Document wq0kQpkb63nbpo6qMk18aZn74

The American Ceramic Society , I i February 15,1993 I hereby certify that the attached copies of Ceramic Abstracts, Volume 16,1937, are true and accurate copies, which are maintained in the normal course of business at the American Ceramic Society, 735 Ceramic Place, Westerville, Ohio 43081. Product Manager Ceramic Information Center 735 Ceramic Place Westerville Ohio 43081.-8720 614 890*4700 TWX: 7101109409 SC-ALL-01285 ' SCF-ALLF-00415 SC-CER-3200 CERAMIC ABSTRACTS Compiled by t The American Ceramic Society Rosa C Pv*Dr* Editor Mahv J* fUoaj*rm ) - Emily C Van Scsotac > initfoad Doxonrr J. Tnufu / - Commitu* on Pubticaiionj: J, D. SCLLIVAi*. Chairmen* E. DC F. Conns. R. F. Sauvooo, W. W. Wctwn*. R. C Pum Volume 16,1937 Abstracters* J. B. Austin, A. A. Ayia Rudolf Sana, A. C. Bonn. Devida* Biswaa. T. BwnimtUer. W. H. Bruckner. P. P. Budmkoff mad . Stefanowsfcy, J. C Ouutoo. W. M. Coha. M. V. Condoide. Maurice Delaacr*. R. BT. Devfller*. A. H, Emery. W. F. Pine# B*. D. Foster. J. L. Gallup. J- D. Gat, P. E. Grout, Max Hartenhdnu P. G. Heck. B- A. Hemdk . B. Hewitt. J. N. HflU G. M. Hutt, J. F. Hyde. Herbert Iasley. C B. Jenni. B. 2, Katnicb. B. . Ktakulkia. Seiji Hondo. E. H. McClelland. F. P. Peter*. O. M. Petcnea. C. J. Phillips. J. G. Phillips. R. H. K. Pierce. Jr-, Alexia Pincus. Katherine Reed, H. K. Richardson. A. B. Searle. Stanford Setchett. M. C. Shaw. G. R. Shelton. H. E. Simpson. A. P. Som. Erich Sceaiel. H. H. Stephen son. A. G.Stere.B.H. Strom, L.Thitss,E.J.Vachttslca,F.E.Vrew7ck.F.J.ZYaiittC Editorial Office: 2525 North High Street, Columbus, Ohio. Publication Office: 20th and Northampton Streets. Easton, Pa.  * 10* No.g J937 Chemistry and Phyrics--Genera! 137 *dracyqu WM. Cc^ dctermiaiai impllfied d* detail. S* fc/.v.* fa days aaf *Tx. Zmt \8.&E. ( alaminoa. . Jour, jU. }; R-F.957. re convert^ The** w<j* oxide, Ah<V value for tk -0.002. : R-AJL; eat. tt. i 935); CU been plotted fa a ternary diagram. These results that the pigments of the best hiding powers were prt pred from solutions with a titanium dioxide cooeeatratlcm between 13 and 19% and ratio* ranging from 2/1 ;a j/0.65. Seeding opalescence occurs at different hydro* .fO-fen concentration* with different concentrations of gbthss. Illustrated. F.G.H. Viscosity end pfattfdty of Asperse systems; YZ f- ^ct of temperature and electrolytes oa the plastic preper- 6c* of kaolin* M. P. XV'oxjutowmar aw D. M. Tot* ftot. roUW-Z.. 73 ni 92-96 (1935); * see Gw** Afa, 15 [3) 101 (2937). VH, Plaetie flow fa an apparatus with erffeders displaceable lengthwise. D.'M. Tolstoi. JCof* &d-Z~ 73 (l I 96-101 (1935).--A method for determining the flow resistance and shearing modulus of high concentre* tfea mineral suspensions Is described. The apparatus was designed particularly to eliminate surface gliding of .the crfi&dcrs. Results agreed well with those obtained by the muting cylinder method of Wolsrowitscb. At very small velocities. Bingham's equation for plastic flow does not hold for high concentration mineral suspensions. For Parts MT see Crram. Afa-13 [7J 222 (1935). F.P.P. * OATWCTS ABuft * sffieate. Asotsu . A. Cosmcuus (Helios Kcmisk-Tekniska Fabriker Swed. 60.000. April 4. 1934. On. Afa.. 29, 6000 (1925).--Steam is blown into an electrically heated bath of alkali silicate formed by .the reaction of aDeal! chloride and SKV During the process the bath is kept covered by e layer of the uomdted charge of alkali chloride and SiO*. with or without another substance. ng, lime, for the formation of double sweatee. Method of manufacture of precipitated xfac oxide. G. AjffTONOrr. Brit. 459,238. Jan. 20. 1937 (June 5. 1935). Production of a calcium almninate suitable for the manufacture of sodium aluxnlnate by treatment with soda lye. AsmstuxAm Koasx Amscnw Co. Brit. 457,676. Dec 16, 1936 (Aug. 30. 1934). oxidising *& 4 of SeOa ea General nature of th at ScOi pt references.^- silicosis. H. SmcsrrVD. fYrfoadJ. t>*uL Pafs. Gu., pp. 252-71 (1934); Cfam. Afa, 29, 8169 d. CTTAlta [51 299-3B residue efts :Ude add fa uolttb&ty d .uarex |iwud afa-fize fee Jott of hydro .1935). / Ctuyatfoo of paeumonoconfoses. Phxlxp Djunezx. /ear. Ini, Byg. & Toxicol. 18 [8) 534-36 (1936).--The various pacnmonoconioset and their causative agents are Sificesxs and aabestosis are deflnlte diseases; ia a&thraeo-sQlcesis and various sHIcateses. modifications of normal lung conditions are seem Effects of carbon or carbonates, gypsum, and iron oxides are also discussed. hr. Resale i fairly r* -*td, all of tht Methods of estimating dust exposures of a workman in* dude the taking of dust samptes from the work place and interpreting the results during the man's total period of The rate a' reasefa grvt EJ.V. exposure. Errors made from estimating the composition of dust from samples which have settled upon rafters inftead of using samples taken from the air are emphasized. nmssKJf. Z Permissible dust concentrations need, not exceed 50 tnilUoa fa. 29, TIB 167(1935). 5de a* ompt, 3fcn*Z Pinkies pet cu. ft. for dust with very low quart* content or 5 million for pure quarts. In defense of the use of standards of dustiness, the experience fa S. Africa where "tet standards 'have *`oetn applied successfully for many which estsb f* Sc, and C instants area MR years Is cited. . EJ.V. Curies If. Brady. Axon. BuU. Amtr. Oram. Foe, tt 21 73-74 (1937). \f Chemical considerations on seme pneumoconioses (lathraeosfa. silicosis); I, ITatare of the problem. Rsxi sffectfag pfa TotX. /d fate solution ?***. Congr, CAim. lnd,, J4ik Congress, Boris, 5 pp. *34); Oem. Air, 29, 5774 (1935). ric anbydri* ctal titanisff / CEnical aspects* diagnosis, and I -aconioiU. V. Iavceo Cuxx. treatment of Jour, Jnd. pneumo* Hyg. 6* ion with ortho* | Toxical^ ]8 [8| 537-49 (1936).--Fneumonoconiosis is s disease resulting from the inhalation of inorganic dust. The two pnrumonocoatoses which produce disability are ectivtly, lA 4f00dhjdhd astc ecd tiuatod nuclei. * | i ?tlkosis and asbestosis. The pathology of silicosis is char* Merited by the presence of flbrotic nodules scattered `trough both lungs, and that of asbestosis is characterized br *a interstitial fibre^ts involving the tower hall of both ies or bidi* l^js. The symptoms of silicosis and asbestosis are simi* ,t. mpostt*0* : the most important being dyspnea. The most com* ydiide-w**? | complication ts pulmonary tuberculosis which. Ta silicosis, is a frequent cause of death. The diagnosis of both silicosis and asbestosis Is made largely by a correla tion of history and symptoms with the X-ray examination. The treatment of pacuxnonoconiosis is preventive and symptomatic. The course of silicosis and of asbestosis is slow but eventually leads to incapacity due either to the disease Itself or to a complication, frequently chronic pulmonary tuberculosis. The number Of workers exposed to harmful mineral dusts fa mining and fa industry fa the UF. has been estimated as 500.000. E.J.V- Clinical hematological studies for (he differential di agnosis of industrial silicosis. C. SafioxcA ams F. A. Xolti. KUn, Wochschr., 14,9S7-92 (J935),--The ao thors have experimented with the pathological-anatomical ac tions of the changes of the silicotic lungs in connection with the heart and the complete bloodstream. With the assistance of.electrocardiograms, they have beta able to Investigate the condition of the lungs of silicotic patients. At the poffcfimc of Bonn University. Rfiatgen observations of the last 190 silicosis patients were taken, and these were axudyxed according to pure'radiological points xd "new. Various tables showing the bloodcounts of several ss&cotir and tubercular patients were compiled. After certain pe culiarities were established fa the blood stream of the silico sis patients, it was found necessary to make further inves tigations of the connections between the studies of the blood and the dfakal Rontgenologic*! status. Toobtain a most secure foundation, it was decided to separate those silicosis patients from the others who showed an important degree of tubercular complications. A characteristic blood status was shows in stone dust patients. This shows dearly excessive iaa-ease of white blood corpuscles with increased sinking at approximate normal counts of red cor- pusdes and distinct small counts of lymphocytes at rela tive transitional forms of lemkocytts is a streak prepara tion. The same symptoms, even U less impressive, are shown fa a second group from the total of sOtcosU patients as positive cases with tuberculosis complications. W.F.F. Colored ceramic aggregate for decorative concrete. 133 Ceramic Abstracts VoL Ul, Xw.; C W. Pla.vj*. Jour. Amer. Ceram. See., 20 (3! 90-9f> um. Diagnosis of silicosis. Exxav ft HAxutraiT. Leber Lef. B. *6* 91*69 (1030); abstracted la /ear. led. Hyt* & TexkoL. 10 [S| 131-32 (1938).--Factors weewy to diagnose chronic iftccm ares (1) exposure to silica dust in euSdent quantity for 3 to 20 yean; (2) determination by latraperitoneal injection of the nodule-forming char acter of the dust; (3) nature of the work; (4) personal fac tors such as mouth, breathing, previous respiratory dis eases, etc.; (5) X-ray findings. Serial pictures should be taken over a period of time. The location of the nodules is characteristic, avoiding the periphery, symmetrical distri bution, shape, and rise. In this phase chrome silicosis is without disability. (B) Physical examination; so char acteristic but some suggestive findings. (7) The pa tient's complaints: these are negligible la the first and second stages, but later cough, dyspnea, pains Inchest, etc^ may occur. E.J.V. Economizers and air preheaters. V. Waltz*. Eire. Ftev^ Up 13082) S53 (1936).--W. discusses the conditions which govern the design of economixers and air preheaters for ose with boilers. . J.L.G. Epidemiological aspects of sinensis and tuberculosis. Atxotr S. Pops jutd David ZaCts. Amer. Rev. Tuberodv rs, 32. 229-42 (1935): Cum. Abs^ 29, 7524 (1935).--In representative groups of both granite and foundry workers In Massachusetts, the frequency of silicosis sud of ifiicpsls and tuberculosis was correlated with the duration of ex posure to dusts containing free sfiiea and to the concentra tion of such dusts la the occupational environment. Among granite workers silicosis was found in 1551% and with tuberculosis in 7.6%. Tuberculosis is the cause of death in over one-third ot all granite workers, a propor tionate mortality 3 times that in foundry workers and 4 times that in all males of 20 years and over. Among the employees of 10 Mass, foundries, silicosis was found in &% and with tuberculosis in 2.6%, a total frequency of one-half that in granite workers. The silicosis In foundry- sun was not only less frequent but also less advanced In degree than la the granite workers. Pneumonia, causing ^ae^ourxh^fndthe.xleaths of foundxymen. Is the.greatest occupational hazard .in the Industry, y Industrial health hazards and employer responsibility. V. J. McConrtU. Trane. Amer. Foundrymm's Azttu, 7 (tj 161-65 (1936).--The Importance of greater attention to the problem of overcoming industrial health hazards for foundry employees Is recognized. Medical aspects are discussed, foundry hazards are outlined, and suggestions for a control program are given. D. E. Ccsoccrcs. Ibid^ pp. 16d~79.--With the Invention of the machine, dust became an industrial hazard. G. discusses the action of dust in the lungs and points out that all dusts are not dangerous. Silica dust Is one of the dangerous dusts hut only when present us certain concentrations of certain par- tide sizes. The silicosis problem is complicated by the fact that In many cases there is also decided evidence of the presence of tuberculosis. In foundries many men with normal lungs work for years and do not contract silicosis although there may he evidence of fibrosis. C. explains the action of dust particles inhaled on previous pulmonary Injuries and testes that workmen who are disabled by oc cupational fibrosis contracted in the foundry general:? are those who exhibit evidence of concurrent pufmona.-? Infection or injury. It b the executive's responsibility to Inform, himself on dust hazards, conduct surveys of hi* plant, and Inaugurate a program of control. Prospective employees are grouped Into three general groups: thoe which are fair risks and those which should not he employe; are indicated, d recommends that an educational pry gram similar to that used In "Safety First" campaigns** Inaugurated to combat the dust hazard. Discussing Avxr d of. IKi, pp. 130-90.--The various ways of pet venting illness are pointed out, and precautionary measurti taken in the foundry are outlined. K.E.3. Industrial pulmonary disease due to iahxladoa of den. with special reference to silicosis. E. L, Mxsqiktox ' M2roy lectures, 1936. Lancet, pp. 1-9 (July 4); pp. **- 64 (July 11, 1936); abstracted In fear. Ini. Syt. 6* Tiri* eel., IS [S| 129-30 (1936).--The first lecture Is devoted silicosis, as bring the most important of the pneumoooo nioses. Particular attention Is directed to the occurrescs of the disease according to occupation. During 1930 f 1934. at least 1521 deaths occurred in England and Wafer of these. 372 were caused in the sandstone industry, asi 326 were ascribed to coal mining: the manufacture of pot tery claimed 270, metal grinding 142, gold miners, rt- Cumed from S. Africa, 104, and tin miners 91. The diteut b always originated by the dun ol fine particles o! tm silica; the way In which this risk is present la a number ri Industries Is explained. Sandblasting and the manufac ture of abrasive soaps receive special note, as In both &s hazard Is so intensive that the onset of the disease It un usually quick and its course rapid; thus only 3 or 4 vein of employment may have preceded the onset, instead :: 15 to 20 years as in most other occupations. The occu rence at cases In coal mining Is unexpected, since coat Itsci is not a dangerous dust; apparently the disease is orip- nated by dust arising from the rocks among which silica i* found or from impurities to the coaL Out of 169 deaths ~ ail cool fields ta Great Britain, 147 came from S. Wife*, this undue proportion has not yet been explained. TU picture, both ctfafcal and histological. becomes aodifiri when silica Is mixed with other forms of dust; when coal i* associated in the dust, the condition is knows as anthrax sis; here the fibrous tissue entangles the coal dust and re tains It to help in blocking up the lymphatics. In & second lecture the influence of the dust of silicates. O of chemically combined silica, is considered. Of the**- asbestosis stands out as most toxic; the particles consist C fragments of fibers, some 3 microns long and */: micron i diameter. They originate pulmonary fibrosis which - more generalized and less nodular than that of silicon the condition develops quicker chan silicosis, but the tec* deucy to succumb to superimposed tuberculosis is cot * pronounced. Other dusts considered are those of r~* manite, china clay, talc. mica, and seriate; none of approach asbestos and silica In their dangerous quafiti^ The harmful nature of any dust may be tested by notis* the reactions which fotlow when it has been richer inject^ subcutaneously or administered by* the tracheal roc- suspended in fluid; injection into the peritoneal cavi? may also be employed. The theory adopted is that def- ezert their harmful influence by reacting chemically * J<V No.-* ssrt? General m tam% tissue* of the blues, the life and structure of which are thereby modified. Each form of dust stimulates a special PoonbOa, ^ctiaa of its own* while mixed dusts set up a mixed re* xCtioa. No evidence b put forward that dusts other than ro*pecti>, 0* of silica or atUcates are harmful, or that any dust is <P: tfca, enable of reducing the toxic influence of any other. -wplow; EJ.V. Sooal pt, jaeestfgatfono on quartz and oeridu analysis of Indus- ^ dust*. P. Ssnosics juo C. V* Jftrmc. Arch. inofprv ;&suq^ m OB of Iffisuni ); pp. 59* -T cT Tori, devoted t teumoaoo* occurreno ag 1920 it end WaJa; fuwry, surf cm of pot. Tamers. tv Thedisoi xb of frs i number rf t atisuf^ m both the seise b to* 3 or 4 Tens . instead d Tlie occor^coelitsd ase is arip* hich silica & deaths oe a S. Wala; lined. T> gn,,* BaiUrioU 113, 133-31 (1933); abstracted in /our. InLSyt* Toxical^. IS [4] 54 (1935).--The separation of Tttnous stomal constituent* of dusts by the use of liquids fcseisr suitable specific gravities is discussed. The standaid methods of mirteralogicil and chemical analysis of 4mts are mentioned* with a description of the X-ray ea* a^ulsattofl. Some of the conunoo minerab are shown. Mention b made of the minenlory of Kricue. E*JA\ Methods of dust controL J. D. Lsxtcic. Trams, Am*. faundrymen's Am^ 7 {1| 209-21 (1936).--The print to begin elimination of the dust hazard b at the wares. Methods used for controlling the dust hazards originating at different types of sources are described. L (focusses the general methods used is dust-suppression problems and the estimation of the hazard, contending that the efficiency of a dust-collection system b best deter mined by dost counts. Methods used for testing ventOaring equipment and the selection bf fans are presented. Dust cdQectors and respirators, such as helmets, filtertype respirator*. and positive-pressure masks, are dis cussed. Maintenance of equipment b necessary to the fucemful operation of such equipment and to the effi ciency of nay matnOatioa. i discussion b Included* H.E.5. Molding of day after heating at various temperatures, ft. Mourn. Corricre Ceram., 15 221-23 (1934); Chfm. Zrxtr^ 1934. H, 3296; Brit. Cmcm. Ab$.-B> 54 [ZT] 391 '1933).--Heating at 1U0 to 500* before molding increases ?he apparent porosity of the product fired at 9t<U* and devTeas^s the resistance to breaking of a specimen dried at :es modified v-fcea cod b' it outhraeo dost and re is* 3a the. ificsttl, ts. . Of them Nomograph for ceramic calculations. A. A. DoscfsxxL *h*tnpoTjm 3 (fi| 374-76 (1933).--The nomograph facili tate* the chemical analyses and the calculation of the mount of oxides in the fired product and of the raw ma*rrial required for a given quantity of the latter. P.B. ft E.S. !<s consist of Personnel management J.- E. Waltz**. factory : * micron 3s ifanazrment Gr Xainttmanu, 94 (121 S333-U (1936).-- n> which * The topic* considered are (1) personnel management costs. of silkosb: selection >f employees. (3) personnel maintenance. (4) bat tic w traming and education. (3) medical and health service. (6) sis is sot 0 ^y and accident prevention, and (7) personnel service lose of sSDr Figures, tables, and photograph* are included. tone of tb& J.L.G. as qualities Significance of tree crystalline silica In the etiology of <d by aotinf sfiicasis and silicotuberculosis. K. B\ JOrrix and H. User isjccttd xns*. Mid. TTrih. 10f 545-36 (1936); abstracted icbed tout* TM /oar, Ind. ffyt. & Toxicof.. 18 [81 130-31 (ifcUl)--The oseot eavitj mh<ir dusted rabbits over a period of four years, first 2. b tbit dust? ;h*n 3. fheu d hr. daily, with porcelain dust having 302J xnicany with silica ami 1 m 2T* srriciie After this period the am- mob showed no typical silicosis although there coaid be seen sharp, pinpoint-sired, subpleural foci and a slight in crease of fibrosis. During the dusting, tubercle bacilli were administered intravenously. These grew slowly, and with indurating processes, into a pulmonary tuberculosis while the coatrob showed no noteworthy disposition to contract tuberculosis. It b concluded that over a 3 to 4 year period of dusting with tubercle bacilli injected. It was possible to produce a tubcrculorilkosb, although with the dust alone it was not possible to show sfficoris. In spite of the presence of scridte. By dusting with pure quartz (without tuberculosis infection and without seriche) for 1 hr. doily for 2 years, typical rifeotie nodules were prtv ducad* EJ.V. Sfileate anolysU la Industrial dusts. F. Saatoam axvd 1C* V. JbTTZN. Ztntr, Geverbtkyt. & UnfalforthuL, 21, 65-69 (1934).--Materials studied were from the Rhine Steel Wbrfcj. the Thyssea. and the XT. S. Steel Co. Tables show la detail the procedure and results, sceompaaied by ample comment and description of methods involved. If dusty occupations are to be graded on a danger scale over long or short periods, the sickness percentages and dust analyses must be carefully compared. These new re search methods an concerned with the size of grams ta dust raised and the accurate preparation of nndissolved arid particles, thus serving the combined purposes of mechanical phase analysis and chemical analysis. Impor tant insight into the structure of different kinds of dust baa been, gamed, and this ha* been Increased by using definite purity tests, Ag*. the ttcralls method. KJL SHIcoiia: harmful dusts which cause it. W. R. Jom Trams. Ceram. Jk, 34, 303-13 (1935); *rr Drum. A&J*. 14 {3] 84(1935). SiHcosis hi the porcelain laductry from the standpoint of the physirian. ScsizyrAxitT. Ber. DeuL Keram. Get^ 17 r6| 322*30 (1936).--It is pointed out that a sili cotic lung rarely occurs by itself, being usually associated with tuberculosis. A description of a silicotic lung is given. S. outlines the two theories of silicosis, mechanical and chemical, and dfecu**e* the chemical aspect of the problem. EJ.V. Training your own instrument men. Airman C. Moos, /fistrumracs. 16 [11 15-18 (1937).--M* reviews basic con siderations. qualifications of candidates, training of instrument men, division d? time bets ten Tailous typcs-ef repair jobs, supplementary educational work, progress re ports, and rating gride to be used in Ktaiaxuuial check up. R.T>ft. BOOKS AMD BVU.m* Determination and Control of Industrial Dust. J* J. Buooxytzku and ). M. Dallavall*. U. S. Health Ball317.167 pp. (April, 1933)*--This brief but com* prehenrivr work presents "the methods and instruments used tn conducting dust studies in industry, the interpre tation of results thus obtained, and their practical applica tion to industrial probUm*. especially those phases relating to control of the dust hazard/' Preliminary procedure involves the sanitary and occupational survey of a plant; final emphasis is placed on personal respiratory protection of worker*. Between the** occurs the dust technique. / J I I ii .V :l * . * .** ,1. i Vj * i * 1 Increasingly Karps verdicts. The Workmen * Compcnsa- dots Act dm applied only to accidental injuries. Occu pational diiciit* should be compensated under an ar rangement similar to workmen's compensation but sepa rately. because there Is so much dUFcrectc* between cheat. Partial disability should be compensated. It b difficult to obtain unbiased and expert medical diagnosis of stBcotis and the degree of disability. There should be a special medical board in each state for such n diagnosis. Preven tion U more important than compensation and much cheaper. W.D.F, Mineral materials which produce lilleorfa. B. Go**- yen. Sprttktaal. 60 {4t|*H-fU2; [421 tftrt-17 Lung disease occurring ia the porcelain industry are not produced by sendee or other minerals containing mica, as it is not present in the dust and mica b not contained by the siliceous materials used. This face shows that lung diseases are not connected with the presence of mica. The appearance of silicosis is chiedy due to the presence of free silica in the siliceous cocks used. 3LV.C Protection of health of glass and ceramic workers. T. Thomas. ClashttiU, 66 [49 J 323-26 (193ft).--Measures to he taken tn the case of various injuries sustained by workmen are discussed. - M.V.C Ratmg and performance of stationary steam hollers. V, S. PaTTIMOH. Cambtuiuiis 8 f2| 23-30 (1938).--The absurdity of the terms **boiUr horse power** and "percent of rating** as applied to modem steam generating units Is discussed, sod more rational expressions are suggested. The effect of variable entering gas temperature, operating pressure, and superheat on the boiler performance is an alysed and illustrated by curves and equations. Gas- temperature gradient and draft loss through boilers are also discussed. H-E.5. ' Report of the Committee on Ceramic Education for 1934. Hafot a E. White. Jfoff. 4tf. Crram. Joe., 10 (3 [ 111-20 (1937).--This report includes tabular data compiled by E. E. Marbaker and E. H. Fritz. . Suggestions* fat starting and maintaining a foundry apprenticeship system. J. E. Goss. Trans. Am*r. Foundry**'* Asstu. 7 (2J 323-30 (193d).--G. outlines points to be taken into consideration in apprentice train ing; such as methods of selection, testing prospects, age Omits, cates of pay, piece work, requirements Of a program, necessity of centralised* activities, trial apprenticeship periods, agreements, kind of instruction, related work, etc. A discussion is included. K.E.S. BOOKS AND StTXrmfS Bureau of Mines activities In the field of budding materials. D. M. Baxes. C. 5. Bo/. Kuw Information Cm-c.. No. 69*24,31 pp. Free. B. collates all publications by members of the Bureau personnel on the subject of buildin g materials and Includes reports published by the Govern ment Printing Office and mimeographed by the Bureau and articles In technical journals and cooperative reports. - R. A. KtSfOt, Chemist's Year Book. Edited by E. Horn. Sberratt Zl Hughes, Manchester; Chemical Publishing Co.. New York, 1936. 13th ed. Price 56,00. 1257 pp. The hand- tvf*dc has complete information OMtcertumr the varum* chemical constants and characteristics and properties <4 most organic and inorganic elements ami compound*, tn addition, various qualitative and quantitative le* termination procedures are given both for organic and inorganic substances. IICJhav National Physical Laboratory Collected Research**: VoLXXV, 1955. H. M. Stationery Office. London. 432pp. Price 13s. The volume contains twenty-three reports of researches devoted cftttdy to the study of metallurgical problems. The reports cover studies of the various iron alloys, alloy* of Au-Cu, Cd-Zo. Ag-So. sad Ag-Kg, meiallie cadmium, and the crystal structure of and .1-manganese. One paper is devoted to special refractories for metallur. glcal research. A brief resume is given of the properties and methods of producing refractory crucibles, muffles, and tubes from silica, alumina, magnesia, thoria. alumina-clay, and silicon carbide-clay. M.C,$kaw Official Year-Book of the Scientific and Learned Societies of Great Britain and Ireland; Record of Pub- ttcatioaa Issued during the Session 1933-1955. Com piled from Official Sources. 33rd annual issue. Charles Griffin and Co., Ltd., London. 1936. vti 4* 1711 pp. Price IDs net. Noted In Xature. UP (330l 31 (1937). J.L.G. Third Ordinance Increasing Compensation of Occupa- y tional Diseases la Germany, M. Backs. Reprint from RcUhsarbritsbUuU Nd. 36, Part IV (1936). 47 pp. Berlin. . 1937. The sew ordinance relating to occupational diseases In Germany went into effect April 1.1936, superseding the Second Ordinance of Fab. 11,1929. Several industries are added to the list of compensable diseases, including all the ceramic industries (previously only the porcelain industry Was Insured), sandblasting, and operations for deaning castings and molds. Asbestosis in the asbestos trades and lung cancer in the chromium industries become compen sable. Severe silicosis, compensable under the Second Ordinance, is still the only form of silicosis insured against, but wfaat constitutes the disease for clinical, rdncgenolog* teal, and judicial estimation Is definitely specified, thus doing away with a hitherto vexatious miscellany of com plications. Severe silicosis accompanied by pulmonary tuberculosis requires only the establishment of the .severe silicons In diagnosis. Amongdamagc-thnss 'reported for occupational diseases since 1929. silicosis has stood at the peak; 1a 1934, of 1043 cases, 522 were for silicosis; ia 1935, of 1161 cases. 627 were for silicosis, with 146 deaths in 1935 from this cause. K-ft- saw jotrexAt. Stunh (Dust). Edited by C L&otgftT. VoL 1. No, i. y April, 1936.- Published quarterly by WUhctm Knapp- Halle. Price 5 Rm. The Association of German In dustrial Insurance Societies reports on the current status of the dust-control compaign and survey* the literature- Two or three original research papers comprise the ant part of each issue, followed by reviews of pertinent litera ture arranged systematically under (1) dust research rnw properties, estimation, and measurement, (2) dust source*. (3) dust diseases, (4) other dust injuries, (3) prevemiv<^ methods, and (6) taws and decisions. K R- naos lancet] : .' ' *. . .v.~ .r; ; [july. >,1930' ADDRESSES AND ORIGINAL ARTICLES' ; / INDUSTRIAL pulmonary disease can be felt above the general surface and to be part: of a nodule which extends into the lung. , DUE TO THE INHALATION OF DUST The cut surface of the lung shows excess of pigmenta WITH SPECIAL REFERENCE TO SILICOSIS* tion throughout = its extent, but the striking and distinctive feature is the presence of numerous rounded . By E. L. Middleton, MJ).Edin., D.P.H. nodules. These are dense, tough, or hard, and the, cut surface is grey or black. Each nodule is from H-M. KBDIOAL dSPSOTOS 07 FACTORIES 2 to 5 mm. in diameter, but several maybe aggregated together to form large composite *nodules, or many' . The aim in these lectnxea is to reach some conclusions regarding the tielogy ol silicosis from a study of the occupations in which it occurs. In order to save confusion as to the condition to which the term silicosis is applied, the typical form of the disease is briefly described. The spread of the disease over the industries in\this country is referred' to and some of the occupations are more closely studied.* ' It will bd'found that in all these occupations in which silicosis occurred there had been exposure to the inhalation of dust of free silica. ' Besides the industries* in * which silicosis occurs, certain occupations are referred, to in which the workers are exposed to dust of silicates without free silica, and the changes following such exposure are described. These form a contrast with the characteristics of silicosis and, in general, they conform to the description of a condition, which has been called "silicatosis." . may be united in a massive fibrosis. In old-standing cases individual nodules may be sharply defined from the surrounding lung tissue, which may show* emphysema. The centre of the nodule may have undergone calcareous change. In fatal cases, where' exposure to dust has' been intense and the course of, the disease relatively rapid, the nodules may be so crowded that practically no lung tissue can be seen remaining. This condition is found in some sand blasters and it appears to follow exposure to highly siliceous dust--Le., dust containing a very high' proportion of free sihea. 1 . Gardner 1 described the pathological changes of the lungs in 15 cases of so-called " acute " silicosis. There, were masses of small nodules embedded in broad sheets of fibrous tissue, a generalised fibrous thickening of the alveolar walls, and slight involvement of the glands. . . : ! ''. The distribution of the fibrosis ` is not always uniform and discrete, but in certain cases it . id Silicosis ' * ' = condensed in large masses, of rounded or oval shape Silicosis is the most important of that group of diseases which have been termed collectively the pneumoconioses. In this country it is always the result of prolonged exposure! to certain kinds of' dust in the course of occupation. The onset of symptoms is marked hy dyspnoea. Slight at first, noticeable only after prolonged or unusual exertion, it remains the . most important symptom and is progressive throughout the course of the disease. In the early stage physical signs are characteristic, but they must be sought for with care. In this first stage the radiograph! shows the presence of discrete shadows indicative of. nodulation. In the second stage dyspnoea and cough become established and greater changes are noted .in' the physical signs. The radiograph showB the whole of both lung fields occupied by shadows indicative of nodulation, and there is some coalescence to form more or less dense opacities. There is always some degree of impair ment of working capacity. The third stage is reached with total incapacity, through increasing severity situated centrally or peripherally in; the lung and usually about the middle zones, but the masses may be multiple. This form of distribution is met with typically amongst coal miners and is described by observers in France and Belgium, as well as in this country.*3 .' The diagnosis of silicosis is made post mortem oil the macroscopic evidence of nodules which are palpable. The fibrous nodule is the essential and characteristic lesion of simple, silicosis. Recourse to histological examination is usually necessary for diagnosis only in the presence of complications-^ notably tuberculosis and malignant disease. The presence of tuberculosis may render the diagnosis very difficult. According to Kettle 4 the differential diagnosis depends on the amount and distribution of the collagen in the tissue reaction; it is a matter of degree and there are no definite standards on winch to base an opinion. Policard and Morel ** applied a speotrographic method for the detection of mineral particles in pulmonary tissues, and Irwin46 has developed a method for the demonstration of siliceous of symptoms of which dyspnoea is the most distressing. material in histological sections, as an aid to diagnosis, The radiograph indicates areas of massive consolida tion. Pulmonary tuberculosis may be present in any stage of silicosis. It may alter the symptoms, physical signs, radiological appearances, and the whole course of. the disease. It is the most frequent accompaniment of silicosis. . by incineration and treatment with acid. Clinical and radiological examinations at earlier stages in the progress of the disease can be of immense importance in the diagnosis of complicated cases. Changes in the lymphatic glands usually occur early in the course of silicosis. At first enlarged, they are Post-mortem appearances.--In fatal cases of found in more advanced cases hard and on section uncomplicated silicosis the lungs are generally large, dark grey or black, often showing several con of increased density, and retain their shape on removal centrically arranged systems of nodular fibrosis.. from the chest. Pleural adhesions are nearly always The lymphatic glands may show foci of tuberculosis present and may be extensive and of long standing. when tuberculous lesions are not apparent in On parts of the lung not covered by adhesions the extensively silicotic1 lungs. pleura is typically mottled a grey colour and studied over with whitish mammillated nodules, each of which Examination of the Dust-cloud . . * The Milroy lectures tor 1936 delivered before the Royal College of Physicians of London on Feb. 87th and March 3rd. The second lecture will appear in the next issue of The Lancet. 5888 The International Conference on Silicosis held at Johannesburg in 1930 4 adopted the view that in order to produce the pathological condition known SC-ALL-01205 SCF-FA-0350 2 THK LANCETJ DK. B. L. MIDDLETON : INDTTSTBiLAL PULMONARY DISEASE [JULY 4, 103Q as silicosis, silica must Teach the lungs: (a) in a chemically uncombined condition, although it might be mixed with other dusts ; (b) in fine particles of the order of less than 10 microns in diameter; (c) in sufficient amount, and over a certain period of time. It is generally agreed that the majority of dust particles found in the lungs are under 5[i and very few exoeed 10jx. There are exceptions, for example, in the asbestos industry and in coal-mining, where the length of some particles found in the lungs, may greatly exceed 10p. * Special methods are required 'for determining the concentration, particle-size distribution, and composition jo the dust-clouds to which workers are exposed. For the numerical method of dust estimation it is necessary to collect the sample in such a way that it can be examined under a high power of the microscope and the particles counted, measured, and their size-distribution ascertained. The instruments used for this purpose are of two kinds. With one the sample is taken in a fraction of a second; * with the other, the process of sampling can be run for over an hour or more. To the first class belongs the original konimetar introduced by Sir Robert Kotz^ in 1916 and used as the standard instrument in the South African gold-mines.* The Owens Jet Dust-Counter, which also takes momentary samples, was designed by Dr. J. S. Owens,.7 and has been used in this country for esti mating industrial dust-clouds since 1922.? . - The Greenburg-Smith Impinger dust sampling apparatus was first described by Greenburg and Smith in 1922.* The standard instrument as now used in. the United States Public Health Service was described by Greenburg and Bloomfield in 1932.10 The latest method of collecting samples of atmospheric dost for enumeration is by means of the Thermal Preci pitator. This instrument was originally- developed by Ptof. B. Whytlaw-Gray and Dr. Lomax at Leeds and has been adapted by Green and Watson for estimating indus trial dust-clouds as a result of work undertaken for the Medial Research Council.11 The results of the counts obtained by the numerical method ore usually expressed as the number of particles in 1 c.cm. of air. In America they ore stated as millions of particles in a cubic foot of air. (One million particles in a cnbie foot is approximately equivalent to 35 particles in 1 c.cm.) Dust-counts recorded in these lectures are of samples taken at breathing level tuiH are stated as a number indicating particles in 1 c.cm. atiH, in parentheses, the approximately equivalent number of millions of particles in a cubic foot, thus: wet, hand grinding table-blades, 280 (8). To save the time of count ing a comparative method of quantitation may be used.1* By the gravimetric method the sample of dust is collected from a large volume of air and is then weighed and the result expressed as the weight of dust in a given volume-- e.g., mg. per cubic metre* When used alone the method is open to the criticism that particles of large size, are included, which, though they have no pathological import ance since they cannot reach the alveoli, yet represent a very high proportion of the weight of the sample. It is useful, however, to combine the numerical and gravi metric methods, especially in initial surveys. The identification of mineral particles of dust is pos sible by means of the petrological microscope, but even under favourable conditions it is not possible to identify below about 2 microns in size. This is important from the pathological aspect, for it is just below 2{i that the average size of all mineral particles found in the lungs lies, arid the majority, over 80 per cent., of particles in an average industrial dust cloud, are under 2p in diameter. Chemical analysis may be of value, but it does not give all the information necessary for assessing the pathogenic importance of a sample of dust,- because the chemical composition may be less important than the mineralogies! character. . - A method for employing X ray diffraction for analysis has been introduced.1* 4 The Occurrence of Silicosis Silicosis is not reportable as are certain other occupational diseases, and, until a few years ago. the term had rarely been used for the purpose of certifying the cause of death. Since the beginning of 1930, by arrangement with, the Registrar-Genoral, the Home Office have obtained copies of the certificates of all deaths due to fibrosis of the lungs, silicosis, ashestosis,- or pulmonary disease due to dust. It is thus possible, for the first time, to present these data and for the present , purpose the five-year period 1930 to 1934 has been taken. ' The number of deaths included in the group during - the period is 4038. Of these, silicosis was mentioned on the certificate as a cause of death in 1521 The distribution by industries is shown in Table I. Table I.--Deaths from Silicosis (England and Wales) -- Industry. 1930 1931 1932 1933 1934 Total. 1 Sandblasting .. .. 10 17 5 10 2 Steel dressing clean 3 45 ing of castings .. 1 4 1 1 7 3 Flint and pebble crashing 1 1 2 4 i 9 4 Refractories industries .. 11 19 5 7 9 51 5 Scouring powders *and abrasive soaps 6 Ttnftmftl maker .. .. __ 13 15 11 7 Metal grinding .. .. 35 37 31 21 18 142 8 Glaziers* diamond setter 11 9 Sandstone quarrying and dittaing .. .. 17 25 13 29 33 117 10 Sandstone masons .. 35 48 44 75 53 255 11 Grave diggers .. .. 1 23 12 Tunnel mining, (sewage works)........................... 1 31 5 13 Granite quarrying and dressing ............... 2 1 9m 3 6 14 SlartrtaeBriTqiguarryin, g, and 1 2 5 3 3 14 15 Slate dressing, with sand *- 1 -* 1 16 Gold mining (South Africa) , .... 24 28 16 18 18 104 IT Tin mining ... .. 10 18 28 17 18 91 . 18 Lead mining .. .. 2 19 20 Copper Twining .. , , Iron ore (haematite) ** 4 2 6 1 .. 1 13 3 mining .. .. 10 7 6 13 36 21 Barytes Twining ,, 22 Fluorspar mining ,, .. 1 1 11 3 1 23 Mining engineers .. 2 2 1 2 1 24 Diamond thIwa manager 1 8 1 25 Coal mining .. 26 Fireclay TwinIng ,, .. 41 50 76 74 85 326 .. 1 1 27 Pottery, manufacture of 53 5T 63 53 44 270 28 Leather dressing .. 1 1 29 Metallurgist .. .. - 1 1 Total sflicoste .. 247 330 308 329 307 1521 It is not claimed that these figures represent, accurately, the occurrence of silicosis. They are almost certainly an understatement. . . - Occupations in which Silicosis Occurs It will be convenient in reviewing some of these occupations to pay special attention to the materials and the kind of dust to which workers are exposed during their employment. , The simplest process, from this point of view, is perhaps sandblasting. It is the process of projecting sand or other grit, by means of compressed air, against a surface. *. It can be carried out in various ways. For large articles the operator works in a specially constructed room, and he is protected by special clothing, and a helmet which is supplied with pure air under pressure. Small articles are treated in a closed cabinet, the worker passing his arms through guarded holes to direct the abrasive while watching the process through a glass panel. The dust hazard is from the abrasive, usually quarfczose sand or crushed flint. Metal grit or shot has now replaced sand as the abrasive to a considerable extent, and where THE LAHOffir] DE, E. D. MIDDLETON : INDUSTRIAL FUXJtfONARY DISEASE [jUXT 4, 1936 3 it is used oil clean metal no siliceous dost is produced. respiratory disease which was regarded as. an acute When it is used for cleaning metal castings, dust is pro form of silicosis.14 . duced from the adherent moulding sand, which is highly sUiceous. The manufacture in this factory was commenced in 1910, but was not important in quantity until 1921, and In the 5-year period under review there were in August, 1928, it was given up owing to the death of 45 deaths from silicosis amongst sandblasters. Of workers attributed to the inhalation of the dust. Of a these, 38 were fully investigated and the ages at death and the period of employment on sandblasting were determined. The striking fact which emerges is the short periods of employment which caused death from silicosis, compared/ with other occupations. All had been employed less than 20 total of 81 persons employed on the process, 22 left during the month in which they joined, or in the month following. One of these, who left in September, 1919, died in 1927 of tuberculosis after ten months* illness. Thirteen deaths are known to have occurred amongst the remaining 59 employed, the cause of death being tuberculosis or silicosis. The Chart shows the total number of persons years; 8 less than 5 years; 15 between 6 and 10 engaged in the manufacture at this factory, the period of years; 11 between 11 and 15 years; and only 4 employment, and the date of death of those who are known over 16 years. In the census of England and Wales, to have died. . 1931, the total numbers employed do not exceed A summary of the history of the fatal cases and of 1395. This gives with 45 deaths in 5 years a one (No. 31) who developed silicosis and is under treat mortality-rate of -6*4 per 1000 living. It is actually ment is as follows :-- higher than this because the census figures include shotblasters working on clean metal, who are not exposed to siliceoife dust. . CASES OF HESFIRATOEY DISEASE INDICATED ON THE CHANT No. Silicosis is found amongst sandblasters in various 3. Joined July, 1919, aged 14 (female). Left Nov. 20th, parts of the world. The same features, a short period of employment and rapid course of the disease, characterise the cases in this occupation. Flint and pebble crushing.--Flint, a chalcedonic 1928. T.B. in sputum December, 1928. Died Jan. 3rd, 1929. At p.m. the tuberculous lunglesions appeared to be of about four months* duration. It is not probable that this person was a source of infection in the factory. Symptoms form of silica, is crushed for making chicken grit, dated only from August, sputum was very scanty sandblasting grit, abrasive papers, and brake-sand and positive on the third examination (December, for tramoars. The flints may be first calcined, in order to make the material more friable and whiter before crushing. The persons employed are few in number and often the employment is casual or intermittent, so that it is impossible to estimate the actual damage to the health of the men employed. 1928). 7. Joined August, 1919, aged 14 (female). Left Septem ber, 1919. Attended hospital March 26th, 1926. Sputum positive; no X ray. Died Jan. 24th, 1927. 17. Joined January, 1923, aged 14 (female). Left March, 1924; rejoined January, 1926, left April, Uncomplicated silicosis, with total disablement, 1928. Sanatorium March, 1928. Sputum negative - was found in one man who had been employed on flint-grinding during a total period of eleven months, in three months of which there was intermittent exposure to concentrations of dust ranging from 6200 (148). to 10,225 (292). During the five-year period, 1930 to 1934, there were 9 deaths from three times. Died April ,26th, 1928. ' 19. Joined May, 1923, aged 44 (male). Left 1926. Died March 21st, 1926, after illness of one month (T.B. in sputum). No pan. . 24. Joined March, 1924, aged 14 (female). Died Jan. 10th, 1927. after illness of a few months. Certified P.T. No pan. silicosis. 26. Joined August, 1924, aged 15 (female), left May, 1928. Refractories industry.--Some 3000 workers are employed. The processes include the quarrying or mining of the raw material, usually a sandstone of the coal measures called ganister, which occurs in open quarries and in mines, or, in some localities, Died June, 1928, after an illness of five months. Pan. silicosis. T.B. in glands. 35. Joined September, 1925, aged 14 (female), left 1928. Cervical glands removed 1928. Died Oct. 10th, 1935. Pan. massive silicosis of lungs and glands . and miliary silicosis of lungs, glands, and spleen. sands or " pocket-days '* are used. 36. Joined October, 1925, aged 14 (female), left March, The raw material, which contains usually from 92 to 98 per cent, of silica, is crushed, mixed with suitable bonding substances, and made into silica. bricks, silica cement, steel moulders* composition, and aimilAr products for'use as refractories in the manufacture of metals, especially steel and steel castings, and in the construction of gas-retorts and flues. ' 1928. Died June 4th, 1928, after an illness of three months* duration. Sputum repeatedly negative. P.m. chronic fibrosis of lungs and glands. No evidence of tuberculosis, no T.B. found. 39. Joined October, 1925, aged 14 (female), left -June, 1926, rejoined February, 1927, left July, 1927. Died Oct. 21st, 1927, after an illness of five months* duration. No pan. X ray in August; diagnosis During the five-year period, 51 deaths were, certified due to silicosis in persons employed in this industry, a rate of about 3 per 1000 employed. There was some diminution in the number in the later miliary T. No sputum. * 42. Joined February, 1928, aged 16 (male), off five weeks August-September, 1927, with cough; returned September, 1927, to April, 1928; then to sana torium until November, 1928. Admitted hospital years of the period. January, 1929, T.B. in sputum. Died Dec. 27th, Manufacture of abrasive soaps.--The raw material may be a highly siliceous quartzite rock containing 98 per cent, of silica, or crystalline quartz or quartz- sand. It is used in the manufacture of abrasive soaps by mixing it with powdered soap, anhydrous 1929. Pan. very advanced P.T. and silicosis. 44. Joined February, 1926, aged 15 (female), to August, 1928. Died P.T. Sept. 8th, 1933. 48. Joined August, 1926, aged 15 (male), left May, 1927. On Nov. 23rd, 1928, X ray negative, clinical examination indefinite. T.B. in sputum June 18th, sodium carbonate, and sometimes other substances. 1932. Died April 24th, 1933. ** About ten years ago numerous firms became engaged in this manufacture, who had no knowledge of the dangers of exposure to the dust and were inadequately provided with protective measures. This resulted in the occurrence at one factory of 3 or 4 cases of 49. Joined September, 1926, aged 15 (male), left August, 1928. T.B. in sputum Feb. 7th, 1934. Died P.T. July 7th, 1935. 63. Joined October, 1927, aged 14 (female), left August 1928. TJ3. in sputum on July 23rd, 1930. Died P.T. Sept. 9th, 1930. 4, thb lancetJ DR, K. L, MIDDLETON: INDUSTRIAL PULMONARY DISEASE [XULY 4,1930 31. Joined January, 1925, aged'.17 (male), left August, 1926. Xray on Sept. 17th, 1932^ diagnosis " miUary . tuberculosis," later changed to " silicosis." No ' * ` sputum: Later abscess in neck. Sputum negative . on March 7th, 1935 (under treatment). ' ': this decline is due to two causes: (1) the change from sandstone to artificial abrasive wheels, and (2) the effect of stringent preventive measures in the grinding rooms. . ' **' It was estimated that in 1926 about 1600 natural grind Cases of silicosis developing rapidly in workers in stones were in use in the Sheffield district for band the manufacture of abrasive polishes have been grinding. . This number was reduced to about 200 in described by (xiese,16 Teleky,18 and Kilgore.17 1933 and many of these grindstones were not in regular, - Polishing compositions and parting powders contain ing silica.--The most important forma of silica used for these products ore Tripoli and Neuburg chalk. use. In the Birmingham district there were 480 natural sandstone wheels in use in 1926 and 452 persons employed. To-day there are only 22 sandstone wheels in use and 18 persons employed. An interesting survey of the Tripoli is regarded as a chalcedonic variety of silica,18 Sheffield experience in tuberculosis amongst grinders is and it contains from 96-99 per cent, silica. The contained in the annual report of Dr. John Rennie,' the substance generally known by the name is imported medical officer of health, for .1934 (Table H, p. 21).. from Seneca, Missouri. The name comes from Tripoli in North Africa, where the product is a true diatomite. . In this .Table the mortality among grinders is compared with that of .all persons over 15, in quinquennia from 1886 to 1934, shown as percentage of deaths from tuber culosis of the lungs to all causes. While this has shown Two fatal casco of silicosis with tuberculosis have amongst all persons over 15 a steady decline from 14*4 per occurred in thia country from exposure to dust of Tripoli. cent, in 1886-90 to 6*7 per cent, in 1931-34, amongst The two men had been employed for periods of 10 and grinders it has shown a variation between 35*6 per cent: 11 years respectively; mixing the ingredients in the manu reaching a maximum of 53*5-per cent, in 1911-15 ; It facture of parting-sand in one case, and of polishing- returns to 38*2 per cent, in 1926-30, and in the last quin composition in the other case. ' quennium falls below the starting point to 27*8 per cent.- - Neuburg chalk is a natural deposit of siliceous material at Neuburg on the Danube, The silica content is given as from 65-97 per cent. At one This may be the first sign of a progressive decline. In Table I, of Dr. Rennie's report the mortality-rates for tuberculosis of the lungs amongst grinders and amongst' Ctitlers are shown in comparison with that for all persons time this material was believed to be harmless, but over 15 as a rate per 1000 of the population for the years recently there have been definite cases of pulmonary 1925 to 1934. The figures show a reduction from 6*3 to disease following exposure to the dust in this country. 4*1 amongst grinders, but no reduction amongst cutlers. Koelach and Kaestle18 examined 30 workers employed The rate for all persons over 15 over the period shows a with this material and found 8 who showed signs of fall from 1*1 to 0*8 per 1000. silicosis. *- .* Glaziers1 `diamond setter.--This unique case was' Diatomite (kieselguhr, diatomaeeons earth) is that of a man. aged 55, who died of massive and composed of minute, siliceous skeletons of aquatic nodular silicosis with tuberculosis. He had been plants. When pure it contains up to 96 per cent, employed for 14 years on a process in which a small of silica. It is used as a mild abrasive or polishing abrasive wheel composed of a siliceous stone gave medium, as filtering material, and for insulating off a fine cloud of dust, which, though scarcely properties. . visible, was found to have a concentration of 350 (10). .Radiological examination of six workers exposed to dust of kieselguhr for ten years, in this country, showed In a petrographic examination of the stone no mineral other than silica was detected. . slight evidence of fibroses in two, and none in the others. . Sandstone industry.--As a cause of silicosis this . Legge and Rosencraatz 20 made an investigation at a is the most important of the group of industries diatomaeeons deposit in Santa Barbara County in in which stone is got and prepared for use or. sale. California, and by clinical and radiological examinations It.includes the quarrying, or mining, and dressing of 108 men, silicosis was found in 81, very early in 16, of sandstones which are sedimentary siliceous rocks, early in 45, moderately advanced in 15, and advanced in: 6. Crodjonsson11 tells of several workers exposed to high concentrations of fine dust of diatomaeeons earth, digging grinding it for many years. It contained over 90 per cent, free silica. No silicosis in an important degree was found. - consisting more or less of quartz-grains, mixed with other minerals, and held together by a- cement of varying amount and composition. About 12,000 men are employed on the process in quarries and, in addition, about an equal number of masons are . Grinding of metals.--The processes which cause employed in builders' and soulptois' yards throughout the country. The workers who are most affected silicosis in the grinding of metals are confined to by silicosis are the stonemasons, and after them the those* in which grindstones, composed of natural quarrymen and rockgetters. .- , Sandstone are used. These are obtained chiefly During the five-year period, 1930 to 1934, the from the millstone-grit sandstones of Derbyshire and number of fatal cases of silicosis amongst sandstone the Sheffield and Newcastle districts. Grinding .quarrymen and stonemasons was'372. About 300 may be done wet or dry, and the metal being ground of these deaths were amongst stonemasons, and as may be moved by hand, or by mechanical power there are probably about 20,000 sandstone masons on a machine. The processes of dressing the surface in England and Wales, the annual mortality-rate of the grindstone are also very important from the for silicosis is about 3 per 1000 employed. health point of view. The following are average concentrations of dust found . The concentration of dust produced varies with the at various classes of work in the sandstone industry: amount of attrition of the grindstone in these processes. masons, 545 (16); rockgetiers, 319 (9); drillers, 939 (27); Rxamples of dust concentrations in wet hand-grinding quarrymen, 1956 (56); crushermen, 1132 (32). An are': table-blades, 280 (8); chisels, 1150 (33); scythes, investigation into the occurrence of silicosis in the 660 (19). At wet machine-grinding: paper-knives, sandstone industry was^parried out for the Home Office 130 (3*7); files, 270 (7*7); edge-tools, 120 (3*4). Dry by Sutherland and Bryson12 in 1929. * Of 454 examined hand-grinding (with exhaust); sheep-shears, 240 (7). - clinically, 268 had fibrosis; radiological examination of * During the five years, 1930 to 1934; the total number of deaths certified as due to silicosis was 266 showed sfiicosis in 112. In a elmifta.1 study of silicosis in 1000 consecutive examinations of workers in quarrying and dressing sandstone, Ferguson 22 found clinical evidence 142. The numbers for the consecutive years show of pulmonary fibrosis in 433. Radiological examination a decline, 36, 36, 31, 20, and 19, and it may be that of 173 of these showed silicosis in 109. 1 f I I L. THE LANCET] DR. E. L. MTDDUCTON : INDUSTRIAL PULMONARY DISEASE [JXTLY 4, 1936 5 Silicosis has been, described by Kranenburg14 in Holland, employment for from 20 to 40 years. Teleky and and by Thiele and Saupe 14 amongst quarry workers in the . Lochtkemper *7 describe cases of silicosis amongst workers highly quartzose sandstone of the Elbe district. Koelsch in "grey-wacke.1* In the sandstone industry of Ohio and Kaestle11 examined 173 sandstone workers and and Indiana15 examination of 919 workers showed that found that .76 per cent, were severely affected after the incidence of silicosis and the number of cases of CHART SHOWING RECORD OP PERSONS EMPLOYED AT ONE FACTORY IN THE MANUFACTURE OF ABRASIVE SOAP-POWDER WITH INCIDENCE OF FATAL RESPIRATORY DISEASE The horizontal linos show the duration of employment of each worker and the black rectangles the time of In the fatal cases that are known. 6 THE LANCET] DR. . L. MIDDLETON : INDUSTRIAL PUXMONARY DISEASE [JULY 4, 1936 tuberculosis increased with age and length of exposure.. An North Wales. His report shows that from 35 years of investigation was made by Wulfi11 amongst workers age onwards, and, particularly in the later agee of life, in Sweden on quartzite sandstone containing 94 per cent, those engaged in the slate industry are very unfavourably of silica. . placed. * Silicosis in a grave-digger.--A case was described by Edwards 30 of a man, aged 32, who died of silicosis with tuberculosis after working as a grave-digger foT 17 years. The graves were in red sandstone A medical inquiry was. undertaken for the Mines' Department by Sutherland and Bryson** amongst slate workers in North Wales. Clinical examinations of 120 workers showed that severe fibrosis of the lungs existed amongst the older millmen. Fourteen out of 52 mining and pneumatic drills were often used for excavating. examined radiologically showed signs of silicosis. The work was very dusty and in dry weather the Dreessen ** described a survey carried out dt two slate men worked in spells of 20 minutes. * quarries and their associated mills. The radiographic Tunnel mining.--Silicosis was certified as the shadows in these cases were of the fine reticulated type of cause of death in five men employed as tunnel- fibrosis, with, in advanced cases, dappled areas showing miners, during the period 1930-34, in which post mortem examination showed extensive silicosis. a tendency to conglomerate. They had not the nodular appearance of silicosis. . In three cases the men had been engaged in tunnelling ' Gold mining.--Gold mining is of importance to the for water-supply or sewer construction work in incidence of silicosis in this country, because of the sandstone in the 'North of England. Cases of severe cases which arise amongst miners who have gone to silicosis in tunnel-miners have been described as work for a time in the South African gold-mines and occurring in Sydney, New York, and Johannesburg. have returned home suffering from the disease. Granite industry.--The granites are crystalline During the five-year period, 1930-34 there were rocks in which the amount of free silica as quartz 104 fatal cases of silicosis amongst these miners rarely exceeds one-third of the weight, and in some certified in this country, an annual average of just granitic igneous rocks frequently included in the over 20. Most of them had worked in the tin-mines commercial term, the proportion of free silica is of Cornwall or the haema tite-mines of Cumberland, much less than this. The other constituents are and went to South Africa as skilled miners. silicates. The processes in getting and dressing Tin mining.--The mining of tin ore in this country granite are rimilar to those used in the sandstone is almost entirely confined to Cornwall. The ore industry, but pneumatic tools are much more occurs in lodes which traverse granite or " killas," frequently used. an argillaceous schist. In 1934 there were 1645 The following are average concentrations of dust found at various classes of work in the granite industry: masons, 412 (12); rockgetters, 343 (10); drillers, 1935 (55); wage-earners. Many tin-miners went from Cornwall to work in the gold-mines of South Africa and elsewhere and, crushennen, 1834 (52). in the early dayB of the Rand, when conditions were In the radiograms of granite workers the prevalent type of shadows indicating fibrosis is somewhat different from that found in workers who are exposed to dust containing a high proportion of free silica. It is a finer type of mottling with more linear striation and reticulation, hut nodulation of silicotic type is also found in some cases. much worse than they are to-day, they contracted pulmonary disease. There is ho doubt, however, that silicosis has been caused by working in the tin-mines of Cornwall, for 38 of the rock-drillers referred to in the report on the health of Cornish miners 40 had worked in Cornwall alone. During the five-year period, 1930-34, silicosis was certified as the cause of death in 91 tin-miners, equal to an annual mortality- An investigation was carried out by Sutherland, Bryson, and Keating*1 in which 494 workers were clinically examined and 211 of these were examined radiologically. Fibrosis was found in 260 (52*6 per cent.) and silicosis in 36 (17 per cent.). Extensive investigations have been made into the incidence of silicosis amongst granite workers at Vermont." rate of 11 per 1000 wage-earners employed in 1934. Hcematite iron-ore mining.---During the five-year period 1930-34, 36 haematite-miners were certified as having died from silicosis. No case was certified during the first year, 1930; the numbers for the subsequent years were 10, 7, 6, and 13 respectively. An investigation was made in a representative group of Until the last few years. silicosis had not been 961 granite workers from four towns in Massachusetts ** generally regarded as an occupational risk in this with clinical and radiological examinations. Silicosis was found in 15 2 per cent. -nH silicosis with tuberculosis in 7'6 per cent, of those examined. Teleky and Lochtkaruper ** found only the slightest evidences of pneumoconiosis in workers on a quartz-free basalt after 20 to 40 years* employment. Gutzeit ** points out the less severe lung changes which follow exposure to industry. In a study of the Registrar-General's statistics for the period 1910-12, Collis 41 pointed out that the Cumberland and Lancashire group of iron-ore miners had a higher mortality-rate than the rest of the ironstone group for phthisis and other respiratory diseases. Since that time a form of dust of granite compared with those following exposure pulmonary fibrosis frequently accompanied by tuber to dust of quartz-schist with a silica content of 91 to culosis has been proved to exist in this industry. 95 per cent. Watson found the following dust concentrations in a Slate.--The industry is concerned with quarrying or mining the rock and making and shaping slates for roofing, and other structural work. It is widely distributed in this country, but about 9000 of the 11,000 wage-earners in the industry axe employed in North Wales. Slate is the typical cleaved rock. haematite-mine at a distance of 50 yards' from the working face without dust suppression; after an average of six shots with 9 lb. explosive: 222,000 (6343); after an average of four shots with 6 lb. explosive: 105,000 (3000). With the use of a dust-suppressing device the air was apparently free from dust, but actually the thermal precipitator showed a concentration of 30,000 (867). The most important constituents quantitatively are At wet-drilling apparently no dust was produced, but silica, free as quartz, and combined as silicates of there were actually over 2000 (57) very amall particles. aluminium, iron, alkalis, and other bases. In Penrhyn (Welsh) slates quartz exists to^ the extent of 34-66 to 43*26 per cent., while the` total silica (free and combined) is from 57*75 to 63*01 per cent.3* Cronin 41 examined 100 drillers and 16 non-drillers, and found 64 of the former and all the latter to be clinically normal. Thirty drillers showed well-defined and constant features which included dyspnoea on exertion, flattening and diminished expansion of the chest, diminished Wade 37 made an investigation into the mortality-rate resonance on percussion, and a change in the quality of the for tuberculosis amongst slate workers in a district of breath sounds. TKB I*ANCBT] . I>R. E. L: MIDBt^rrON: iNDtrsraiAI. PUMONABY DISEAJBB [JULY 4, 1936 7 Radiological gnearmnatinim of haematite-miners show . industrially healthy South "Wales coal-miners.4* The changes in the lungs which resemble those of silicosis as distinction in the degrees of change found between workers it occurs in other industries, and the changes progress like in anthracite coal and in bituminous coal agree with those those of silicosis.. Stewart and Faulda 41 have described reported by Russell.44 .In the Welsh study the anthracite 15 fatal cases of pulmonary fibrosis in haematite-miners. group showed a degree of " mottling " greater than that Fatal cases of silicosis have occurred in a haematite-mine found in the Bemi-bituminous group. Harper44 found in the South of England in which the country rock is no radiological difference between cases of silicosis in granite, which contains 27 per cent, of free silica and South Wales and those seen by him in the Belgium coed- 64*5 per cent, of total silica. fields. Lyle Cummins 44 directed attention to the variety Coal mining.--During recent years evidence has of occupations included in the coal-mining industry. been accumulating which shows that certain workers Table II.--Silicosis in Coal-mines employed underground in coal-mines contract a Certificates issued, by the Medical Board, for Silicosis and disabling and even fatal fibrosis of the lungs. Silicosis with Tuberculosis during the period June 1st, In 1909 the Royal Commission on Mines 4i realising 1931, to Dec. 31st, 1935. ' the possible danger of drilling in siliceous rock in coal-mines recommended that " water or some equally effective means '* should be used when the process is being carried out. Cases of silicosis were found in rock-drillers employed in Somerset coal mines 44 in 1925, and in 1926, Tattersall 46 reported cases of silicosis among hard-ground workers in coal TUWlSoufrildCnuf* Number of Number of wage- certificates issued for-- earners on Dec. 14th, 1935. Death. Total disable ment. 3 I & ma mines in South Wales. - XKOiiArrD. The processes underground in. a coal-mine which involve direct exposure to. siliceous dust are : (1) Northumberland .. m9 Durham .. .. ., Cumberland and Westmor- 43,865 104,344 ,, 1 2 ** driving a hard-heading, cross-measure drift, staple pit or sinking pit; and (2) ripping or brushing, land .. .. South Yorkshire .. West Yorkshire . .. 4,862 ,, 94,437 .. 41,991 .. 4 .. ,. 8 3 # 10 1 i.e., cutting the roof, floor, or sides of a roadway to increase height or width. These processes involve boring - the shotholes, shot-firing, and loading the Lancashire and Cheshire North Derbyshire .. Nottingham .. .. South Derbyshire .. Leicestershire .. ., ,,, 59,607 41.623 44,832 3479 9,055 5 ,,. 1 ., 5 '2 ,. 5 '* ddbris.47 Cannock Chase .. ,, 21,366 1 2 The following dust-counts are of samples taken by Watson with the thermal precipitator at various distances North Staffordshire .. ., South Staffordshire and Worcestershire ,, 22,543 4,460 3 ., 16 1 6 mm from the working point in a coal-mine, while means were not taken to suppress the dust. As usual the samples were freed of carbonaceous matter by incineration. Drilling, Shropshire .. Warwickshire Forest of Dean Bristol .. .. .. .. .. ,. ., 2,623 16,391 5,075 838 .. .. ,, 1 .. 2 m_ 2 usually in sandstone, at 15 yards, 10,860 (310); at 65 yards, Somerset ,. .. 3,410 5 i.7 7 860 (25); at 160 yards, 650 (18). Shot-firing (with Kent .. .. .. 7,303 3 6 4 24 ok. explosive), at 65 yards distance, 2000 (57); (with Total .. - - 531,694 22 66 35 40 oz. explosive)* at 160 yards distance, 2300 (65); near the bottoms of the upcast shaft, 550 (15). W4XBS. South Wales and Monmouth 130,552 147 511 198 In the period June 1st, 1931, to Dec. 31st, 1935, North Wales .. .. 8,676 1 the Silicosis Medical Board issued a total of 987 Total .. 139,228 147 512 198 certificates on account of silicosis in coal-mines. SCOTLAND. These included 237 suspensions, 581 for total disable Fife ft-r|d f!l<wlrrmuiT>Rn .. 21,625 .. 1 ment, and 169 for death. The distribution of these L^hfauw (Mid and East) Lanarkshire .. .. 12,472 .. *2 .. 38 A 30 .. 1 3 cases in the different coal-fields is shown in Table II. Ayrshire .. .. 113U -* * *- The numbers of certificates issued in respect of Total .. 84,238 .. 3 4. fatal cases, if calculated on the number per 100,000 wage-earners employed in December, 1935, is 22-37 great bsctajh .. * 755,160 169 581 237 for Great Britain; 4*13 for England; and 112*59 for South Wales and Monmouth. The Somerset coal-field has the highest rate, of 146*62 certificates for death per 100,000 wage-earners. No completely satisfactory explanation of this distribution has yet been reached. A clinical and radiological examination of workers exposed to anthracite coal dust was arranged by the Industrial Pulmonary Disease Committee of the Medical Research Council in 1933.fiT The 40 selected at random from amongst the 250 workers were coal-trimmers at Swansea docks. The committee was unable to find, Fisher 44 has shown that there is no constant relation in this series of cases, any evidenoe that the inhalation between the amount of drilling and the incidence of of anthracite or other coal dust had caused fibrosis of silicosis. The same is true of the practice of stone-dusting. the lungs. It is held by some that a risk of bronchitis is incurred,4* Collis and Gilchrist 44 described results of the clinical by the men,,overheated, travelling out of certain pits by and radiographic examination of eleven coal-trimmers. slants through chilling currents of air which reach a The radiographs showed mottling in eight cases, massive velocity of 2500 ft. per minute with a temperature drop bilateral shadows in one, and no definite mottling in two. of 20 to 40 F. T. David Jones 44 found that four times In the report of a study made in the Anthracite Region as many cases of silicosis were certified from collieries with of Pennsylvania by the United 8tates Public Health slants as from those without slants. W. R. Jones81 Service ** the results of examination of a total number stated that the mineral sericite is present in the sandstones of 2711 workers in 3 anthracite coal-mines are described. of the anthracite coal-field, while in those of well-known Anthraco-aikcosia was found in 23 pear cent., and the Scottish collieries, sericite is either absent or rare. Accord incidence varied with the period of employment, and the ing to Cooke, *1 sericite is constantly present in the concentration nature of the dust to which they were atmosphere of the Lancashire coal-mines, but he found that exposed. Bdhme 40 described the results of examination silicosis was extremely rare amongst the coal-miners there. of 3318 rock-drillers working in the Ruhr coal-mines for That " prolonged exposure to the working ` conditions periods from 5 to 25 years. Of these, 19*44 per cent, incident to coal mining is frequently associated with the showed changes, due to dust, of varying degrees of severity gradual development of alterations in the radiological from slight, 14*7 per cent., to grave, 0*18 per cent. appearances of the lungs" is a conclusion reached as a From a study of systematic examinations of 9807 result of a radiological study of certain groups of stone-workers in the coal-mines of the Ruhr district 5 THE LAKCET] DR. E. I*. MIDDLETON : INDUSTRIAL PULMCONART DISEASE [JULY 4,1936 ' Reichmann nH Schurmann 11 found, tba prevalence. and degree of severity to be 1048 (10`6 per cent.) slight, 89 (0*9 per cent.) moderate, and 14 (0*16 per cent.) severe. In 493 cases of severe silicosis the duration of employ ment was, on the average, 18*3 years. Death was due to simple silicosis with heart failure in 37 per cent., and to an accompanying tuberculosis in 63 per cent. Courtois ** made a study of pulmonary disease in 136 coal-miners at Charleroi. Radiological examinations of these workers are classified as negative' 33, positive (nodular opacities 30, confluent opacities 61) 91, other conditions (bronchitis, emphysema, and deformities)' 12. Post-mortem examination showed that the nodules were typical, simple, silicotic nodules. In the massive fibrotic areas the nodular arrangement had disappeared except at the periphery. Leclercq u has described the occurrence of silicosis amongst coal-miners in the north of France. >Tnrnvn 44 found .that the disease produced amongst workers underground in the coal-mines of Central France is silicosis, which occurs in nodular and pseudo-tumoral forms. Badham and Taylor * found in the coal-miners of New South Wales several different types of pulmonary Table III.--Pottery Industry Mortality-rates for silicosis in certain occupations calculated on fated cases .investigated by the Factory Department in the five years, 1930 to 1934. > 1. EXPOSURE TO FLDTX DUST ` Occupation: Maks (H-), Females (F.). . numbers employed. Deaths in 5 years. AflTTTIftl mortality- rates per 1000 employed. M. Flint millers, and mill F. JuL F. M. F. .. .. .,labourers .. .. .. 240 .. . ..nhirvA biscuit ware placers.. 162 7 9 .. 5-84 11-84 ,. .. ..nMna biscuit oddmen . . 70 7 20-00 .. ., ..Polishers and grinders .. 330 14 8-48 rrhinA biscuit warehouse .. - 223 - 7 6*28 Totals .. .. 792 223 37 7 9-34 6-28 2. EXPOSED TO DUST OP EARTHENWARE BODY Slipbouse .. .. .. 417 .. 6 2-88 Throwers .. Turners .. .. .. . .. 24 132 .. Handlers............................ 113 336 3 4 ,,. 3-02 7*08 Platemakers .. .. 364 108 16 ,. 8-78 Dishmakers .. .. Handbasin makers .. . 113 .. 95 64 4 .. .. 7.-.08 Saucer makers .. .. 52 156 3 1 11-54 Cup makers .. .. Jiggerers and Jolliers .. .. 46 261 248 * 1 122 21 ..3 4*34 16-92 Preasers and casters .. 221 592 19 1 17*18 Hollow-ware dressers- .. 248 22 17-74 Throwers* assistants .. *30 i i . . . 1 28 2 42 . 0 36 3 33 _ Totals* .. .. 2086 1602 98 9* 9-49 3. EXPOSURE TO DUST 07 CHINA BODY .,Sliphouse........................... 121 1 Throwers .. .. - - 102 8 0-1. 6 Turners .. .. .. 161 18 5 0-62 ,Handlers .. - .. 33 211 Platemakers .. .. 52 , 2 7-69 Dishmakers .. .. .. 10 Handbasin makers .. .. 7 Saucer makers .. - .. 74 6 5. 13-51 Cup and bowl makers .. 14 Jiggerers and JoOiers .. 18 6 Jiggerers, flat ware .. 45 2 Preesers and casters .. 140 152 4 5-71 1-12 Totals .. . 761 417 17 447 * * Include 3 deaths of towers (females) for which numbers employed are not obtainable. fibrosis. One type was thought to be either a silicatosis due to silicates, or a pure anthracosis due to coal dust. Pottery industry.--This industry includes several distinct branches, subdivision being determined by the nature of the article manufactured and the materials entering into the composition of the ware. The occurrence of silicosis is especially associated with two branches--earthenware and china. In. the manufacture of earthenware, the ingredients-- ball-clay, china-clay, china-stone, felspar, and flint--in a ground state, are mixed together in the form of liquid slip, from which excess water is removed by pressing. The resulting composite body is made into, the consistence convenient for the manufacture of the various articles. In the plastic state it is used by throwers, preasers, jiggerers and jolliers, handlers, modellers, and others, Table IT Summary of mortality-rates for silicosis in certain occupa tional groups, calculated on fatal cases investigated by the Factory Department in the five years 1930 to 1934. * Occupations exposing Numbers workers to dust of-- employed. Deaths in 5 years. Armria.1 mortalityrates per 1000 employed. Flint........................... Sanitary ware (body). General earthenware (body) .. * .. China (body) .. .. Tiles (body) .. .. Placing sand .. .. Saggers .. .. (M. & F.) 1015 736 3688 1178 975 947 608 (S,* S+T*) 44 (27. 17) 25 (12. 13) 107 (54. 17 ( 7. 12 ( 6. 53) 10) 6) > 8*66 6-78 4*17 2*89 2-46 2-32 0-33 3 eiheoais ; S +T Bfllcoflls with tuberculosis.. . according to their craft, in the potters* shops. So long as it remains moist it is harmless, but in the process of manufacture fragments fall on benches and floors or adhere to the clothing of the workers, become dry, and give rise to dust. After the article has been made in the plastic form, partly dried, it is frequently subjected to the process of towing on a revolving disc, thus giving rise to dust. Processes of fettling, to remove irregularities of surface and edges, are done by hand. The articles are then placed in fireclay saggers with some sand, and fired in the oven. On removal from the oven the loosely adherent sand is brushed off. Subsequent processes of decoration and glazing are not associated with the occurrence of silicosis. For the manufacture of china, the ingredients are calcined bone, china-clay, and china-stone, but it contains no flint. The processes of making the articles are similar, in general, to those employed for earthenware,* but the articles require much more support in the process of firing than do earthenware articles, and to provide this support they are placed in finely powdered flint,. The flint is prepared by calcining and subsequently crushing it in the dry state. The placing of china in. Baggers with flint is done by the china biscuit placers. When the saggers of china ware are taken from the oven they are emptied by the placers and ' " oddmen " and the flint, which was used in placing the ware, is removed by women in a series of processes known as " scouring." Finally, after the ware has been decorated and glazed, blemishes are removed by polishers who frequently use powdered flint, mixed with water, as a finishing abrasive on a rapidly revolving wheel. Exposure to flint dust in the pottery industry occurs in the processes of the preparation of the flint by grinding; in the manufacture of general earthenware, earthenware tiles, sanitary earthenware, and electrical fittings, amongst those manipulating the earthenware body in the plastic and semi-dry states ; in the manu facture of china, amongst those employed in placing the biscuit ware in powdered flint, and in removing the flint from it after firing; and in polishing finished ware with the. use of flint. It is in those processes that the highest incidence of silicosis is found to occur. This was brought out as the result of a medical inquiry made by Sutherland and Bryson.* The following results are selected from counts of samples of atmospheric dust taken by Watson with the thermal precipitator at various processes in the pottery industry; at breathing level, unless otherwise stated: (a) Flint grinding, dry, with exhaust, 150 (4*3); flint-milling, wet (general air of the room), 109 (3); placing china biscuit ware (general air of the room), 121 (3*4). (6) Earthenware tee LANCET] pa. 3. ZITCKFIRMAN ; CESTRONE IN UTERINE BLEEDING * [JULY 4, 1036 9 plate-making, 176 (5)fettling (damp), 168 (4*8); fettling, dry, ,201 "(5*7). (c) Tiles, pressing, 213 (6); fettling, 275' (8). (d) Sanitary earthenware; general air of a gating shop, 164 (4*7). (e) China, cup-making and turn ing, general air of the shop, 181 (5). ' INHIBITION AND INDUCTION OF UTERINE BLEEDING BY MEANS OF (ESTRONE In countries in which flint is not used in the manufacture of pottery respiratory diseases amongst Bt S. Zpckbbman, D.So.Lond., M.R.C-S.Eng. pottery workers appear to be less prevalent than in BEIT MEMORIAL RESEARCH FELLOW England. {From the Department of Buman Anatomy, Oxford) The occurrence of silicosis amongst pottery workers has been referred to by Koelsch *67563a8n5d6495H5a5rt6m5a7n5n88589 60 61 62 63 64 65 66 in Germany, Langelez * in Belgium, Mailer 70 in The increasing clinical importance of oestrone* Denmark, Quaintance and Morris,71 7P2a7n3coast and in the treatment of conditions such as amenorrhena Pendergrass,7* 79 and others in America. or sterility resulting from uterine hypoplasia makes it necessary that the available data about the physio* REVERENCES logical action of the hormone on the primate uterus 1. Gardner, L. U.: Amer. Jour. Pub. Health, 1933, xxiii., 1247. 3. Magnin, J-: La MW- dn Travail, 1935, vil., 137 3. Courtois, R.: Rev. Path, et Phya* du Travail, 1933, ii., 37 should be properly understood. At the' present time two apparently conflicting statements are made on 4. Kettle, E. H.: Proo. Roy. Soo. Med., Sect. Path., 1933, xxvi., 28. 4a. Policard, A-, and Morel, A.: La M6d. du Travail, 1932, this subject: the first, that the continuous injection of the hormone inhibits menstrual bleeding, and the tv . 56. ' 4b. Irwin. D. A-: Canad- Med. Assoc. Jour., 1934, ml-, 135. 5. Silicosis: Internat. Labour Office, Geneva, 1930, p. 86. second, that uterine bleeding occurs, even in ovariectoraised human beings and monkeys, during the 6. Final Rep. Miners* Phthisis Prevention Comm.: Govt. Sfcat. Office, Pretoria, 1919, p. 10. 7. Owens, J. S.: Proc. Roy. Soc., Series A, 1922, cf., 18. course of prolonged cestrin treatment. The purpose of this paper is to examine the facts hearing on these 8. Same author: Jour, of Indust. Hyg., 1923, iv., 522. ' 9. Greenberg, L-, and Smith, G. N.: Reps, of Invest., Bur. of two points. Mines, Washington, 1922, No. 2392. Allen's 1 observation that the cessation of injections 10. Greenberg and Bloomfield, J. J.: Pub. Health Reps., Washington, 1932, xlviL, 654. . of cestriii into castrated monkeys is succeeded after 11. Green, H. L-, and Watson, H. H.: Med. Research Council, a few days by a phase of uterine bleeding constituted Spec. Rep. Ser. No. 199, London, 1935. 12. Hatch, T., and Thompson, E. W.: Jour, of Indust. Hyg., the first definite knowledge of the endocrine control 1934, rvi., 92. of the primate endometrium. His finding has been 13. Bale, W. F., and Fray. W. W.: Ibid., 1935, xvii.. 30. 14. Macdonald, G.. and others : THE Lancet, 1930, ii., 846. repeatedly confirmed, both on monkeys and on 15. Giese; Qnarzst&ab, Schwielenlunge u. Lungentuberkalose, human beings, and the bleeding occasioned in this Jena, 1931- - 16. Teleky, L.; Jahresb. 6. d. T&tigkeit d. preuss. Gewerbemed, way has been justifiably related to that occurring 1927. either after removal of the ovaries oy after rupture 17. Kilgore, E. S.: Jour. Amer. Med. Assoo., 1932, xeix., 1414. 18. Abrasives, Part I., Dept, of Mines, Ottawa, 1927, No. 673, of ovarian follicles. In both cases the bleeding that p. 70. normally follows these procedures can be delayed if 19. Koelsch, J., and Kaestle: Silicosis, Internat. Labour Office, Geneva, 1930, p. 372. treatment with osstrin is begun immediately after 20. Legge, R. T-, and Rosencrantz, E-: Amer. Jour. Pub. the operative interference. , Health, 1932, xxtt., 1055- J 21. Gudjonsson, S. V-: Aertzllch. Sackverst.-ztg., 1934, x!L, 1. The normal histological effects of osstrin on the 22. Sutherland, C- L., and Bryson, S.: Rep. Oocurr. of Silicosis Among Sandstone Workers, HJkf. Stationery Office, London, 1929. ^. primate endometrium have also been elucidated. The hormone, in castrated subjects, promotes con 23. Ferguson, T-: Jour, of Indust. Hyg., 1934, xvL, 203. 24. Kranenburg, W. R. H.: Silicosis, Internat. Labour Office, siderable mitotic activity in the uterine epithelium. ~ Geneva, 1930, p. 512. 25. Thiele and Saupe.quoted by B6hme, A.: Ibid., p. 356. * (Estrone (keto-hydrory-ceatrin) Ib at present one of the more 26. Koelsch, F., and Kaestle : Ibid., p. 371. readily available and most commonly need of the oestrus-pro 27. Teleky, L., and Lochtkemper, I.: Archivf. Gewerbepath. n. ducing female ser hormones to which the general term " tnetrm ** Gewerbebyg., 1932, iii., 693. _ was applied before their chemical nature had been elucidated. 28. Russell, A. S.: Silicoeis, Internet. Labour Office, Geneva, Where the term " cestrin ** is used in the present paper it should 1930j_p. 549. . be taken to mean oestrus-producing female sex hormones in' 29. Wolff, hT B.: Acta Path, et Microb. Scand., 1934, xi., 389. general. 30. Edwards, P. W.: The Lancet, 1931, i., 1238. _ 31. Sutherland, Bryson, and Keating, N.: Rep. on Silicosis Amongst Granite workers, H.M- Stationery Office, 1930. 32. TT-S. Public Health Bull. No. 187, Washington, 1929. 33. Rep. Special Indust. Oommiss. Commonwealth of Massa {Continued from previous column) chusetts,- Boston, House No. 1350,1934. 53. Ann. Report, King Edward VH. Welsh Nat. Memorial 34. Lochtkemper and Teleky ; Archlv f. Gewerbepath. Assoc., 1930. n. Gewerbebyg., 1932. ilL, 711. ` 54. Russell ; Silicosis, Internat. Labour Office, Geneva, 1930, 35. Gutzeit,K.: Zeits. f. Tuberk., 1934, lxix., 412. p. 538. 36. Reade, T. M-. and Holland, P.; Proc. Liverpool Geol. Soc., 55. Hamper, A.: Brit. Med. Jour., 1934,1., 1920. 1898, viiL. Part 2. p. 293. 56. Cummins, 9. L.: Ibid., 1935, 1., 287. 37. Wade,. T. W. : Rep. on Public Health, No. 38, Min. of 57. Ibid., 1934, t. 198. Health. Welsh Bd. of Health, H-M. Stationery Office, 58. Collis, E. L-, and Gilchrist, J. C*: Jour, of Indust. Hyg., 1927. 1929. x., 101. 38. Sutherland and Bryson: Report on Inquiry into 59. Spec. Bull 41, Commonwealth of Pennsylvania, Dept, ot Occurrence of Disease of Lungs in Slate Industry, Mines , Labor and Industry, Harriesburg, Penn., 1934. Dept. London, H.M. Stationery Office, 1930. 60. Bfihme, A.: Silicosis, Internat. Labour Office, Geneva, 39. Dreeaseo, W. G.: Jour, of Indust: Hyg., 1933, xv-, 66. 1930, p. 354. 40. Haldane, Martin, and Thomas; Report on the Health of 61. Reichmann and Schflnnann: Zentralb.f. Gewerbebyg., 1935, Cornish Miners, Od. 2091, HJ1. Stationery Office, London, xxii., 121. 1904. 62. Courtois, R.; Rev. Path, et Phys. du Travail, 1933, x., 37. 41. Collis, E. L.: Proc. Roy. Soc. Med., 1923, xvi.. Sect. 63. Leclercq, J.: La M6d. du Travail, 1933, v.f 222. Epldem.. 96. 64. Magnin, J.: Ibid., 1035, vii., 137. 42. Cronin, A. J.: Jour, of Indust. Hyg., 1926, vili., 291. 65. Baobam, C., and Taylor, H. B.: Med. Jour. Australia, 1933, 43* Stewart, M. J., and Faulds, J. 3-: Jour. Path, and Beet., i.. 511. . 1934, xxxix., 233. 66. Report an an Investigation into the Incidence ot SflicoedB 44. Second Rep. Royal Commission on Mines, 1909, Cd. 4820. - in the Pottery Industry, HU. Stationery Office, 1926. 45. Fisher, S. W.: Trans. Inst- Min. Engrs., 1935, UxAvili. 377. 67. Koelsch, F.; Silicosis, Internat. Labour Office, Geneva, 46. Tattezsall, N.: Jour, of Indust. Hyg., 1926, vili., 466. 47. Hay, P. S.: Personal communication, January, 1936. 1930, p.373. 68. Hartmann: Zentralb. f. Gewerbebyg., 1935. xxii., 143. 48. Fisher: Trans. Inst. Min. Engrs., 1935, lxrxviii., 377. 69. Langelez, A.: Bruxelles M6d., 1935, xv., 272, 303. 49. Haldane, J. 3.: Ibid.. 1935, lxxxviii., 388. * 70. MfiUer, P. F.: Acta RadloL. 1934, xv., 587. 50. Jones, T, D.: Ibid., 1935, lxxxviii., 406. 71. Quaintance, P. A., and Morris, F. J.: Calif, and Western 51. Jones. W. R.; Jour, of Hyg., 1933, Txxlii., 327.__ Med. Jour., 1934, xttv., 337. . 52. Cooke, W. E.: Trans. Inst. Min. Engrs., 1935,Ixrrvill.,393- 72. Pancoast, H. K., and Pendergrass, E. P.: Amer. Jour.. (Continued at foot of text column) Roentgen, 1931, xxvi., 55$. 73. Same authors: Pneumoconiosis, New York, 1926, p. 136.- ;;; t( *: 'ii = \;,r i ; r* ` ) Mi: j THE CAUSATION OF PNEUMOCONIOSIS* n` Philip Drinker From the Department of Industrial Hygiene, Harvard School of Public Health, Boston, Mass, HERE are four different types be small enough to float about in the Tof reaction produced in man by the inhalation of dust. The air and be carried by rather slight air currents; otherwise they cannot be in first and most important are hthaeled. pneumoconioses, such as silicosis and The modem word, pneumoconiosis, asbestosis, which cause specific lung is a shortening of Zenker's original pathology and often are followed by pneumonokoniosis. Zenker (1) de pulmonary tuberculosis. The second picted lungs definitely damaged by type of reaction is caused by toxic dust particles, but today pneumoconio dusts like lead, cadmium, and radium. sis is generally used to describe any A third type of malady follows the lung which has been dusted to more inhalation of finely divided metallic than the normal degree--there need fume particles such as zinc oxide and not necessarily be demonstrable lung is known as metal fume fever. Fi pathology. Silicosis, asbestosis, an- nally, the fourth reaction, allergic in thracosis, anthraco-silicosis, and simi character, is caused by breathing or lar terms indicate the different ganic dusts such as pollen and certain causative agents (silica, asbestos, and types of pulverized wood and flour. coal) in various kinds of pneumoconio In all four instances dust inhalation sis. can be the sole cause of the disability The International Silicosis Confer but with the toxic dusts characteristic ence in 1930 (2) defined silicosis as a reactions result from swallowing as "pathological condition of the lungs well as from inhalation. The latter due to the inhalation of free silica route, however, is much the more im (SiO*)". The American Public portant. Health Association (3) described it as In the present instance we are con a "disease due to breathing air con cerned only with the pneumoconioses taining silica." Sayers and Jones (4) which result solely from the action of state that "from the viewpoint of inhaled dust upon the lung tissue. Of etiology, the harmfulness of a given necessity then, the dust particles must dust containing free silica is directly Received for publication July 14, 1936. Read before the Harvard University Tercentenary Celebration, 1636-1936, Sym posium on "The Environment and its Effect upon Man", Harvard School of Public Health, Boston, August 27, 1936. influenced by the number of particles of free silica less than 10 microns in diameter that it contains". Collis has claimed for years that free silica, es pecially quartz, was the all-important 524 SC-ALL-01221 SCF-FA-0365 vol. IS, no, 8| CAUSATION OF PNEUMOCONIOSIS 525 factor. In summarizing his South African experience, Watkins-Pitchford (5) wrote in 1927 that dusts other than silica could "give rise to such non permanent and relatively harmless conditions--one can hardly call them diseases--as anthracosia, aluminosis, siderosis etc". In figure 1 are shown data from Collis indicating the etiological im portance of free silica. The U. S. Public Health Service's data (6), opal, which is non-crystalline, have not as yet been appraised hygienically and there are no statistical studies to show the relative potency of the vari ous forms of pure silica. Silicates.--Silicatosis is a word sug gested by Badham (7) to describe a lung fibrosis caused by dusts in which silicates and not free silica predomi nate. The distinction between free and combined silica is best shown by a simple example: A granite dust (8) occupation 8 QURRTZ CONTENT 1 of over PERCENT fiermtSNtON poutowurr rveorcutosis (Onmctev) &RIHOER9 (jheffitlat) G/t/wim-cumes (Mm. mnd R.H.) POTTERS COm-MiMiHG & SO t \90% IB1BI,B 307. SSS3 Ccrbrh prvcmasm* on/y ) 77.9% S.9% Fro. 1.--Mortality from pulmonary tuberculosis in various dusty trades. (After Collis) shown in table 1, emphasize still fur ther the importance of free silica. Silica.--Silica occurs most com monly as the mineral, quartz, which is a natural contaminant of most ores, occurs in many rocks, and is found in a fairly pure state as beach sand, chert, Hint, sandstone, gritstone, ganister, quartzite, and jasper. Quartz is a hard crystalline mineral which is weakly birefringent, that is, its two indexes of refraction are near together. Chemically it is very inert and inactive. In fact its hardness and inertness are the two properties which make it especially useful in industry. Other varieties of pure silica such as might have the following mineral com position : Percent Feldspar (orthoclase)..................... 70 Quarts.................... 25 Mica (muscovite)............................. 5 100 Chemical analysis of this granite would give the following result: SiOt (total)......... AlsOi........ .......... KiO...................... H*0...................... Percent . 72.55 . 14.80 .. 12.42 100.00 vol. 18, no. 8] CAUSATION OP PNEUMOCONIOSIS 627 Recently Jones (9) showed that sericite was the outstanding common mineral constituent of a considerable series of lungs he analyzed. Sericite is a variety of mica with the formula KaO * 3Al*Oj 6SiOa 2HsO. Its occur rence in nature is widespread but the quantities actually found are much less than those of quartz. It has not been shown that sericite, without quartz, will produce silicotic pathol ogy; all investigations along such lines have been negative. Asbestos is the only silicate at pres ent recognized as causing pathology which is definitely and distinctly dif ferent from that due to silica alone. The condition known as asbestosis, like silicosis, predisposes to tubercu losis but to a much less degree. Since, however, asbestos is handled by far fewer persons than are dusts contain ing free silica, asbestosis is much less common than silicosis. Asbestos is not a true mineral but is a name applied to any mineral which is easily separable into more or less flexible fibers. In this country, the commonest asbestos is the fibrous va riety of serpentine in the form of the mineral chrysotile, 3MgO * 2SiO* - 2H*0. Other silicates such as talc, 3MgO4Si0a*H10, which resembles asbestos chemically, shale, kaolin, Al*Oj-2SiO*2H*0, feldspar, and pure mica have been studied in both the field and the laboratory. The pathology they pro duce is much less significant than that from quartz and the fibrosis rarely is disabling. Carbon.--An extensive examination of coal miners' lungs was made by Cummins and Sladden (10) as the re sult of which they wrote that "coal is only retained in large amounts when there is a really high silica content" and "we believe that in the absence of the silica factor there would be, under modem mining conditions, no serious degree of anthracosis. . . Men who were engaged in trimming coal ships with virtually no quartz exposure but undoubtedly with very heavy dust exposure, showed some fibrosis but it was not considered disabling (11). The study made by the U. S. Public Health Service (12) in the anthracite mining district of Pennsylvania adds much weight to statements quoted from Cummins and Sladden, namely, that the harmfulness of a coal dust varies with the silica which contami nates the coal. Haldane considered that coal dust might even reduce the severity of a quartz dust exposure; he suggested actually blowing coal dust into a mine with high quartz content as an anti dote for the quartz dust (13) but no Berious attempt apparently was ever made to test the validity of Haldane's claims. The recent statistical analy sis of lungs autopsied in the Pittsburgh district (14) shows beyond doubt that city air, contaminated by an unusual amount of coal dust, does not produce a disabling fibrosis. Many of the lungs were markedly pigmented but the pathology found was not, in gen eral, significant. Calcium and magnesium carbonates.-- These substances occur in nature as the minerals calcifce, CaCOj, magne site, MgCOs, and dolomite, CaCOaMgCOa. Limestone and marble con tain high percentages of calcite while the bulk of the rock from which cement is made consists of these carbonates. All three minerals are a great deal more soluble in water and inj>ody fluids than 528 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Oct., i9$6 is quartz. Furthermore the solubility of all three substances increases greatly if the solvent is saturated with carbon dioxide, a condition which occurs in the lung fluid which wets inhaled dust. The several studies which have been made on calcium carbonate dusts indi cate that the dusts are not harmful probably because they are so readily dissolved (8). Gypsum.--This mineral, CaS04* 2HsO, is very common and is mined and milled all over the civilized world. It is an essential ingredient of ordinary plaster and is now used extensively as a wall board. When partially de hydrated it again takes up water readily, but in neither that state nor as the native substance has it been shown to be harmful (15). It is an interesting fact that pure limestone (quartz free), dolomite, and gypsum are recognized universally as the dusts safest (hygienically) to blow into soft coal mines to prevent explosions. Iron Oxides.--The mining of iron, next to coal, is perhaps the mining industry in which the greatest number of men are employed throughout the world. The ore generally is hematite, FeiQs, but other oxides, and sometimes the sulfide, pyrites, FeS*, are handled on a considerable scale. As a result of the improvements made in machine-tool steel, it is possible today to see iron dust created by work on lathes, drills, mid the like. Yet there are no data to indicate that iron, in the absence of silica, causes pathology in any way comparable to silicosis. However, lungs which have been heavily dusted with iron in any form are generally colored distinctively and were called by Zenker (1) siderotic. Estimation of Dust Exposure The effect of any inhaled dust varies more or less directly with the duration of the exposure, the dust concentra tion and the volume of air breathed. In the case of the gas, carbon monox ide, our knowledge of the relationship of these factors is sufficiently exact to permit the use of a simple rule (16) for predicting the effects of breathing various gas concentrations under vari ous conditions. Unfortunately, one cannot estimate or predict the severity of dust exposures with any such nicety. In cases where men work for a num ber of years at different jobs with dif fering degrees of dustiness Bloomfield and DallaValle (17) compute exposures by averaging dustiness in these various jobs over the total period in question. In their anthracite coal dust study they found that computations so made agreed well with the results of the phys ical and x-ray examinations of the men. A typical example of their method of computing dust exposure is reproduced in table 2. The advantage of these estimates lies in their simplicity and the fact that they have proven useful in corre lating dustiness with physical examina tions. The error in such calculations is that the effects of dust, do not vary exactly, but only very approximately, with the dust concentration and with the exposure. Thus, Mavrogordato (18) writes that "Lesions of silicosis in a mild degree can be produced in an animal by 30 hr. exposure to intense dust clouds, and one is inclined to suspect that it is intermittent exposure to relatively dense clouds that is the deciding factor in producing the dis ease in susceptible human subjects." These momentary excesses of dusti vol. 18j no. S] CAUSATION OF PNEUMOCONIOSIS 529 ness Mavrogordato named dust floods. Bloomfield and DallaValle's calcula tions of necessity ignore dust floods and use only figures of average dusti ness. The Value of Dust Samples The purpose of dust sampling is to make possible the control or elimina tion of dustiness rather than to obtain a precise measure of dust concentra tion. Conditions may vary greatly almost from moment to moment and ards of dustiness and is in reason able agreement with Mavrogordato's "figures of merit" as obtained by konimeter samples. A great deal of time can be saved by ignoring samples which are obviously too dusty--it is as well to take the sample for a matter of record but it is absurd to work long over it if it is cer tain to be vastly in excess of the ob jective. Mavrogordato dismisses such samples with the laconic symbols "T.M.C." (too many to count). TABLE 2 Example op Method Used in Determining an Employee's Total Dust Exposure4 OCCUPATION TKABS IN OCCUPATION Slate picker (dry breaker)........................ Patcher (dry mine).................................... Mule driver (dry mine)............................. Miner's laborer (chamber)........................ Miner (chamber mining)........................... Section foreman......................................... 2 2 3 3 3 5 AFBBAON OUST CONCBNTBATION, MILLIONS FBB CUBIC FOOT 380 71 71 480 480 7 MILLIONS OP PABTICL1 YBABS PBB CUBIC FOOT 760 142 213 1440 7200 35 Totals...................................................... 30 9790 9790 millions of particle years per cubic foot , ----------------------30 yearB------------------------- 13 326 millions of particles per cubic foot 4 After Bloomfield and DallaValle. only occasionally are they reasonably constant during a working shift. In general, then, it is advisable to give the results of the final estimate with an indication of the expected variation. "Thus, as a means of classifying proc esses according to their respective health hazards, it appears to be un necessary to arrange them in concen tration groups closer than 100 per cent, i.e.9 0 to 5, 5 to 10, 10 to 20, 20 to 40, etc." (8). Such an arrange ment is consistent with the few American data we now have on stand- On the other hand, it is well to have records which indicate that the en vironment is as clean as is desired. In our own experience the ignoring of such samples has raised difficulties in prov ing in court that adequate dust con trol had been enforced. There is no doubt whatever that, in the United States at least, dust samples now have a very definite place in depicting work ing conditions to compensation boards or to a court. Under the circum stances, it is very unwisfi in making surveys to ignore the clean places. 530 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Oct, 1936 Methods of Sampling Dustiness is given gravimetrically if the dust is tq,be determined chem ically and by counts if the chemical determination is especially difficult. Thus, lead is always recorded in milli grams per cubic meter but dust which may cause silicosis is given in particles per cubic foot or per cubic centimeter. Sometimes one may wish to convert one set of readings into the other. If the dust particles are perfectly uniform and of definite shape such as spheres or cubes and of known composition the conversions can be made with pre cision. In such a case, it does not matter how dustiness is recorded. But in practice the dust particles are never uniform in size and rarely in composition. Conversions are, there fore, apt to be misleading. For prac tical work, 1 mg. of fine quartz as collected by the impinger contains 300 million particles (by the light^field counting technic). A great deal of energy is being wasted in deciding which dust sam pling method is best. The rapidity with which new methods are appearing, each claiming unusual points of merit, indicates that standardization is un likely. An international agreement on a reference standard would be welcorned by all working in this field but, at present, such an agreement seems to be far off. In the United States the impinger technic is most used, largely because our only extensive field data come from the Public Health Service whose workers favor this instrument. If one wishes to compare his results with those of the Public Health Service he must copy their technic. But copying the Public Health Service's technic for the sake of the legal prestige thus gained has its drawbacks. We know of one case where a gasoline motordriven generator and electric pump mounted on a mine car and hauled by tractor, with three men in attendance, resulted in obtaining only four samples in one day. In South Africa where dust sampling has been done on a scale far beyond anything attempted elsewhere the konimeter and sugar tube both have been used. In England great hopes for the new thermal precipitator have been advanced but the results pub lished so far have added nothing sig nificant to the data already available from methods which are less accurate. In Australia several different instru ments including Owens' counter have been used while the results coming from Germany were obtained by filter methods and by a modification of Owens' counter. In our own studies we use several different methods according to the problem. There is every reason to encourage rapid methods which are particularly applicable to routine con trol and to discourage the widespread use of the impinger technic except for occasional check-ups. The impinger has little to recommend it in control work while a light portable instrument, such as the konimeter, has already proven its value in practice. Composition of Air-Floated Dusts It is rarely that one meets exposures to pure silica; generally the dust is a mixture of which the original compo sition either is fixed, as in granite, or variable as in most foundry and mining operations. But the composition of vol. 18, no. 8] CAUSATION OF PNEUMOCONIOSIS 531 the dust breathed from a mixture is seldom the same as that of the parent material. If a dust arises from the grinding or comminution of a comparatively pure substance, such as beach sand, the resulting material must have sub stantially the same chemical and min eralogies! analysis in all stages of particle subdivision. But if a com- frequently sample and count air-borne dust by the impinger technic and then for chemical and mineralogical anal yses take samples of material which has settled on rafters which will have a quite different composition. To make bad matters worse, samples for mineralogical and chemical analysis usually have not been graded into various sizes. 05 0607 06 09 IO If l IC5 94 IS 16 17 16 19 0 21 S2 6324 plex material like granite is ground and the dust then scattered in the air, samples of different particle size will have very different composition. Many examples of the changes in composition of air-borne dust can be found in the literature to prove these statements but it is interesting that the facts generally have been ignored. Thus, in this country, investigators Jones (19) has given indisputable proof of the carelessness of which most of us have been guilty in recording the composition of air floated dusts. In support of Jones* contentions an in teresting example is given by Drinker and Hatch (8) for foundry dusts. "A good molding sand is made up of about 80 per cent quartz in the shape of coarse particles; the bulk of the re 532 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Oct., 1956 maining material is clay in the form of fine particles which coat the coarse quartz grains. Jhe ' chemical com position of the finer fraction (say below 10 microns) of material in foundry sand is markedly different from the composition of the coarse fraction." Thus, the original material contains about 76 per cent quartz, while par ticles above 10 microns have 85 per cent quartz and those below 10 mi crons have only 19 per cent (see table 3). Under the present methods of estimating dust composition and dust hazards a large error obviously would be made by assuming that the changes in the composition of Barre granite, of 35 per cent original quartz composition, and of various coal-silica mixtures take place on settlement in air. Obviously, changes will occur (probably great changes) but they have not been measured as yet al though we have all welcomed the figures of reasonable dustiness sug gested by the U. S. Public Health Service for the two industries in ques tion, granite cutting and coal mining. Their analyses were all made from samples which had settled out on raft ers, and no samples were separated into various particle size fractions. TABLE 3 Composition op Coarsb and Fine Fractions op Unused Foundry Sand (Containing Natural Bond) COMMIT UKNT Combustible........................................... .. HC1 soluble................................................ HjSiFi soluble (clay)................................. Residue (quarts)........................................ * PBECENTAOH DT WBIGHT Total sample >10#* 2.3 5.5 16.0 76.3 0.7 1.6 12.7 85.0 <10#. 12.7 30.5 37.5 19.2 Total........................................................ 100.0 100.0 100.0 original material represented the fine air floated dust. Another example is given by Jones (19) from the South African "banket" --large crystals of quartz held together by fibrous seridte. In figure 3 are illustrated the changes in dust com position which he noted as the dust was allowed to settle, as it would in practice. Obviously, the quartz con tent decreases as the sericite increases. Jones remarks that "when a wall built of quartz boulders is pulled down, the bulk of the dust comes not from the quartz boulders but from the mortar." It would be interesting to know what Particle Size It is well known that in silicotic lungs dust particles under 3 microns vastly outnumber those which are larger. It has been alleged that the respiratory mechanism, the hings, and the phagocytes are mostly responsible for this size grading. However, it is easy to show that the size grading is done in the air before the dust is breathed and not later in the human body. That is, we find an excess of small particles in the lungs simply because that is the way that they oc cur in air. It is physically impossible for any but particles below 5 microns 36 i vol. 18, no. 8] CAUSATION OF PNEUMOCONIOSIS 533 to remain a.lfloat in air long enough be carried abl out by gentle air currp: and to be in]:ialed. It is perfectly that the a,ll|eoli are large enough rarely remain in air more than mo mentarily. Bloomfield (21) has re corded hundreds of measurements of air floated dusts. His average sizes * * ,. v D:: *71 . .. 4;Q" ''e o . 0: t Or * Q* o *4 \'Q o Q (a) p 0 , 'a v o Ck I ;<> * o t> V */- *\o *V - a? > D* o - 'Q , ' O' (b) V / ' M- -- * t *t ` '^ '- ^ 4 (C) (d) Fig. 3..--Skietches illustrating the i ncrease in the ratio of fibers of sericite to quarts particles at different periods after bli isting in a Witwatersrand gold mine, (a) about 15 minutes after blasting; (b) about 1 hour after blasting; (c) about 2} hours after blasting; and (d) about 3 hours after 1 lasting. (After Jones, courtesy Inst. Mining and Metallurgy.) admit parti]ries 100 or even 200 crons in lenifdb and that such partji are occasio]r ally found in lungs But the rea^ion that they cure foun| lungs so infrequently is that are all of the order of those found in lungs and in phagocytes. Gye and Kettle (22) showed that colloidal silica was extremely toxic and that it could initiate fibrosis. It 534 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Oct., 1956 is claimed occasionally that the dam age done by quartz particles is due en tirely to those which approach the colloidal in size. Usually particles possessing colloidal as distinguished from crystalloidal properties are con sidered to be less than 0.1 micron in size. All colloidal particles are so small that they can be measured only ultra-microscopically. There is no evidence indicating that appreciable or significant quantities of ultra-microscopic quartz can be made by any known process of grind ing or comminution, including blast ing. In fact, the difficulty of prepar ing even small specimens of quartz below 0.5 microns is considerable. Furthermore, there are no published data indicating the relative potency of quartz particles in various sizes be low 3 microns. Under the circum stances, then, there is no good reason to blame colloidal particles as the in itiators of the silicotic nodule when it has been demonstrated again and again that such nodules can be pro duced by particles approximating the common bacteria in size. Standards of Dustiness Under one name or another the plant or mine manager always wants an objective for his dust control pro gram. It serves no useful purpose to evade the issue on the ground that precise figures are not available. Probably they never will be. The practical man argues, very properly, that if dust is the cause of silicosis there must be some degree of dustiness or of air cleanliness which is safe. Having been told that silicosis is a disease caused by breathing silica, the practical operating man naturally ex pects of the physician or hygienist some objective of air cleanliness, call it by whatever name one likes. In this country the U. S. Public Health Service studies have furnished the only published data we have from which we may suggest dust standards. In the case of Barre granite it was pointed out that a dustiness of 10-20 million particles per cubic foot was reasonably certain not to cause dis ability. The coarse dust, in this case, contained about 35 per cent quartz. In their recent anthracite coal study the Public Health Service found that counts of 50 million per cubic foot, with 5 per cent quartz in the coarse dust, seemed safe. In the case of pure quartz Cum mings (4) suggests a figure of 5 mil lion particles per cubic foot which is not far from the South African figure of 1 milligram per cubic meter (fig ure 3). We have then 50 million for dust with less than 5 per cent quartz and 5 million for pure quartz. It is very questionable if one has any. right to interpolate for the quartz percentages between 50 and 5 but the figures certainly invite such inter polation. These standards do not answer the question of the plant which handles dust of no proven pulmonary signifi cance. What standard should the manager of such a plant take as his objective or need he take any precau tions at all? We cannot give him any standards but we can only suggest that he investigate one of the many plants which has reduced dustiness without waiting for any physiological justifica tion . Generally the manager and workmen of a clean plant will uphold eloquently the advantages of dust control. wse aist call blic bed om :ds. tfas -20 vas iisise, rtz. idy md bic the un til t is ure 5gfor rtz It aiy rtz the ihe ies ifidie his m- ny iat its >ut la ud >ld let vol. 18, no. 8] CAUSATION OP PNEUMOCONIOSIS 635 It is only in South Africa that dusti ness and silicosis have been correlated routinely over a considerable period. There they realized at the outset that dustiness would not be controlled properly unless measured and re corded routinely. Concerning the re sults of their procedure, Irvine (23), Chairman of the Miners' Phthisis Medical Bureau in 1934, stated that "No `New Rand Miner' who has en tered the industry since August, 1923, i.e. 10j years ago, has as yet contracted silicosis. These facts demonstrate that the engineering and medical measures which have been directed against silicosis have achieved a very significant degree of success." It would be hard to devise a more eloquent or complete proof of the advantage of dust sampling and of dust standards. Summary The various pneumoconioses and their causative agents are discussed. Silicosis and asbestos are definite dis eases ; in anthraco-silicosis and various silicatoses one sees modifications of normal lung conditions. The effects of carbon, or carbonates, of gypsum and of iron oxides are also discussed. Methods of estimating dust ex posures of a workman includes the taking of dust samples from the work place and interpreting the results dur ing the man's total period of exposure. Errors which have been made from estimating the composition of dust from samples which have settled upon rafters instead of using samples taken from the air, are emphasized. Permissible dust concentrations need not exceed 60 million particles per cubic foot for dust with very low quartz content or 5 million for pure quartz. In defense of the use of standards of dustiness the experience in South Africa where such standards have been applied successfully for many years is cited. BIBLIOGRAPHY 1. Zenker, F. A.: UeberStaubinhalationskrankheiten der Lunge. Deutsch. Arch. f. klin. Med., 3, 116 (1867). 2. International Labour Office: Silicosis (supplement). Geneva, 1630. 3. American Public Health Association: Report (joint) of the Committee on Pneumoconiosis and the Committee on Standard Practices in Compensa tion of Occupational Diseases. A. P. H. A. Year Book, 1933, p. 100. 4. Saranac Symposium on Silicosis, 1935. Employers' Mutuals, Wausau, Wis., 1936. ' 5, Watkins-Pitchpord, W.: The silicosis of the South African gold mines, and the changes produced in it by legisla tive and administrative efforts. This Joub., 9,109 (1927). 6. Thompson, L. R., et al. : The health of workers in dusty trades. General statement and summary of findings. U. S. Pub. Health Bull. No. 208 (1933). 7. Babham, C.: An investigation concern ing ventilation and the sandstone dust present in the air of certain sewer tunnels under construction at North Shore, and in other sandstone work ings. Kept. Dir.-Gen. Pub. Health, New South Wales, 1924, p. 52. 8. Drinker, P., and Hatch, T.: Indus trial dust. McGraw-Hill Book Com pany, Inc., New York, 1936. 9. Jones, W. R.: Silicotic lungs: the min erals they contain. J. Hyg., 53, 307 (1933). 10. Cummins, S. L., and Sladden, S. F.: Coal-miner's lung: an investigation into the anthracotic lungs of coal miners in South Wales. J. Path. Bact., 33, 1095 (1930). 11. Collis, E. L.t and Giixhbist, J. C.: 536 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Oct., 1939 Effects of dust upon coal trimmers. This Jour., 10,101 (1928). 12. Sayers, R. R., et al.: Anthraco-silicosis among nard coal miners. U. S. Pub, Health Bull. No. 221, (1935). 13. Haldane, J. S.: The avoidance of sili cosis with dry methods of working. J. Chem. Met. Min. Soc. S. Africa, SO, 54 (1929), Abst. at length in ;THis Jour., IS, 77 (1930). 14. Schnurbr, L., Allison, W. C., Boucek, C. M., and Haythorn, S. R.: Pneu moconiosis in the Pittsburgh district, based on a study of 2,500 post mortem examinations made in Pittsburgh hos pitals. This Jour., 17, 294 (1935). 15. Riddell, A. R.: Clinical investigations into the effects of gypsum dust. Canadian Pub. Health J., S6, 147 (1934). 16. Henderson, Y., and Haggard, H. W.: Noxious gases. Chemical Catalog Co., New York, 1927. 17. Bloomfield, J. J., and DallaValle, Ji M.: The determination and control of industrial dust. U. 3. Pub. Health Bull. No. 217, 1935. 18. Mavrogordato, A.: Value of the konimeter, being an investigation into the methods and results of dust sam pling as at present practised in the mines of the Witwatersrand. S. African Inst. Med. Res. No. 17, p. 45, 1923. 19. Jones, W. R.: Silicosis. Inst. Min. and Met., 42d session, London, 1933-1934, 20. Cooke, W. E.: Modern views on sili cosis. J. Hyg., 36, 207 (1935). 21. Bloomfield, J. J.: The size-frequency of industrial dusts. U. S. Pub. Health Repts., 43, 961 (1933). 22. Gyb, W. E., and Kettle, E. H.: Sili cosis and miners1 phthisis. Brit. J. Exp. Path., 8, 241 (1922). 23. Irvine, L. G.: Miners' phthisis. J. Chem. Met. Min. Soc., S. Africa, 89, 304 (1934). me ALLS, ntrol e&lth e ko. into sama the L S. P* 45, i. and 1334. * sili- aeney [e&lth Siliit. J. . J. a, 89, 'ir. 0/ *-. .>2*' -' `> ^4;.. ,:i-- sV . ; i- 'rt % */ ' >< v i- - r r CLINICAL ASPECTS, DIAGNOSIS AND TREATMENT OF PNEUMOCONIOSIS* W. Irving Clark Frem the Norton Company, Worcester, and Harvard School of Public Health, Boston, Mass. HERE are two types of dust might be called the normal breathing T which may cause some degree of pneumoconiosis; these have method. 2. Injection of suspensions of dusts. been termed inert and active du--stsT. his consists in injecting suspen The determination as to whether or sions of dusts into various parts of not a dust is active or inert has been animals to detect the capacities of reached by pathological examination different dusts to provoke reaction in of the lungs of those dying of pneumo the tissues. Results are obtained coniosis, by clinical studies, especially more rapidly than by dusting but do x-ray, and by animal experimentation. not correctly show the natural de Review of Animal Experiments velopment of disease in the lungs. The dust suspensions may be intro The study by animal experimenta tion has been particularly valuable as it provides a method of determining the effect of a given dust upon the liv ing tissues and a comparison with the effect of similar exposure to other dusts. The animals used have been duced into the animal by: 1. Intratracheal or bronchoscopic injections. 2. Intraperitoneal injections (Mil- ler-Sayers method (2)). 3. Subcutaneous injections. 4. Intravenous injections--showing white rats, rabbits, guinea pigs, mon the effects of the dust on the extra- keys, fowl, cats, and, for some ex pulmonary viscera. periments, tadpoles and fish (1, p. 44). 5. Intracutaneous injections--for The methods used have been: 1. Dusting.--This consists in ex posing the experimental animal to a "high concentration of dust (up to 10 or 12 billion particles per cu. ft. of air, dark-field) to produce maximum effects in short time." This method gross reaction. 6. Intra-lymphatic injections--for reaction of lymph node cells (3). All animals tested either by dusting or by injection showed a tissue reac tion to silica. This reaction was typi fied by the formation of fibrotic Received for publication June 24, 1936. Read before the Harvard University Tercentenary Celebration, 1636-1336, Sym posium on "The Environment and its Effect upon Man," Harvard School of Public Health, Boston, August 27, 1336. When presented, the paper was illus trated by lantern Blidee showing x-rays and specimens of pathological conditions. nodules except in the cold blooded ani mals where there was necrosis followed by some fibrosis. Changes in sus ceptibility of animalfi to tuberculosis as a result of the effects of various dusts have also been studied, and the 537 SC-ALL-01222 SCF-FA-0366 I"! li ;ts$ v .,:3 |J| If 1 li !1! 538 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY lOcl.f 193$ activating effect of silica demon strated. The effect of the inert dusts upon the animal tissue was fdund similar to that of any foreign body. There was reac tionary enlargement of lymphatic nodes, slight fibrotic reaction imme diately surrounding the injected dust but no continuation of this fibrosis and no formation of nodules. The exact pathology noted was scattered or clumped cells containing the inert dust lying in the alveoli, slight inflam mation or no inflammation of the adjacent walls, a slow accumulation of dust-containing cells in the lymph nodes with enlargement of the nodes, and a deposition of dust about the lymphatics of the lung or pleura. When inert substances were injected intravenously, intraperitoneally or subcutaneously, there was no reaction beyond that of any foreign body (2). As a result of such experiments which have been repeated in many parts of the world, it is believed that of all suspected dusts only silica has a Specific action upon animal tissue which results in fibrotic nodulation. Asbestos fibres produce a peculiar re action in the lung which is different from silica. Following the inhalation of asbestos dust' there are formed "cuffs of more dense connective tissue about the terminal bronchioles" (1, p. 46). Contraction and collapse of the alveoli supplied by the affected bronchioles occurs. This is followed by induration and fibrosis of the col lapsed alveoli, presenting the picture of diffuse fibrosis of parts of the af fected lung with persistent foci of normal air spaces. Silicosis The Committee on Pneumoconio sis and the Committee on Standards of the American Public Health Associa tion (4) adopted in 1932 the following definition: "Silicosis is a disease due to breathing air containing silica (SiOa) characterized anatomically by general ized fibrotic changes and the develop ment of miliary nodulation in both lungs, and clinically by shortness of breath, decreased chest expansion, lessened capacity for work, absence of fever, increased susceptibility to tu berculosis, (some or all of which symp toms may be present) and by charac teristic x-ray findings." J. Pathology of Silicosis Dust particles after reaching the lung alveoli may remain quiescent for a considerable period as is the case with the inert dusts, or they may pene trate the lymph spaces in small num bers. The bulk, however, are phagocytosed, that is engulfed, by wandering endothelial cells which at first, lining the wall of the alveolus, become de tached, and then, having taken up the dust particles, pass by ameboid move ment through the walls of the alveolus into the lymph spaces. The cells now slowly migrate to the minute lymph islands which guard the entrance to the small lymphatic vessels, pass through these, thence to the lymph vessels, and finally are caught by the large group of lymphatic glands which form part of the hilus or root of the lung. These wandering cells are com monly called dust cells. The piling up of cells and the reac tion of the glands blocks the free circu- > i \ \ : vol. : iatk tenc root late: guai sels. by the neig the of f fon whi the the the maf fibr on, ext* tiss con are of lyn the anc stn 1 of J alii noi ms of SCO 14( r tiSE vol the of As ent cai vol. i8, no, S] CLINICAL ASPECTS AND DIAGNOSIS OF PNEUMOCONIOSIS 539 l&tion of lymph so that the dust cells tend to move slowly toward the lung roots, blocking the lymph vessels and later the minute lymph masses which guard the entrance to the lymph ves sels. The dust cells which are killed by the silica disintegrate and free the silica dust for further injury to the neighboring tissues. The reaction of the tissues to silica is the production of fibrous tissue. Thus fibrous tissue forms along the lymphatic vessels which accompany the blood vessels of the lung, invades the septa between the lobes, and spreads its shoots into the lung tissue itself. The minute masses of lymphatic tissue become fibrotic nodules and these, as time goes on, increase in number to such an extent that, combined with the fibrous tissue of the former lymph channels, conglomerate masses of fibrous tissue are formed, blocking off large portions of the lungs. The blocking of the lymph flow toward the hilus increases the spread of dust cells to the pleura and eventually leads to fibrosis of this structure. The fibrotic nodule is characteristic of silicosis. It is a small, discrete hy aline mass surrounded by apparently normal lung. It does not exceed 6 mm. in diameter. "Occasionally some of these nodules may show micro scopic foci of central necrosis" (1, p. 146). This increasing amount of fibrous tissue obliterates the alveoli and pro vokes a compensatory enlargement of the alveoli elsewhere. This condition of enlargement is called emphysema. As the amount of air space is insuffici ent to permit the normal oxygencarbon dioxide interchange of the lungs required by the body, the effort of the heart to pump blood fast enough may promote enlargement of that vital organ. This, however, if it occurs, is a terminal condition infrequently ob served, as the patient usually develops pulmonary tuberculosis or dies of an intercurrent disease before this stage is reached. It must be remembered that only one-fourth of one lung is necessary for life, and that the amount of fibrosis mu$t be enormous to re strict the lung capacity to this extent. II, Symptoms The effect of the underlying pathol ogy upon the workman is at first too slight to be detected by physical ex amination and the worker shows no symptoms. While there is a patho logical condition present, it is to all intents and purposes harmless, in that if it does not progress rapidly it may not provoke symptoms during a work er's life, or only during the last decade. Even respiratory disease of another nature, such as bronchitis or even pneumonia, may occur with recovery during this period. As the condition progresses, how ever, more Mid more of the lung tissue is converted into fibrous tissue, and the patient begins to show certain symptoms. He complains of short ness of breath when he goes up-hill and says that he notices his heart beat on exertion. He also mentions a cough which is at first dry and infrequent, but which gradually becomes moist and frequent. With the cough he raises scanty, stringy sputum which is some times discolored. The sputum is never large in amount unless he catches cold and develops bronchitis. At this 540 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Oct,, 1936 stage an attack of bronchitis does not disappear but becomes chronic. Dur ing this period the silicotic may com plain of pain in the chest due to pleu risy or to epigastric pain, anorexia, and morning vomiting. While he is able to work, the victim cannot carry on his usual tasks and seeks lighter work. Slowly the shortness of breath in creases, the patient has poor lung ex pansion, and his color becomes pale and his lips bluish. At this stage pulmonary tuberculosis is a frequent complication. When this occurs, the cough becomes more severe and continuous, the sputum free and moist, areas of dulness to percussion are noted, r&les are heard over the chest on physical examina tion, and cavitation may be detected. Tubercle bacilli may or may not be present in the sputum. Many of these cases are able to carry on light work for years before finally succumb ing. Hemorrhage from the lungs oc casionally occurs. During the early stages when peri vascular, peribronchial, lymph node reaction is present there are only in definite physical signs. Irvine (5) de scribes these as follows: 1. A certain lack of elasticity of the chest wall during movements of respiration to gether with 2. A somewhat reduced air entry, and 3. A characteristic alteration of the in spiratory murmur from the normal vesicular character to a higher pitched or "harshened," thinned and commonly somewhat shortened type, the expiratory murmur although somewhat prolonged remaining fainter than the inspiratory. There is little change in these signs as the disease progresses. "The per cussion note is somewhat flattened without being definitely dull especially posteriorly. Breath sounds have more definite characteristic thinning, the expiration being longer and fainter" (6). With the advent of tuberculosis the physical signs are those of that disease. Ill. X-ray The most important evidence of silicosis is obtained by x-ray. While a flat film gives valuable information, an accurate diagnosis requires a stereo scopic set of films. In many cases a lateral film is desirable in order to de termine the amount of emphysema present and the size of the heart. Fluoroscopic examination is of inter est in cases where diaphragmatic ad hesions are suspected or shown on the film. # The old classification into first, sec ond and third stages has been recently changed to a more descriptive nomen clature. The conditions noted on the film are now called: 1. Stage of perivascular, peribron chial, lymph node proliferation. Ir regular exaggeration of linear mark ings. 2. Stage of nodulation. 3. Stage of fibrosis with conglomer ate masses. 4. Any of above stages complicated by shadows characteristic of tubercu losis. The first is not considered as diag nostic of silicosis as it may occur in persons who are in good health or in a number of pathological conditions which have nothing to do with silicosis. The stage of nodulation is pathog nomonic of silicosis but may be con fused with films of miliary tuberculosis. voL 1 T1 ate ! broit D 1. mat* dust 2. 3. 4. sis a O are mos whe Abs weq sugj chet T the case bac: Thi pro can "E ma cer tiss cer fib: gei ' ub vel "P sill etc vol 18, no. 81 CLINICAL ASPECTS AND DIAGNOSIS OF PNEUMOCONIOSIS 541 The stage of fibrosis with conglomer ate masses may be confused with fi broid phthisis. TV. Diagnosis Diagnosis is made upon: 1. Occupational history with esti mated length of exposure, quality of dust and quantity of dust. 2. Physical examination. 3. X-ray examination. 4. Presence or absence of tuberculo sis as a complication. Of these measures the first and third are most important. Probably the most difficult thing to decide is whether or not tuberculosis is present. Absence of fever and maintenance of weight, with absence of physical signs suggesting active inflammation in the chest, is indicative of simple silicosis. The absence of tubercle bacilli from the sputum is inconclusive, as many cases of silico-tuberculosis fail to show bacilli in the sputum. V. Progress Silicosis once established in the lung has a strong tendency to progress. This appears to be owing to the toxic properties of the silica particle. What causes this toxic action is still in doubt. "Experiments and human pathological material indicate that in high con centrations silica is toxic and kills tissue; prolonged action of lower con centrations cause proliferation and fibrosis" (1, p. 46). In spite of the fact that quartz is generally recognized as relatively insol uble, there is great rapidity of de velopment of body reactions to silica. "Possibly unexplored properties of silica, electrical charge, adsorption etc., are concerned" (1, p. 48). This progressive tendency has been noted by Irvine, Bohme, Russell and others (1, P- 28). The question is not what is the pres ent condition of the silicotic, but how rapidly it will advance and how far. This is a serious problem in industry, for a worker having no symptoms and an early stage pathology by x-ray, may develop a disabling silicosis or a com plicating tuberculosis. It is, there fore, possible for a worker to contract his disease while working for one em ployer and to develop symptoms many years later while working for another. If the work he is doing for the second employer involves exposure to an in ert dust the employer may have diffi culty in proving that this was not the cause of disability. One of the striking differences be tween the effects of the inert dusts and silica dust is the lack of progress of pathology in the former as compared with the latter. Bohme (7) found that silicosis progressed after removal from exposure in 20 per cent of the cases diagnosed as having silicosis grade 1, in 40 per cent of the cases in grade 2 and in practically all the cases in grade 3, The experience of the State of Wisconsin, however, suggests that silicosis detected at an early stage in many cases will not progress if the worker is transferred to nondusty work (8) though the reports of Watkins-Pitchford (9) and Britton and Head (10) make this somewhat doubtful. Infection may play a part in the de velopment. In fact, it is the frequent and serious complication of silicosis, and of the common infections, pulmon ary tuberculosis is by far the most serious. 542 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Oct., 1936 Tuberculosis may develop early or late in the disease. In those who have an inactive focus in the lung, the silica dust may change the condition to one of activity, or in cases of well-de veloped silicosis, tuberculosis may be superimposed upon the silicotic fibrosis. Thus Kettle writes, "harmful dusts if inhaled into the lung may excite to activity a latent tuberculosis infec tion; they may exaggerate an active tuberculosis lesion or a coincident in fection; and they may render the lung less able to cope with a superimposed infection" (11). The course of silicosis with a second ary tuberculosis is usually slow and without the usual symptoms of in toxication and may be carried for years without serious impairment of working capacity. While tuberculosis is the most fre quent complication and cause of death, other infections do occur. On the Rand pneumonia is a common cause of disability and death. Pope and Zacks found pneumonia occurring with great frequency among foundry workers in Massachusetts. Proske and Sayers have confirmed Cummings* discovery of fuso-spirochetal organisms as a cause of infection among miners in Picher, while chronic bronchitis with asthma is fairly common (12, p. 47). Collis and Yule (13) compared the mortality experience of an occupa tional group exposed to silica dust with that of the general population, and with that of an occupational group exposed to dust not containing silica. As a result of the study, they con cluded that silica is a body poison like lead. Even though it exerts its primary injurious effects on the re spiratory tract, the silica slowly invades the body, involving the circulatory system, the nervous system, the diges tive organs, the kidneys and liver, and eventually causes death through its harmful effect upon one or another of these organs. Asbestosis "Asbestosis is a pneumoconiosis caused by the inhalation of asbestos dust. It is distinct from silicosis both in its pathology and clinically. As bestos is a hydrated magnesium sili cate containing no free silica but about 44 per cent of combined silica, 43 per cent magnesium, nearly 13 per cent of water and traces of iron and nickel" (14). I. Pathology of Asbestosis Asbestos dust differs from other inhalable dusts in that it exists in thread like fibres in which the diameter may be very small (5 microns or less) but which may be many microns in length. These dust fibres do not appear to enter the alveoli. They are stopped at the neck of the alveolus where they are phagocytosed or penetrate the tissues. Acting specifically or merely as a foreign body they become sur rounded first by mononuclear phago cytes, later by giant cells and last by fibrous tissue. There is no migra tion in dust cells to the lymphatics and lymph nodes as is seen in silicosis. The newly formed fibrous tissue con tracts, constricting the neck of the ah veolus so that no air can enter. Col lapse of the alveolus follows and subsequent fibrosis. In this way the lower parts of the lungs are filled with interstitial fibro sis and the air space markedly dimin- vol. ishe maj lun* the alw con | i- 1 I\ con free l i bod (15 dri< ii luc* t I dui I are ini occ din dia t cor exj th( pn wh tof Tt cai vit Tt lot ou be f by by ge fri fii ta sb im vades atory diges- and ;b its xer of niosis estos both Asi silibont 3 per cent e\iJ t in- ^eadmay but igth. u* to pped they the jrely suragot by graitics osis. con i atCoJand the i>rooin- vol 18, no. 8] CLINICAL ASPECTS AND DIAGNOSIS OF PNEUMOCONIOSIS 543 ished. A compensatory emphysema may occur in the upper part of the lungs. Thickening of the pleura over the lower half of the chest is almost always present. Tuberculosis as a complicating factor is not common. The asbestos fibre after it has be come fixed at the neck of the alveolus frequently develops into a "curious body," the asbestosis body of Cooke (15). This is a long, narrow, cylin drical body, golden yellow and trans lucent, often with rounded ends like a dumbbell. These asbestosis bodies are found on autopsy and occasionally in the sputum. As similar bodies may occur in lungs not exposed to asbestos dust, the finding of these bodies is not diagnostic of asbestosis unless ac companied by a definite history of exposure to asbestos dust. II. Symptoms of Asbestosis The symptoms of asbestosis, like those of silicosis, are cough and dys pnea. With the cough there is sputum which may or may not contain asbes tosis bodies. Hemoptysis is rare. There is loss of weight in the advanced cases, and marked reduction in the vital capacity and in chest expansion. The patient's face has an "earthy" look. In advanced cases the dyspnea is out of proportion to the physical signs, being very severe, and is accompanied by blueness of the lips and occasionally by clubbing of the fingers. The fin gers frequently show "asbestos corns" from the penetration and irritation of fine spicules of asbestos which are de tached from the asbestos in handling. III. Physical Examination The patient, if an advanced case, shows loss of weight. The chest is emphysematous, and respiration is shallow, expansion being frequently less than 1 inch. The percussion note is one of dull tympany but with no definite dullness. The breath sounds are distant and expiration prolonged. The heart is normal in size, but lateral x-ray may show an anteroposterior enlargement. IV. X-ray This shows a fine mottling of a "ground glass" quality over the lower half of the chest. There is often an obliteration of the costophrenic angle and pleural thickening, shown par ticularly in the interlobular pleural on the right. The lateral view may show well-marked compensatory emphy sema. A spot of tuberculosis at either apex is occasional but rare. Still later in the course of the dis ease the appearance is that of a very fine stippling that obliterates most of the natural markings. The pleural shadow is definitely thickened. In some of the advanced cases the heart is enlarged and radiating from it into the lung fields is a series of heavy fi brous bands. This picture has been re ferred to as "porcupine heart." Anthraco-Silicosis This disease occurs among hard coal miners and is commonly known as miners' asthma. It is caused by the inhalation of large amounts of dust consisting of a mixture of anthracite coal and quartz, the quartz coming from the rock in which the coal is imbedded. The pathology consists of a clogging of the lymph spaces with carbon par ticles which invade the upper lobes especially. Accompanying this is a linear or nodular fibrosis due to the 544 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [OcL, 193$ inhaled silica particles. When large areas of the lung are involved there is a compensatory emphysema. I. Symptoms of A nthraco-Silicosis The cardinal symptom of anthracosilicosis is shortness of breath, which explains the term "miners' asthma." With this there is cough and sputum. The cough may be dry and the sputum scanty but if infection in the form of bronchitis is present, the sputum is muco-purulent and colored with coal dust. As in silicosis, tuberculosis is a frequent complication. The physical signs are similar to those of simple silicosis or of silicosis with infection. Diagnosis is made largely by x-ray which gives a picture very similar to that of simple silicosis. The U. S. Public Health study on this problem (16) suggests that the true lung injury is due to the silica inhaled rather than to the carbon particles. Carbon has been found to be harmless when inhaled in the form of smoke and by animal experiment. Inert Dtjsts I. Pathology The inert dusts are relatively harm less. They may increase the fre quency of respiratory disease when inhaled in large amounts, but this has not as yet been proved statistically. Workers inhaling these dusts develop a mild fibrosis which follows the course of the lymphatics along the bronchoarterial tree and is accompanied by enlargement of the trachial lymph nodes. This reaction which is very slow, after a number of years may progress to a moderate amount of in terstitial thickening. The pleura may be thickened and there may be dia- phragmatic adhesions. These later manifestations only appear after many years of constant exposure to a high concentration of dust. II. Symptoms Caused by Inert Dusts The symptoms of the pneumoconio sis of inert dusts sure negligible. If the exposure has been long and the dust discharge abnormally heavy, there may be some dyspnea on moderate working. This is not usually severe enough to interfere with the worker's normal activities and may be caused by degenerative changes of the heart due to advancing age, as much as to the pathology of the lung. There is no evidence that the inert dusts, un less mixed with an active dust, can produce disability. Ill, X-ray Picture, Physical Examina tion and Diagnosis The x-ray picture is that of peri vascular, peribronchial, lymph node thickening which does not progress. Some diaphragmatic adhesions may show in cases with long exposure to heavy concentrations of dust. Serial pictures fail to show nodulation or the massive areas of fibrosis which char acterize silicosis. ' The physical examination of those exposed to inert dusts is usually nega tive. In' a few cases where there has been prolonged exposure to great quan tities of dust there may be some re striction of chest expansion and signs of emphysema. The diagnosis is made by physical examination, occupational history, and x-ray. A typical inert dust is that of the artificial abrasive, aluminum oxide. This material is widely used in grind- tm iter any ugh its oiothe lust lere rate ^ere er's tsed jart j to e is uncan ina~ riode ess. nay * to ;rial the lar- lose Jgahas tanre igns leal and the ide. nrl- t | \ | i ; r ; j, | '| \ \ f Vol J8, no. 8) CLINICAL ASPECTS AND DIAGNOSIS OF PNEUMOCONIOSIS 545 ing wheels and for polishing, sand paper, etc. In the year 1929 over 71,000 tons were sold or used in plants in the United States and Canada (17). The use of aluminum oxide creates a certain amount of dust. The effect of this dust has been studied by Clark (18) and Simmons clinically and by Gardner (19) on the experimental animal. In a factory where artificial abra sives and grinding wheels are manufactured, Clark has studied the effects of inhalation of this substance for 25 years. He believes that in factories which provide proper dust removal, the continuous inhalation of artificial abrasive dust extending over many years of work does not produce the symptoms or present the x-ray find ings of crippling fibrosis of the lung; that the number of cases of pulmonary tuberculosis does not greatly exceed the number normally present in the community; and that workers using wheels made of artificial abrasive or using this substance for polishing or other purposes run but slight risk of pneumoconiosis if excessive dust is removed by exhaust systems. In spite of the fact that clinical and experimental evidence points to the relative hannlessness of the inert dusts, an effort should be made to keep the dust count around 20 million particles per cubic foot of air. This will make working conditions much more satis factory to the worker and will reduce the hazard of respiratory disease. Treatment of Pneumoconiosis The only method of treatment of the pneumoconioses is prevention. Dust in quantity must be eliminated from industry wherever possible, and in most operations this is feasible. In a few where it is not, protective de vices such as respirators or positive air pressure helmets must be used by the worker. When a worker is found upon ex amination to have lung fibrosis it is wise to keep him at work in a nondusty department. While his lung con dition, if it is due to silica or to asbestos dust, will progress slowly, many years of profitable work are before him un less infection intervenes. As dyspnea increases, lighter work must be pro vided. If tuberculosis complicates the picture and the patient develops tu bercle bacilli in the sputum, he must be isolated from other workers, but even then may be able to do light out door work. In more severe cases where there is temperature, all work must, of course, be stopped. Exposure The rapidity of development of sili cosis and of asbestosis depends upon the amount of dust inhaled and the percentage of free silica (S104) or of asbestos in the dust. In men exposed to heavy dust clouds with a high concentration of silica, silicosis has developed in as little as 2 years, but under the usual exposures of mining and of industry where the free silica usually varies from 13 to 35 per cent, the development is slow and symptoms do not appear for 15 or more years. In the case of asbestosis, the de velopment of symptoms is more rapid, 5 to 8 years being the usual required time of exposure. Efforts are now being made to corre late the exposure with the pathology, as shown by x-ray, and with the physi- 1936 TMg, the by 'hey ;on1: oin- lies and nd- rill- uu'ust ted md een ich ure isis 3ns oth isa . of be . of ind cu- led 2nfc >sis in .a l&t in re* reho 3is voL 18, no. 8] CLINICAL ASPECTS AND DIAGNOSIS OF PNEUMOCONIOSIS 547 (23). "The initial studies of silicosis by workers in South Africa were started by a demand made upon health authorities to determine the cause of the excessive mortality from tubercu losis which was increasing at a rapid rate among the miners there." Russell found an excessive number of deaths from tuberculosis in his Barre, Vermont study of the health of granite workers (24) and Gardner (25) believes that at least 75 per cent of those who develop silicosis contract tuberculosis. berculosis is so often associated with asbestosis that it seems probable, that the association is more than acci dental". Gardner (1, p. 51) says that many autopsies show a combination of tu berculosis with asbestosis and other silicate dusts but "that surveys of liv ing American workmen show no great excess of this infection", while Lanza (28) in a study of dust conditions in asbestos mines and mills in Canada and in fabricating plants along the Atlantic seaboard found in his study TABLE 1 Silicosis and Asbestosis in Great Britain, through 1934* inrasn of DBATHS AVEBAQS AOS AT DEATH DUHATXOH OF BMFLOYVENY IN T2ABS Minimum Average Silicosis................ .................................... Silicosis with tuberculosis........................ Asbestosis.................................................. Asbestosis with tuberculosis..................... 261 315 41 26 55.4 60 2.3 34.8 52.5 67 2.0 32.0 41.0 27 1.5 12.9 38.0 29 0.8 9.9 J. C. Bridge: Report of Chief Inspector of Factories and Workshops, London, 1934, chapter 3. ' II. Incidence of Asbestosis The health hazard of asbestos dust has only been recently recognized. The Regulations for the Asbestos In dustry in England have been in force for only 4 years. Bridge (26) says: "Over a number of years" (number not specified) "the deaths from as bestosis reported to the Department and compiled in 1934 numbered 41 while those from asbestos arid tubercu losis numbered 26". (See Table 1.) Wood and Gloyne began their studies on pulmonary asbestosis in 1928 and published results of the study of 100 cases in 1934 (27). Most of these cases worked in the same factory. According to Wood, "pulmonary tu- of 126 workers by x-ray that 67 were diagnosed as having asbestosis in some form, but that no predisposition to tuberculosis due to asbestos dust was indicated. Clark and Drinker (29) in summing up present beliefs say that while a secondary tubercular in fection is not uncommon in asbestosis, it is far less frequent as a complica tion than in silicosis. Summary 1. Pneumoconiosis is a disease re sulting from the inhalation of inor ganic dust. 2. The two pneumoconioses which produce disability are silicosis and as bestosis. 548 JOURNAL OP INDUSTRIAL HYGIENE AND TOXICOLOGY [OcL, 1936 3. The pathology of silicosis is char acterized by the^presence of fibrotic nodules scattered through both lungs, and that of asbestosis is characterized by an interstitial fibrosis involving the lower half of both lungs. 4. The symptoms of silicosis and as bestosis are similar, the most im portant being dyspnea. 5. The most common complication is pulmonary tuberculosis which in silicosis is a frequent cause of death. 6. The diagnosis of both silicosis and asbestosis is made' largely by a correla tion of history and symptoms with the x-ray examination. 7. The treatment of pneumoconio sis is preventive and symptomatic. 8. The course of silicosis and of as bestosis is slow but eventually leads to incapacity due either to the dis ease itself or to a complication, fre quently chronic pulmonary tubercu losis. . . 9. The number of workers exposed to harmful mineral dusts in mining and in industry in the United States has been estimated as 500,000. BIBLIOGRAPHY 1. Gardner, L. U.: Second symposium on silicosis at Saranac Lake, N. Y., 1935. Employers* Mutuals, Wausau, Wis., 1935. 2. Miller, J. W., and Sayers, R. R.: Microscopic appearances of experi mentally produced dust nodules in the peritoneum. U. S. Pub. Health Repts., 60, 1619 (1935). 3. Drinker, C. K., Field, M. E., and Drinker, P.: The cellular response of lymph nodes to suspensions of crystal line silica and to two varieties of sericite introduced through lym phatics. This Jour., 16, 296 (1934). 4. Lan^a, A. J.: The etiology of silicosis. J. A. M. A., 101, 583 (1933). 5. Irvine, L. J.: Report upon the work of the Miners1 Phthisis Medical Bureau over the year ended July 31, 1928. Pretoria, 1929. 6: Sayers, R. R.: The clinical manifesta tions of silicosis. J. A. M. A., 101, 580 (1933). . 7. B ohme, A.: Die Prognose der Staublungenerkrankung (Silikose). Beitr. z. Klin. d. Tuberc., 84, 119 (1933). Abstr. in This Jour., 16, 57 (1934). 8. Nelson, H. A.: Silicosis problem solved in Wisconsin. Am. Labor Legis. Rev., U, 53 (1936). 9. Watkins-Pitchford, W.: The silicosis of the South African gold mines, and the changes produced in it by legisla tive and administrative efforts. This Jour., 9,110 (1927). 10. Britton, J. A., and Head, J. R.: Pneu moconiosis, the delayed development of symptoms. J. A. M. A., 96, 1938 (1931). 11. Kettle, E. H.: The action of harmful dusts. Inst. Min. & Met. (London), June 24, 1934. Abstr. in This Jour., 16, 125 (1934). 12. First Symposium on Silicosis, Saranac Lake, 1934. Employers* Mutuals, Wausau, Wis., 1935. 13. Collis, E. L., and YuLe, G. U.: The mortality experiences of an occupa tional group exposed to silica dust, compared with that of the general population and an occupational group exposed to dust not containing silicaThis Jour., 16, 395 (1933). 14. Lanza, A. J.: Asbestosis. J. A. M. A., 106, 368 (1936). 15. Cooke, W. E.: Pulmonary asbestosis. Brit. Med. J., $t 1024 (1927). 16. Sayers, R. R., et al.: Anthraco-silicosis among hard coal miners. U. S. Pub. Health Bull. no. 221 (1935). 17. Roush, G. A.: The mineral industry, itB statistics, technology and trade during 1934. McGraw-Hill Book Co., New York, Jfi, 9 (1935). 18. Clark, W. I.: The dust hazard in the abrasive industry. I, II, and III. This Jour., 7,345 (1925); 11,92 (1929); and IS, 343 (1931). 19. Gardner, L. U., and Cummings, D. E.: The reaction to fine and medium sized quartz and aluminum oxide particles. )ct., me nth the oconiolatic. I of as- leads he disn, freibercur xposed mining States Pneu>pment 6, 1938 armful ndon), Jour., aranac ltu&ls, The ;cup&dust, eneral group silica. >ailiU. S. istry, trade :Co., pot. 18, no. 8] CLINICAL ASPECTS AND DIAGNOSIS OF PNEUMOCONIOSIS 549 Silicotic cirrhosis of the liver. Am. J. Path., 9 (whole no. 64) 751 (1933). 20. Van Siclen, M.: Health hazard from dust in the mines and allied industries of the United States--Initial survey of the extent and severity. Am. Inst. Min. & Met. Engin., Contribution no. 45 (1933). 21. Lanza, A. J., and Van, R. J.: The prev alence of silicosis in the general population and its effects upon the incidence of tuberculosis. Am. Rev. Tuberc., 9, 8 (1934). 22. Pope, A. S., and Zacks, D.: Epidemio logical aspects of silicosis and tuber culosis. Ibid., 82j 229 (1935). 23. Summons, W. E.: Report of miners* phthisis submitted by the Committee of the Bendigo Hospital, Victoria, 1907. 24. Russell, A. E., Bhittrn, R. H., Thompson, L. R., and Bloomfield, J. J.: The health of workers in dusty trades. II. Exposure to siliceous dust (granite industry), U. S. Pub. Health Bull. no. 187 (1929). 25. Gardner, L. U.: Silicosis and its rela tion to tuberculosis. Am. Rev. Tuberc., 9, 1 (1934). 26. Bridge, J. C.: Extract from Annual Report of the Chief Inspector of Factories and Workshops, 1934. (CMD) 4931, Chap. 3, Health, p. 12-13. 27. Wood, W. B., and Gloyne, S. R.: Pul monary asbestosis: A review of 100 cases. Lancet, , 1383 (1934). 28. Lanza, A. J., McConnell, W. J., and Fehnel, J. W.: Effects of the inhala tion of asbestos dust on the lungs of asbestos workers. U. S. Pub. Health Repts., 50, 11 (1935). 29. Clark, W. I., and Drinker, P.: In dustrial medicine. National Medical Book Co., New York, 1935 (p. 119). m -to;. I mm