industry occurs (an exposure to "m ixed" dusts which contain appreciable amounts o f free silica but also contain considerable amounts o f other types o f material) it is believed wise to refer to the formula* developed by the National Silicosis Conference with reference to a working criterion with respect to satisfactory or unsatisfactoryconditions, when exposure to `mixed* dusts occurs. It is to be borne in mind, however, that any unprotected industrial operation, which involves the production o f a lot o f fine dust particles o f material containing a relatively large percentage o f free silica, offers a potential silicosis hazard. T he incidence of silicosis is not known with any degree of accuracy, although various estimates have been made. One of these made some time ago by the American Institute o f M ining and Metallurgical Engineers indicated that in the United States the number o f industrial workers exposed to the silica dust hazard is in excess o f a half million. Figures quoted by the Com mittee Reports o f die National Silicosis Conference disclosed estimates that approximately 2 % o f the working population of the United States or about one million workers are exposed in some w ay to the potential hazard o f silicosis, and that perhaps half o f this number, 500,000, or 1 % o f the total, are exposed to a serious hazard. I t is furthermore believed that approximately 110,000, or 0.2 o f 1 % o f the total, have silicosis to some degree, but likely only 4000 to 5000 (a small fraction o f I % o f the total) suffer any degree o f disability from the disease. (These figures are based upon prewar estimates.) I t can readily be seen that silicosis, although not a rare disease, is not common and furthetroore ro t as common as may ordinarily have been supposed by many persons. Recent conceptions with regard to the contraction o f silicosis have established the belief that approximately 2 5 % of those exposed to a real silica hazard will eventually develop silicosis. * F O R M U L A A : "`M u ltip ly th e p erccorace o f free silica h r d i e t o n ! d o c o u o r. I f th e r o u t s * tra d e r 5 xb*1Iior. rh * co n d itio n m * J be con sid ered perm issible., i f (h e re v o lt tc o v e r 5 trvot*. cHe- * ik m a n m ay be considered to o high. Tor exam ple. 10 p s cent free trficz wtrfi an average to tal d a it cerK cntrvion a f JO p*ncte* p t t cubic fa c t w ould g > ve9.l0 t i n u JO miHion. w hich ^tiaJa J rndkoft <Ded practice} 30 p e t era* w ith i n a v e rse * tnca! d a n e o e e e n ffa rio a o f SO roiUtofi. w ovM cq o a t 0 3 tim e s 50 , w 13 m illion ( u B w a r a c to r r ) . T h is fo rm u la ip doc ap p lica b le t o a n y d u s t COO- M iiu o t l*i< th a n S p e t t a t free sibc*.'* 10 Clinical Examples W ith respect to the occurrence o f silicosis in the foundry industry, a prewar survey by the Division o f Industrial Hygiene o f the N ew Y ork S ta te Department o f Labor, based on a stu d y o f 3 11 foundries, o f which 80 plants included X -ray examinations involving 4,754 employees, provides some interesting figures: the X -ra y summary showed th at 3,259 or 80.2% were negative; 185 or 4 -5 % showed fibrosis; 1 10 or 2 .7 % showed silicosis with and without infection; 485 or 1 1 .9 % showed healed primary and re infection types o f tuberculosis; 27 or 0.07% showed clinically significant tuberculosis. I t was concluded, as stated in the report, that it would appear th at the silicosis hazard in the foundry industry in N ew Y ork S tate, while existent, is o f mild degree of severity and m ay be expected to yield satisfactorily to appropriate measures o f control. T h e report further indicated that tuber culosis as manifested b y X -r a y films o f the chest was found to be more prevalent among silicotics than among non-silicotics in foundrymen. T h e occupational history, as previously indicated, is o f con ' siderabte importance. Forms for the recording o f occupational records have been devised by various organizations and groups and by physicians and insurance companies. One of the most complete and longer forms has been devised and used b y the Saranac Laboratory, Saranac Lake, N . Y ., in connection with silicosis studies and symposia on silicosis which have been held b y diis group. I t is suggested that the physician, if interested, should contact the industrial hygiene bureau o f his state health department through which detailed forms m ay be secured or information relative to them. T h e symptoms and physical signs are not characteristic; they m ay be confused even b y skilled diagnosticians in other diseases, with the sym ptom s and signs which commonly occur in both minor and the more serious types o f the well-known respiratory infections. Characteristically, shortness o f breath on exertion and decreased chest expansion frequently occur in advanced cases o f silicosis, bu t these findings must also be differentiated as it Dusts and Fumes in Industry to their casual relationships and their possible association with other diseases. T he clinical confirmation o f the diagnosis o f silicosis rests m a n ly on the characteristic X -ra y appearance o f the chest. T h is shows the typical lesions o f silicosis, hyaline fibrous nodule$ which are scattered as opaque bodies throughout both lung fields, the density o f these nodules being somewhat less than calcified bodies, bu t discrete in outline, all about the same size in the early stage (so-called millet-seed size) and evenly dis tributed throughout both lung fields. These nodules appear as the first indication o f silicosis, later become somewhat confluent and in the latter stages, there are large masses o f opaque material found near the periphery o f the lung fields. In the later stages of silicosis, the disease is frequently complicated by infection, usually tuberculous in nature. A s an aid to interpretation o f the X -r a y films o f the chest where silicosis m ay be suspected, it is suggested th at the physician refer to a tabulation o f the X -r a y changes in silicosis, with the underlying histological conditions which cause them, published in the transcript o f the Second Silicosis Symposium, Saranac Lake, N . Y ., 1935. Diagnosis rests upon proof o f occupational dust exposure sufficient to produce the disease, and the presence o f character istic nodular lesions in the X -r a y film o f the chest. T h e mere mention o f occupation is not sufficient for diagnostic purposes -- adequate knowledge concerning the quality and quantity o f dust exposure, as well as the length o f the em ploym ent period, is necrasary to establish a distinct causal relationship. Although considerable diagnostic reliance is usually and properly placed upon the history o f adequate occupational dust exposure and the characteristic chest X -ray appearance, a thor ough physical examination w ith appropriate clinical laboratory examinations should be done, especially with reference to the ruling out o f other respiratory diseases. Diagnosis becomes essentially a differential diagnosis, as before explained, one which is likely to be difficult, necessitating special experience Clinical Examples and knowledge. Some o f the conditions requiring differential consideration here are miliary tuberculosis, multiple calcifications o f healed tuberculosis, cancer o f the lungs, and fungous growths o f the lungs. W ithin recent years, superimposed infection has come to be the accepted cause for disability. T h e outlook in simple silicosis, therefore, [that is, without infection) is more favorable than was formerly believed. I t is obvious that the chief problem for the silicotic is to avoid superimposed infection, which is usually tuberculous. There is no one specific, efficacious treatment for silicosis, although in recent years, the inhalation o f metallic aluminum powder has shown some promise. In cases where tuberculosis complicates the picture, it is obviously to be treated b y the best known methods for that disease. There is some recent evidence that surgical therapy as used in ordinary forms o f tuberculosis is also a help in the type o f tuberculosis which follows silicosis. T h e evidence for this is not conclusive, but there are good results on record. In general, recommendations for the treatment o f cases of silicosis vary with experience and with the findings o f each case. It is believed, for example, that no treatment is necessary in the case o f an individual without symptoms, whose X -r a y film o f the chest (taken perhaps in a routine industrial survey) shows only widespread discrete nodulation without localized shadows indi cating infection. However, the employee should have serial X -ray examinations with physical examinations o f the chest at least once a year and should be removed from further silica exposure to some other jo b , since the disease is very slowly progressive and there is at this stage no disability which precludes continua tion in employment. A person with localized conglomerate lesions m ay have symptoms and usually cannot do as heavy work as formerly; therefore, a lighter jo b should be found. In the presence o f active infection where there are symptoms or incapacitation, the individual cannot obviously continue in his 13 Dusts and Fumes in Industry former employment. I f the case is one of open tuberculosis with positive sputum, it is evident that such an employee is a source of danger to his fellow workmen and should be placed in a sani tarium or hospital. In cases o f inactive infection with no incapaci tation, lighter work should be provided, without further dust exposure. Dusts containing silica in combined form do not cause silicosis; however, one such dust, asbestos, a magnesium silicate, will produce a characteristic fibrosis which is called asbestosis. T h is disease is quite different in its pathology from silicosis, and has a characteristic `ground-glass' appearance on the X -r a y films of the chest. Animal experimentation indicates that the action of asbestos is probably mechanical, since it cannot be produced in other than the pulmonary tissue. Asbestosis m ay cause disability and a few fatal cases have been recorded, but in those cases show ing marked disability, other organic disease is usually also present. T h e sym ptom atology and physical findings include cough, dyspnea, pallor, clubbing o f fingers, and diminished chest expansion, with a characteristic X -ray appearance as previously mentioned. Lead Poisoning Lead poisoningoffers a good example o f an industrial poisoning which is contracted by the inhalation either o f a toxic dust or fume, and has been stated to be one o f the most frequent and important types o f metallic poisoning in industry, on account o f the wide, spread use o f lead and its compounds. Although there are no reliable statistics available with respect to the national incidence o f lead poisoning, it is believed th at lead poisoning is very prevalent and that most o f it is mild. The incidence o f severe types o f cases, particularly lead encephalo pathy and the more severe types o f nervous system involvement are not seen with as great frequency as in former years. M an y physicians who arc used to handling industrial cases now rarely see a case o f wrist drop due to lead poisoning, whereas ao to 25 years ago it was a rather common phenomenon, in cases o f lead Intoxication. i4 Clinical Examples T h e industrial history is o f great importance," as previously indicated, and a thorough consideration o f the nature and extent o f the exposure to lead and its compounds is an essential point in the etiology. It is now generally accepted that the standard of the U . S. Public Health Service and the American Standards Association o f 1.5 milligrams o f lead per ten cubic meters o f air, is the maximum allowable concentration. Because it is now con ceded that practically all industrial lead poisoning is contracted by the breathing o f lead dust and fumes, it becomes o f considcrablc importance in working out the etiology to ascertain the amount and quality o f lead dust and fumes in the air, during the occupation o f the involved individual. T h is point will be dis cussed later with reference to prevention. Formerly, the nature and variety o f non-industrial sources of lead intake made it particularly difficult to establish industrial etiology on a sound, and competent basis. More recently, how ever, non-industrial lead intake has been measured b y scientific methods and with the exception o f an occasional difficulty with various types o f homemade beverages stored in utensils glazed with a lead compound, the non-industrial lead intake is not believed to be a considerable factor in the production o f lead poisoning m adults. There are, however, some exceptions and these should be taken into account, as indicated. T h e diagnosis o f industrial lead poisoning is not a simple m atter on account o f the fact that clinical sym ptom s and signs are protean and are liable therefore to simulate other diseases. Great increase in our knowledge, however, has occurred within the past ten to fifteen years, and it is now known that there is a close relationship between the action o f lead and its compounds within the body and the calcium metabolism, and further, normal and abnormal excretion o f lead has been worked out on a scientific basis. I t is now an accepted fact that persons without industrial exposure normally excrete a certain amount o f lead in the urine. I t has been stated that definite clinical findings o f lead poisoning are practically always associated with abnormal urinary lead 15 _ I ' ; \ 1 * f 1 SC 030907 ` Dusts and Fumes in Industry excretion -- the reverse, however, is not true -- that abnormal urinary excretion o f lead in the absence o f characteristic clinical findings indicates lead poisoning. t Other laboratory findings are important, particularly the examination o f the blood, some investigators and clinicians using the increase in basophilic stippled red cells as an indication o f positive findings and others using w hat is known as the basophilic aggregation test. Both are found to be successful, the former more adaptable in cases o f frank poisoning, the latter more useful in cases o f lead absorption and suspected incipient poisoning. Although as indicated, the clinical symptoms and signs of lead poisoning are protean, the principal effects are expressed in the blood, the gastrointestinal system , and the nervous system, named in order o f their usual chronological occurrence. In brief, the most consistent findings are changes in the color and form o f the red cells o f the blood, colic and constipation, and weakness and atrophy o f the extensors and flexors o f the muscles o f the I wrists, with partial paralysis in the more advanced types o f cases. T h e differential diagnosis, as m ay be obvious, has to do mainly with differentiating industrial lead poisoning from non industrial diseases which may involve the blood, the gastro intestinal system, and the central and peripheral nervous systems, producing changes which are similar to those observed in frank lead poisoning. Such non-industrial diseases show a considerable variety o f pathological processes aifecting the above-named systems. T h e treatment o f lead poisoning has undergone considerable change within the past ten to fifteen years. In general, the treat ment consists mainly o f appropriate therapy for the toxic episodes and the mobilization o f stored lead in the long bones. I t is usually agreed that it is wise to facilitate the storage o f lead b y an excess calcium intake rather than to set lead free in the blood stream; after the passing o f acute toxic episodes, the elimination o f lead m ay be assisted b y means o f low calcium intake, the administra te SC 030908 Clinical Examples lion o f weak organic acids and ammonium salts, sodium bicarbo nate, and potassium iodide. C are should be exercised in using such forms o f treatment on patients who have nephritis. Tw o schools o f thought with widely divergent views exist with reference to deleading the body: there are those who feel that in the m ajority o f instances deleading will accomplish good results, while there are others who adopt a conservative attitude and because o f the possibility o f precipitating acute sym ptom s, feel that it is safer to produce artificial deleading b y slow methods, or to resort to the natural process o f letting the bod y delead itself over a period o f time. T h e choice in the m atter depends upon the individual case and the previous results which have been achieved at the hands o f the physician in charge o f the case. Storage o f lead m ay be facilitated in acute cases b y a high calcium diet or by the slow intravenous injection o f ro cc o f 2 0 % calcium gluconate; variations with relationship to this form o f treatment have been devised b y various physicians. In the delead ing process, low calcium diet together with oral administration o f ammonium chloride has been found to be effective, whereas in certain cases parathyroid extract and sodium bicarbonate also have been useful. W ithin recent years it has been established th a t large doses o f viosterol have been instrumental in increasing the excretion o f lead. Other investigators have found that an adequate phosphorus intake is essential for the depositing o f lead in the bones and for the removal from the bones o f the excess cations, as the insoluble phosphate salts in the feces; it has therefore been recommended th at deleading m ay be accomplished b y giving a diet low in calcium and relatively high in phosphorus, using viosterol 20 minims daily. There are also variations o f treatment with reference to the amount o f intoxication, and where there has been high, medium or low lead intake in industrial occupations. In all these types of treatment, deleading should be done in the hospital where the patient m ay be closely supervised. Some investigators advise 17 Dusts and Fames in Industry j against deleading more often than once in four weeks and the J course should not be prolonged for more than three or four days; some physicians believe that it m ay take from six to fifceen courses o f deleading to free the individual o f his most loosely- combined lead, which o f course is the most dangerous type o f lead. I t is again warned that deleading should not be undertaken in the presence o f acute symptoms; it is further agreed by all in vestigators that calcium therapy is considered to be the most specific at the present time. ' T h e outlook in cases o f lead poisoning is much better now than formerly because o f the occurrence o f moderate types of effects, the severer forms being a great deal less frequent than in former years. Metal Fume Fever This name is applied to the condition which results from breathing fairly heavy concentrations o f freshly formed metallic oxide fumes, principally zinc and one of its alloys, brass; although the condition m ay result from the inhalation o f other metallic oxide fumes. M etal fume fever is not a system ic poisoning, but it should be borne in mind that some o f the m etallic fumes that can cause it, such as lead, cadmium, mercury, and manganese, m ay also cause systemic poisoning. T h e sym ptom s come on some hours after exposure, usually after leaving work, a dryness o f the throat being first noticed, which m ay be followed b y a dry cough and a feeling o f heaviness in the chest. Rise o f temperature, accompanied by sweating, and leucocytosis and elevation o f the pulse rate and the blood pressure usually follow, sometimes with chills. T h e sym ptom s ordinarily pass off in 12 to 24 hours and the usual experience is that the employee returns to work the following day. A natural immunity is conferred in certain types of workers, which seems to be lost rapidly after removal from continuous exposure. Diagnosis is made usually on a clear history o f industrial exposure to metallic oxide fumes. It must be remembered that 18 ' SC 030910 Other Dusts and Fumes the effects and symptoms o f metal fume fever are very similar to those o f influenza and that the m alady is more often noticed in the fall and winter, when influenza usually occurs. T h e in dustrial history is, therefore, important in diagnosis, particularly with reference to a causative exposure to metallic oxide fumes. T h e outlook is good for complete recovery in a short rime and usually there is no rime lost from work, although there m ay be temporary incapacity in terms o f hours. T h e treatment is symptomatic and especially directed toward comfort because the patient usually recovers within a relatively short rime in all events. R est in bed with adequate warmth and protection from drafts are recommended. However, all suspected cases o f metal fume fever should be attended by a physician because the symptoms m ay closely simulate influenza which makes the differential diagnosis important. O th er D csts a n d F umes I t must not be concluded th at although clinical examples were given o f silicosis, lead poisoning, and metal fume fever, there are not other examples which are o f importance. These subjects were selected because o f their frequency o f occurrence and because o f the fa ct th at they are commonly encountered as examples o f dust alone, dust and fumes, and fumes. Am ong the other metals which m a y be mentioned are arsenic, antim ony, cadmium, manganese, mercury, radium, selenium, silver, tellurium, thallium, and vanadium. N o t all of these are equ ally important with reference to toxic effects. Probably the m ost important o f these from a toxic point of view are arsenic, mercury, manganese, and cadmium. Arsenic pro duces chronic poisoning chiefly from breathin g over a long period of thin air containing dusts or sprays o f arsenic compounds. The compounds o f arsenic such as lead arsenate, paris-green, arsenic oxide and arsenic sulphide are among the more dangerous forms. J9 Dusts and Fumes in Industry Where dusts o f mercury are present, they will be in the form o f either mercurous or mercuric compounds, where metallic mercury is used in the manufacture o f such items as thermometers, mercury switches, mercury vapor lamps, mercury boilers, etc., the hazard is from the vapor since mercury has a considerable vapor pressure even at normal temperatures. Mercurialism is characterized b y three features: inflammation o f the mouth, muscular tremors, and psychic irritability -- sometimes all of these are encountered and sometimes only two or only one. In the more chronic or slow form o f poisoning, a characteristic tremor is the commonest symptom, coming on late, and has been noted to occur particularly among mercury miners. Manganese poisoning is an old industrial poisoning, having been described more than 100 years ago, but has receded in incidence in American industry. Characteristically it produces a peculiar slapping gait with phenomena o f retropulsion and pro pulsion; masklike faces; monotonous voice with economical speech; muscular twitching varying from a fine tremor to gross rhythmical movements o f the extremities; languor and sleepiness; cramps in the calves o f the legs with stiffness; slight increase in the tendon reflexes without any disturbance o f the deep or super ficial sensation. Studies within the past five years indicate that dust is the most important type o f exposure. Cadm ium is encountered in the smelting o f ores, the handling o f socalled 'blue powder' compounds, the spraying o f pigments, the welding o f alloys, and the melting of cadmium metal itself, as well as certain non-industrial exposures where utensils have been plated with this metal. In recent years there have been several outbreaks o f cadmium poisoning among non-industrial users o f such utensils. T h e use o f the metal has increased tremen dously and therefore, there is more industrial exposure. T w o types o f effects have been observed, those with reference to the lungs and also those with reference to the gastro-intesrinal tract, the former being more important and more frequent. Pulmonary involvement is characterized by a feeling o f constriction in the - 20 * SC 030912 1 WuirijS!SBW Prevention chest, edema and congestion of the lungs, sometimes with hemorrhage, proliferative interstitial pneumonitis; while the latter is characterized by nausea and vomiting and a general irritative reaction o f the gastrointestinal tract, with diarrhea, I hiccough, and oliguria. I f further details are desired on the clinical aspects o f the metals mentioned, standard works on industrial hygiene and occupational diseases should be consulted. P revention T h e general principles o f prevention involve first the identi fication o f industrial exposures and the evaluation o f such ex posures b y proper scientific methods to determine whether or not they represent actual health hazards. This is done by sampling 4 the air and determining the amount o f air contaminants and the } quality o f them in each type o f occupation or problem involved, and comparing the results with the accepted standards o f maxi mum allowable concentration that have been adopted by official bodies. Second, after it has been determined that there is an actual health hazard represented by the occupation, control measures, both engineering and medical, are instituted to control the hazard, providing it cannot be entirely eliminated. In discussing the methods o f engineering control, we arc con cerned with three basic principles: 1. Investigation o f occupational conditions. 2. T h e measurement o f the occupational exposure and the rating o f the hazard, if one exists. 3. Putting into effect the specific measures o f protection which have been indicated by information secured under (1) and (a). Am ong the methods o f approach for engineering control measures m ay be mentioned: 1. Physical and hygienic survey o f plant conditions. 21 SC 030913 Dusts and Fumes in Industry 2. Occupational history and analysis. 3. Adequate information concerning materials and processes used. 4. Atmospheric and gross sampling o f materials, combined with quantitative physical and chemical determinations. 5. T he rating o f the hazard b y comparing the findings in the given instance with accepted standards. 6. An appraisal o f the efficiency o f protective apparatus and devices. 7. An adequate and proper interpretation o f the information so that it can be applied practically to the industrial problem involved. When the foregoing methods o f approach to engineering control have been carried out and information secured from them, the information can indicate the necessity for using specific methods o f protection which have been found useful in different com binations; 1. T he use o f mechanical devices, such as exhaust ventilating systems, respirators, masks, and the like. 2. T he changing o f processes (segregation, enclosure, w etting, etc.). 3. Substitution o f nontoxic materials for those o f proved toxicity. 4. Educational programs for management, workers, engineers, and physicians. j . Continuous maintenance and checking o f the efficiency of protective equipment. A tm osph eric Sam pling T he best method for collecting a sample o f a dust or fume from the air will depend somewhat upon the type o f contaminants to be sampled. T he degree o f hazard o f fibrosis-producing dusts is measured in terms o f particles per unit volume o f air (example: Atmospheric Sampling io million particles of silica dust per cubic foot ol air) while toxic dusts and fumes which m ay cause systemic poisoning are usually measured in terms o f weight per unit volume o f air. (Example: lead dust 1.5 milligrams per 10 cubic meters o f air.) Since results may vary with the type of air sampling device used, it is important to select a type accepted through general usage in the practice o f industrial hygiene. The larger Impinger which samples one cubic foot o f air per minute by impinging the air containing the dust particles from a nozzle submerged in w ater or alcohol against a place or bottom o f the flask was used in all o f the original studies in the United States on fibrosis-producing dusts. T h e large Impinger, however, has the disadvantage o f being bulky and requiring electric current or compressed air for operation o f the motor-driven air pump, which produces the suction stream for air sampling. A portable M idget Impinger has been developed which has been proven to give results as reliable as the large Impinger. This apparatus samples a t the rate o f 1froth o f a cubic foot per minute and is operated b y a hand cranked, positive action, four cylinder pump, in conjunction with a vacuum regulator which maintains an unfluctuating suction regardless o f minor variations in rate or smoothness o f cranking. A fter the sample has been collected in the Impinger flask, a portion is placed in a special dust counting cell and counted under a microscope with an eyepiece having a special ruling similar to a blood count ruling. Further analyses are necessary with reference to the amount o f free silica in the dust and this is accomplished b y the use of specific chemical, petrographic and X -ra y diffraction methods. T he Impinger method o f sampling is not entirely suitable for collecting fumes or dusts o f toxic materials such as lead, cadmium, and others because the efficiency o f the Impinger is not adequate when sampling the very fine fume particles and since the amount ..* * li ' MiHBMtM Dusts and Fumes in Industry or concentration o f such materials in air which m ay be injurious is much smaller than the safe amounts o f fibrosis-producing dusts, a correspondingly large air sample should be taken for reliable results. T h e Electrostatic Precipitator is widely used in the collection o f toxic dusts and fumes, particularly o f metals and their com pounds. A Portable Electrostatic Precipitator has been developed which operates from n o volts, 6a cycle current, and by high voltage electrical precipitation collects the sample o f the particu late m atter dry on the inside o f aluminum or glass cylinders. T h is device samples at the rate o f 2 cubic feet per minute. After the sample is collected, a quantitative chemical analysis is made in the laboratory. This type o f apparatus permits determinations o f very low concentrations o f many different kinds o f atmospheric particulate matter. Where equipment or personnel is not available for atmospheric sampling, state industrial hygiene bureaus or private testing laboratories m ay be engaged. M an y insurance companies also have facilities for such work. T h e Industrial Hygiene Foundation in Pittsburgh, Pa., an association o f industries for the advance ment o f healthful working conditions, also have an excellent staff o f technicians for industrial hygiene surveys or consultations in this field. R espiratory P rotective E quipm ent - . -I t - frequently, happens that because o f the nature o f the operation or process in an industry, it is not possible to thoroughly control a hazardous exposure resulting from the evolution of dusts and fumes. In such instances, it is considered wise to pro vide employees with personal respiratory protective devices. These vary with the kind o f exposure and with the amount of materials in the air. For ordinary conditions in which only dusts and fumes are present, simple filter type respirators are available which will - ' SC 030916 Respiratory Protecttoe Equipment protect the worker against the hazards o f breathing these dusrs and fumes. Such respirators normally consist o f a facepiece covering the nose and mouth, made o f some pliable material such as rubber which will conform to the face and provide a comfortable and dust-tight fit, and to which is attached a filter made o f treated paper or felt through which the air is inhaled. I f the filtering materia! is o f the correct typ e and density, it will effectively filter particles down to less than a micron in size from the air. Com fort is a most important consideration in a device o f this type. Since a high breathing resistance will materially affect the comfort o f the wearer, the filters should be o f large area so that the inhalation resistance will be as low as possible. Valves should be provided which open on exhalation and further lessen the exhalation breathing resistance. T h e particular type o f filter employed will depend upon the kind o f contaminant present in the air. Since the am ountsof such toxic materials as lead which will affect the wearer are much smaller than the harmful amounts o f fibrosis-producing dusts, a filter will have to be more effective when used against toxic dusts than against fibrosis-producing and nuisance dusrs. For special operations such as sandblasting, a mechanical filter type respirator is not practical because o f the extremely high concentrations o f dusts present. In such conditions, special airsupplied masks or respirators should be used in which air from a compressed air line is supplied through" a hose to the facepiece for breathing. Such devices may also be employed if desired as protection in less severe and hazardous operations. T h e advantage o f an air-supplied respirator is that there is no breathing resistance and the wearer is protected against any and all dusts and fumes in the surrounding atmosphere. However, the restriction by the air hose which must be attached to the wearer a t all rimes be tween his facepiece and the air supply, prevents the use o f this device in m any operations where the worker must move freely Dusts and Fumts in Industry over a considerable area. Furthermore, caution must be taken to see that the air supplied to such devices is free from all in jurious or objectionable odors and contaminants and that the humtdity and temperature o f the air is such as to provide reason able comfort. T h e United States Bureau o f Mines (Department o f the Interior) tests respiratory protective devices against various air contaminants under carefully controlled conditions. Devices meeting its tests receive that Bureau's official approval, and this is indicated by approval numbers on the device and a reproduction o f the certificate on the package. Equipment approved by the U. S. Bureau o f Mines for the particular contaminant or class of contaminants in the air should be used. M EDICAL CONTROL It is o f course obvious that medical control measures are futile after a disease has been contracted because o f the exposure to dusts or fumes except when the information is adapted to prevent additional cases. However, before the diseases are contracted, there are a number o f things that can be done b y physicians to prevent such occupational diseases, which may be summarized as follows: j . T he intelligent use o f preemployment physical examina tions, including chest X -ray films, and appropriate clinical laboratory tests as indicated. 2. Similar use o f periodic physical examinations, chest X -ray films, and clinical laboratory tests on employees in occu pations where typical hazards have been proved to exist, by industrial hygiene investigations. 3. Responsibility for seeing that hazardous exposures are properly taken care of, by various efficient methods o f protection, including the supplying o f personal respiratory protection, where industrial conditions make it impossible to control the hazard b y other means. 26 Medical Control 4. Prompt transference to non-hazardous occupations of employees found to have symptoms o f an occupational disease associated with their exposure. J. Prompt removal from work o f all persons suffering from active occupational diseases, when such persons are a menace to themselves, their fellow workmen or the em ployer. 6. Adequate provision for treatment, rehabilitation, and prompt return to work, o f employees having disability resulting from occupational diseases. Summary In this brief discussion o f dusts and fumes in industry, the sources, effects, and control have been considered under the following headings: 1. Definitions. 2. Incidence and etiology. 3. Genera] diagnostic methods. 4. Clinical examples. 5. Prevention -- general principles, including specific methods o f air sampling and apparatus for this purpose; specific methods o f protection, including mention o f respiratory protective equipment available; and other general methods. It should again be emphasized th at industrial managers are interested in the prevention o f trouble that m ay arise from exposure to dusts and fumes in industry, and that this principle is particularly important nowadays because o f the need for every person in active production, and in addition, because so many physicians are being used in the armed services. I t is believed that if the suggestions made in the foregoing pages are followed, the problems arising from dusts and fumes in industry can be successfully managed. 27 A pproved M -S -A Equipm ent for D u st a n d Fum e Protection M SA Protection for men and women workers against harmful dusts is the result o f many years uf research into all phases o f every in dustry's respiratory protective prob lems. In a well-equipped D ust Re search Laboratory, which is a special division o f our Research Department, continual study o f dust hazards is maintained, and from this research group have come many o f the most important improvements in dust pro tection-- dating from the first U. 5 . Bureau of Mines-approved dust respi rator, the famous M-S-A "C om fo." The M-S-A trademark on the pro ducts you recommend is a solid assur ance o f excellence in design, manu facture and performance. A il applicable M-S-A personal pro tective equipment against harmful dusts or fumes is approved by the highest authority-- the United States Bureau of Mines, official testing agency o f the United States G overn ment for safety equipment. The ap proval certificate o f the Bureau signifies that each product has passed the most stringent impartial tests-- fit for the most exacting service in industry. W e will be glad to send you, upon request, descriptive bulletins on any Or all o f the products mentioned in this booklet-- without obligation. 28 M -S -A ' Filter R espirators Dcvigncd for against lurnv ful du*ts anti fumes b y the cse u f iruef- ihin^csble filters, Each uf these Ropi* m o r s a n g e r s ail rfivpirau>r> print* th e requirements against pneunimunmsjv predating, nuisance o r toxic dusts. M-S-A'* D ustfoe 66 bureau of M ines A pproved. An improved j to m p aa and bgtmvetghc Respirator with larger exhalation valves reducing resistance to a minimum. These spring-retained valves diroi- rate disturbing variation in breaching, resistantx, and prevent a rc id e n u l rn n o v ai o f valves, Pace , piece cushion of neoprene sponge is contoured to provide autom atic &t, great wearing uunfurt. I | and air-tight veal w ithout adjustm ent. Elcctro- \ statically charged rerin*trea(ra filters supple- mecu mechanical bedding action o f filter's fibers. Simple focotcuctson a zu res guide and easy filter changing and cleaning oF Kc*piratt>r, W eight, including headband: 3 ounces. . M-S-A D ustfoe uitm*FHter R espirato r This to m fu it and lightw eight Respirator oF aluminum is designed fo r unusually toxic du>ts and extremely fine particles, its filter holder allows For good field o f vision and freedom f head movement. Facepiece forms to contour of wearer* face. N eoprene sponge cushion assures a irtig h t seal with minimum adjustment and maximum comfort. N eoprene stays Ft and Sliable: w ill not harden ( Ultra-Filter protects with age. M-S-A T jpe against toxic aerosols, radioactive dusts and fine panicle smoke; also effective against airborne bacteria and refrain viruses. Construction is simple fut easy filter changing and cleaning. M-S-A C omfo Filter R espirator i M ost versatile of the M-S-A Respirators. Facepiece is made of a special new soft com pound for improved wearing comfort and greater durability. Provide* dependable air-tight seal with wearer's face, and wilt not harden o r crack with age. Positive-arttoe a b ila ttu n valve offer little resistance to air. The Comfo features ia terch an g tab ilitr >f rhrec filters; Type F (Bureau of Mines Approved) for dusts not ignifitantly m ore toxic then lead; Type S (B ureau o f M ines A pproved) fur du>tv, m isu and metal fumes: and T jp e H Ulmi-Filters fur toxic aem sohy etrvm tly fine particles, radio active dust, bacteria and certain viruses. y> SC 030921