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FILE NAME: New York State & NY Times (NY) DATE: 1951 Feb DOC#: NY005 DOCUMENT DESCRIPTION: NY Dept of Labor Monthly Review - Dust Inhalation in Relation to Pulmonary Disease division o f In du strial H ygiene &SafetyStandard Vol. 30 February, 1951 DUST INHALATION IN RELATION TO PULMONARY DISEASE No. 2 I* f J ohn E. Sil so n , M.D. r Medical Unit ! Everyone is inhaling some dust with almost that disease and some other pulmonary pathology V every breath taken, but the results of this dust of non-industrial etiology. When the x-ray pic upon the lungs is considered part of the natural process of aging when it occurs outside of his oc ture is characteristic, as in an obvious case of nod if y/, cupation. The relationship of dust inhalation to ular silicosis, the physician is apt to inquire very y pulmonary disease is therefore usually considered carefully into the worker's occupation, and to en only from the point of view of industrial exposure. list the aid of industrial hygienists or other ex Observations on the effect of dusts in industry have consequently been limited largely to those pathological processes which can be clearly difierentiated from pulmonary diseases of non-oceupational origin. To these characteristic changes in the lungs produced by dust, the term pneumo perts in an effort to establish a dust etiology. When the clinical and sometimes even the pathological findings are almost identical with some non-oc cupational disease of the lungs, however, he is not so likely to seek far afield for an occupational coniosis has been applied. exposure. It was not until the unusual incidence Diagnostic F actors in P neu m o co niosis of workers dving from what was presumed to be Boeck's sarcoid in a plant manufacturing fluor escent lamps was noted, that the toxicity of one In order to establish the diagnosis of pneumo of the materials which they were handling was coniosis. two factors must be present: 1. pulmon even suspected, and that the identity of chronic ary pathology whi.h might have been produced pulmonary granulomatosis due to beryllium was 1u by exposure to a particular dust, and 2. an occu established.' Recognition of the dust etioiogy is y pational history of exposure to that dust. The even more difficult when the pathology is identical chest physician is generally in a good position to with that of a non-occupational disease, as for in evaluate "the first factor, through the medium of stance the primary lung carcinoma seen with .signs, symptoms, x-rays and laboratory tests. In increased frequency in chromate workers.2 determining the second factor, he is often handi capped by his paucity of knowledge of the nature Another way in which dust inhalation may affect of his patient's work and the materials handled. pulmonary disease is by aggravation of a pre or co Most physicians are aware that a rock miner or existing non-occupational disease. Today, the fact stone cutter may be exposed to free silica in am that silicosis predisposes a worker to tuberculosis, ounts canable of causing silicosis. They may not and renders that tuberculosis much more severe, lie aware, however, that a worker in a soap factory, is well established. We are just becoming aware, which includes in its products scouring powders, however, that some of the more innocuous dusts may be handling large amounts of silex. which is may adversely affect the course of tuberculosis almost pure pulverized silica. In other instances, and other pulmonary infections." It is no longer the etiology of the pulmonary pathology may not be so readily recognized because the physician is considered good practice for an individual with arrested tuberculosis to return to work in any * unaware of the more obscure effects upon the dusty environment. We all too frequently, how lungs of a material such as talc or bagasse. ever, see workers with chronic bronchitis, pulmon ary emphysema or even bronchiectasis who are Another factor which makes it difficult to recog permitted "to work in an extremely dusty atmos nize the importance of an industrial dust exposure phere. Even the increased coughing induced by in the pathogenesis of a pulmonary disease is the a dust which is slightly irritant to, the upper res dose resemblance which frequently exists between piratory passages, or neceS&ryfto clar these pas sages of the accumulate^particles, may be suffi i ' : t i i t \ J Jf Mu* Ar-.u.i! Wevtint: m he New 't>rk S t j t e C h a p t e r , Amcr- . .a n Cull*, ,,c >.<! t . l u -t I'ebrujry tilth. I'dfu- New York City. cient to nggravate a chronic*'', pulmonary 'disease.4 MONTHLY REVIEW of the DIVISION OF I N D U S T R Y HYGIENE AND SAFETY STANDARDS NEW YORK STATE DEPARTMENT OF LABOR 80 CENTRE STREET NEW YORK 13, N. Y. Industrial Cirr. musioner EDWARD CORSI - 1st Deputy Industrial Commissioner THOMAS F. MOORE, Jr. Deputy Industrial Commissioner in Charge EDWARD A. NYEGAARD The Division LEONARD GREENBURG, M.D., Director MAY R. MAYERS, M.D., Medical Unit WILLIAM J. BURKE, Chemical Unit GEORGE P. KEOGH, Code Unit ARTHUR C. STERN, Engineering Unit Industrial Hygiene LEONARD A. PERRIN, Engineering Unit E&* Building Plans Over and above all of these specific aspects is the general effect of dust on the aging processes of the lungs. I would like to quote an observation made by Dr. Edgar Mayer, in an article5 he pub lished a few years ago: " . . . . Respiratory infec tions and . . . . general dust exposure eventually provoke pulmonary changes. There exist only dif ferences in degree, not in kind, between the socalled normal amount of pulmonary fibrosis so prevalent in the general population and those severe fibrotic processes which destroy the lungs of workers in industries wherein exposures exist to more concentrated and continuous effect of the same agents present in greater dilution in the at mosphere of industrial centers." Dust Ch a ra cteristics A pre-requisite to the understanding of the ef fects of dust inhalation upon the lungs is a know ledge of the type of material under discussion. We have chosen to cover in this paper all forms of solid particulate matter generated in the course of industrial operations, because in so many instances their effects are similar or even identical. Fibers and fumes as well as dusts have therefore been in cluded. Since some uncertainty exists as to the exact meaning of these terms in industrial hygiene, we shall start with a few definitions. The term dust is applied to the solid particles produced by handling, cutting, crushing, grinding or pounding organic or inorganic materials such as rock, ore, metal, coal, wood, grain, etc. Fibers are the par ticles similarly produced from organic or inorgan ic material composed of thread-like or slender el ements such as cotton, wool, fur, bagasse or as bestos, and are also created in such operations as stripping, spinning and weaving. Fume is a term limited to the solid particles created by condensa tion from a gaseous state, generally after volatili zation from molten metals, and often accompanied by a chemical reaction such as oxidation. Ton trary to general usage, it docs not refer to con densations to a liquid droplet form, which ar< called mists, or to a uniform gaseous dispersion whether visible or invisible, which is referred ti as a vapor or gas. The common denominator of all these material is thus the fact that they are present in tin atmosphere as solid particles. An importnn characteristic of these particles is their size.'1 1 has been shown both theoretically and experiment ally that on inhalation those which are too larg*. do not reach the lung hut are filtered out in tie. upper respiratory passages. Particles which an too small, on the other hand, do not settle out and are therefore theoretically not retained in tin alveoli but are re-exhaled. The question of the in nocuousness of these sub-microscopic particles h.v recently been open to question. It is a genernlh accepted principle, however, that the particles ex ert their greatest deleterious effect upon the lung; when they are between 0.5 and 3 microns in di ameter. The other important factor determining the re action of a dust upon the lungs is its composition that is, its chemical and physical characteristics. Where it is a mixture of several different com pounds, such as the dust created in a granite quarry, the percentage of the most active ingred ient (in this instance free silica) is of the utmost importance. Even where the mixture is man-made and not a natural product, its composition has to be taken into consideration. For example, the sand used in an iron foundry may consist of almost punsilica, but the dust released in a shake-out opera tion will have a much lower silical content because a large part of it comes from the iron oxide par ticles separated from the surface'of the casting. The particle structure also appears to play a role crystalline silica has long been considered a far more active substance than the amorphous form, Fumes from a melting operation are frequently much more reactive than the same material creat ed as a dust by grinding or crushing. In some in stances even the shape of the particles has signif icance, particularly when their effects are depen dent to a large extent upon local mechanical ir - ritation. P rotective Mechanism s There are a number of mechanisms by which the lung perenchyma is protected from inhaled dust. ' Many of the particles may be filtered out by the coarse hairs guarding the entrance to the nose, or trapped by the moist walls of the turbin ates. Particles deposited on the surface of the mu cous membranes of the trachea and bronchi are carried back towards the pharynx by the wave like vibrations of the cilia, and also by the cough reflex induced by the irritation to the lining mem branes. Particles which succeed in passing these barriers and gain entrance into the alveoli are ingested by macrophages which arise from the alveolar walls and are commonly referred to as "dust cells." Some of these phagocytes, laden with dust, may pass up into the bronchioles and eventually be car- ricd off in the sputum; the others pass through the walls and into the regional lymphatics. Some of the latter are arrested locally in the peribronch iolar tissue, but the remainder pass onward into the peribronchial and perivascular lymphatics, and are finally trapped in the lymph nodes at the root of the lung. Types of P athology The type of pulmonary pathology which may be caused by the inhalation of a specific dust is de termined'by the manner in which this lung cleans in'5 mechanism is disturbed, and by the type of reaction which results. Probably the best known is the fibrotic reaction produced by exposure to silica.' This reaction represents a specific cellular response to the material. The particles engulfed by the dust cells stimulate the production of fibroblasts in any area where they are congregated; am! these fibroblasts arc eventually replaced by dense fibrous tissue. In the ease of dusts other than silica, this fibrosis is usually fairly generalized; but with silica, it tends to nodular formations along the lvmphatics. In either case, the net effect is to make the lungs less elastic, increase their bulk while decreasing their capacity, and decrease pulmonary circulation and aeration of the blood. Less characteristic is the action of those dusts which act as general irritants,0 particularly on the respiratory passages, but do not exhibit a specific fibrosing action. Included in this category are most of the organic dusts. Workers first exposed to them respond by sneezing and coughing, hut usu ally quickly become acclimatized so that the ir ritant action is no longer found troublesome. Con tinued inhalation of these dusts, however, may re sult in chronic inflammatory changes in the mu cous membranes. In addition to this generalized irritant action, certain dusts may elicit a specific inflammatory response.This may he of a chemical nature, as in the case of beryllium or Thomas slag, or may be infectious, due to bacteria or fungi carried in by tlie dust. In both instances, the pathology of the response depends upon the material producing it. ami may tie acute or chronic, reversible or per manently damaging. With sonic materials, for .in stance beryllium, the pathology is quite character istic. Even when the dust particles exert no irritant action whatsoever, there may he slight pulmonary changes dim to their mechanical effects." After all. insoluble particles which are phagoeytized and passed into the lymphatics may he permanently retained in the lungs. It is no? reasonable to cxnee1. that the lungs can become a physiological Iran for inordinate amounts of died and yet retain all their elasticity. Prolonged exposure to exee.-su e quan tities of even completely inert dusts, therefore, may eventually accumulate in sucm amoutus as to impair funelim.. Such impairment would Im the result of a mechanical process: the physical mesenee of large amounts of inert forc'gn material. The term benign pneumoconiosis has been given to this type of pathology in order to contrast it with diseases resulting from the inhalation of irritnnt matter. Pulmonary allergy is a type of response observ ed with certain organic dusts, ,J particularly those of plant or animal origin. The picture is one of a tvpicnl asthma, and only the occupational history differentiates it from identical reactions so com monly seen from pollens or house dusts. The dis tinction often can only he made by patch testing or similar procedures, which will demonstrate that the responsible antigen is present in the man's occupational rather than non-occupational environ ment. Primary carcinoma of the lung has at one time or another been ascribed to a great many of the industrial dusts produced in industry. Proving or disproving the carcinogenic properties of any par ticular material is often an extremely difficult procedure, because the pathology in no way differs from that of a lung cancer of unknown etiology. Merely demonstrating the co-existence of cancer and some other pulmonary disease such as silico sis, is not sufficient, since there is no reason why the incidence of malignancy in silicotics should be anv lower than it is in non-silicotics. The only sat isfactory proof of such carcinogenicity is the un equivocal demonstration of an incidence of cancer in workers exposed to a particular dust which is sufficiently higher than that of a comparable group of non-exuosed workers to have statistical signincance. Great care must be taken in selecting the control group to insure that all extraneous factors, such as age distribution, sex and non-industrial environment are identical. The high incidence of lung cancer in the uranium mines of Schneeberg and'joachimatal has been known for some time.13 More recently, an increased incidence of pulmon ary malignancy has been demonstrated in workers exposed "to chromate dusts,- although the statis tical significance of the data which have been col lected on this material is still being investigated. Asbestos lias on occasion been indicated as predis- posing to lung cancer. P u lm on ary Disease Due to Silic a Having presented the general types of pulmon ary pathology which may he produced by dusts. I would like to devote the'remaining time to a brief description of the specific pulmonary effects pro duced by certain materials. As has been previously no'nted out. undoubted!'' the most important of these is silica. This is the' oxide of the element sil icon. and is widely distributed, both free and com bined. in the earth's crust. Crystalline silica occurs put-.* as quartz and as beach sand, and is also scat tered in' varying percentages throughout many forms of rock, such as granite, marble and sand stone. Dusts eont-iining free silica can be created im'nslrial!v in a multitude of ways, such as drilling and blasting np<>r; lions in the course of mining and -vine, v."d-O". and ;L..,'iin; of atom , reck rrii .bine. etud. o!.'>,i*ig or *iny other operations in which quartz, .emu `or siitca-contairuiig rock is processed. Tim disease' is characterized anatomic ally by gcncraliz.. i fibroiie changes and the devel opment of miliarv undulation throughout the lung fields, ami clinicallv bv cough and progressive shortness of breath. Chest x-rays show at first an exaggeration of the lung markings and lymph node enlargement, which is followed by nodulation, and finally by coalescence and conglomeration Tuber culosis may be super-imposed at any stage, and is believed by some to be present in all areas where coalescence has taken place. As a rule, there is no fever or weight loss in simple silicosis, and these signs may be indicative of a complicating tuber culosis. The patient tends to go downhill very rapidly with the development of an active tuber culosis lesion. % Many observers have been-of the opinion that silicosis could be caused only by the crystalline form of silica, but evidence is accumulating to the effect that the amorphous form as well is capable of producing pulmonary damage. Observations upon the effects of amorphous silica15 have been made largely on workers exposed to diatomaceous earth, which is a light fluffy material formed by the accumulation of skeletons or shells of diatoms. It has a wide use in industry as filters, fillers and absorbents. In contrast to crystalline silica, it pro duces fibrosis of the lungs without discrete nodu lation. The fibrosis is much more marked when the exposure is to calcined material, during which pro cess microcrystals of chrystobalite may be formed. Another possible example of pulmonary damage due to non-crystalline form of silica occurs in work ers fusing bauxite in electric furnaces in the man ufacture of alumina abrasives."' The fumes given off in this operation consist17 of 25% to 40% sil icon dioxide and 40% to 60% aluminum oxide, together with small amounts of iron oxide and numerous other impurities. Under the electron mi croscope they are revealed as fused particles vary ing in size from 1/100 to Vt. micron in diameter. A high percentage of the workers exposed to these fumes have developed cough with expectoration, weight loss, anorexia, tightness in the chest, and dyspnea on exertion. X-ray examinations show a lace-like or granular increase in the lung markings, beginning at the apices. These gradually extend to involve the entire lung fields, and may be ac companied by pleural adhesions causing distor tion of the thoracic contents. Spontaneous pneu mothorax is a common complication. While the al uminum oxide has generally been advanced as the etiological agent responsible for this disease, it seems quite possible that this may be a response to silica fume with a particle size far lower than that generally considered injurious. Silica, when present only in combined form as a silicate, has usually been regarded as relatively inert. Considerable evidence, however, has been accumulating against this concept. Probably the best known of the silicates producing severe pul monary damage is asbestos.18 This is a mineral sil icate occurring in the form of long fibers, which renders it capable of being carded, spun, and wov en into threads and cloth, or bonded with cement into building shapes. Inhalation of these fibers in the course of mining or processing asbestos has been shown to be responsible for the development of a progresive pulmonary fibrosis with diffuse thickening of the alveolar walls. The outstanding symptoms are dyspnea and a dry cough. Emphys ema, pulmonary infections, and secondary cardio vascular changes due to increased pulmonary re sistance arc the most common sequelae. Chest x rays show a "ground glass" haziness, rather that the reticulation and nodulation of silicosis. Another combined silicate which has been showi to be not completely inert is talc, a hydrated mag nesiuni silicate used extensively in its powdcm form as a dusting agent. It may contain variabh percentages of free silica; and when these an high, the classical picture of silicosis has been oh served in workers mining, crushing, grinding ot otherwise handling it. Even when it contains unde: 1% free silica, however, as is usually the case the dust, when inhaled, is capable of producing a fine diffuse pulmonary fibrosis similar to asbes tosis.10 It tends to be disabling, and is frequently accompanied by dyspnea, cough and fatigue. In addition, deposits of x-ray opaque material on the pleural surfaces in the form of plaques have been observed. Still another silicate showing definite effect? upon the lungs is mica, which is a double silicate of aluminum and either potassium or magnesium. This mineral, because it splits into thin sheets which are quite transparent, and have a high di electric constant, has innumerable uses in industry, particularly in the manufacture of electrical equip ment. For some time, it had been believed that the chest pathology so prevalent where it is mined was due to the free silica present in the rocks in which mica deposits occur. Even among workers exposed solely to pure mica dust in grinding operations, however, there has been observed-0 a high inci dence of increased pulmonary fibrosis, with cough. X-rays show a fine granulation of uneven density with coalescence of the lesions in more advanced cases. In all these exposures, the common denominator has been silica, whether free or combined. Recent ly, however, carborundum, which is an almost pure silicon carbide containing less than 1% free silica, has been suspected of being an agent capable of causing pulmonary changes indicating more fibrosis than usual. P ulm onary Disea ses of N on-Silico tic Origin The pulmonary changes seen in coal miners has long been attributed to the free silica content of the shale through which they had to dig to get at the coal. Recent large scale studies in Wales have indicated,'-- however, that exposure to very heavy concentrations of coal dust with a negligible per centage of free silica, such as occurs among the coal trimmers on the docks, leads to a form of pneumoconiosis differing from the anthraco-silicosis of miners. There is a massive fibrosis of the lungs with nodular deposits of anthracotic pig ment scattered throughout. The principal symp toms are due to the marked secondary emphysema, and the cardiac changes produced by pulmonary hypertension. Susceptibility to tuberculosis is in creased. The x-ray picture is one of reticulation rather than nodulation, because of the lack of opacity of the nodules. (Continued in the March, 1951 Issue.j -e - iNC W l I i Y >3 t a LC X J C J J c tl U l l C i i L O j JU ctM O I',u ^ division o f In du strialH ygiene & S afety Standards Yol. 30 __________ March, 1951 ____________ ............. . No. 3 INDUSTRIAL NUTRITION FOR DEFENSE Florence F. Brener, Nutritionist Medical Unit ^ ARM Y m ed ic a l MAr 4 I95i Industrial expansion for defense, as for war, im mediately involves shortages in manpower, which are reflected in the need for longer hours, a faster pace, more night shifts and the employment of an increasing number of women. These special con ditions inevitably result in added physical stresses and strains. The physical needs of the body to with stand this additional strain may, in part, be met by having good wholesome food available in the plant. In industrial establishments, desirous of maintain ing optimum production and good worker morale, serious consideration should be given to providing the best in-plant feeding facilities practicable. This need not necessarily be a cafeteria. A lunch counter or a rolling cart mav, under certain circumstances, adequately meet the needs of the particular plant situation. The foods served should be selected to provide maximum nutrition at low cost. Menus should be adapted to the particular type of feeding facilities available in the plant. They should be planned with an understanding of food values, good nutrition and a knowledge of the dishes which are popular with plant personnel. The foods served should pre sent eve and appetite appeal. The menu should al ways include the standard basic seven nutrients re quired for good health, while consideration is also given to the caloric needs of workers -- a higher calorie menu for those doing heavy work or work ing unusuallv long hours (3000 - 4000 calories per dav) ; a menu of lower caloric content for workers on" light assembly jobs or sedentary white collar workers (2500 - 3000 calories per day). A low cal orie diet for workers is not to be confused with a reducing diet. In general, the food eaten during the lunch hour, in the plant, should provide 1/3 tol/2 of the worker's total food requirements for the day. Milk is always the beverage of cho'ce.whether one is considering a high or low calorie menu, because it is an unusually nutritious food. The menu is not only the bill of fare or list or dishes available to patrons; it also provides the bas ic pattern from which the food is purchased, pre pared and served. The menu should be planned at least a week in advance; preferably two weeks a head. When planning menus for industrial cafe terias or other in-plant feeding facilities it is nec essary to be guided by the number of work shifts or whether the plant will be working overtime. Con sideration should also be year, holidays and pay days. Tifcggnerfc that during periods of heavy produetiq-pE^ time work, and on pay day (particularly if the checks are cashed on the premises) the industrial feeding facilities are patronized more than on other days. . In plants where the majority of workers are en gaged in heavy production, the caloric needs are high and should be met by properly planned menus offering hearty foods which will supply a high total caloric intake. This may be obtained by introducing into the menu, foods which are high in fats, starch es, and sugar. Examples of foods high in fats are: fat meat or bacon; butter or margarine, gravies, mayonnaise or other salad dressings made with oil; and cream, either sour, sweet or whipped. Foods high in starches c.id sugars include such foods as: bread or bread products; waffles and griddle cakes; puddings, pies and other pastries; maple syrups, jellies, jams, preserves, sugar and candy. It is not usually sufficient, however, merely to offer the high calorie foods; portions must be large if a high total caloric content for the meal is to be obtained. With increased hours of work, special attention should be given to mid-morning and mid-afternoon rest periods. Snacks delivered by rolling carts dur ing these rest periods, or otherwise available to workers, will contribute greatly to reduction of fa tigue and to increase production. The same prin ciples apply to industries where heavy seasonal activities are the rule. The following is an example of a high calorie lunch menu: Cream of tomato soup or other creamed soup Roast pork or other fat meat, with gravy Fried potatoes or candied sweet potatoes String beans, carrots or other green or yellow vegetable Waldorf or banana salad with chopped peanuts % or mayonnaise Bread or rolls with plenty of butter or margar ine Pudding with whipped cream or pie a la mode Milk Tea or coffee with sugar and cream or hot chocolate with whipped cream The high calorie foods in the above are the creamed soups, fat meat with gravy, fried white or sweet potatoes, salad with nuts and mayonnaise, 9 pudding -- preferably in such form that they may be conveniently taken away from the counter to be eaten at a nearby table or elsewhere. Limiting the menu in this manner will avoid the possibility of too many left overs. It will facilitate speed of prepara tion,' thus making for more efficient use of limited counter personnel. It will also help' the worker reach a decision quickly when choosing his noon day meal, thereby saving everyone's time including his own. It is recommended that whenever possible a nu tritious and low priced "Special Lunch'1- and"Special Snack" for mid-morning and mid-afternoon be offered and an effort be made to promote interest in it on the part of workers. The "Special" for the day may not realize a large profit, but the wise cafe teria manager knows that increased volume in sales can overcome this disadvantage. It is essential to add, at this point, that industrial feeding facilities should be operated primarily for the welfare of the worker rather than for profit. Nevertheless, the industrial cafeteria manager never wants to operate at a loss, if he can help it. Moreover, the extent of the subsidy required from management will often determine whether or not feeding facilities in the plant will survive. A particularly well thought out nutritious "Special" either for lunch or the mid morning or mid-afternon "Snack" will be found to provide necessary volume of sales to make it prac ticable and at the same time give the worker good value for his money. To help boost sales for such "Special" food offer ing, effective use can be made of nutrition educa tion posters or other literature. Talks to workers on the subject are very useful. For the "Snack Special" in plants having mid-day rest periods, many simple inexpensive combina tions are possible. In general it is desirable to have it priced at no more than 12 cents, because in most industrial plants coffee and a doughnut are sold at that price. A snack combination consisting of milk, fresh fruit and a cookie can be sold for 12 cents. When featured it is a popular choice as against the less nutritious doughnut and coffee. Other snack combinations can be made up of (1) 1/2 pt. of milk and a sandwich of cream cneese on whole wheat raisin bread; (2) ice cream and a cookie or a simple ice cream sandwich; (3) 1/2 pt. of milk and a bag of raisins and nuts. With imagination many other inexpensive combinations can be devised. The industrial worker during a period of rapid industrial expansion for defense, or for war, is call ed upon to make a supreme effort to achieve maxi mum production; To provide him with the best possible nutrition in the plant at the lowest possible cost is a vital contribution not only to his health but to the country's defense effort. If the industrial cafeteria manager is not well versed in nutrition, as applied to menu planning and food preparation, he should not hesitate to seek advice or counseling on the subject. The nutrition ist of Division of Industrial Hygiene of- New York State Department of Labor is always available for such consultation, without charge. DUST INHALATION IN RELATION TO PULMONARY DISEASE J ohn E. Sil s o n , M.D. Medical Unit {Continued from the February 1951 Issue) Specific pulmonary pathology has also been shown to be produced by exposure to fumes and dusts of certain of the metals, notably beryllium and cadmium. Both these substances actually are systemic poisons, but since industrial exposure to them occurs primarily by inhalation, the principal pathology is usually present in the lungs. Beryllium is responsible for two types of res piratory diseases.-1' One is an acute inflammatory reaction varying from a mild pharyngitis or bronchitis to a massive pulmonary edema, which occurs principals among workers exposed to sol uble salts in the' beryllium refining industry. The other is a chronic pulmonary granulomatosis de veloping after a delay of several months to years, which occurs primarily among workers exposed to dusts and fumes of the metal, oxide, and certain complex silicates (fluorescent compounds). It is characterized by a nodular fibrosis giving a char acteristic x-ray "picture, and a diffuse thickening of the alveolar walls. The outstanding symptoms are dvspnea. fatigue, anorexia, severe weight loss and intractable cough. The mortality is high, and some degree of permanent disability remains a mong nearly all those who survive. Inter-relations between the acute and chronic forms, and the oc currence of an intermediate subacute type, indi cate that they are probably all widely different manifestations of the same disease process. The pulmonary pathology due to cadmium24 is generally encountered when workers unwittingly create cadmium fumes without adequate protec tion: for example, in flame cutting or welding cadmium plated iron. It first causes a cough and dryness of the throat, which then progresses to severe constricting chest pain and dyspnea, diz ziness, chills and prostration. The pathological pic ture is that of pulmonary congestion and edema, with interstitial pneumonitis, hemorrhage and cel lular infiltration. The term siderosis-3 has been applied to a be nign pneumoconiosis due to exposure to dust and fumes of iron and its oxides, usually seen among hematite miners, welders and other iron workers. Pathologically, siderosis consists of a deposition vof phagoevtized iron particles distributed in nodQlar fashion along the lymphatics. Outside of the mechanical effects of excessive pulmonary accum ulation previously discussed, its importance lies chiefly in the necessity of differentiating it from silicosis, with which it had frequently been con fused in the past, particularly among foundry workers. The nodules in siderosis are more dis crete and sharply defined on x-ray, and there is no tendency to cor fluent nodulation or hilar en largement. Organic Dust Diseases A few materials of organic origin have been found to be responsible for specific types of pul monary pathology. Notable among these is ba gasse,-" which is the residue of sugar cane after extraction. This material has been extensively used in the manufacture of insulating board and other building materials. It shreds readily when handled dry, with the production of a fibrous dust. A high percentage of workers exposed to these fi bers have developed, after about two months, an acute bronchiolitis with high fever, extreme dys pnea, productive cough, weakness and weight loss. X-rays show scattered miliary shadows through out the lung fields which may go on to a confluent pneumonia. The disease usually clears up, but may be fatal or result in chronic fibrosis or bronch iectasis. Both acute and chronic pulmonary diseases have been reported among cotton workers. The former- consists of an acute febrile illness with productive cough and dyspnea, resembling an acute bronch itis. It usually resolves completely, but may oc casionally result in a chronic bronchitis. It is be lieved to be due to the dust of the fungi or bac teria which grow on damp, unsterilized cotton. The chronic disease,28 known as byssinosis, consists of a progressive fibrosis, usually associated with emphvsema and bronchiectasis, which develops after many years of inhalation of cotton fibers. It is not yet known whether it is a specific fibrotic response, an allergic reaction, or the end result of repeated subclinical acute infections. . Sum m ary To summarize, there are a number of types of pulmonary pathology which can be caused by the inhalation of excessive quantities of particulate matter, varying from specific fibrotic reactions with a characteristic picture to an increased in cidence of a form of pathology usually considered non-industrial in origin. Size, composition and structure of the particles are all factors determin ing the nature of the response. Pathological re actions generally result when the capacity of the filtering and phagocytizing mechanisms of the res piratory tract are exceeded. These reactions may be fibrotic, inflammatory, degenerative, allergic, carcinogenic or merely mechanical impairment of function. The best known cause of pneumoconiosis is free crystalline silica, but amorphous silica, silicates, and even silicon carbide have been shown to exert deleterious effects. Coal dust, certain metals, and a few organic compounds, have also been indicted as the cause of specific lung pathology. 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