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FILE NAME State of the Art Literature SAL DATE 1930 DOC SAL006 DOCUMENT DESCRIPTION Journal Article - Pulmonary Fibrosis in Asbestos Workers Pee REAR CRM SE LER Eg EO adie E Oy wa ode OLY LG ty Sa8TS COE bod raw te ape il ra i | THE JOURNAL OF INDUSTRIAL INDUSTRIAL INDUSTRIAL HYGIENE | XDivetah, - EDITORS | DAVID L. EDSALL M. D. S. D. United States _ ; lad 7 > sind EDGAR L. COLLIS M. D. M. R. C. S. Great Britain spas. aenturcmanit = : wee : VOLUME XII JANUARY DECEMBER 1930 ATES i { PUBLISHED BY HARVARD SCHOOL OF PUBLIC HEALTH A Wont mr Boston Mass _ oe Cpewet, area oo ... . Prot ' ... ... ...ORS ... ... ... | erOO ...THE ut IM]oe tie Oe CRATE aes 18 tea | he fa het . ret Site bed oa) i bea ase coe Sorte f THE OCCURRENCE OF PULMONARY FIBROSIS AND OTHER PULMONARY AFFECTIONS IN ASBESTOS WORKERS ... .- E. A. MEREWETHER M.D. -. -- M. Medical Inspector of Factories |: + INTRODUCTION - He He was treated in the Charing Cross Hos- -- RIOR tothe commencement of pital for two months and then returned to work After a few months however he this inquiry in February 1928 became ill again and was admitted to the definite knowledge existed of Hospital in April 1900 where he died The only two deaths of asbestos workers about whom there was expert opinion that the inhalation of asbestos dust mortem examination confirmed the clinical diagnosis of extensive pulmonary fihrosje There was as evidence vi puimonary tuberculosis and examination of the had at least contributed to if not sputum for B. tuberculosis was negative caused the fatal outcome -- = -- The first of these in retrospect the The second case was reported by Dr. most suggestive only came to light W. E. Cooke in 1924 eighteen years some years after the occurrence when later 2 mS - full information was unobtainable All that is known of this case now referred to as the Montague Murray Case is contained in the evidence given by Dr. Montague Murray before The deceased a woman aged 33 who died in 1924 had worked in asbestos for 18 years but intermittently for the last 5 years owing to periods of health The . mortem examination revealed not the Departmental Committee on Com- pensation 1000 1000 1 1 for Industrial Diseases in From this source we learn that The patient a male aged 33 came under the care of Dr. Montague Murray at the Charing Cross Hospital in the beginning of 1899. He had worked with asbestos for only extensive fibrosis of the lungs but also much change due to pulmonary tuberculosis Although Cooke 3 and Stuart McDonald 4 were conclusively of the opinion that this case the lungs showed a progressive dust fibrosis together with a chronic tuberculous in- some 14 years 10 years as a cardroom ~~" hand and the remainder in some other room of the factory where there was much less dust He volunteered that of the 10 people working in the cardroom when he went into it he was the only survivar and that all the others had died somewhere about 30 years of age There is no note as to the nature of his work previous to that in the asbestos factory fection the etiologic relationship be tween the inhalation of asbestos dust and fibrosis of the lungs would have been strengthened by the absence of a tuberculous tuberculous infection Cooke's case is however of outstanding importance not only because of the discovery of curious bodies in the discussed later also .: =, ~-* Received for publication Feb. 17 1930 and of more importance generally be- 198 J. L. Maw, 1930 esa . 1 nen tee ae ivey mentemeter a0. Sy IE se on Ow ot eet 8 gnmme een raes ees mee ves ~~ Re OR Meme ered, nice yon fess RY Lae ; 2 Si ORT oe ~ + eee made rm eae wee: am ee A-metrer 1 - te nee See SEED OT baring Cross Bos- ~' - then returned to 2- ths however he *" admitted to the ce 7 died The confirmed the -.... sive pulmonary - dence of pulmo- - ..__. amination of the was negative . eported by Dr. } eighteen years aged 23 who sabestos for . for the last 5 health The wemeee revealed not : = lungs but also rv tuberculosis and Stuart lusively of the -se the lungs st fibrosis to- berculous in- ationship be asbestos dust would have absence of a | - - 5 77777 ver of out- a only because ious bodies also enerally be IS: "Fj ~via! > = at ns -~ fo { H. + 1930 - z3 a = PULMONARY FIBROSIS IN ASBESTOS WORKERS 199 cause its publication again directed attention to the possibility that inorganic dusts containing little or no free silica may be productive of extensive pulmonary fibrosis Of these dusts the silicates form a very large class of which asbestos is but one example Many other members of the class such as the feldspars kaolin French chalk and pumice are extensively used in industry The importance therefore of delimiting the potentialities of the class as producers of pul- monary fibrosis is clear Cooke's case was the first to be generally reported in the medical press the facts of the Montague Murray case although contained in the evidence presented before the Departmental Committee in 1906 and . published in 1907 were liable to be overlooked in the mass of important material on industrial diseases elicited by that Committee Since Cooke's case Dr. I. M. D. Grieve has made a careful study of a group of asbestos workers in his prac- tice and has courteously allowed access to his records In February 1928 Dr. MacGregor Medical Officer of Health for Glasgow drew my attention to an asbestos worker who was receiving treatment in one of the hospitals in that city This case the details of which have been reported by H. E. Seiler 5 pre- sented both clinically and radio- logically signs of a diffuse pulmonary fbrosis with no evidence of a tubercu- lous infection On further investiga- tion into the patient's industrial and medical history no presumptive cause __-, other than the inhalation of asbestos dust was found to account for the existence of the fibrosis This case at that time the third of which the Factory Department had knowledge was however the first in which the four essential conditions necessary to establish a relationship between the inhalation of asbestos dust and the development of fibrosis could be demonstrated These conditions are 1. Work involving exposure to asbestos dust 2. The existence demonstrable clinically and radiologically of a definite pulmonary fibrosis 3. The absence of previous or present infentione panum to nquen pulmons pulmons Pisania e.g.tuberculosis influenza or pneu- monia 4. The absence of previous or present work involving exposure to other dusts which might cause pulmonary fibrosis These conditions being fulfilled a relationship between the inhalation of asbestos dust and the development of the pulmonary fibrosis may be pre- Bumed The importance of establishing whether the supervention of this dis ease in an asbestos worker was an exceptional occurrence or evidence of a grave health risk in the industry was now apparent and steps were taken forthwith to obtain prima facie evidencein proof or disproof of the exist- ence of such a risk _ A number of workers in asbestos were selected and examined clinically and radiographically The findings invited further investigation through- out the industry with the result that a comprehensive inquiry involving the investigation of the different processes in relation to the evolution of dust and the examination both clinical and ra- diologic of workers was undertaken during the year 1928 commencing Vol 12 No. ee to ee Pe. oe: Ii biewnsr sur os . Oe A ramets ae neath eee ree SL a Se * Se fe> o- we . ae. : ent ae aT rere: + ear wl womenrR - ne ee tl <p . 200 THE JOURNAL OF INDUSTRIAL HYGIENE with the carding spinning and weav and any methods of ventilation which ing processes of the industry had been found of especial value In the meantime in March 1928 the death of an asbestos worker one of Dr. Grieve's cases occurred in another part of the country and on post- The result of this investigation did not conclusively prove that asbestos possessed injurious properties but it -pointed to the probability that such mortem examination a condition of widespread fibrosis of the lungs without tuberculosis was revealed The was the case It is interesting to consider why it was that no conclusive proof one way or the other could be microscopic examination also disclosed ~ the presence of the curious bodies In 1928 also Dr. F. W. Simson 6 reported a fatal case of fibrosis of the lungs occurring in a native working in an asbestos mill in southern Rhodesia ~ "=~ In order that this brief survey of the events leading up the present inquiry may be complete it is necessary to review the investigation made in 1910 to 1911 by Dr. Collis and Miss obtained then as to the injuriousness of asbestos dust Some if not all of the factors which affecttehde position then are in varying degree continu- ing factors and have an important bearing on the present inquiry Their operation while providing a solution to this query also affords an explanation to another pertinent question Why is it that this industry founded in antiquity has only recently excited attention by reason of its raw material . _'. Whitlock only previous inquiry becoming suspected as a cause of indus- into the subject trial disease In May 1910 the Registrar eral drew attention to a death which had been certified as acute pulmonary phthisis in an asbestos worker and to a statement for which he was un- The answer appears to be that in the past it was not practicably possible to obtain proof of the injuriousness of asbestos dust considering the limitations imposed by the state of the indus- from phthisis had occurred in the same try and the point reached by research work into the relationship between factory dust inhalation and diseases of the Following this extensive inquiries lungs were made a medical report on all the employees in the factory concerned The industry itself not a large one today was then 1910 consider- was obtained and Dr. Collis and Missably Missably Missably smaller Certainly it had begun a v Whitlock investigated generally the to grow rapidly but the number of > ~ various processes in the industry with workers who could have been employed e - respect to the evolution of dust for a period of time long enough to t rT methods of ventilation lost time due to allow of the development of dennite ? Ley tr+yi eamy sickness sickness etc. Also inquiries were made of the Canadian government as to the conditions in the asbestos > physical signs of pneumonokoniosis must have been quite small and dispersed over the country | isyreuypCOUAPEREN quarries and mills in that Dominion --- evidence of increased Bickness and ~~ mortality rates among the workers Precise knowledge of the ~ morbid affections of the lungs produced by the inhalation of dusts was more fragmen- - oe ae tr x ^' trale eevate ~ 3 =? rs et - ay tb oa ih lation which = value tigation did ~ * ~ at asbestos __ ties we but it ythat such ting to con- -- serene - ) conclusive - =" +--+ er could be njuriousness oe if not all of- position the ee continu- ~ 1 important airy Their y a solution explana- ae - = = - ____..-_- question ry founded atly excited aw material indus- - - SN oe . be poto poto poto - iousness of the limita- of the indus- : by research on ip between ses of the ' ot a large ) consider- had begun number of nemployed enough to of definite onokoniosis 1 and dis- ; ~~ - : ~~~ - 2.) ? be morbid Iced by the e fragmen- |. a PULMONARY FIBROSIS IN ASBESTOS WORKERS 201 tary than it is today The position was clearly stated two years later in show an excess mortality from phthisis and those which do not well as evidence placed before the Royal Com- mission on Metalliferous Mines and Quarries This Commission when re- being a comparative index of the industries belonging to the former group not only is of little value as a means of porting in 1914 7 stated we do not know whether other dusts besides those containing free crystalline silica induce classification in the latter group but also tends to distract attention fron it and to result in the associated dusts be- a pathological condition in the lungs ing dismissed as more or less innocuous though the experiments of Professor - Beattie in animals suggest that this occur It is only in the last year Evolution of dust is only one factor though an important one which may cause variations in the phthisis mor- or two that research has produced some definite evidence as to the precise tality rate in different industries Wages hours of work aggregation of effects of some of these dusts on the workers amount of food housing and 12 lungs 8 9 10 11 In 1010 radiography radiography radiography of the lungs in both its technical and its interpretative other social and environmental conditions are however powerful influences in the same direction and are not aspects was still in its infancy and necessarily comparable as between the so far from having attained its present workers in any two industries status of being an indispensable aid to In thus reviewing some of the influ- the diagnosis of the dust diseases of the lungs was an unused ally ences which have retarded recognition of the baneful effects of some dusts In addition the existence of a meas upon the lungs the singular attributes ure of exhaust ventilation in the most of pulmonary fibrosis the most impor- dusty processes of the industry incom- tant of the diseases caused by the in- plete as it was had important results halation of dust must not be over- in modifying the onset course and looked duration of any pathologic lung conditions resulting from the inhalation of This discase insidious in its onset stealthily advances with but faint the dust This influence has been much more pronounced in the period warnings of its progress inexorably it cripples the essential tissues of the intervening between 1912 and the present inquiry and will be referred lungs yet for a considerable period causes almost no inconvenience to the to again ~ Another factor which has tended and still tends to obscure the possible deleterious effects of the silica dusts is the general use of the phthisis mortality rate as comparativa comparativa comparativcoamparativa inden of the degree of injuriousness of the dust encountered in the various dusty worker As time goes on however the lungs find more and more difficulty in aerating the blood and breathing is quickened on slight exertion Still the worker is able to remain at work but is anart of his undue shortness of breath on extra effort Usually bow- ever he ascribes it to causes other than occupations This rate while of great value in separating dusty industries - into two great groups which the dust he is inhaling As the disease progresses if no acute illness has caused a fatul termination Vol 12 No. $ e e WET: e Ee FEIT Oe Fh ARE Ser, Bo egjume=speQhuenedmaeeeing 816s wee ocaete:e aimed tee Sm meee mace owe 1 em ene ee. lee Tet TTR ew Dee ae 0 | iD Tow n ceateprae mn gear ea btn nreae ee ; Ef 202 THE JOURNAL OF INDUSTRIAL HYGIENE sob :* i AF : ate mae LE t. _ i Fe 7t5=- - cE! -bee "Era . fit <7 . i] . " " ig <n: EPP! TEE pb Bit : a stage is reached when the lungs can asbestos dust has a totally different cue a from much silica do ^...ttiemore than maintain iiie and physicochemical constitution that Jaksi the shortness of breath is extreme of dusts containing free and terminal stages disease Even in its the causing silicosis It was felt that JJaakkssii deceitful to the last may masquerade although much ~~~ valuable guidance -. ~ as chronic bronchitis pulmonary tu- could be obtained from the methods tz -.- aes bronchopneumonia berculosis or the of investigation of silicious dusts care : 7 like " had to be taken to keep an open mind fibrosis ~ While more or less acute cases of closely simulating miliary tuberchuavle o oscicsurred country 13 they have all been asso- ciated with the inhalation of dense free silica dust concentrations of and an insiumairly the exception exception the rather rather than difficulty - The difficulty of diagnosing pulmo- so as not to be unconsciously biased in the direction of assuming that effects of the dust must com- parable in some degree to those of crystalline silica =~ ASBESTOS And the ^ 8ESTOS INDUSTRY AsbAessbteosstos 7 -- -~3 . - ~~ .._., - + ; A i] a Ft + 4 a et nary fibrosis especially in its early The term asbestos is a collective * stages or if complicated by tubercu- name of no definite mineralogic sig- , losis has been stressed by a number of nificance which has been applied to a authorities and has undoubtedly con- variety variety of silicate minerals which differ ~ "==- tributed to impede the attainment of precise knowledge of the extent to from one another in chemical compo- sition and physical properties but oe which the various industrial dusts which resemble one another in their _ affect the lungs ~~ finely fibrous feature and flexibility Difficulties and obscurities still im- 14 Their value depends on the pede though to a less degree than in facility with which they are capable of a wt a the past any investigation into the being spit up into long and flexible effects of an industrial dust upon the lungs of those exposed to it but prior to the War although there were certain slight indications that asbestos in common with some other dusts might produce permanent pathologic changes in lungs it was not possible to obtain evidence sufficient to prove or disprove this hypothesis At the nitent of the mensent inquiry fibers which can be spun like cotton and woven into cloth on their resistance to heat and acids and on their insulating properties with respect to heat and electricity --- Varieties of asbestos possess these qualities in differing degree Com- mercially therefore selection is made by the manufacturer of that variety and mende which is most suitable for _ Do of = =< ~ op: : ____i: e i. i=? into what if any pulmonary diseases workers exposed to the inhalation of asbestos dust are more prone to con- the purpose in view regard being paid to ordinary economic factors such as the cost of the raw material and the . tract than the general population it ~~" was considered essential to view the may be price which the finished article expected to command ~ -------- problem afresh and with complete detachment because of the fact that Consignments of asbestos of the same general variety but with differ- H. J. eg STE  a from that silica : 3 4 ore j . --= > guidance + =} ne methods SS biased open mind* zd usly feet ones ng that the ust be com- ae = SBESTOS SBESTOS B collective .. eralogic sig- applied to a _hich differ rr pe but her in their d flexibility ads on the capable of and flexible + the cution . their resist- 4 | . --- 3 en and on their h respect to f possess these tion is made that variety . suitable for ~d heine naid ve tewk eb ae on tors such as rial and the rticle may be Se wy. Easve Sare tRECe T,sits "eae ce Maas BEY ME WF pant fae cen ta a red aks se Cl AEaAOR Cee Ter. e ewe PULMONARY FIBROSIS IN ASBESTOS WORKERS 203 ent countries of origin are frequently mixed in the preliminary processes of manufacture Thus Canadian chrysotile may be mixed with Russian or Rhodesian chrysotile and on Less frequently totally different varieties * such as amosite and chrysotile may be mixed bined water and usually more calcium aluminium iron Members of this group are resistant to acids but are more difficult to spin some being quite unsuitable for this purpose The most important members of this group are crocidolite amosite and tremolite Practically speaking all that goes "~~ under the name of asbestos in com- merce is either fibrous serpentine or a fibrous mineral of the amphibole or hornblende group The former is the most important commercially but strictly the mineralogists confine the _.. Crocidolite and amosite are mainly silicates of iron the former having a beautiful lavender color the latter being brownish Both are spun and the yarn is woven into cloth for various purposes such as acid filter- ing and for making into insulating TABLE 1 COMPOSITION OF SERPENTINE AND AMPHIBOLE VARIETIES -I OF ASBESTOS PERCENTAGE OF MINERAL GROUP | VARIETY Sio | Al O FeO i NO MgO | CaO | KO Com- Water Water Serpentine | 50.5-2.1 | 35.-37.4 35.-37.4 Amphibole {} 0-0.35 13.-16.5 born{|1| | 1.2-9.4 0.9| 0.7-6.4 | blende Chrysotile Crocidolite Amosite Tremolite 39-42.5 50.5-52.1 48-53 57.2 0-3.7 0-1 1.2-9.4 0.7-4.4 39-43 0-0.35 . ... 35.5-37.4 0-3 0.75 6.2-9 ... 34 44 0.7-6.4 0-2.5 ... 3.2 22.8 13.4 13.3-16.5 1.0-4.5 2-3.8 2.4 term asbestos to ^,,brousforms of horn- blende These two types are sharply distinguishable chemically and mineralogically Serpentine asbestos or chrysotile is a hydrated magnesium silicate con~~ taining practically no calcium a high percentage of combined water and a low percentage of iron This variety is very suitable for spinning but is attacked by acids Nearly 80 per cent of the world's production of asbestosis derived from Canada and is of this variety the remainder comes mainly from South Africa and Russia The amphibole or hornblende vari- eties contain less magnesium and com- mattresses as well as for other pur- poses Both are produced extensively in South Africa from which quarter all required commercially is obtained Amosite a comparatively recent discovery is found there in very large deposits its use is steadily increasing the initial difficulties associated with the manufacture of textiles from this variety having been overcome Tiemonte found in various quarters of the world has been mined in northern Italy since the time of the Romans Its chief use is in the manufacture of asbestos millboard and for filtering purposes Table 1 compiled from various Vol No. 6 * wee oe conden See Pee eb ey s Kie xee Ogee tet RIsAA ee a som =. - ee ee eeeee ree _~v ore. Fe em ees. s tees tee cee me LS an ae ate Be ek ees ap ear ate Arete DRG ISDN ' me Ib ae eae ne Oy Gwent rR enter oo ee Seaside. _ ~_. ma wwe mee oe oe ... . ... oe ' oh, ... ...aoe - ' + ...dd fo hi...tb t M...B) i * 204 THE JOURNAL OF INDUSTRIAL HYGIENE sources shows the main differences in reexported Thus the consumption of the composition of these four varieties asbestos in this country trebled within Only a very small proportion of the five years world's production of asbestos which The Industry is between 300,000 and 400,000 short On considering the uses of asbestos tons per annum is suitable for spin- one is astonished not only at the wide ning and the most desirable grades of of articles manufactured from spinning fiber consequently command range this mineral in greater or less propor- ^ high price over 100 a ton - ' tion but also at the diversity of indus- _ The shortage of this grade has led to tries which nowadays find its use improvements in manufacturing proc- either in the form of the raw esses which have enabled less expen- necessary material or as manufactured articles sive grades of fiber to be utilized for Evidently therefore with the multi- spinning some of which give rise to an amount of duint plicity of processes and dus 'sencoun- amount increased increased amount amount of duindt uint About fifths of the world's pro- duction of asbestos is fiber unsuitable for spinning and this is used in the manufacture of asbestos millboard tiles sheeting paper and many other _ articles It is the discovery of indus- tered in the ramifications of the indus- try discrimination would have to be exercised and some limit set to the processes included in the inquiry The processes selected may - be divided roughly into trial uses for these very short fibers and the dust waste which has been _ responsible for the phenomenal expan- 1. Processes involving the manipulation of asbestos either pure or admixed with a small proportion of cotton or other vege- table fiber sion of the industry as a whole The 2. Processes involving the manipulation spinning and textile section has also of asbestos together with other dusty ma- shared because of the extensive use of the Julu and cloth in the manufacture of steam packings insulating mattresses brake linings for motor cars fireproof curtains and the like In 1880 three years after the discovery of the large Canadian deposits - the world production of asbestos was little over 500 short tons by 1900 it had risen to about 35,000 short tons terials 3. Processes involving the makin up of asbestos cloth into other articles Group 1 entails exposure to asbestos dust mainly and to cotton or other vegetable dust very slightly group 2 entails exposure to asbestos dust in very varying amounts and also exposure to divers other dusts such as brick dust magnesia kieselguhr fossil meal by 1920 to over 230.000 short tons and by 1925 to over 330 000 short tons 15 The imports of asbestos all grades into the United Kingdom rose from 18.591 tons in 1922 to 33,520 tons in 1927 16 The figures for 1927 refer ~ to Great Britain and northern Ireland only Of these quantities 8.844 tons and 3,794 tons respectively were and cement in group 3 the exposure to asbestos provided no other as- bestos processes are being carried on in the vicinity in the majority of cases negligible Processes belonging to all three groups may be carried on in the same factory and workers may transfer from one department to another 30 J. mene Ky 1930 Tos ns nen Te rr i ne 2 weit ee Ce Oa, Oe, OOO OEY Leanna ere a = ws ne es ae a te vow ull Hic M flea Seta BTWBE di on Aaah. BE ann^'e eee, eso Rs ee ee Ee | ae we see sete ae te | onsumption of 7 iF ot ee trebledwithin-To aeSee sesof asbestos y nly at the wide factured from ... Tt i + or less propor- > ersitoyf indus fw pen, find its use.. | form of the raw . atured articles .~~-- - with the multidusts encoun- Pi 1: tir of indus- _ | | ild have to be mit set to the inquiry Se he manipulation } admixed with a | or other vege- 4 ~~ be manipulation -2 other dusty ma- Le making up of ticles ure to asbestos tton or other | 4 eed lightly group bestos dust in and also exposEuch as brick 7 -..___# E ; 9 E: .hr fossil meal < ; he exposure to ai 1 no other asng carried on ne majority of i - ' sses belonging | __ _t se carried on in === S workers may epartment to 3 ~ .- J. May 1930 ae 2 ee Lo bert: ot Nt PULMONARY FIBROSIS IN ASBESTOS WORKERS 205 Investigation into the intricate ques- tion of the effects of mixed dusts while possibly productive of some general ~ corollary would lose much of its value in the absence of knowledge of the effects of the several component dusts and moreover would introduce an in- calculable ~ results variable into the final For these reasons and also because the Montague Murray case Cooke's Grieve's and Seiler's cases all occurred in processes included in group 1 it was considered advisable to exclude as far as possible from the inquiry all workers exposed to the influence of mixed dusts and all those not employed in processes included in groups 1 and 3 The processes included therefore are the crushing preparing sieving opening mixing carding spinning doubling plaiting braiding and weaving of asbestos together with the operations incidental thereto Also included is mattress making where the filling is asbestos and the manufacture of some insulating materials where the dust produced is asbestos The carding and spinning processes have many pointosf resemblance to the corresponding processes in the cotton industry but with essential modifications and restrictions caused by the different physical characters of the asbestos fiber These processes are aided by an admixture of cotton or other vegetable fiber and usually from 2 to 10 per cent by weight of cotton is added More rarely and for special purposes fibered asbestos is carded and spun with no admixture of vegetable fiber but usually asbestos yarns contain a core of either cotton or metal wire Asbestos yarns are not only used for the weaving of fabrics which themselves are used for a multitude of purposes but braided together are made into ropes for use as steam packings and other purposes The interstices and center of the rope may be filled with other materials such as talc oil _ or graphite depending on the precise _ use to which the rope is to be put Asbestos mattresses used for blan- keting steam engines and for other insulating purposes are made of asbes- tos cloth stuffed with asbestos fiber The stuffing material may be however slag wool magnesia containing approximately 15 per cent of asbestos fiber or kieselguhr with a small per- centage of asbestos fiber The manufacture of mattresses filled with mixtures of asbestos fiber and other materials has not been includeind this portion of the inquiry The shortness slipperiness and lack of strength of the individual asbestos fiber as compared with cotton flax wool and other textile fibers have been the cause of much technical diffi- culty in manufacture The efforts of manufacturers to cope with these diffi- culties together with those due to wide variations in the physical properties of the raw material are reflected in the methods employed each For these | reasons and because of the great num- ber of patented and special products manufactured one finds considerable differences in detail in the processes in use The majority of the processes mentioned result in the evolution of dust although by no means to the same extent Differences in plant quality of asbestos used methods of manufac ture type of finished article and extent of application of exhaust ventilation Stal No. - aetna ce Spat blag Be 2 SS So Syl PRA Hie ES :REA A ree wwe ey . eer tht Mita tai Tnctatianlh, tat Nn Bs oe tepmeriesrsewree seh tfre e eeyy 6 mintcn ege inegsfsareg peed ge th Pevep PE RS vf + ee tl Pr > ep Waye wyt arpa ir per ces ep pes pauera Cp pep nye repr 200 THE JOURNAL OF INDUSTRIAL HYGIENE all result in variations in the evolution of dust in similar processes in different factories Variations in the evolution of dust in different processes being of outstanding importance a series of samples of dust from the air of workrooms was col- lected by means of the Owens jet apparatus Population at Risk calculation of the total number of workers employed in the processes already enumerated as and most probably an overestimate is 600. Thus about 2,200 appears to be the total population at risk in this country for the purposes of this in- . quiry This figure however does not include the large number of workers engaged in the processes in group 2 which involved exposure to the influ- ence of mixed dusts of which asbestos is but one and commonly not mormeore than 20 per cent of the mixture ---.--.. _ This estimate of the population at risk although it may be excessive is TABLE DISTRIBUTION ACCORD ING TO LENGTH OF EMPLOYMENT useful since it enables us to judge of the adequacy of the sample of workers . -- OF A 775 WORKERS ENGAGED examined and to apply more correctly IN ASRESTOS PRAEFECTS AND the incidence rates of any pulmonary B SELECTED SAMPLE OF 363 WORKERS affections disclosed by the examination of the sample 30 A B The sample examined after eleven cases are excluded of fibrosis and pre- TRE EMPLOYED CENT . PER . PER PER 04 5-9 . 10-14 neeeees 15-19 ose eee es eeeee 20 and over 483 62.3 25.8 51 6.6 24 3.1 17 2.2 a 89 141 84 25 21 24.254.5 35.8 23.2 7.7 5.8 775,100.0 363 36,10.0 Total | 775,100.0 363,100.0 fibrotic conditions due to causes other than the inhalation of asbestos dust numbered 363 representing 16.5 per cent of the population at risk esti- mated as above The manner of selection of the sample must be referred to since just interpretation of the results depends upon a due appreciation of the relationship of the sample to the whole population at risk ___7 eS e 4 t included in this inquiry but excluding those engaged in processes included in group 3 in which the exposure to as- -- bestos dust is negligible gives a figure of approximately 1,600 if we could add to this the number of workers engaged in handling pure asbestos fiber only in the limi stages stages of the processes included in group 2 we should obtain the total population at risk from the effects of asbestos dust it- -self Unfortunately this latter figure _ is unobtainable but a rough estimate The principle of selecting primarily those longest employed was adopted but regard was also paid to the other end of the scale so as to obtain infor- mation as to the length of exposure to ~" dust necessary before effects are mani- fested and also as to the particular process in which the worker pee ged ged It was It was was felt felt that that in in was the maximum information would be obtained in the shortest time Table 2 shows the distribution according to length of employment not necessarily in one factory of ae Ard? eter i: tel bon 1 5 Te 4 Spre a 6 tyae amt | oo ae H. ag ~ May 1930 4 ! PULMONARY FIBROSIS IN ASBESTOS WORKERS 207 estimate ppeartso sk in this of this in- - - ,does not f workers een re ey 1 group 2 the influ- ^ asbestos . ' not more ulation at cessive is o judge of - of workers e correctly pulmonary Lamination fter eleven :( eleven wn r estos dust g 16.5 per risk esti- manner of be referred on of the e appreciasample to g primarily * [oben is adopted the other . btain infor- exposure to pavitas is are mani- particular Forker was in this way : would be e istribution 20. mployment actory of 775 workers engaged in the processes under review and of the sample of 363 workers distributed in the same way The enormous preponderance numerically of workers employed under five years in these processes is striking as is also the very low percentage of workers employed ten years or longer tae Comparison of the two parts of the table shows that the effect of this method of selection is that the number examined in each succeeding year employment group is a progressively greater proportion of the total number which could have been examined in each particular group With a soli- tary exception all those examined were at work on the day of examination Not only the value but the neces- sity of radiographic examinations of the chest in investigations into the effects of dust upon the lungs has been emphasized repeatedly by Watkins- Pitchford and reaffirmed by the Departmental Committee on Compen- sation for Silicosis 17 A high standard of radiography is essential as Pitchford phrases it the radiograms must be technically satis- factory Indifferent films are useless since it is the fine detail of the lung which is being studied In a general inquiry such as this which involves the examination of { I | | workers in factories large and small scattered over the country it is not practicable nor is it necessary con- sidering the special purposes of the inquiry for radiograms to be taken of all the workers examined The dislo cation of work in a factory caused by the absence of a number of hands for this purpose cannot be viewed with unconcern especially when as is not infrequent the factory is remote from a center which is equipped with the necessary ray plant and where the services of a consultant versed in the science of radiography of the lungs are available Furthermore it must not be overlooked that such examinations are voluntary and not as in South Africa compulsory Moreover repeated and protracted examinations only result in the exhaustion of all concerned and much depends on the willing operation of employers and employees since the only incentive is a desire to further the common welfare Radiography therefore has a differ- ent function in these inquines than when it is applied to individual cases for compensation or other legal pur- poses This function is not that of replacing careful clinical examinations as has been recently foreshadowed 18 p 40 but primarily that of being an indispensable aid in diagnosis especially of doubtful cases in the determination of complicating lesions in measuring the extent and progress of the disease in locating the point at which the earliest radiographic signs appear and finally as a check upon the human factor presented by the examiner himself The examinations except one were carried out at each factory in a room set apart for the purpose suitably warmed and with the necessary appointments On occasions the noise of traffic or from the adjoining factory was a hindrance but in one way or another these difficulties come or minimized werewere over All the selected workers were exam- ined by the writer At three factories however a number of workers were examined jointly with Dr. E. Middle- ton His reaching experience of the Vol 12 N- o ame as x pat Stee RIAD Wes, 2 ead ow me e ...Meg. TTL og ... WLIO ... Ce ... ... e ) a8 1-1 no eel --- oii 208 THE JOURNAL OF INDUSTRIAL HYGIENE pathologic changes in the lungs produced by the inhalation of various dusts was of great value and his assistance was much appreciated Every effort was made to complete the clinical examinatioonf the workers before the onset of winter introduced difficulties due to ephemeral bronchitis colds and influenza which would tend to obscure the main issues Thus the clinical and thirds of the radio- graphic examinations were completed by the middle of NovemberNovember 1928 prior to the commencement of the influenza epidemic early in 1929 these it diminishes in intensity but still persists In other words we find tacked on to the paravertebral dulness an area above and below of impaired resonance which is much more exten- sive than that usually associated with old inactive hilar tuberculosis Impairment of the percussion note was found to be constantly more marked in the right side in fact at first it was thought that in the earliest degrees of fibrosis it was confined to that side but later and more extended observations lead to the conclusion that the earliest detectable cases are CLINICAL EXAMINATION biisterai although the signs on the left side are tenuous - . Percussion This change is so constant that it has The inhalation of asbestos dust originates changes in the lungs which may be looked upon as a measure of the efforts of the living tissues to repel been adopted as the most reliable single clinical sign presented by this type of pulmonary fibrosis and no case has been classified as fibrotic in its ab- Bence or incarcerate the irritant particles of Considering the frequency with dust These changes modify the per- which signs indicating what may be cussion note It is true that the note termed enlarged roots were found in elicited may be similar on both sides asbestos workers it may be that but the note is not normal It is para- vertebral dulness is one of the earliest thinner and higher pitched pitched than nor- signs produced by the inhalation of mal and there is a sense of resistance asbestos dust indicating congestive imparted to the plexor finger In changes in the root areas and a choking -. other words there is a diffuse but of the lymphatics with dust slight impairment of resonance Reflex impairment of note due to irritation of This alteration in the percussion the lung tissue by dust is however an note however is more difficult to attractive explanation It does not recognize because it is bilateral and extends over a wide area consequently the aid of contrast percussion is denied follow of course that workers present- ing these signs will ever develop a defi- nite asbestos fibrosis Batt intercurrent It is best elicited by rapidly and Clearly the physical physical sigus presented very bghtly percussing the back of the by any case of diffuse pulmonary fibro- chest from apex to base on each side It will be found that the extreme is not only may be modified by | changes produced by some Oe, apexes remain clear but below the lung disease but ab initio will 2.2... apexes the impairment is general It vary according to the state of the lungs be increases over the root areas below fore the onset of the fibrosis Thus an) Seneiaes J ie -~ + May 1930 ora om oN prKa inard, ine 2 fe Shoo eye 3 ak co ory iF tad Xe ae= s hs tnt Peea a eave . POT coat Meee lege sotee) ee ie) PULMONARY FIBROSIS IN ASBESTOS WORKERS 209 ~ sity but , we ad ; dulness ~ * = impaired =; | . re exten- "> ated af ooo with _ - 4 4 > the fibrosis may be implanted upon a perfectly normal chest in which case the problem of diagnosis is straight- forward In other cases however ' preexisting root changes so common in industrial community may be pres- _ ent or the lungs may be already the to healed tuberculosis That there is an extensive fibrosis is clear enough and that most of it is not due to asbes- tos is strongly suggested when examination of the lower portions of the lungs shows that they are comparatively slightly affected Further help n a ee ee sion note 6 tly more -- ! seat of emphysema and chronic bron- these cases of course may be obtainedet ame mete chitis or of definite old tuberculous from the history and symptoms ae first ~~~ e earliest o-oo onfined to extended lesions or there may be a massive pleural thickening the result of an old pleural effusion All these examples have been noted in the present investi- The third type also rare is that in which changes following an old massive pleural effusion on one side so obscure the physical signs of any dust fibrosis conclusion ALGAR oa... gation and others will readily come to mind as to render that side useless clinically for diagnostic purposes If the side left . ) --- Although in most of these cases the dust fibrosis if moderate in degree can _ affected by the pleurisy happens to be the right the radiographic picture is that has able single is type of be confidently diagnosed especially with the aid of radiography it must be admitted that the problem becomes = very difficult when the dust fibrosis is also curtailed by the normal partial obscuration of the left lung base by the heart shadow These three types were with the / a / weeed ncy with may be re found in ! - comparatively slight and the changes produced by other conditions are pro- nounced and diffuse Three types of these cases have caused most difficulty among those examined fortunately possible exception of the first uncommon and are mentioned merely to call to mind some of the ways in which an asbestos fibrosis may be masked in greater or less degree by changes due that paraha melint alation of congestive esto choking is st Reflex see rritation of owever un me does not re present- e elop a defi- rt ' --- i t tl on ee 0 aan | numerically they were few The first of these is where the dust to other disease Only passing reference need be made fibrosis has been implanted upon lungs already emphysematous It seems * that at any rate in the case of the asbestos fibrosis until the fibrotic to the other physical signs found in the asbestos fibrosis since they do not differ materially from those presented bysilicosis Chest expansion dimin- . changes get the upper hand clinical ished and may be reduced to half _.. diagnosis of the fibrosis in these cases inch or even less in advanced cases ~ is impossible Nevertheless although the problem of the diagnosis of a fibrosis implanted upon an emphy- sematous chest has caused some diffi- Retraction of the apexes is common and sometimes shows a peculiar feature differentiating it from that found in fibroid phthisis Instead of the im -- s presented ~ nary fibro- Loni odified by ntercurrent eg nen . will vary 9 cesesce e lungs be Lt culty in this inquiry it seems likely thatit can arise only under exceptional circumstances mobile and sunken apexes seen in the latter disease the apexes are seen to descend during inspiration and to rise The second type of case which has __ again during expiration This seems been a source of difficulty in clinical to indicate the anchoring of normal _ . .' diagnosis is that in which there are apexes by fibrous tissue in the lower oo an | is Thus extensive bilateral fibrotic changes due portions of the lungs Some confir- - ee 8 MA H. ~ 1977 Feo xf - 4 a laa td Tae Vol 11 F. eee ee vee e . ae woe er, 3 ' 3 : ...La ... ... ...- iy 3 o n r f = $... = : e - ...2 ry ... 9 r + ee ... Pty ... ... nee 210 THE JOURNAL OF INDUSTRIAL HYGIENE mation of this was obtained radio- logically Auscultation In the majority of the cases of fibrosis the respiratory murmur is + weakened much or little generally more on the right side and often still more at the base the expiratory sound is +--- - --- weaker than the inspiratory and often becomes less and less audible as one approaches the bases Transitional phases between this and harshened breath sounds and pro- - longed expiration are not uncommon even in the coms UL The intter may be noticeable in the upper por- tions of the lungs but progressively diminish toward the bases Other combinations were also noted how- ever Symptoms The symptoms exhibited by these cases of fibrosis as might be expected closely resemble those of silicosis The distribution of the main symptoms and of one sign cyanosis which is included with the symptoms for convenience is given in Table 3. A few cases have been excluded on the grounds that one or other of the symptoms complained of might be assigned to causes other than the fibrosis such TABLE DISTRIBUTION OF FOCR COMMON SUUPTOVA AND OF CYANOSIS AMONG CASES OF FIBROSIS SYMPTOM EXAMINED CABES IN EXAMINED WHICH EXAMINED BYMPTOM EXAMINED WAS PRESENT ee ee The dry character of this type of fibrosis during most of its course is rather striking Scattered fine r^les . No. NO | No. Per Cent and clicks in the root areas axillae Cy dosis 22221 and bases were not infrequent slight - Dyspoes ceceeeed 22221 lunge edema of the lower halves of the was noted in one of the more advanced Expectoration 22221 Pain te eeeee 94 52 | 55.9 47 | 51.8 31 | 34.1 10 !' 10.8 rases but in number 0 adventitious Bounds at all were heard Pleural crepitations and rarely a Excluding those in which the presence of the symptom is referred to other causes slight pleural rub were noted attacks seem to cause little pain in one case a little fluid at the right base 0 |... ee No doubt this variability in the sounds heard on auscultation reflects underlying changes temporary or permanent in the lung and is depend ent inter alia on the extent of the fibrosis with its associated pleural thickening due to past dis- ease catarrh or other intercurrent affection and to the degree of compen- compen__ satory emphysema present as complaint of shortness of breath in a case with a past history of mild thyroid intoxication or of dyspnea associated with obesity Between 50 and 60 per cent of the cases complained of cough or of shortDess of breath on slight exertion or Suuncu some degree of cyanosis whereas only about third com- plained of expectoration and onetenth of pain or discomfort in the chest Also while 14.6 per cent of the cases had no complaints and showed no cyanosis and only 3.4 per eee . J B. cn setae we ain symp tosis which me for COD- = ~~ 3. few ed on the . | symp- A be assigned brosis such - tems ' made ene rem og dats = Pes Vt : OF FOUR AND OF CASES - ee ee re i CABES IN { WHICH -- ------ ---- -- ; WAS PRESENT i f ea! ij a Per ~ | See, | 52 t 47 47 31 10 9.3 | 55.9 51.6 34.1 10.6 | . the presence olber causes of breath ry of mild of dyspnea cent of the - -- 1 or of short- exertion or ... f cyanosis _thied NAM 1. and one- fort in the per cent of plaints and only 3.4 per -* * ! -- J. I.E. May 1930 PULMONARY FIBROSIS IN ASBESTOS WORKERS 211 cent presented all four complaints and were cyanosed 60.6 per cent presented two three or four of the five items Clearly none of the four complaints or the presence of cyanosis can be an infallible indication of the existence of fibrosis but the presence of two of them shortness of breath on slight find asbestos dust irritating but to this day cannot work with a cotton scutcher as he occasionally does without precipitating a coughing attack within an hour or two Although he suffers from winter cough and some shortness of breath he stated that his health has been much better since the exertion and cyanosis in some degree in an asbestos worker is highly suggestive in the absence of other evident cause change Asbestos dust therefore has only very mild powers as a reflex irritant of the upper respiratory tract and is in Nevertheless an advanced degree of fibrosis may be present and little com- plaint made Symptoms unless distressing are so often a function of The introspectiveness of the patient Slight degrees of fibrosis too give rise to no symptoms in the absence of an intercurrent bronchitis since the remaining sound lung tissue is still - amply sufficient for all purposes Cough was the most frequent symptom and was of types For few weeks after commencing work in a dusty process asbestos workers often find the dust irritating and cough while in the dusty atmosphere this lasts for a few weeks and then usually disappears The writer has noticed this effect on himself but only while in a very heavy cloud of asbestos dust The dust seems to be only slightly irritant in this way One or two men who had previously worked in cotton --~-- card rooms or bl^rrooms and were affected by that dust stated that they were unaffected by asbestos dust cause Certainly asbestos dust does not sese tthhmma attiic c aattactks tackattackss lilkieke those those seen seen in cotton card room workers One man who migrated from a cotton card room hard waste nine years ago to an asbestos card room on account of the irritating effect of the dust does not this respect comparable to free silics This is an unfortunate attribute since it leads to the assumption that the dust is more or less innocuous The second type of cough is more intimately associated with the development of fibrosis and occurs or perhaps is noticed after a varying number of years work Usually is present only in the morning on getting up when after rather a sharp attack of coughing a little viscid sputum like an oyster is brought up A similar bout may occur at night after ceasing work at times it is sufficiently sharp to cause retching It is generally rather worse in winter and may be noticed only then Although it closely resembles smokers cough its features are pre- cisely the same in nonsmokers Persons giving a history of cough dating from an attack of pneumonia or other illness in childhood almost in- variably state that the cough has not become worse since working with asbestos One worker succinctly described the cough as first in the throat later catches the chest Generally this cough causes very little inconvenience and may pass unnoticed until the development of some other symptom directs attention to the general state of health Thus out of i | | re | | S e Vol 12 No. 6 Crean Spey i |t | ene en tlie we Peied Snes eRe Se eee Parana ard bagyeey *BAA eteery t: fs; ; Tame? <B bee, oe Ye: e, Fw Say 2 say S: erg tee Ra aa Eee ae Tyeae Se binned sates 212 THE JOURNAL OF INDUSTRIAL HYGIENE ek w sixty cases of fibrosis in thirty- and in the remainder of the cases eyoBO^' hte ty MtTHe erateg OEE m HY OTSGaleAPE Pali three 50 per cent the cough was stated to have preceded the onset of shortness of breath in twelve 18.2 per cent to have developed contemporaneously and in twenty 31.8 per cent was either not noticed until after the onset of shortness of breath or although the latter was complained good Radiography Radiograms of the chest were ob- tained of 133 workers or 35.5 per cent of the number examined clinically Of these over 100 were taken by Dr. E. W. Twining of Manchester and rqae:pee tae epee bh pone * 1~'t Mek of cough was not admitted TO ~ Complaints such as colds go to the chest and frequent colds on the chest were not uncommon Com- plaint of spitting of blood was excep tional and in all cases in which this complaint was mentioned the exciting Dr. N. Tattersall of Leeds and the remainder except one by Dr. F. L. _ _- Henderson of Glasgow To all three I am much indebted Dr. Twining and Dr. Tattersall have devoted many hours to the joint study with the writer of the radiograms and have drawn coust was primmanly some disease freely on their wide experience of radi- other than the fibrosis in one it ography of the chest in furthering the was due to pulmonary tuberculosis purpose of the investigation in another it occurred only during a Dr. R. S. Paterson of Manchester prolonged attack of pleurisy and in a too added his experience to a final third the hemorrhage was gastric in review of the films and Dr. E. Barclay origin Cyanosis a valuable sign now of Cambridge lent his assistance when present rarely amounts to more in interpreting some difficult films than a duskiness or slight blueness of to both grateful acknowledgment is the lips it contrasts however with the made general pallor of the face with which The standard of radiography was it is often associated in these cases very high indeed a high standard is Cyanosis in some degree was noted in indispensable if it is desired to trace 50 per cent of the cases It may be the cause of such a fine and diffuse absent even when there is a consider- fibrosis as that produced by asbes- able degree of fibrosis or it may come and go tos The films are superficially but only Pain in the chest is rarely com- superficially comparable to silicosis plained of and then it is usually described as tightness of the chest soreness or aching It was noted In the earliest negatives studied with | Dr. Tattersall a characteristic slight obscuration of the lung fields a general in 10.6 per cent of the cases lack of translucency was noted This marked clubbing of the fingers appearance for want of a better term was noted in a Paw wo nen 444 , ... ...Was denominated as veling Dr. nutrition is hardly affected except in Burton Wood has independently noted the latest stages Only ten 10.5 per 19 and confirmed this referring to it cent were noted as being thin In as the ground glass appearance one the nutrition was very poor in Dr. Tattersall also drew attention to twenty 22.1 per cent fair the more or less rounded whorls of PULMONARY FIBROSIS IN ASBESTOS WORKERS 213 0 the cases t were ob 6 0" F7 : cent clinically sen by Dr. neater and - 15. and the Dr. F. L. To all three r Twining ee Cee voted many | h the writer have drawn nce of radi- ----=- = thering the 3 3 Manchester to a final . ... E.Barclay is assistance 1s Ce is eOe D craphy was ; standard is red to trace and difuse 1 by asbes lly but only to silicosis : ~~ ~~ 7? studied with week aristic slight ds a general -- _ coted This better term | iling Dr. iently noted ferring to it ppearance Attention to : ae Leo whorls of varying size seen in the striation in the zones in some of the films The radiographic appearances in the earlier stages are most marked on the There was general agreement as to right side at the base or in the central the fine and delicate nature of the zone This corresponds with the clin- characteristic mottling Dr. Twining ical findings This preference for the in a personal communication dated Aug. 2 -while lamenting that there has been as yet neither time nor right side has been noted also in silicosis by the South African observers The cases showing radio- opportunity to study the changes from every aspect and therefore his present graphic signs of a dust fibrosis have been classified in three broad groups views may be modified on considera- This grouping although unscientific ' - tion of all the evidence is convenient practically considering the main purpose of this investigation In general my opinion is that the earli- est stages are not characteristic radio- Indeed more precise classification based on the particular radiographic logically but that the stage of fine dusty stippling is almost certain to be eventually provable as an early asbestos lesion We saw it constantly in a large series of films and after a little experience it is quite easy to detect it changes noted might well be mislead- ing at the present time Much Much Much ccoombined mbined combined ccomobimnebd icnomebinded clinical clinicclinicalal radiologic radiologic and pathologic study is required into the whole subject of these fine types of Some of the other cases abowed a few dust fibrosis which have been noted in grouped lesions like rosettes or leopard markings each component being about the size of a primary lobule These are similar to lesions sometimes seen in tuberculosis In the asbestos cases I regard them as being workers exposed not only to silicate dusts other than asbestos but also to other inorganic dusts containing no- silica before it will be possible to groups of primary lobules making up a lobule the walls of which are infiltrated They certainly seem to correspond in size with the macroscopic lesions seen in the pathological specimen The advanced cases show heavy basal and ^-eldmottlings common in pacumoso- pacumosoconiosis with a tendency to avoid the classify the radiologic changes as has been done so successfully by the South African workers in respect to silicotic fibrosis The hypothesis that because asbesios dust produces a pulmonary fibrosis with consequent deviations from the 2, _-- eo apices On the whole the lesions are distinctly less dense than those of silicosis and are less easy to group into defined stages but think we can recognise A very doubtful stage of increased linear striations 2. Fairly definite fine dusty stippled appearance 3. Coarser mottling with increased linear striations 4. Gross lesions with pleural changes and displacements due to the pull of the fibrosing legions The few tuberculous lesions we have come across have been easily distinguishable normal in the lung skiagram the de- gree and potentialities of this fibrosis can be assessed by comparison of its radiologic picture with those of standard silicotic films is untenable At least two general types of pulmonary fibrosis caused by inorganic dusts can be recognized A third representing the purely peribronchial variety of fibrosis might be added or it may be that all dust fibrosis will be found to approximate more or less closely one or the other of these two en cn te te ree ] 1 t dk mee oe ben J. H. May 1930 owe. de 214 THE JOURNAL OF INDUSTRIAL HYGIENE +8 is + types These types are 1 that pro- ieee pe. duced by combined silica dust an me te example of which is seen in asbestos 04ea g: fibrosis and 2 that produced by free rng ee silica dust represented by silicotic UPd fibrosis gee Teg MULE These two types while resembling | one another in clinical signs and symp- taf toms differ materially both in the nature of the lesion produced in the o2_____.. lung and in the character of the asso- ciated radiographic picture Thus attempts to weigh consciously or unconsciously asbestos fibrosis or any dust fibrosis other than silicosis by means of the standard radiographic changes found in silicosis is unsound and is likely to lead to a misconception of the potentialities of the dust in ques- tion Badham 8 gives an example of this source of error in reporting the unex- On studying the development of asbestos fibrosis as displayed in a series of radiograms and especially in the few available taken a year or more before a fatal termination one cannot help asking the question What is there here which could have this effect The answer is that the damage to the lung is much greater than it appears to stand- be when judged by the silicotic ard Asbestos fibrosis is much more diffuse it spins its fine web as it were crisscross throughout the lung enveloping and eventually strangling the ultimate lobular structure rather than depositing itself in numerous SEG. wa ices isolated ioci as in silicosLS Thus at any rate in the less advanced stages the radiologic picture of the lesions does not impress the eye uncon- sciously viewing it from the standpoint of silicosis pectedly early death of a man affected with a fine fibrosis caused by an orthoclase basalt containing no free silica Referring to some of the radiologic differences between the fine fibrosis of dusts other than silica and the nodular fibrosis of quartz dust i.e. true silicosis he states ; _ The radiographic picture may show soft and fairly.coarse fairly.coarse nodulation but it is never so impressive as the nodulation in a silicotic film Paradoxically the distinctive feature both clinically and radiologically of the asbestos fibrosis is its uniformity The modesty of the symptoms the Moreover the coarse fibrosis of silica gave clear interspaces of normal lung while the fine fibrosis presented a uniform granular mottling leading to the conclusion which is probably erroneous that the actual develop- ment of fibrous tissue was greater in a nodular fibroaia as silicosis than in a general- ised fine fibrosis caused by silicates To ~ me it appears that the mechanical damage to the lung is greater in a fine fibrosis than in a coarse fibrosis when both well unobtrusive but diffuse impairment of the percussion note the homo- geneous stippling of the skiagram all are fragments of an entity unmistak- able when assembled but enigmatic when divorced Se Only two references to the radiographic appearances of the chest in asbestos workers have been traced one in a report by Pe oe| developed Pendergrass 10 and the other in an _ The evidence obtained in the present inquiry amply confirms this general __ . statement article by Burton Wood 19 Pancoast and Pendergrass together with Miller and Landis examined 17 asbestos workers 2 of whom showed "7 H. May 1230 opment of in a series in the lew re before a nnot help at is there is effect age to the appears -- ' otic stand- - ee ee ae nuch more web as it t the lung strangling ure rather kid penre er o rerr T srm in silicosis 3 advanced ure of the eye uncon- standpoint my tion but it Dodulation active fea- iologically iological y Tulformay Tulformay toms the mpairment the homo- iagram all unmistak- -- enigmatic the radioe chest in an tranon: coust and ther in an s together mined 17 In showed PULMONARY FIBROSIS IN ASBESTOS WORKERS 215 first stage changes and the other and by the time the stage is reached 15 definite second stage appearances when the features discussed above are Of the men longest at work one after seventeen years occupation showed ~ very definite diffuse soft spots throughout both lungs and another showed about the same appearance in varying degree positive and the radiologic picture is recognizable the fibrosis is not in its inception nor even in its earliest stages but is developed and fairly widespread after fourteen years occupation Very slight nodular shadows were flflfounidn one man after only two years occupation Most of these second stage cases showed also marked first stage appearances still present indicating a persistence of free drainage We must therefore recognize an earlier state when the fibrosis is present ... in slight degree and also when there is evidence of choking of the lymphatics and of a measure of pulmonary catarrh This stage may be referred to conveniently as the prefibrotic stage hilumward all instances the nodu- characteristically ial shadows were soft and varied considerablyin size The indications of this stage are indefinite and some at any rate not specific If however they can be Their first stage appears to correspond determined and applied with only a with stage 1 and their second stage moderate degree of accuracy informa- with stages 2 and 3 mentioned above It appears from the context that tion of practical value will be available Efforts have been made therefore to these observers regard asbestos fibrosis as being really a silicosis due to admix- ture of free silica derived from the distinguish workers in this stage The following tabulation shows that twenty workers out of 363 exam- original rock view difficult to sub- ined 5.5 per cent were so classified stantiate ; Burton Wood 19 in a series of fif- teen skiagrams of asbestos workers notes Ihe most noticeable feature of skiagrams of workers exposed longest Clinical Examinations 363 No. Fibrosi Fibrosi eee eee cece 95 Prefibrotic conditions 21 Radiologic Examinations Per Cent 20.2 5.S to asbestos dust is the presence of shadows suggesting a diffuse fibrosis affecting chiefly the lower thirds of the lungs The fine quality of the 155 Fibrosi changes 6s .20 52 Suggestive changes not definitely diffuse 6- brogie sees cere eens m 39.1 16.5 ---~- shadows is worthy of note Some of the cases exhibit a ground glass appearance though on close inspection fine mottling mom defnite is evident ' . when it it mattling is mattling mattlinmatgtling is present present present lacks the coarse quality described in the skiagrams of chests showing pneu- moconiosis e.g. South African gold miners " ., Clearly the maturation of asbestos fibrosis is spread over a period of years Many of these cases present a slight diffuse impairment of percussion note perhaps better described as slightly increased sense of resistance feit on percussion mostly of the right lung at least as contrasted with the left and associated with some weakening of the respiratory murmur Probably this early stage could be detected radiographically but only by means of Vol 17 No. 6 Tne phe mB oats RS aay ONE Seth pel ase de Si dem ieee bey mie & 216 THE JOURNAL OF INDUSTRIAL HYGIENE - Arecge kurt comparison with a radiogram taken + prior to commencing work with asbes- th: wemseRb ikka tos By such means the earliest stages of silicosis have been worked out by the South African observers , There the radiograms taken at peri- etinge _ odic monthly medical examinations cp can always be compared with initial kutsemeqe radiograms taken before the employees he are .1.1 permitted work underground . gee am te ee pe 441 group is dismissed from any further consideration A general summary of the findings in the 374 workers who were examined clinically classified under the most important lesion is presented in Table 4 ILLUSTRATIVE CASES _ The salient points of a few cases are set out below to illustrate clinical and UOTRete He te ae | 4 11RTE TUME wre t : = ee oe TABLE GENERAL SUMMARY OF FINDINGS CLASSIFIED UNDER THE MOST IMPORTANT LESION momo ut ENFLOTED ENFLOTED ENFLOTED ENFLOTED - ENFLOTED . TRS TRS FIBROTIC FIBROTIC CASES PREFIBROTIC PULMONARY OF Fishueie) CONTI- TIONS TUBERCU LOSIS TUBERCU- CONCERTION CONCERTION TUBERCU- CONCERTION CONCERTION | BRONCHIAL BRONCHITIA BRONCHITIA BRONCHITIA | Causes Causes | le- Lesions Causes Causes Causes of of Lesions le- | | Causes Causes Fibrosis Inactivo EXAMINED Asbestos Other Asbestos Fibrosis Active Inactivo Asbestos Other Asbestos Other Fibrosis Active Inactivo Other Active Inactivo EvidencAce tive O| F i| Dust EXAMINED to Dust Other Due Due WiOtt her Ch ARES Due Due With BUGGESTING BRONCHITIA BUGGESTING BRONCHITIA ~ILAR BUGESTING BRONCHITIA BUGGESTING ROOTA AND OLD RLARGO EMENTROOTOTAA AND OR PULMONARY PULMONARY LUNG CATARKII | LOS18 LOS18 CATARKII CATARKII CATARKII CARES PULMONARY OTHER FULMONARY FULMONARY FULMONARY LESIONS LIMITO LIMITO LLIIMMIITTO O NORMAL Lesions NORMAL Emphysema Lesions NORMAL Lesions i Lesions NORMAL Emphysema Emphysema 1 WITHIN Pleurisy Emphysema WITHIN Other WITHIN Pleurisy Emphysema Other WITHIN 0 920 3151 52310 5-9 142'36 | 3151 52310 10-14 .....0. 89'27 3151 52310 15-19 30'15 22 52310 and over | 21:17 22 52310 Jo COO10 | 33500 0 1 COO10 | 4310 33500 {0 3 COO10 4310 33500 4 COO10 4310 33500 4 0 COO10 4310 | 33500 Total 374.95 10 95 21 15 15 18 15 18 | Percentage 25.4 2.7 03130321 03130321 2.1 21 56 One case of thickened pleura due to old gunshot wound * One case of emphysema due to gassing 7302 153-0 0 J1 2231- 7302 153-0 ]2 12 | 2231- 7302 153-0 327 327 2231- 327 327 2231- 327 327 2231- | 13 10 631 631 150 35 j 271606 271606 271606 271606 27160 35 | 271606 1.6 0.8 48.1 In other cases included in this group diffuse weakening of the respiratory murmur noted with fine sticky r^lesin the root areas At present nu stress can be laid upon this group The clinical changes are so slightly marked that until comparative radio- other features Five radiograms are reproduced to illustrate the radiologic appearances of some of the peers There are insuperable difficulties however in reproducing the finer changes depicted in the original nega- tives grams are available it would be unsafe 24 eg to draw any deductions For the Case This worker a female aged pur- .-. poses of this inquiry therefore this has been employed in asbestos half years- a card for ten and tenter one year 7 A. a, ae be ere PULMONARY FIBROSIS IN ASBESTOS WORKERS 217 ara ge i and as a doubler nine and half years Her family and personal medical history old tuberculosis of the lung roots and general increased striation especially in the findings -.-- examined . the most im- suggesting 1 contain contain nothing nothing of of note note She has no com- lower half of the right lung early plaints and feels quite well Her nutrition good She is pale but shows do cyanosis Chest has a chest expansion of 1 -- fibrosis CASE This worker a male aged 23 has been employed in asbestos for nine in Table 4 - inches - No impairment of the percussion years mostly mattress making His family note is detected The breath sounds in the and personal medical history contain noth- SES cases - clinical and - right lung are weaker generally than those in the left Expiration is prolonged at the right root no added sounds are heard A skiagram showed some very slight and ing of note He complains of occasional pain in both sides of the chest and perhaps a little undue shortness of breath on exer- doubtful changes in the direction of in- DER THE creased striation CASE This man aged 24 has been employed in asbestos for five years carding and mixing Previously he worked for four JONARY SIONS years in the cotton trade yarn weighing the lamu ,y and personal contain nothing of note medical history history He has had a LIMITA slight morning cough and expectoration for a year His nutrition is good His esiona . esiona semat semat a NORMAL NORMAL WITHIN Ed WITHIN Ed |} WITHIN 12000 22311 0221 12000 22311 12 12000 22311 0221 22311 22311 6 3 150 480.. 6 41 8.1 ee ee dg aovepn ene ee re cn diograms are the radiologic 4 the cases difficulties ag the finer original nega- Temale aged 24 color is fresh and there is no cyanosis There is some impairment of the percussion note over the middle third of the right lung behind and slightly at the right base The breath sounds are harsh and expiration is prolonged in the upper balf of the right lung behind expiration is also prolonged over the left upper lobe behind The respiratory murmur is weakened at the right base and the breath sounds are of a whiffing character There are no added coumde ekingram showed enlazeeraent of the right root and slight haziness and striation in the central zones in both lungs suggesting early fibrosis CASE This man aged 32 has been employed in asbestos for six years in the card room and as a stripper and grinder Previously he was employed in a cotton card room for nine years He had army service for five years but was not gassed He gives a family history of asthma otherwise there is nothing of note in his family or personal medical history He has no complaints and feels quite well His musculature is very good His color is pale but he shows no cyanosis There is slight impairment of the percussion note generally particularly at . the right base The respiratory murmur is FIG Case 4 Moderate fibrosis Un- due degree of striation and fine mottling in of central zones both lungs calcified glands in roots with rather course striation in upper lobes ? interlular pleurisy on right side between the lower and middle lobes emphysema at bases tion His color is normal His muscula- ture and nutrition are good There is no retraction of the apexes but there is a slight flattening below the right clavicle The percussion note is slightly slightly impaired generally betinu partieularly on the right side The breath sounds are weak generally and expiration is prolonged No added sounds are detected The skingram Fig 1 shows an undue degree of striation and fine mottling in the Los for ten and cater one year a little weakened generally No added Bounds are detected A skiagram showed central zones of both lungs calcified glands in the roots with rather coarse striation in J. May 1930 Vol 1 No. 05 eee ee Samir > v a ERY boiew awe ot ve: ... ...... ... ... ... *... ... ... ......... ... ... ... ... ... 3...1 ... 31 31 218 THE JOURNAL OF INDUSTRIAL HYGIENE the upper lobes ? interlobar pleurisy on the right side between the lower and middle moderate fibrosis most marked toward the bases laundry lobes and emphysema at the bases The CASE This worker a female aged 31 case was diagnosed as moderate fibrosis has been employed in asbestos for _ Case This woman aged 40 has been seven + employed for eleven in years opening and has been exposed to years asbestos for much dust Her previous employment , most of the period mattress making Pre- was dusty Her family and personal viously she was employed in a history disclose nothing of note She She has recently been ill for three months _ com plains of having had a cough for five years with pleurisy no history of tapping otherwisewiseher family and and of shortness of breath on hurrying _ personal medical history She is thin and undernourished and pale Fig Case 6 Moderate but fully developed fibrosis Enlarged glands in both roots diffuse fine mottling in both lungs especithaelrilghyt Fig Case 7 General fibrosis mostly linear but with little mottling of right lung Old puerile tuberculous scars at apexes negative She complains of having had a winter cough for three or four years and of shortness of breath on exertion since her attack of pleurisy Her nutrition is good her weight is stationary She has normal color and no eyanosis Chest Theries some impairment of the percussion note over both lungs be- hind more noticeable at the bases The respiratory murmur is weakened generally Persistent crepitations and medium r^les are noted low down in the right axilla A - ekiagram showed diffuse fine striation and fine nodular mottling with light opacity at the bases The case was diagnosed & Dust is present on her hair and in her nostrils Chest has a chest expansion of onefourth inch There is slight general impairment of the percussion note definite at the apexes and the bases The breath sounds at weak capiration is slightly prolonged No added sounds are heard Her heart is not enlarged and no murmurs are detected The skiagram Fig 2 showe a number of enlarged glands in both roots and a diffuse fine mottling in both lungs especially the right This is a case of moderate but fully developed fibrosis Case This woman aged 45 has been May 1930 er re yr ern e as d toward the male apu^ 31 Los for arven ee in exposed to = employment and personal ste She com- or five years on burrying hed and pale ry { i 4 . 1 ; 1 fibrosis mostly ing of right lung afe a ' ajuAUS ajuAUS hair and in her abef red f ? 11 J thidesl eo = expansion of one1 general impair- e definite at the e breath sounds . . - chily prolonged 1. Her heart is - curs are detected ws a number of ta and diffuen 25 especially the oderate but fully ee 4 ~, ; a: aged 45 has been 3 ene nee ates Loe J. th: May 1930 PULMONARY FIBROSIS IN ASBESTOS WORKERS 219 219 employed in asbestos for thirty years- about three years on cards and the remainder as a spinner She has done no other factory work Her family medical history discloses nothing of note She has a personal history of nephritis seven or eight years ago causing three months illness Her complaints are shortness of breath hills and winter cough for about six years Her nutrition is fair She is rather pale Chest has a chest expansion of one- half inch No retraction of the apexes is noted of the sounds There is general slight impairment percussion note behind Breath are harsh and expiration is pro- longed No added sounds are heard No gross enlargement of the heart is noted but the second sound is found to be accentuated over the aortic area The skiagram Fig 3 shows a general fibrosis mostly linear but with a little mottling of the right lung There are also very oia pueric tuberculous scars at the apexes The cast was diag- nosed as general fibrosis This case should be compared with Case 6. In Case 6 there was a heavy exposure to dust extending over a few years in the pres- ent case there was exposure to very much less concentration of dust except possibly in the first three years but extending over many years CASE This worker a male aged 62 has been employed in asbestos for twenty years as a weaver He was previously a cotton and silk weaver His family and personal medical history show nothing of note except that he was regarded as delicate child His complaints are shortness of breath on exertion and on going upstairs for three years morning cough and a little expectoration for the last three winters He is thin and pale with some cyanosis Chest expansion is 1 inch there is retraction of the apexes The percussion note is impaired over both upper lobes in front and over the upper thirds of the right lung behind Expiration is prolonged at the bases Pleural rub and inconstant r^lesare noted at the left base and a few rules at the right base A Shingrum showed a definite diffuse fibrosis with nodulation This is case of fibrosis in the early advanced stage CASE This man aged 41 has been employed for twenty years in asbestos in many capacities There is nothing of note in his family history He gives a history of pneumonia a number of years ago His complaints are a little shortness of breath on snortion for the last two or three years otherwise none His nutrition is fair only His color is fresh but there is slight cyano- sis of the lips at times Chest skin is poorly elastic there is some retraction of the apexes There is an impaired rather boxy note on percustion generally especially over the upper half of the left lung and over the upper twothirds of the right lung behind and in front Respiratory murmur is generally weak Expiration is slightly prolonged but diminishing toward the bases Pleural crepitations are noted low down in the right axilla A skiagram showed a definite fine diffuse fibrosis Neit lunh g le ighr ts up very wen anu turuughout both there is a busy fine diffuse reticulation and mottlingmoderate but fully developed fibrosis The fine diffuse character of the radiologic appearances is particularly noticeable here CASE This man aged 46. has been employed for twenty years in asbestos during nine years of which he was not ex- posed to dust For eleven years of the remainder he was employed in the card room and mattress making His family and personal medical history disclose nothing of note His complaints are shortness of breath on exertion for three months cough after a few hours work in dust during the last twicor three years with little or no expectoration and pain in the left side of the chest for the last three months His nutrition is good He is pale with slight duskiness of the lips There is some retraction of the apexes The percussion note generally is impaired and of a boxy character Breath sounds are harsh and expiration is prolonged over the right upper lobe else- where the respiratory murmur is a little weakened and expiration is not materially prolonged No added sounds are heard The heart is bortal The skiagram rig 4 shows diffuse striation and fine speckled mottling throughout both fibrosis fully developed CASE This worker a male aged 40 Vol 12 No. -0 oe ... . ... ...... ... ... ... ... ... ... 220 THE JOURNAL OF INDUSTRIAL HYGIENE has been employed for twenty years in asbestos the first eleven years on cards and as a weaver during which he was exposed to a considerable concentration of dust During the remainder of the time he was employed on a dusty process but was exposed to a less concentration of dust derived from other processes His family and personal medical history give nothing of note His complaints are shortness of breath on climbing stairs for the last five o + o years slight morning cough and expectora- over the right upper lobe in front The heart is normal Sputum is muroid but is negative for Bacillus tuberculosis Club bing of the fingers has been noted for about two years A skiagram showed an sive diffuse fibrosis in a advanced stage exten- fairly Case This worker a male aged 60 has been employed in asbestos for twentysix years in the card room Previously he -was a sawyer's laborer There is nothing of note in his family and personal medical history He complains of slight shortness of breath on exertion of recent years and of winter cough for the last three or four years expectoration is stated to be ail His musculature and nutrition are fair There is slight evanosis of the fare Chest has a chest expansion of threefourths inch The percussion note is im- paired generally especially over the left upper lobe in front The respiratory mur- mur is weakened over the whole of the chest except the left upper lobe where there are whistling breath sounds and medium r^les . The heart is normal A skiagram showed very extensive changes throughout the chest ofa coarse type without fine stippling The roots showed a choked appearance There was beavy mottling at the base One old tuberculosis focus was noted at the left base and some calcified glands in the left hilum The diagnosis was fibrosis in the advanced blake sis FIG Case 10 Fully developed fibrosis Diffuse striation and fine speckled mottling throughout both lungs tion for about the same time and slight aching of the chest in front below the left clavicle His nutrition is good There is slight cyanosis of the face Chest Chest expansion is I inch there is retraction of the apexes There is im- pairment of the percussion note generally most evident over the whole of the right lung behind and over the right upper lobe in front The note is boxy over the remainder of the chest The breath sounds are slightly weakened generally except at the right apex but there is no gross change Expiration is prolonged generally Fine crepitations are heard in both axillae and CASE This man aged 66 has been employed in asbestos for twenty years as weaver For about sixteen years pre- viously he was a cotton and silk weaver His father died of chest trouble at the age of 45 his sister died aged 15 of pulmonary tuberculosis He has only been away sick a week or two in twenty years and bas never had any serious i lness His com- plaints are undue shortness of breath on exertion during the last two years cough for the last twwor thrno wintern ee ation is creamy and occurs a fair amount of times He has lost weight and thin He is pale but with some cyanosis of the face and with a malar flush Chest Chest expansion is 1 inches there is retraction of both apexes Dulness is detected on percussion over the upper thirds of the right lung and over the left JURH MAS 1930 in front . The 8 mucoid but is -ulosis Club- oted for about xed an exten- ~ s ina fairl|y. male aged 60 5 for twenty- Previously he ere is nuthing ' -sonal medical ight shortness nt years and three or four ed to be nil tion are fair face | asion of three- - . ni^-ctonir^-ctor~~ im over the left piratory mur- le of the chest mere there are ... medium r^les igram showed igram hest - uh, The it vs rance here 480 One old the left base ke lot hilum the advanced 60. has been one years ven yeare pre- silk weaver de the age of pulmonary naway sick a mars and has . His comof breath on years cough Expector- sir amount of ... of the face 1 inches PS Dulness r the upper over the left 7. H. a= 3, 1930 ) > ih PaaS sa e Sh e hd. aeamtd were ee enhance nade PULMONARY FIBROSIS IN ASBESTOS WORKERS 221 221 upper lobe behind and over both upper lobes in front Breath sounds are rather the sputum had remained smali in amount and its appearance did not suggest tubercle weak with prolonged expiration Scat- tered variable rhonchi and r^les are heard My diagnosis from the beginning was one of pulmonary asbestosis with possibly over the right lung behind over the left upper lobe in front and over the left root The skiagram showed a definite diffuse fibrosis plus tuberculosis Sputum was negative one examination The diagnosis was dust fibrosis in the advanced stage with added tubercle " took two rays of him neither of which showed appearances suggestive of tubercle everything pointing to a very extreme degree of fibrosis He died on Oct. 13 1928. No postmortem tuberculosis probably active examination was obtained Case This worker a male aged 36 commenced work in an asbestos plant in 1910 but was employed on other work until January 1914. During the next five ee ee e years until early in 1919 about three years and nine months were spent in army serv- ice for nine months of which he was a pris- e oner of war but he had two short periods ete ee work in asbestos cleven months in the weaving and six months in the mattress departments From early in 1919 to November 1927 he worked in asbestos pro esses but for only six years and ten months in a dusty one mattress making He then ceased work He was referred to tubercu- losis dispensary on Oct. 19 1927 when he gave a history of bronchitis in 1916 and 1917 during the War and of never being very well since complaining of dyspnea pain in the right side and a slight cough of only about six months duration with a small amount of grayish sputum Dr. N. Tattersall states that at that time Dyspnoea was very marked even on talking and there was definite cyanosis He had marked hollowing and respiratory retraction at both apices especially the right loss of note over most of the right lung and the upper half of the left bronchial breath sounds at both apices fairly numer- ous crepitations mostly on the right side and a pleural rub the right base He had a systolic bruit at the apex and pleuropericardial friction examined him a number of times the last occasion being April 20 1925. In that time in had just pounds felt h^ ng mean mean and the dyspnoea was increasing The signs remained much the same though neeasionally if he got a cold the moist sounds were more numerous bases Seven sputum especially at the examinations were FIG Case 14 Massive fibrosis with pieural thickening thickening retracted apexes and pneumothorax on left side with incomplete collapse of lung It sure been will be noted that the length of expoto asbestos dust is unlikely to have more than about ten years and two months and of this time he was employed only about eight and half years in a dusty process War service of course may have reduced his resistance The skiagram Fig 5 shows a massive fibrosis with pleural thickening retracted apexes and pneumo- thorax on the left side with incompiete incompiete coi- lapse of the lung No doubt fibrosis of the type pro- duced by asbestos dust can of itself itself negative and up to the time I last saw him lead to complete disablement and Vol No. 6  ... eT) ... he te er a ... ... re ... eo 1 } eT } oe * to ith Tn toe. ' 1 a 222 THE JOURNAL OF INDUSTRIAL HYGIENE finally to a fatal termination even in the absence of a superadded tubercu- lous infection | The primary effect of the fibrosis illnesses are avoided Ultimately however the margin of safety already diminished is lost and the circulation slowly fails with the usual signs of would appear to be that of causing defective aeration of the blood result- edema of the lungs More often however an attack of bronchopneu- ing in an added strain on the heart monia influenza or other acute infec- For many years and even with an tion adds too much to the strain im- . advanced degree fibrosis this may pairs the cardiac musculature be of little inconvenience provided results in a fatal termination and physical exertion is limited and acute To be concluded BOOK REVIEWS BLEIVERGIFTUNG By Prof. Dr. Paul Selamidi Direktor des Hygienischen Instituts der Universitat Halle a d .; Priv Dr. Adolf Seiser Oberassistest am Hygienischen Institut Halle .; und Priv Dr. Stillfried Litener Assistent an der Medizinischen Klinik Halle a d S. Paper Pp 79 with index illustrations and bibliography Berlin and Vienna Urban & Schwarzenberg 1930 This monograph is divided into a short introductory or general section and a special section The first part is devoted principally to a discussion of the outstanding diagnostic symp toms of lead poisoning and of the work done by Dr. Schmidt and his collabora- tors in the microchemical determina- tion of lead in blood urine and feces The second part discusses in detail the usual sources of lead poisoning the absorption distribution and excretion of lead the pathology and clinical findings associated with lead poisoning and finally the diagnosis prophylaxis and therapeutic treatment of lead poi- soning Dr. Schmidt's monograph is particu- larly apposite It brings the literature of the subject down to the present date and represents the mature thought of an investigator who has long made this field particularly own The discussion of the diagnostic features of lead poisoning is especially clear and to the point In this connection it is of interest to note that emphasis is placed on the importance of the determina- tion of lead in the blood No attempt is made to discuss the details of technic The monograph presents instead a critical review of the more recent experimental work relating to lead poisoning and will in consequence doubtless have a wide appeal to all investigators in this field The bibliography which contains 298 references to the recent work and brings the literature of the subject down to 1930 is particularly valuable Bleivergiftung may well be recon- mended as a valuable addition to the library of students of pubne health L. T. Fairhall ' TT eset det eny Os HE UPSD 98 at ' re Ap ated he Dsode es th t ime 4Son a. Seve if | vay or ae s em fae twe J H. May 1230 a a te a "4 se el