Document Ex4yQRmVRL1voy5vz60LnRjyg

1932 TRANSACTIONS National Safety Council Incorporated TWENTY-FIRST ANNUAL SAFETY CONGRESS Washington, D. C. October 3 to October 7, 1932 Tlic Wardniait Park and Sliorcham Hotels Copyright. 1933, Notional Solely Count it. Inc. 32 WC < r:. oo cf 3 3 co a ri o na --* o s* Sg o 3O* * ^ 25 =* tk ao o* 3 ff Ms co !i * p II! 5n SST B.So< 3 <V *< s^ 3 S 1? * 5ft* CftO -a 3a P^ /m> ar *2 o Sft =Q:, e S5* !1 * a* *. a *g*=*' w?c o cr ** S:lr 8 2 oS' C ^ 2. 2g. nO n. 5* 2 o 5 3- an O? a f < rf*' M sr ^ O 3ft r ro> S32 cr. O 3 S p* s3o. co V H, Jf I* g" . v2*Zi a5oo3 sr E sr J n o* 3- *fM^r*tr sr Pf*t J 3 OO tpl g5 *o J |3 *" w S R a < Sp HVl " Oft* 3O xt* 3* A *' o rt .. ft ft tJ U?g*g * n ;r.. ft c. g-g^ ft u f 3 < C "8 S? tE3 a -- v 3 3. o* S 3 o o n o3 -a P3 a; jo c j c O' tr P XT ~ 2 W" W ?,3 C. W I V *0 *u ^ :^SH. 2 2." n J? n5 I3 .5? S co *d 3. ft c o J CO ft 3 aC o o __ 1 oC.3 W .3 - ** *51* * d rt Is? I' M wu 2. *> v o Ut/ o sr 32 3 o 2L -- nCO 3ss* cr. '' ^ ^ 5 c ft 2 3 s w s S. 3 XoS3w_ fc23 Xaf-t. S? < o w 2- -- f,,t 3 3o.Wa 1 ^w CO fftt 3rr. S 3 x* O W O3 n r* 3 f *"< 3 ft Oft ^ 3 w 33 ca'. o. c H"n. n M 2c Xft 3 3* mC> >> a 33 33 *? A ~w **, <s. PS 3 ? j s a. = K, 2 3. O p. n 5 a -}ft f* io 53 2.D n 2 :; = ]1 5 S. a * o 3W c Esft: w3a. co co rr ft o 5i 3 c flT'O 33 cr < 3. o O ftE P ^ * s. 3 S A g 5. O 3 o' o X* H ~ co a 2" PO 32 83 co X ft sr ao x* o. *d > a uw o o 2 *-3 W h CO 5** ^ Ci V-' o ir'-i x .Kr i17 C * o' e 5 PH? PS . _( n w w P3* rn 5 s. H ^ '/. n .y F.Er> ;> * tVft P MffPHtt c sa g >i' <'ic**1-h . P V ?<* < * 2 <' n< - to 3 ft; 3 <<S.s-<? sP 3 1 |L o' n -- ? n` "3 *? op H` 7? ? = 0? 3 >3 a ft- o H2 H H M W /ft <tt\of>> 0Cto9o- a. yfPA/Act->1o o' 7 o ft* ft _ j\ 2 >' y Cu 2tX ft X. X. 3 ^ f3 3 3 fCt. -5 oHT a oo. a ~3 n0^o' n O* O o srpm..x--pt ^fpl--i=Ot/-'**2"s*1Puao!/) 3a-C->o#r-ao..a?sf32aoSt*" "--^3ft *onpL<Cc^O*" O -- o w CAOJ /ft ttC1ooo ''.wCCtooo' aK^; *o3* 0 EC o "O >w 12 O w c ^99 - c > < ^ S? < P ng_ I2>B rron25 cohmfrt ywjE; tuo % O*OJ/- D p<* mVrcxr>ns>=? i CO n cforHtq) I' o J3 P fpoofott Qo. V-f J p CD eft- o o c V {3 n 1 c = r* n "si n; rr'--' ^Tia^OSSJH^pROPr: V * *'^. *} O r: > ' -- . > ft > ` f ?22 t* Sfi '*< H ^co?'*n\. !as-s9*i.a50-?,, "e23 -* 0y5r->02a w oo5 ~ 8 * r- S'.1* W a: oJ ' ; 5^n D ", St O " A'Z "1 -O 3 Oa V6 --o 32 n|?s*r- ^3-ifS" U3n _, <2. r.S? S? g <s. 2. s n Jj s V! 2,a-*< 2 S P-5 *|O p H 31c 5 s/> m s n s> t S '5 s'?s O 3 :C?0 S|"3B 5.2: >n5.~ <s> '5>SOS;otToS5i;*>-p*2SrtaS--3"n*'*"*--BtL-St*nx85ArtW3o3j>`--s;*tS-*o<'-:S*o`>sA?siS2vT*!45'*^l^**RiH"3t*_ol'ssrv*MooY-<i#*-n?.*"~Ow"na?P<`'?aC55^'^Sycy5?;/-*'J.s'"^dSoyt.S/*l5*.s>--3n5,,~<5OBfr->' 5qKaPAt--Swf-OSSt'a-*W"5a^SrHciWt2ii-n.*l,*`i.Sv!wS;1crf"<it1it>agO2<*nAt5"(Mm"t1i .O"j-./3<"aTno<VAa52^*o.,fa*:wHo52UwE8w|i*..SS*5H5OWoa2rp23s*-g^S$amJ33nOt!"/T!:.ao-,*O3>s:/3MsaP3**s-*a.-*`>5w'a55K,,*''s.03Sfi.Vr*-i-Ssgn5rgrrko-- K.O 7* 2 c->no,?<#tmao?2***.5c 'sx'2ao"c*3 o n o- ocr*r* ^ Vr. n? Ssg O* o ? o= c rj zr r> ~ tu rci S- 3 P 3 crr Ps S, *> - o 5S " aP. n ?. I p o"t nOO '3 ?3 S"2 P ft *< c vT o r</i s O3 3 oo 5T nO O n n a H o H O co oto> K * o o> u> r>:^^ipjcri^pr 5- 5 r >-- ,, i-jjitf * t/>p O " 5 /*r j2 pa>wg.:- T, 52 KPgC^, lia'i^k >^ 4< o Sa 3g 3o *Z 2." 3o'2 5C? .s3* 73 5C*L. Wa_ a ^< ^ SBO't) co. 3 j{sJ:' o. 5s;2. n -- -- 3> PQn n 5 p " 3' --tC " 3 n8 n : *Lyf/>An 3i*0L* 2i Ao- SsS!3 5 = fSwl* S H2. *. ST nO Is5 gs5 j b' p M o'^'< <2 c P? S n 8S *< 1- CL Bn no ^1 52 32.c5* 0-.0c ft* hB CO o 73 C 3o **Ci < C3 do! : )*^* r) > H ^ d " r* __ ! IV ^\* X * CI" P > CO ! x*yr ^ i ' 3O nhl3 On-73 r_; "` O * * r\ 5i r*iC 2*n *: VO - rso*-1 *. X.*n < C? ft: ? 3 --^ j f > ^^ 5 > ^t2 jr o m^ ^ i O --V s 5 n ?J?F Xr 5X C.l|f " -r S g 5 f 8 5 " 2 C 5r* "?5 ^ HllY. % 5 2> <M x e: w e- =; oym 5 o Jw . r o v^ wa aor ,^> C2. V2 o3 * * T3_t n 7?; iO J, A a> ^ ~ 1. W atov1 ;c* g s.% m ET to p* 2. =: -v ft n ~ 0*5 P tc O r. 3 A.Spn-wXr-Cr.Orsw_S--P*Sr?-Y.:5*C2"T'.*at*<>! *7J* o< rj - o 0 2 o S' - 6T>V< K* OP ' wJ2i?=: .r M1 OA (/>) < < co 5 o 3 < rt "* 2. o " 2. tr, ? o o' p ws: Oo w 3 OO --o' sI s < CO rg's- 3 ' *3 t/> v p2 w < 0~- A < Q ' ?2rLcTFrt SP0i'C*3c 2 5 = *< = ?*' O * vh o* < a ' ~ T1 > '/ V ** > V ** > '`^-A., v,,bv. ? r h? mtVh ^ ^553 ' F-7r;v-~ 3* 3 5.^-2 -s = ~ x ij - - , S r- r- | 5p ri A|< 5;u;pp2 ?. P < r 2 >-Tia - s -x:2 ?;-3 ^.3- c 5 *=zsg 5 ^ 2. QoS ^ 5 g o 5* 7? v 2 E-J.S:-4 = S | - >:? ` > z3 ? ? OA?<- - o3w r'X^33' r"g3is--.=^- a-- ' 2n ~ C.- S- ' %'J2^Ix_^.5Lo?. sE.<^L3t ?xi.g?' a p*> rU \J> CO *n p 5&.2a3o- <w S<i 5-aa 2H-- ^ 3= 522T.-a2- wW<Rv.*i'?gs..5^5x ?s.=5t3'.,,2 o .2 S o J>na r .$ g x Sl^-ami^Sc SI a 2 A P .0 _-3 O Op o 0 3- *". co.32fcorrco_ 05 2 2---21* p-- s--**^> -.5 sr ---- b S>_ --. - P 2 co ? 2. H. cj 3e a **< n3 O c r.* -- x 3* O ft V i. 3 -- 3* 2 56E* .-n:--^"f--fSZs-gCsB-.-S5-2' *5-" ?r o 0^:^= ?2 E 5. ^ ?2?" = Qr 5 c *- vi S 7* >. 5 g S P ? -=1 s 55 5 3 ` 55P> SoPSVl^ "5 ?3 25 s'^g ? I Pgiil =-i ^V opi-'-r-i'l 3 <X P" A s -.5 2 2 ' nS g " o I ?" r* ' xr L53J s s .*, " ?I n." ' n >Sc 5 tn h? -- c = x . M r Co w? > W i - x=i< '> *< fcj |B i w yn* i** zftr *ft o HS JTn 3 5 r 5iS1 n-oA'o- ii O -5 =- g. a 0 = s n So < tn-g - to 5 *. 0^-5 r.f- 3' 3 *< r2-.o0 -- Wrs H 8 Is n3 o o o o 3 8 B! PI' o o g 8 P^al s. ~ -a igc sv P c Pi 3 -i = 8? *S0I 3 n *fo/t> -Q rg p-- Sc- 3 ? 51 O o O3 O o AT. o CO CO P *? s^ A^ O 0o s2 3 e *d5 OA C* 6 Tzoeiity-first Congress--National Safety Council C. L. Rice, Chicago Safety Council.' Dr. A. D. Risteen, The Travelers Insurance Company. John Roach, Chemical Section. Ch AS. J. Ron, Newark Safety Council. Tomas Roth, Rochester Safety Council. John Russell, Jr., Construction Section. G. E. Sanford, General Electric Company. Henry G. Schaffner. Erie Safety Council. Otto Schenk, Wheeling Safety Council. Robert L. Schmitt, Metals Section. Charles .15. Scott, Bureau of Safety. Gf.n. John H. Sherburne, Massachusetts Safety Council. Dr. L. A. Shouuy, Bethlehem Steel Company. Ernest L. Simokds, New Haven Safety Council. Georce P. Singer, Reading-Berks County Safety Council. Oliver T. Skellet, Safety Division, St. Paul Association. Charles F. Smith, Rubber Section. C. VV. Smith, Standard Oil Company (Indiana). E. J. Smith, Power Press Section. H. S. Smith, ASSE--Engineering Section. R. T. Solensten, Accident Prevention Equipment Manufacturers' Section. E. C. Spring, Lansdale, Montgomery Co., Pa. George R. Stephens,' The Safety Bureau, Buffalo Chamber ol Commerce. Etit elbert Stewart, Washington. D. C. Carl Storck, Automotive & Machine Shop Section. Luctus S. StoRRS, United Railways & Etcclric Co. Alfred H. Swayne, General, Motors Corporation. John H. Taylor, Birmingham Safety Council. Henry D. Tefft, Meat Packing, Tanning & Leather Industries Section. Norman F. Titus, Hudson County Safety Council. Arthur M. Tode, Consulting Marine Engineer. W. D. Turbf.ville, San Antonio Safety Council. William E. Veecii, Rahway Safety Council. Vincent Wakefield, Kansas City Safety Council. George H. Warfel. Union Pacific Railroad Company. Dr. Cassius H. Watson, American Telephone & Telegraph Company. Harry M. Webber, Illinois Bell Telephone Company. Carroll V. Wells, Delivery, Taxicab & Bus Section. Albert C. White, Jr., Springfield Safety Council. W. L. White, Jr., Cement Section. S. E. Whiting, Liberty Mutual Insurance Company. A. H. Whitney, National Bureau of Casualty & Surety Underwriters. W. H. Winans, Union Carbide & Carbon Corporation. C. T. Winegar, Detroit Industrial Safety Council. Dr. C--E- A. Winslow, Yale Medical School, J. M. Woltz, Youngstown Sheet & Tube Company. c tl it ni in the our fir net T deta undr waul -Yen mem T\ Wcr rcinv; anu l>rc\ i acciil. exai, ; tent,.-. S in dent I mot'-, oi pr. dccre;, years ; effectn safety to pc... These i accidc::' Sir.c best r<made 74 pi- L i 50 Tn-cnty-first Congress--National Safety Council a proper staff, and not by some enthusiastic person who has not been trained for the work. Why not use more registered nurses in the smaller plants? The registered nurse is much better qualified to interpret a physician's plan of medical service than any lay attendant. Much depends upon the physical condition of the employees. I am of the opinion that the physician, by reason of his professional attainments, is best qualified to handle some of the problem cases among employees. Mental symptoms, brought about by worry over home affairs, quite often produce accidents. In many eases the fear and worry of sickness in the family can be greatly allayed by a talk with the doctor or the hursc. Many of these cases have come under my personal observation. It should also be absolutely the part of the physician to say when a man shall return to his regular employment after injury, and this decision should not be in fluenced in the slightest by its possible affect on any "no-lost time accident" contest or record. These contests are proper and have brought about outstanding results in the reduction of lost-time frequency figures. However, there have been cases of injured employees being urged unduly to return to some form of work merely to prevent the marking up of a lost-time accident. Nothing should be allowed to inter fere with the employee's welfare. The physician has every motive to return the employee to his regular work as promptly as possible, but his higher duty is to conserve both the physical and economic welfare of the employee as well as the employer. The safety director has need of the medical service, and the two should earnestly co-operate and seek to bring about a mutual feeling among the employees. Both departments are striving by all possible means to prevent economic waste chargeable to the disabilities and hazards of industry. TUESDAY AFTERNOON SESSION October 4, 1932 The delegates first attended an informal luncheon, and then gathered for the after noon meeting in a Joint Session with the Metals Section. This session was devoted to a symposium on the dust problem in Industry. Chairman Grccnbtirg immediately introduced the first speaker. ' - - U ' The Effects of Inhaled Mineral Dusts By LEROY U. GARDNER Director, Saranac Laboratory for the Study of Tuberculosis, Saranac Lake, N. Y. As long as men have worked in stone it has been appreciated that an unusually large proportion of them suffer from disease of the lungs. It was natural to assume that such disease would be caused by the dust generated, and this belief was strength ened by the discovery of black, grey or red pigments in- the lungs, sometimes accom panied by the formation of scar tissue. The term, pneumonokoniosis was introduced to describe the lung pigmented in this manner. With further observation pathologists attempted to classify various forms of pneumonokoniosis on a basis of the type of dust inhaled and such names as anthracosis, siderosis, chacicosis and even byssinosis and tobaccosis made their appear ance. It was recognized that some forms of the disease were -attended by severe symptoms and result in death but there was no correlation between the clinical and pathological pictures and the causative dust. Finally, statistical study demonstrated that of alt kinds of industrial dusts silica generally produced a definite type of disease with a characteristic pathological lesion and complex of symptoms. ; ] j < ; I \ / 1) T. is qi has tom Tl spre: vidu. been tailcof t! client ance been Fo quen: medi. refier were quern in pti silicotuber produ Th. cut a due ti demoi progr. tuber, rated is lacl Not facilitamnn, native comm* Wl the n t ic-:I:.: and 1 c.tpab., ashest. panic! tissue portine specific For has hr nodule: drainac remova frameu of the symptnexcess: a trained tor .'lie register^ il service than opinion handle about by the fear and > the doctor or ition. r. a man shall >tid not be in cident" contest .;ing results in !>een cases of i-rlc meroly to "owed to interto return the "er duty is to .. well as the .luld earnestly . loyees. Both ,iste chargeable . for the after.11 was devoted irg immediately tV ? \ tac__.<0, N. Y. at an unusually /.oral to assume : was strengthmet imes accom- :gmented in this various forms h names as andc their appear.nded by severe the clinical and !y demonstrated : type of disease Industrial Health Section 51 I ... .... I Today the clinical entity known as silicosis is one form of pneumonokoniosis which is quite clearly defined. Moreover, within the last three or four years asbestos dust has atso been shown to produce another specific type of reaction attended by svmp- ' toms differing in some respects from silicosis. The other forms of pneumonokoniosis still lack complete definition. The wide- ! spread use of radiography has brought together a mass of descriptive data from indi- , viduals exposed to many kinds of occupational dusts but these findings have not yet I been correlated with pathological anatomy, chemical studies o( the tissues and dc- | tailed analyses of industrial atmospheres. There is a tendency to assume that many ; of these pulmonary changes are due to the action of silica perhaps modified by the j chemical components of the dust. We shall only be in a position to speak with assur- f ance about them when the pure types of dust and their various combinations have been studied in human beings or in experimental animals. J For the sake of clarity no mention has been made of the infections which so fre- j quently complicate some forms of pneumonokoniosis. In the prcbactcriological era of medicine the tise of such terms as ''grinders' consumption" and "miners' phthisis" 1 reflects the popular association of pneumonokoniosis with tuberculosis. The names I were justified both by clinical and pathological observation for it has been subse]: quently shown that, in silicosis at least, a super-imposed tuberculosis may cause death in perhaps 75 per cent of the cases. Some observers even go so far as to state that silicosis itself docs not develop unless the lungs arc previously damaged by a latent tuberculous infection. This is probably an exaggeration, for typical silicosis can be produced in the experimental animal by the inhalation of silica without infection. The role of asbestos dust as an excitant of tuberculous infection is not as clear cut as that of pure silica. While there are numerous reports of death in asbestosis due to a terminal tuberculosis, nevertheless surveys of living workers have failed to j demonstrate any excess of such" infection. Simple anthracosis is said to prevent the j progression of tuberculous infection. Statistics from coal mining districts do show a tuberculosis rate much lower than that "normal" for the age group. As yet corrobo- ' rated experimental proof of protective action of coal against tuberculous infection i is lacking. ' Mot only the Utberclc bacillus but other bacteria seem to develop with special facility in the tissues previously damaged by silica. For example, the pneumonia rate ' among silicotic native laborers ol South Africa- is many times that in non-silicotic | natives living under similar conditions. In coal miners, likewise, pneumonia is a | common and often fatal complication. . What has been said of the effects of inhaled inorganic dusts would indicate that 5 the reaction of the tissues is not merely a response to mechanical irritation by par- >. ticulatc matter. Today it is generally accepted that the injury is chemical in nature : and that only certain of the common types of industrial dusts possess properties >. capable of exciting reaction. In the cases of silica and the silicate of magnesium or [ asbestos the slightly alkaline body fluids probably effect a slow solution of the dust particles liberating silica in colloidal form. This substance irritates the connective tissue cells which respond by multiplying. The result is-an overgrowth of the sup porting framework elements at the expense of the more delicate cells specialized for specific functions. * For these two types of dust the character and form of the pathological changes j has been carefully worked out. In silicosis the essential tissue change consists of I. nodules of connective tissue which develop first in the lympoid tissues situated in the j drainage apparatus 'of the lungs. These nodules interfere with the physiological i removal of foreign bodies and subsequently inhaled particles accumulate in the j framework of the lung itself. Such reaction gradually decreases the normal elasticity . of the organ and encroaches upon its functional elements. As a result the cardinal symptom of the disease, dyspnoea or shortness of breath develops. Because of the 5* excessive amounts of scar tissue formed in the lungs the right side of the heart Illicit In an attempt to . heavier and unless tils an3 death occurs i- 'ot altogether y nodules of .. die same nmst they remain in the story. The silicotic nued multiplication ;hown that even atirulosis in a silicotic 'isting latent tulierrcssive and spread. !>cen ascertained hut caused by the toxic lie phagocytes which migrate rapidly and king. transported very far 'es and little of it is i-ihly initiated by the he case of silica this ' is later transformed -siliceous dust whose When a measured to the car vein of a There they remain. ' icing no reaction of -nne quantity of the scar tissue that the :ans are reduced to pigs for periods as :h of the connective :io nodules. *'--t the cellular i to chemical or solubility in tissues offers Vis this substance is loke an overgrowth Most city dwellers life-time to pigment ' will be found along II is associated with .ng is much blacker 'i such reaction docs lungs. The presence ! olization of mod- as in pure silicosis ea, is therefore dif- Imlustnnl Health Section ferent from that of the pure quartz worker. When the amount of inhaled silica is excessive, the effect of the coal is negligible and the reaction approximates tliat in : pure silicosis. There is said to be more reaction to hard coal than to the bituminous variety but there is evidence to suggest that this is due to the greater amount of t siliceous rock which must be worked in mining anthracite coal. Finally, consider the silicosis of granite cutters. This develops somewhat more slowly titan that of the pure quartz miner and it has been maintained that.this is due i to the relatively small amount of uncotubined silica in granite (25 to 40 per cent). But it is believed that other components of the glomerate grauitc may neutralize or at least inhibit the effects of the silica so that only after prolonged exposures' to high concentrations docs significant reaction occur. While typical siticotic nodules develop in guinea pigs inhaling pure quartz for a year, not even the earliest sug gestion of nodules have appeared in the lungs of animals inhaling comparable concen trations of granite (40 per cent silica) for four years. *r This brief discussion of some of the problems involved in pneumonokoniosis draws attention to the limitations of our present knowledge. It indicates that the reaction to an inhaled dust is determined by the chemical and probably physical composition of that dust. It emphasizes the need to further study of different types of dust both in the pure state and in measured combinations. The ultimate aim of such a study should be the neutralization of the toxic action of such dangerous substances as silica. . . "I The Dust Content of the Atmosphere in Various Dusty Industries i ! By J. J. BLOOMFIELD i Sanitary Engineer, United States Public Health Service, Washington, D. C. The speaker said in part: The properties of a given dust which determine its i capacity to produce pulmonary" pathology are. the nature of the dust, that is. its : chemical, and mihcralogical composition, its particle size, and finally the quantity of the dust dispersed in the atmosphere. : I One of the outstanding results of the last 20 years of research in the field of dust inhalation is the demonstration of the fact that,, in general, the degree of i health hazards associated with the inhalation of any dust, all other factors re maining constant, is dependent upon the mincralogical composition of the dust. For \ example, it is now well established that the inhalation of certain types of dust, ! such as granite dust, will in time produce fibrosis of the lungs, at times associated with tuberculosis. In other cases cxjiosurc to dust may result in the production of t much less fibrosis without notable tendency toward subsequent tuberculosis; tins is t true of cement dust. And finally, there arc certain types of dust, as typified by marble dust, which in the quantities and lengths of exposure so far observed produce little lung fibrosis. In general, it lias been iuund that those dusts which are high in i i i quartz content arc the ones which produce a disabling fibrosis of the lungs most readily. So far as the sire of the dust particle is concerned, it is.apparent that in order for any given dust to produce injury to the lungs, it mbst gain access to the parenchyma of the lung, the site where the harmful effects of the dust take place. It is known that not ail of the particles of inhaled dust gain access or are retained by the human lung. In this connection it is of importance to have regard to the i size of the dust particles present in the industrial atmosphere. I With reference to the quantity of dust present in the air of a workroom it is apparent that when the dust concentration is high the exposed person will inhale a greater quantity in a given period of time than he will when the dust concentration of the atmosphere is relatively low. and since the rate of production of the fibrosis 54 T-.rcnly-first Congress--National Safety Council is partially dependent upon the rate in which the dust is inhaled, this latter item plays an important role in predicting the relative danger of different environments. Hence the need for the evaluation of the quantity of dust in the industrial atmos phere is obvious. Research on the problem of industrial dust inhalation has indicated that so far as their fibrosis producing qualities are concerned, dusts may be divided into three groups: (1) those composed completely of combined silica, that is silicates, such as pure asbestos; (2) those containing free silica in the crystalline form known as quartz, (granite contains approximately 35 per cent of quartz): and (3) dust con taining free silica in a non-crystalline form such as diatomaccous earth. In general, it has been found that the harmfulness of a quartz containing dust is in direct proportion to its quartz content. For this reason, in attempting to evaluate the harmfulnc.es of a dust, it is of the utmost importance to ascertain its exact minrralogical composition. It has been our experience thar to determine accurately the exact mineralogicat composition of a dust one should resort to a combined chemical and petrographic analysis. By no other method have we found it possible to determine the amount of quartz present in a given sample. In certain instances, such as when one is dealing with a mixture of quartz and pure potash feldspar, it is possible to deter mine the amount of quartz present in such dust merely by a chemical analysis. However, most dusts which come into question are mixtures of quartz and silicates. Take granite for example. The average granite is made up chiefly of three min erals in about the followinc proportions: feldspar 60 per cent, quartz 30 per cent, and mica 15 per cent.. Chemical analysis shows that this average granite contains 70 per cent of silica. Of this 70 per cent, 30 per cent is present as quartz (free silica) and the other 40 per cent is present as combined silica, in chemical com bination with the other minerals that make up granite; it is possible to determine these proportions only with the aid of the petrographic microscope. We find in practice that samples of dust settled out of the atmosphere at the breathing level of the worker serve admirably for both chemical and mineralogicat determinations. Table 1 presents the quartz content of dusts obtained in various industries which we have studied. TABLE 1 Percentage'of Quartz Present in Various Industrial Dusts Kind of Dust Percentage oi Quartz Rock drilling dust (bituminous coal mine)....................... Granite cutting dust............................................................. Rock drilling dust (anthracite coal mine)....................... Brass foundry dust.............................................................. Dust from raw mills in cement plant................................ Slate mill dust (Vermont redslate)................................ Silverware polishing dust..................................................... Anthfacilc coal dust............................................................. Bituminous coal dust............................................................ Cement dust ......................................................................... Slate mill dust (Vermont greenslate)............................... Talc mill dust........................................................................ Marble cutting dust............................................................... 54.0 35.2 31.0 19.0 6.5 3.0 1.7 1.5 1.2 1.0 trace none none It is evident from this tabic that rock drilling occupations in the coat mining industry and certain occupations in the granite cutting industry anti in brass foun dries would be in the hazardous class as judged by the proportions of quartz in the atmospheric dust. i 1 l V X t. 1- It has be-, microns in It larger panic' greater than lower sizes, tratc to tlie t. ourselves wi: mention. In order t. access to the in the dust .. may be obtain instrument ophcric dust it; slip may then In another : lion; the par means of a u measurements may be grou; curve is easily As pointed atmosphere is the injury wil. From the i quantitative in size range of : requiring care will depend or the refractive i observer. \W industrial hyg. the dust contcu and certain i;.This differcnc onc-h.-.!f and tsuch normal mination the ; in all air. So far as by the South dimension are, size limit of p. who examines silicotic lung. i. and about 36 ; majority of tit: The median si/ in comparing t: tides measured mills, found a by Navrogordat In connection nificancc the ic or indirect of . ' this latter item ent environments, industrial atmos- ' so far as into three ,,.iicates, such c form known as nd (3) dust conirth. In general, iust is in direct -r to evaluate the in its exact min- *.act mincralogical . and petrographic nine the amount i as when one is "ossible to deteriiemical analysis, -nrtz and silicates, fly of three tnin:.irtz 30 per cent. granite contains ' as quartz (free .-. chemical com mie to determine '.-nosphqre at the nd mincralogical ' tained in various Dusts -ccntage of Quartz __ 2 31.0 19.0 6.5 3.0 17 1.5 12 1.0 trace none none the coal mining ...1 in brass foun tains of quartz in Industrial Health Section 55 It has !>ccn demonstrated tliat particles of dust of a size greater than 10 to 12 microns in longest dimension arc very seldom found in the lungs. This absence of J larger particles is partly due to the fact that the numbers of such particles greater titan ten microns in size present in industrial air is. as compared with the i lower sizes, comparatively small; furthermore, these larger particles do not pene trate to the terminal portions of the respiratory tract. Hence we need only concern ourselves with those dust particles that are less than ten microns in longest di mension. In order to ascertain whether or not an industrial dust is -capable of gaining- access to the lungs, it is necessary to know something of the size of the particles in the dust - under consideration. In practice the samples for particle size studies may be obtained by the use of the Owens jet dust counter. The advantage of this instrument over other devices is that the Owens apparatus projects the atmos pheric dust in unaltered condition directly on a microscope cover-slip. This cover- slip may then be properly mounted and examined by any one of several methods. In another method a microphotograph of the dust is made at a high magnifica tion; the particles revealed on an enlarged print or screen may be measured by means of a millimeter scale. No matter which method one uses for particle-size measurements the results may be treated in the customary manner. The--particles f may be grouped in classes according to size, from which a percentage distribution curve is easily obtained. As pointed out eat tier, a knowledge of the quantity of dust dispersed in the i atmosphere is very important, since with any given dust the rate of production of ! the injury will be dependent upon the total quantity inhaled. ! Front the practical hygienic viewpoint, the particle count is at present the best ! quantitative index of the degree of atmospheric pollution. The decision as -to the size range of the particles which should be included in the dust count is a question requiring careful consideration. Obviously the size of the smallest visible particle will depend on the magnification and type of illumination used in the microscope, I the refractive properties of the dust and to some extent on the visual acuity of the observer. Wc must bear in mind that our chief interest in this problem is in the industrial hygienic aspect. Primarily we are interested in differentiating between i . the dust content in the ordinary normal atmospheres, not yet known to be harmful, t and certain industrial dusts which arc known to be associated with lung damage. f This difference is sharply marked so far as the dust particles between approximately i one-half and ten microns in diameter are concerned; but the difference between such normal and abnormal air is masked and lost when we include in. our deter i mination the particles of ultra-microscopic size which are present in vast numbers i in all air. So far as the upper limit of particle size is concerned it has been demonstrated i by the South African studies that particles greater than ten microtis in longest i dimension arc, as a rule, of negligible importance. The data concerning the lower ! size limit of potentially hazardous dust is not so conclusive. Moir of South Africa, who examined microscopically 120 dust particles obtained from two specimens of silicotic lung, found tliat only 13 per cent of the particles were less than 0.5 microns and about 36 per cent of the particles were less than one micron in diameter. The majority of the particles, 60 per cent, were between one and three microns in size. ; The median size of the dust was found to be 12 microns in diameter. Drinker, in comparing the size frequency of the particles measured by Moir with the par ticles measured by him of the dust found in the sputum of men employed in ore mills, found a close correspondence. These findings have also been corroborated by Navrogordato. i f In connection with the lower limit of particle size of dust of pathological' sig nificance the following pertinent question arises: Aside from the evidence direct { or indirect of the non-retention of minute particles of dust by the lungs, what 1 : *r ; I i !1 m1 56 Twenty-first Conr/rcss--National Safely Council TABLE 2 Average Dust Counts in Certain Dusty Trades Industry and Occupation Talc Mining and Milling: Jack-hammcr drillers ................. Packers ........................................ Muckers ........................................ Cruslicrtucu and cylindermen... Slate Finishing Mills: Floormen ...................................... Loaders ........................................ Disc crusher operators............. Quartz Grinding Plant: Mill operators ............................. Laborers ...................................... Packers ........................................ Graniie Quarrying and Finishing: J.eyucr drillers ........................... Jack-hammcr drillers ............... Hand pneumatic tool finishers.. Machine pneumatic tool finishers Plug drillers ................................. Attendant labor (indoors).......... Anthracite Coal Mining: Miners and hcli>ers .................. Attendant lalmr ....'................... Bituminous Coal Mining: Coal cutters and loaders............. Attendant labor ........................... Marble Cutters .................................. Cotton Cloth Manufacturing: Carders ......................................... Weavers and spinners............. Silverware Manufacturing : Dusty trades ................................ Non-dusty trades ......................... Dust exposure in millions of particles per cubic foot 2,160 50 45 M 1.598 1.276 312 173 83 :o 144 m 59 36 37 1/ 232 31 IP 33 Average per cent of quartz in dust None None None None None 3 3 3 3 S9 99 99 99 35 35 35 55 35 35 55 1.5 l.S 1.5 17 10 1.2 N'onc None None 1.7 1.7 1.7 evidence is there that appreciable percentages of ordinary industrial dusts ever fragment into those minute sizes less titan 0.5 microns in diameter: The best answer to. this question would be data ot actual measurement oi such dust. Un fortunately we have but scant published data on the particle size frequency of dusts in the air of industrial establishments. In 1929 Fchnel made some particle size measurements in connection with the dust study of hard rock drilling in New York City. He reported the findings on three samples, which showed the dust which was less than 1 micron in size to vary from 1 to 15 per cent. Most of the Badham. in studying the dust hazard among sandstone workers in Sydney, Aus tralia, measured some 16,000 particles of dust .in the air of work places and found that 67 per cent of these particles were about I micron in size. In a particle size study madc speak Only than I and Fr. contr: * betwr limit metin' of du . high finds Heaki being Du' bazarsumn - indust mines indust' grind!' tries 1 most I it Si t : hv ; in the more ' ord. ti load, a their known The loss 01 Johanr dollar.ization. Mint compe." ing to other p against has gri It is pay mu Strai. Average per cent of quartz in dust None None None None None 3 3 3 3 99 99 99 99 35 35 35 35 35 35 35 ' 1.5 1.5 1.5 1.2 1.2 1.2 None None None None 1.7 1.7 1.7 rial dusts ever ter? The best nch dust. Unmcncy of dusts :ue particle size "'rilling in New bowed the dust .:. Most of the nicrons in size. Sydney, Ausi.-ices and found a particle size Industrial Health Section 3/ study of twenty-five samples of eleven different kinds of aerial industrial dusts nude by the filar micrometer method at a magnification of 1,000 diameters, the speaker found that practically all of the dust was less than 5 microns in size. Only 2 per cent of the particles were less than 0.5 microns. 21 per cent were less than 1 micron, and the majority of the dust, 71 per cent, was found to be between 1 and 3 microns in diameter. From all of the evidence therefore, and in the absence of conclusive proof to the contrary, it is apparent that we need only be concerned with those dust particles lietwecn one-half and 5 microns in size, and from a practical standpoint the tower limit of particle size to be counted may well be taken at about 1 micron. Many methods have been devised and used for the purpose of' determining the quantity of dust in air. Suffice it to say that for the purpose of dust sampling in cither high or low dust concentrations, the Grccnburg-Smith impinger apparatus now finds universal favor. This instrument has been used by the United States Public Health Service in all of its dust studies during the past nine years and is also being used by other workers in this field in this country and abroad. During the past nine years the writer lias made numerous investigations of dust hazard in many industrial establishments throughout the country. In Table 2, a. summary is presented of the average dust content of the air in a few of these dusty industries. This table clearly show's that the highest dust exposure was In the talc mines, slate finishing mills, quartz grinding plant, coal mining and granite cutting industries. Owing to the high percentage of quartz present in the dust of the quartz grinding and granite cutting plants, as compared with the dust in the other indus tries listed in Table 2, quartz grinding and granite cutting are revealed to be the most hazardous outlie occupations we have stj^jicd, ClinicaFand Statistical Aspects of Silicosis By ALBERT E. RUSSELL, M. D.. F. A. C. P. Surgeon, U. S. Public Health Service; Surgeon, U. S. Bureau of Mines, Washington, D. C. It would be dillicult to estimate with any degree of accuracy the number of people in the United States who arc engaged in dusty trades. It is evident, however, that more people arc exposed to dust, which constitutes the greatest single industrial haz ard, than is generally supposed. Certain dusts contain poisonous elements, such as lead, arsenic, mercury, etc., which give rise to general conditions resulting from their absorption. Tin's paper .however will deal only with those dusts which are known to. be direct factors in the production of pulmonary diseases. Economic Aspects of Silicosis The economic problem presented by silicosis is tremendous. The suffering and loss of life due to it cannot be adequately measured. In the gold mining area around Johannesburg. South Africa, during the licriod 1911 to 1929. more than 53 million dollars have been paid in compensation alone. The costs of medical care, hospital ization, and legal proceedings further augment this enormous figure. Mines in Australia are reported to have been bankrupted by payment ot silicosis compensation. I know of a company in our own country which has claims amount ing to more than a million dollars for disability due to dust inhalation. There arc other plants in the East which wilt lie bankrupted if all the claims which are filed against them are allowed. In most of the industrial states the number of claims filed has greatly increased in recent years. It is clear that dust-prevention work, like any health-promoting activity, would pay many times in money, good health, and efficient operation. Strangely enough, only during the past 25 years has dust received much attention /h .K l 12