Document J7xOjyLVgv1v6rdgaZrv2r82

/ Final Report upon the Physical Condition and the r. 1th of ITT- Tnyloye*.:.; in t he U.S.Gypsum } l~nt st h A Ui- Uk -1L O 'w- %*5*> 4 r."\w - -f The following report is subnit ted on the study began on June . 19, 1933, of the dust hazard in the Oakfield plant of the TT.S .Gyrsvr A SURVEY OF Thu PLAHT was first iM.de and. our impressions were j* c.iwMkScu ... w-.e pi cirr.lii^ry reporo cu June orieA^y >; * these observations yielded the following points'which were regarded 4 .* 4 as significant: ' The nine apparently offered no particular harsra " ' as the ventilation was excellent, the operating r.ethtns generated no great amount of dust and the rock and ore , canape. ' The portions of the plant devoted to crushing, ^ - calcining and grinding gypsum were quite dusty but owing - to the nature of the dust this was not considered hazard ous encept in one particular. Certain grinding`operations were done in cuhr stone mills. The stones themselves being quarto contained high percentages of crystalline sills, which is a v.ell-rc ocgr.icc d couse cf pulmonary fl- lo. _ o1 r.alor stress v.us. laic upon the necessity of protecting the man or men who dress tho- huhr stones as these persons would be subjected to dangerous quanti- :Y!,` '.X V*. . j ir : .I o *-> H- 1P/ t. ir i . i. <J *1 i t T* . *I <; I > <1 f > 1 i i 1 1 t-* f 1 ; , i - i 1 1 1. D. 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M P- 1' 1 c> . 14* JJ ** * i O ' f1t ** .1 l 1 Ci CD w IV ` > * Ma4 r. i 1\> tt * (J 4 . 1'- 'U CD cl f" \ 1- o h` ; P i / 0! 1 , MP i> 1 ` CD o : id . rt J'V ---. \r'l* ; *- O 14 tM- 4- ft t o CD t >. o U 44 f . t y <; p r* *i o M p r* t t *J M ; n Cl f4t ** 1 ft 1 44 FJ VI CC Ci *- r|. \ (D y ; o * i ij- ;i CJ i -o i+ CD o o t. i f i 1 0 O y i: 1 r r! M p. f i in y H- p- * > f1 O p. H- it lft l ! yp y p oc ,A yti '- :P (1 ! .J r i \\> o ir y p - rf H i P y p r ? --* >- \ ^ >/ * 11 rt- i c. cl 1>1 y . CD P* & P P cr p i'i j 14 ft 4 O y Cl r - f; j ft c ~ U CD 3 y yrl H- *r r. F*- i-i c* c-e Ot ik* ;. c *1 \< PID CD to f1 y* r t i. ft-*^ *. - j ' f;.'. t-/ . I-*. t - r j.* i r .. {'; Id r *' P t , ,4* . *. 1 l ;* i i ?1 i 1 "arr-le "o.l -ccieion: Operation! Tine: . June 10, l?2'o *1 - *. st - lst.dcuoh - li Rt.Waii: South - Rt.Zntry Drillinr ir. Gyreur ' " ' ' First Hole ^ ^ O -- , W kal T n *f f\*O Second Hole IJotes: Zlectric Drill. A **- N->4-V4- -- w- -- '* r ^ r -- * .. J .* M a ' -- - ^ Drilled one hole. Started second at 2 r:=u r.u.chin; v.'ithir. ter. feet. ?.oo. 4 -4 *? * O v -> w - <-\r . -* n O ........... ^ " ,' *% $ * ----T.ww * I|~ -- J *- ^ 'J 9 - v '-J 2,050,COO j* w l. it -t . . - . ,. j.. .trc^rachic onolysis cf die cypsua .y 7c" CaS0.fi : cH-C, 10;.' CaSC4, and r nt - Or~? at Icn: Tin: ;cr. 27 - Ic Rt. 3rd 2cv.tr. - 2-i Rt. Main Scuta 'illin- in tiraiin" ' ' ................... "': '' Started: 10:57 em * er) n C r 5^ tr i - - -------1 'cr . 2 roles Ko mc::i Dc.d ended - air in drcm near He of 3 1/2 rt. ' ' w" ^ ^ j o - j ^ . 2 ndard lirht field com . - roriracsly 1,500,000 > i t * W <5 W Hiilshed- 11:29 Air res chine - :vUto. feed - I" Trill. :.c - livmber of particles (less than 10 u) per cu.ft. Li :*ht 'field i:,1:1,000 -** * i -* "- - j - ^ w e::ce-=u v. silica co ilioa at t ir.uri. es : i* rr. I; J 1i t" o r-.< ' o o* tf p0 c* to la rn [; j mID i-3 o 1- P- o *. * 11 J ID y p p p *.n f i 1 * i. */ p 1* y *' i * I *! * i . * ps * * tfc (/ , i **t P ,. # * , * Hi ' '} < 'f \ .. 1 P I 1 * ,l . <! ! ' i f, I 1*1 * '! * 1' <M it * ** r : 6 * 1 i ( t !i *i i i* k\* *, O y t > o i j : % ll (i> (i <n ( i m l) o>* 1 id u;i ID i i ; >, p. Cl *J o. pii ii |j wy i * ri w Jr ; v p- fr I-1 in p- P- >j O H l * P (.u |.l o 1> >)' J-' p. rlOO ,-i O 1) I'M ; <d o ;i Oi i ;f ; H d PM y t- l* P ! 1 { 'c* u oil y *; .o J* J-J JV i*fc!1 a [j t i. n* i oM (J 1 ts II tip 1' I"1 P S 'i(H (0 y o - -p lit I-* P< t 1 Ml P |J H 1.) Ii ; 1 . o ;- O it -i > i-*- ;i y . (H - rt P *4 rr P O H (0 to ,*. l- P (a ta rt S' .-}!') I-* to j. i-j 1 , S* min CO ( i i >i < 1 O(ii > C. ri o O<) o ooo y o s i: ---, *d ID *4 q p - - ** tt * *, o f / P y . i. ji- i p.. j in .i, rpii :: O 11. JV -* y iti :n i ii ' >> ' 1 <t -o 1 .* ' 1 ^> -0> (ll I,' ',}jl O 'uO] 'J 'll i , iI ' * - ij Co Py- Cpii py P. rt <D pa. pi PH l-*P ID i CJ iitt*. CItl' M * uT cf (C w u y i^-< H' I-* y Cl p- y y. >- c py- p Cl10 l1 t) r^ , a" m d- i C-l y u. t'l o y ti *> 1 (U P- O(r> c-t y J 'S p. * 1-1 i'.l) y rt y M I' I r i Io.25 Opera ti on: Time : .. a -` ' '" .' ' J\ ** p '' "* .W' "1* ~w o M*- 2-14 F.t.Main South, next to ^ir Drill Drill ins.i n the Roof.- , ,. ,,..... Started Finished 2:22 2:23 1/2 ' .... ' not es; rlas.: he Id close to head of .ran operating air drill. Counts: ... l.'urjfcer of, particles- (less than 10yu) per cu.ft.of "sir. . , linht. field -isaeetarc t ci-o rro *v # , Vs *r r* - - * ^; ` - J. ` " ~' V - ; * - ^ w v ; v wv * ' ^ _ i t\, ; j...w retrrrruphic analysis shows the rr.a- ---- tc i e U.I*m w i-.'-T ...r l*c c5 i c s ^ t * *' i*"* -i * 2.i j C C ^ ^ ----------- v w*; <o 2 Zz.rr.~le c. 24 Location; ' ` Operation: ' Time: ' 3rd i.'orth - end -auch,l4 Kt.. ain South - In Passageway. Kao iir.g'Gyps'. V ' "' ' " ' Started Finished 1:37 2 *57 "* i I'* i I` - & U" ' ^ C - 0 0 -i`i . I lO oc.vc n-~uua over oracd and close .junction. with other drift. .-Counts ; 1. x. .~"S. of oartio ie-s '(less' than 12 ai} oer cu.f' air. L j t - O f ^ s.' 2 > . - v.' I -- w, -* V er.ar. standard licht field count is approximate!" - . . . . v Sar.rio ::o.: Operation: - r.e : . .-it foot of 7/3 si.'aft. Loading ... . ..... Started 3:47 1/2 . Finished ' 3s62 1/2 75 ft C u::c- i: - O v- O2.-vn mcs ; Fit sk-5* above' crrund r.eor mi t n 1 = rf ro.rr-r-e v:--- shiited past set-up. cassaire. oder&ts draft of ..air through, or of parti ole'r (loss'than 13 /a) per cu.ft.cf ai: - L* -- -- .M V* ; -- .* >n C 2 = ~ -- /*\ y x v -- V --W *" *" ; - f - - * ~ ^ * - ^ j1a5.2^ cc*.:n i I -reraticr.: '..e inning r'lc or ' V. sighing and Crushing- Started 1 Ptr. i .'S d 1 -*Ot fcS One car rer -chute (2 chutes) cwT.t'ec c or n r ci' chute. .rti c* *r **"..*.i;**j4 X"I w *m* ;' a c. ^ w. a . t f' ,*.4 f i i * * v 9 icld count io i Tl:ce : ' ------- '9 -- Cet-up rent tc too at elevator at conveyor belt (conveyor bolt was carrying r-ypsun) ana stcrare ca crusr.ea Started ' 2 :31 2/3 V4-- ?v - ^ `' -- e.r**- * -- ^ w* accve conveyor be^t* ^yote ' **imcvs open and strong -draft acro3 3- floor. ' lvr.ber cf '-articlec ' (les s the f. 1C u.) ~er cv. f *:. - - - '*" * c M r: 7 --- *-*- -- /*> j ! j V ^ 'v' rr r cw . J - .. * J ~ J -- - J- * J pr r- f ? 1 t. 1 t* i o * .. HO l * ci.!i , f*- m v* . ir> 0 :: * > !i i . r ,i i .. P rt | *.j rl I1 ii PO p i i* ", Ot1 1 ; P..* 11 t : OP If ' 1 m : 1: ; 0 r i .' f. 1 - ct p q a> i, ru l ; ii rt *!*>: M' <;> ;i` A i- i :t p M . j: P | - j ; - M tj 11111 ,1 J *,* in f.1 p nM. i p M ft (V ' {* ' a> j * ;y s* P ! 1 * . o h : t p. . Jt I3 t i s O I> n VJ J m H rip t * * 1 \* * 1 *j : i . . p- u ( t 1 j. (1 M, ! | : *r | O .. M *; :i ii c 1 no i 11q ; , , 1* p '.j . .. .. p !-* *. cl 1 J 1 i rt I* 1 1 1 > l-fc l-M 1 1 * ! rt i ' ! i. o . t {M O' : |J O : P P 1 -J *1J rtH- 0- 1 - , 1 l-j >1 |J 1 * * .> u * |-W | . i u . \ P . to t+ -I to j; to J V) q w ,*3 p ** rt h : p- M O i > :/ --- 1 o li. . M O :? M tv 't 1Ji 1 i : c+ h* ;; ir> OOP'1' u j o n o r .P rt O :i n p ^ p < : O i ** i Ol o n fl > ' '^ cl ;t o trp-: o '.V *.-j rti P oJ \ . < ;i * iN f P \* rt> 'J ' 1 M- !j P* (J 1 * 15 ' rt *i r ct 1 *' ,r. i ' . < - O' >O C) ( ! ' ' \* o V_^ t 1 ' i- ^ IS P Vt |-i o . r (- pon 0 O tt . -1 r , a* z: r> ** O O .J ** tv 10 ri : 0 O O i st 11 I-* ' t J3` 1 ri. 1+ to > p- t-> tl .7. i 1 t>. (B < 11, :* ' t p o'. i'-l.. >: i-* . ' .. . . 1 "-) r ,| r.i i-i*- i .1 '1 :i .* 'i .. t * > c` r > c !-> i , c 1 1 t * : <! r J . ' n 'i 1. .. >: , . tv 1; ii J III f1 n i , (ft 1-1 O t ' J-fc ii i* J ill c. o IP J r< * i' i-f i f:> l-'- o <> J ". ! , . I-I ' VtV-l i: ;i i'JCI' Mi'ii' t r 1 11 ti M ll-. 1t 1 0 l l o is l-^ c t fit :t p r. cm I I V O *.. : p- O 1 CP Cl l> i * {, > M *( 1 J* M t1 **> :i & 1-- rl 3\ i -* } p, fo S Is oo - If H n t :.v n o rl *i -p :/ OO * If 9 * i 1 * Mm t* I' , H O o I* 1 n; t! \i " r-il . . 11. i p- 11 'ii i >. 11 t-i m !: o> ,\ Cl 1 1 O 11 , . 1' < >* s-roi .* i > u * :: -< I-. <> U P> Cn >! : i) '1 c I' M S' I-* M \\ 10 10 1 M. Ivt o f 1ft u p. P i) O '* w fi ;t C) . . o to , i-;j i Oi t.: m I-* o- M n i ; P :*i r M O J r ii r'ttl'H- PP .. 1 **' * o : :j * !! ! r. - < > r> Cl < 1 < ' o ' .> i ' 1 III o It I-* o p J !-, f' <: ci m }; (I- m o 1 * -1 i ft . M -> . 1 *H OO .. ( i M 1 . i. 10 'i \\ ;( ti jo * Cl r, . <11 I* - P Q * V <> H i *M :0 fO l* 1 1 1 . !-* p 1 r . <-> % o ** C.I :i o ,1 Cl I :t to Hurcr.er Screens Ported: . 10 -54 1/.4'iriohed: 12 * 70 1/4 .. _ . i~* - - v- J 4 1/21 1 - * / .r -- cr:.:'t of air rase screen convenors, ?ast flask and cut betrosr. screens." '' ' ic c o1 Location: - rerot i or. : 1 ins : - Between Bs.ll I>*11 s ' Hall '.'ill Irindi:..- ' 'Started: Finished 11:18 11:2" ** . <? 0 -Tur.s 23, 1935 .-COOS C cunts: Flesh 5f hi ah, 1C* ire re each r.ill - 2 01 freer, era wall having :re eper. window. l-.cderate . .ncverr.ent of air. - Floor covered with fine dust; ' snail an:cunt leahir.t from one mill. . ... . ...... lot counted - "bacteria noted. C t' _oc_ticn: Creratiar,' -Tire ---or*- ouhr btor.e Grinders . . -- J ___________ . . _ _,, _ _ . Flask . about .4 1/2 above floor; about 5 ft. above- and Z ft. fro::. arsnir.c rf cricaer. ..derate craft, of air across rccc. ' ' " VS i. i Cr <Oo J vWJ > *-r<^ "*<1 oo > w ** . f". ~ "V -SC. Cperati s; fr t - . U V- 1L' OO wlc.ci: ?1 Lr.z - Over ..cceler.-tcr Grinder Grinding -'Coeie ter. .. i r 0 re c sun s : 40 it s. ''z:zz: ; -lasi: o' above and 41 over .'"re- chute v;he accelerator dust is oeinrr chalcen on r.c**ir. H t?i flr 4 --, . I ... n: r Pl-r/w . W mmm <*> 9 ! -- v V o*i 4? T4 A* ^ i ^ - ) -- *- n ?n /i i i7 > -v- . <-> f i.' > } ^ r *i ,* e ,.o I/s-.r. ibpv-3 floor, in center of roox (500* ::2CCr). ' *,Vindov:s or-sr* on 3 side, "icrror. 7/ side- ,v;iis:.. ... . _ - a r* w j w v* w I I location; Operation: ^ 7 ^ *' * a * ~j Jut-3 taps vim o macnine D^ Fading isypsun plaster in* -jute "bass on machine rrovidei vith erahnvst -^ - ---------- * i w w* ts W * ..* -- .3 > -- - . J * * . m. Cl - J -- - > -- - -------------' 13 approni: o one a ntration l t Leoat ion; June 20, 1333 Cet-up r.e::c to ,/? .T.o.cV.i.-.e packing ..eci-fiber piaster. Close to ope: &toa* as for sanple #8. - -0 ttinutes Eenarks; . .. A. - J -- ^ r.._ i s** -- - --i.-'j - v * - - S . .. - c:_;u;.-: of line (25r per ten), .o sancea piaster being -ace at :f air j -v, " jC - n^ II - PiarJct on . II -->iSoeeting --c, s o 0, o 0 0,500,000 cC, 'sC 0,000 The standard light field count is approrinutely15,000,000 v/ith .a low silica cor.: fat: ati ;n. ' / c: I coat ic;:: Cp n .is - * * '.*. : J3 - z -- _ * i- rpscs:'. s; ticces v -; s s 1C uj per _ - , . _ - , - -w ; 1,3-0#COO I eld c:u::t is approximately v; silica concentration. i Sansls ::o. 1-3. Location; '"n A **p . 'e.tc to 9 I-Iinar. * i ^ Cement-Plaster. Started: 2:50 1/2 Finished: 2:54 S/4 above floor, 20 ft. from side wail .nd I w ir : \t * j * ^ * M b. ^ l4 field conr.t is a??ro::i_-utely lov/ silica concentration. 4 \ S 0 V ;r!2 O w------ - piaste: 11 i v* ; at shoulder lovel r.t 11 s.r.1 c ten lee * - ar "a 1 * '" J Ji V*J - Loco, tic i :cl;i. vide a 3 rc-tau st i ac .1 sm.- . r- r* .C w y -- S t wT :ro- l' o V Sonvl; Location: Co o rat cc n : Tir.e: Lent to :->'I2 Liner - 2'..dec. Piaster Lininr sanded r lasts'" Starred: 9:50 1/2 n wj Co .-.lr Pre ure : 40 s. 11. Iron machine in different positions. of ins: pint isles (lees oner. 1C ,u) C J CO CO J ?hs standard li f i ; c .n rl M la is -la - - , -- ".n - ----->------ - } - i s CIO,-/ coarse .sin. 1 9o .'ext tc .'-12 I.lxer - Sanded ; looter ;;i er. /* > a * * *_/ -* _ w V.'l cv;s ooo i ** -j 7l *l <*v **. , wW t;*.o ssna -iso1 j - V- - eo en -iroot 3 C;*.Ut-3 n * o osits tr.ic u on 6CC-/ --- - -- r**,f7 -*--= .. X- il'i'.w C TO icr F2l.z.z "I %* f "* * *s 1 ! i.i S i --J w. > < v \~j~ C O li. 1' C C 27.21 t^ \ o i-.xr ..l.. . air V. a* W: r v. o i* suj.v Truant. ..Oiler crusner :::::. _ tarr.eo a vt -- .. a * v.i:; = r, - - z rtajr. -rcr. crv. 3. -- * -- * * . ------- 1 4 -- '* C v 2Z2* C*l. *" --* . 3 as.tie -- ^ Cl. L x 0 Cy .* V. vt b *^ X - X -> s *-> 0+ . TT c '!*<2! c. i.; a ar. c r\x2^i<> r4"-~ *^ .-*< 2tone tririndna . C LA l C 9 < ( ) ; O 9 ** w j C ~ c,rid a i' ** i ~ *'^i - is I w' ' 9 CO and the 'cits t is r-rt.c ca I .*w C'i` 11 }T. , -. -- W v--.f w X* j? tf- v*`r . ;ca^s of .-.ci soluble l&ter'is.l ~sun: oust I c? tht: ckhfhv ,-\r ni-. TV; f'r ' 'f\ Tro r of siiico.is or ary other form of pneumrrrkcricris must rest upon the presence in the industrial atmosphere of a sufficient quantity of silica particler. or other dusts known to produce permanent injury to the lungs in such a state of fineness that they can he inhaled. The foregoing tables report in detail the results cf dust sampling in represer.tc tive locations throughout the plant and in addition there are appended, in appropiate places, analyses of the various types cf material encountered, In the mining operations men are engaged in work -- --- i. c greatest quantity. Chemical analysis of representative samples of gypsum s/. ;v,s chat tr.e total acia inso-uo-e material varies from: a trace to about 20p. Petrographic analysis of this rock indicates that it ~ : cntair.r approximately 7c.Cm gyps urn (CumCu 2 HgO), anhydrite (CuCCu), and lo.C.n calcite (CaCCg). rcrtur.ately there is not enough silica r: ere in th.c- r.acive ryrsum. to constitute a hazard `unless f- - he. total rarticues in air are in excess of the 25C,CC0,C1C particles per cubic foot. The actual dust concentration produced by drilling gypsum rock is less than 2,CC0,0C0 particles per cubic foot of air. Previous studies have failed to indicate that there is army ha sard associated with calcium carbonate dust. -Con: equently it . is is evident chat there is nothing associated with the mining of ordinary gypsum which could be considered responsible for the production of silicosis. I he second moot important reck enccunt -red underground is V' * '"nr,ed anhydrite end represents a native anhydrous calcium sulphate. v, . This naterlsl shows frcr. a trace to O.C,' acid irso:urie i:.atr:Jrl. .. i'.'.cc i .i: r r :k is hr.re :r thaw rr-'-.-vr w : 1: ' : : ' ' ' is reruir-?d in the driving operation : nd hi.-'-fr cis: r 'wr1 : rc-svli. nverare counts obtained curlr.g this operation showed 11,650.000 parti cles per cubic foot of air. Since the silica co:::e:.t sf thp s reel: is negligible, the dust produced in drilling it can not be regarded as capable of producing silicosis until concentrations of nearly 1,000,000, 000 particles per cubic foot of air are created. ground involves the removal of roof rock from the haulage waps. This to 58.0% of acid insoluble material. Petrographic analysis of this about 60y calcite and 40;-; clay. Clay contains aluminum silicate ar.d ..ere for- it oar. non be said that drilling the r:cf rock presents no , dust haaard since certain silicates are known to produce pulmonary r* s ** i c v4 m rr x * --.ck from the haulare waps is terfor ed with a **ack harmser drill and the dust concentrations produced are very large. A count made near the head of an operator during a typical operation, disclosed 1,930,000,000 particles per cubic foot of air. Obviously, this work is theoretically the most hazardous, from th< pnevmonokcr.iosis standpoint of all t.,e tasks per- f creed underground, ar.d yet it can not be regarded as a serious hazard far several reasons. -he work is not very extensive, it is intermittent in character, it involves only a few wcrlor.er., and the dust produced is not free siller, rut contains less than 40% shuir.u;; silicate. *. . l V A Duct sampler secured in the haul;';*' w yr re: J 1 . J _ J r ' roc din* c1 ;k i:u\ i t ' .................... suspended in she general nine cir is r.ct once r i'u. 1 RAY." CTiTSUk .FL.nkT lien engaged ir. this portion of the plant are exposed only to the dust cf raw gypsum. Samples were taken on the weighing floor, over the conveyers on the upper floor, an! near the hammer mill. These samples were all taken during regular operations end the counts obtained indicate that there is not an excessive curnMtg hammer mill the concentration -..as found to be 11,500,CCD particles per .;:.gerous, bu; it is advisable to install equipment which will reduce the concentration -- ^ ' -- V *- U. - ~ m m. ~ w ^ w W V ^ -- -- V >>* -- J .V W * -* %. w' W> '------I- M c --- rust createa - t,.' Jr- 1 Chea:ical scaly: is of this dust shows luble material does not'exceed Z.Q^. Petrographic a:--pot- -- --u-u aT'trormm--te --y ne:.'.in^ ar -- te D-auaC i/a HCw),5p dead burned gypsum, IS.OJj calcite (CaCOj), and ifd anhydrite (CaCC^). There are two sources from v/hich a siliceous contamination may occur in this plant, namely: the refractory material lining the kiln and the tvf r stones used in one portion of the grinding operation. Neither cf thes? sources of silica can be regarded as creating a real hazard for the following reasons: both the refractory material and the bujtr stones are '.veil enclosed, the actual amount of cilice cue erntaminati 'added to the gyro urn is very c:: all (less than l.C"), end the duct con 's cer.trations around these operations is not excecslve. Samples taken ,1k . . . . *' * 4^'( *** -t ivajr-y. bctv.'cor t? c cu 2 cir c' z zsi d 'vvz t' f ovl.r 5 tor;-. V _.i - ; - >. w , u:... ; ic y.: s p-; r curie - r> ~ 4 vc;o:: .vc:;;, iitu:.r.le3 v,c't also t: kc-r r.o.r the hammer screens end near the call r.ills but due to bacterial contamination it will be r.eces: : o obtain new sarries from tnese locations. One individual operati on, that of trimming the bu.hr stones, will be con sidered later. BLOCK PLAKT. The dust created in clock riant is largely air but this is r.ot regarded as significant. sample reervered near th* hs-i a; an opera;or using a hand miner shored less than 5,000, COO parti cles per cubic f- ot cf air. This concentration is lev.- and would be perr.is cable under ar.;.* conditions, -l;e grinding of accelerator (gyp u \ 't,cc -- 1 23s ccn^^r^'tr'^.vi-ons 0*^ *.*'""*c"r^"^c.i`l".r ^5/3CO|vC'C .S- - * - vww 1-*-- - - * v- U^A. *.. ,, -- ^ - -- C-.c-* . .u > equipment shcld be provided whlcii v.lll reduce this concentration to --- S% A.r.S dust oraated in tire beard plant is identical with that produced in the block plant and consists almost entirely of gypsum. A sample tuken near the center of the plant shows only about 500,010 particles p-r cubic foot of air. This concentration is lower than chat found on moot city streets. The grinding of accelerator (gy-su_ blocks ) produces cor.cer.trati or.a of apgr:rim.a tely 12,SCO,000 particles per cubic foot of air. 3his operation might be improved to reduce the concentration of dust, though it is not h.acrrdouc la cither composition or . sar.tlty. At the southern end of .ye board plant is a ;hlne for polishing veneered boards. Samples were not obtained near * j- ' \j i.* - i t . ^ f .1 1 --4 i. . A r* . .. . wW -* 1 _ *0 ^% . , ,, . . U- W .. * ; ~ ' ** ` r* p .-* ' r * * " 5 .-;A \' <- .*. J. I- *V . is being used "* ^ ^ ^ ^ ^ ^ in this laboratory :.-z shov/n slo:-;ite to be relatively ir.aayaolc of rroduc- 4.ny*\ ^`'4 ' -\ v* ,-\ ^ e* tits introduction of silica abrasives .vcv.id create a very significant hazard. "-i yVARZHDUSn^here are a great variety cf cuscs present in the air cf the -are';:ruse. r.'h lamest sin.cle c ::::1 it:f tl.es-. QV-i--,4 ^ol rjp ^ ^ 4 s* 4-V* ja 4* 4 silica, and that 5- 2.0,-V%-* of the sand is freo quarto. ^i Petrc.rrs.phic analysis iU*-f** --- c--*- ov ; m- A -> J ^ ~ e re - ** CL " ^ t- "P Ck used in .Lc*. or. c heroics! seraphic ana lysis dis 0% free quartz. '12 miner at the ns oluble material. Similar duct ::: over if7 r.ir.cr shews 3.0,, acid ... _ ^ 1 . .V. 1 . .aterial, while the oust above i'4 miner shows only 2.0;"^ acid insoluble materiel. The lamest part cf the sanded plasters ore node at the ,,'12 machine. Sand- - A- .f v Q** *** i - r. + d since the sail'd contains Iren 2S.0,v to 53.0,^ quarto, the dust in the air may contain from 10.0,^ " o 33.0^ quartz. . Obviously, the dust created in the making of sanded hv:- /?*"4 , "* yt*vi,: plaster must be regarded as hazardous but this hazard appears to be . -- '' . S.0 ^ cw * **T* * ' ' * * ** ^ Samples cVt:ii-:--'i dvr ir.g *.*.: : p.:.ckir_ :f :r din-ry ; emcut plaster in both paper and Jute bare on machines provided with exhaust ventilation showed fren ,CCO,CC: to 11,000,000 partic?.es per cubic foot of air. another sample taken near the same machines during the packing of wood fiber plaster showed 15,000,000 particles per cubic foot of air. These concentrations represent about the highest remiss ible counts and it would appear a dp-* sable to improve the ericauca sgs-?:- ------------- ------ ; ----------- / - ed the head of the operator. In general, hov-'ever, the tv : ;f gypsum or wood fiber plaster on the machines protected with exhaust C O-.w S taaCSTl OZ1 wi;6 S C T ni 1*2.002? cl* t td '' CC 21 -- -- 22 T* 3?** OO* mOCU 1*0. O' 'sZ'' ~L,Z.S't,:d2~ Oil C 'V. r o com.os from 11,100,000 to 32,000,000 particles per cubic fret of air, ^ >-> r* e* ^ - - - -- - U J v- ~ ^ --* -* ^ ~ ; ruuutiaies of silica, the concentrations are two or three times -reate: than the usual standards remit. Samples secured near the ^'12 Bates Packer (which has no exhaust system) during the parking of sanded plaster showed from' 2E,COO,COO to 44,000,000 particles per cubic feet cf sir. Since as much as cne third cf this dust car.be pure quarto, it is obvious that men pecking sanded plaster breath an atmosphere containing from ,011,000 to 15,100,000 quartz particles per cubic foot of air. This ic c:..si cured .r be a definitely hazardous eor.ee `.ration of harmful dust. The concentration of quartz particles per ruble foot of air L 'j re:1 this r--..scn iis 1;; re:c::.-enied tint the epsr-tions involved ir. the evure of sanded plasters be given special consideration. A sample taken near the A12 mixer during the mixing of sanded plaster showed 146,000,000 particles per cubic foot of air. This o onoer.tr?.ti on is excessive and hazardous and should be reduced to within 10,000,000 particles. A sample recovered near the point where fine sand is delivered tc the mixer sh~'-d more than 11, OCC, CCO,COO Ihe mixing ana caching ci sanaea piasters snouia oe acne in a section of the warehouse which is separately enclosed and special equipment should te installed to redvee the amount of dust suspended ^ T> *"0 w-- i * -- ^ - 3.h~ TlAbT. -he dust created in the sand plant is all produced op th^ voces ring of the s.stds whose'analysis have been given it ah-. -----lin- '..sah she v;arbhouse. The silica content varies from 32. oo'll.Cd and the amount of free quartz varies from 26.0,u to 52.0, v. A sample taken in front of the furnace showed approximately 3.000.000 particles per cubic foot of air. Though the dust is definitely dangerous, the concentration is not high and the `hazard can not be very great in this position which the operator of the sand plant occupies a considerable portion of his time. A sample taken in the center of the roller crusher rocm showed the excessive concentration of 227,000,000 particles per cubic foot of air. Every effort should be made to keep the amount of due. in the air of this plant to a ni zmum which should nr v exceed 10,000,000 particles per cubic foot for in these con- cv. :r vrt is dsisi^-,c3'*C'Vir, Chemical unalvoi: or the ct n- stone: has shown that they contain 97.0;^ acid insoluble material an.', petro graphic analysis indicates that the material is practically . ure normal quartz. ^ sample obtained near the head of the man engaged in trimming these stones with an air hammer showed 6,SCO,CCD g: rtisles per cubic foot of air. This concentration is near the maximum per missible for cure cuartz dust and is he regarded a: haza mcus. or to eov.ir the oreratcr with srecioc exhaust V '-J - W v. ntil' tier. It is recommended that the following men be required to .i_l respirators until such time as the hst concentrations * n v;'n i: them are werbir. ~ are reduced to within the recommend-: ^ * - 1 o driving roof roc,-; cr as: 2. rnf J ym, r \ j y* -+ ^ - ..A..w ; -J - r ^ ^ r* All employees in the sand plant, lien trimming buhr stones. the methods employed it would :rrc r t::: r ' : V- 1 expect'd to excessive concentrations cf duct . Since- it i:- :r.cvn that severe julncnary das.age is produced by silica, and if it is assured that gypsum or calcium sulphate ir relatively harmless it becomes essential to ascertain the relative proportions of these two sub stances in the atr.ospheric dust of this plant. It was srsumed that this could be accomplished by railing a preliminary count of the total dust particles in the air samples, then dissolving the c loiun sulpha t-' icles which would not be attached by acid. For technic: I reasons this procedure has proven unsatisfactory and it is deemed advisable to make a special study of this rrobiem in another visi- to the slant which will b; :ace in J-Va iJr--sr.e dis.te fuf; csea - -. * J ' w* W W ~* a as: _e s cr. cover g. n.n i direct micr..:ccpic examination the relationship, cf various particles lued. By the use cf this apparatus it will be possible to determine not only the relative proportions-' of gypsum_and silica in the atmos pheric dust but tc learn whether the gypsum may not have been respons ible for the formation of aggregates of silica particles too large ' tc be inhaled. The subsequent sections dealing with she condition cf the wo rimer, will disclose there is no demons treble siliocsis ancr.g them, and seme explanation is necessary in view of the high cor.cer.tra- tiens of silica to which they have been exposed. F171J11.. 1 ~ M'J.l I'.'J. h I Oh 3 - wore made on 1-1 men employed for maximum periods in various portions of the plant . '.Vith two exceptions there was no evidence of disease of the lungs and in the two cases y _W ^ . -. 1 to. 4 */ X * C< * U to ^ to 4 t- J. fc. 4 4 ^/ 4a O 4 i *- Cto C -`i--'- curve fu: . cf the spire and a lev.- charges in treuth sounds with rales in the top of his left lung. His x-ray picture showed charges which c-uld be interprets - as healed tuberculosis. Another man, Arthur L'.orette, was employed for nine years as a mason and brick layer. While he worked in all departments he spent most of his time in the power plant furnace and repairing the calciners. "Squeaks," both exprr t nr.d ir.spi: o*. , ~=restive of asthma, were discovered on o..o at examine.a -ns. His x-ray pictu: t shewed a ohard. degree fully developed silicosis. Otherwise the physical examinations cf the che : in the : men were quite negative. In 7c of the 111 cases cloudiness of the sinuses in t-e he d were noted cr. tr&nsillumir.aticr.. In the absence of a definite his-.cry of sinus disease and without a thorough x-ray study of this ccniltior. a ,,ef 1 r.ite diagnosis cf sinusitis could not be made. An er.mll" high incidence of this'condition has been observed in other dusty occupations. Two cases of heart disease and' one of hyperthyroidism were discovered but neither of these could in any way be caused by inhalation of dust. In addition there were numerous .cases with bad teeth, tonsils and nasal conditions which were reported to the men t'.u-u hr. Daniels with the recommendation that they be given proper medical or dental ettentlcn. . r.'i::TGi::C'LOGIc;X showed some evidence* of abnormality ir. the lungs of 68 of the group of -s.l, but in none were the changes very pronounced. No case could be diagnosed as silicotic. * ' - 'd? -'bf.rvea could not be correlated with the tyre or dura r.'..:n v ere grcup-d according to the theoretical hacard of their occupation us hollows: Table I. QcoupatIon . Dumber In Group Euhr Stone Dressers ....................................................... 2 Warehouse only...................................................................... 6 Warencv.se rius Other .s.................................................. '9 with Miscellaneous Occupations with ::o "tr house Work......................... Bloch Plant ............................................. hi .ir.r Only............................................. Lobcratcrv Tester .............................. IS 10 22 1 T'.vo main _ypes cf change, which right b-e due to dust, were ob served ir. -.he roentgenograms} (1) an increase in prominence of the normal linear shadows of the lung and (2) a diffuse haolness throughout the central portions of the lung fields. In the table following, the first change is designated as "F" and the second as "p". The appended numerals indicate the intensity of these changes. Their significance will be discussed below. Table II. rv of R oerttrenolcrical Findings Occupation Ho. in Group Pneumcnolconios 1 s Tuberculoais 0 i-l ?2 i'3 *" 1 :r2 ?3 healed Ohlldhood healed Adult Uincrs 22 1 10 0 0 8 3 C Elock Plant Only 10 1 3 0 0 0 6 0 Miscellaneous with Occasional Ware- house exposure 13 2 3 0 0 3 4 1 3 1. 2 2 0 1 1, M>. II . (Continued) Os cup: t icn C-rcvr Board Plant Only Warehouse Only Wererouse plus sene work else where Miscellaneous Occu pation. with no Warehouse Buhr Stone Dressing Laboratory 19 6 9 IP 2 1 p u J 1 y2 ~ i . i:ee icu r. e u x c a L licheed du1t 52 2 0 8 2 0 21 0 0 2 1 0 4 i 1 0 2100240 3 0 110 0S9 0 00000.20 0100000 0 1 0 0 1 0 classification indie at inn a diffuse type of interstitial (?) reaction occurs nost irequently in men exposed to pure gypsum dust, the aresene; of this tree of reaction in the different occurs ticnal rreves i: - w U. ZZX 4 cr -//j hiscellar.ecus Occurstione with Occasional '.York ir. Y,'arehouse.................................................. 'Eoard Plant................................... . . ......................... Warehouse Only...................................................................... Warehouse with Miscellaneous Occupations Elsewhere. .............................. Miscellaneous occupations with no 'Warehouse Exposure...................................................................... Buhr Stone Dressing........................................ ..... . . 17/3 16# ll 0 The significance of this charge hs: not been definitely ascertained for lack of autopsy material upon'which to base an inter pretation. Individuals do not always show a degree of reaction corresponding to the duration of their employment, but among the ^ rrcv.p of nlners 56,": of those employe for 9 to 12 years show It while oft or mining from. 13 to 25 vow *- 5?.;.' of the men have x-ruy changes of this type. In the block plant croup the corresponding percentages for the same employment periods were 20 and 40^ re spectively, while in the "Occasional Warehouse Employment Group" none showed it under 13 years of exposure. In two diners exposed for 9 and 21 years respectively this change was complicated by seme emphysema. For these reasons we are inclined to associate this change with an exposure to gypsum dust, but we have no clear ur.der- standing cf the underlying prthcicyical cent It 1 The ether type of rear.-, penological change encountered whit:; is labeled :!F" consists of an accentuation of the linear shadows cast by the bronchi and blood vessels. This change could not be correlated with the type of dust to which the men in the various groups were exposed. It occurred in both the tuhr stone-~ dressers who must have been exposed to considerable quantities of fine silica tut only two-thirds of the x-rays of Warehouse men displayed It. John mi"h, who had v. cried for 10 years on the Sates racier where he would theoretically inhale large amounts of silica had a noivsal chest picture. This warehouse group of only 6 men is probably too small and the duration of their exposures is too limited (all under 12 years) to permit statistical analysis. . Possibly if the group were larger the figures would: have proved more enlightening. It is still our belief that if silicosis should appear after further exposure it would occur in men exhibiting an "F" type of roentgenogram. Or.c man, honotte, a mason and-bricklayer for 9 years, as already mentioned, showed a change classified as . In his cose the accentuation of the linear markings was accompanied by a sug- yection of 'beading along the trunks such as occurs in early sili cosis. This non may have .inhaled con :id:-i a l 1 e cue hit:':r rf ; ilia: in wo: repairing furnaces arJ calcir.i.rs which i re presumably lined with refractory silica-brick. However, even he could not be called a case of fully developed silicosis. Tuberculosis was always manifested as healed lesions in the roentgenograms. The changes were of two types, (1) the "child hood type" which represents the first conts.ct of the body with the tubercle bacillus and (2) the "adult type" which occ-.u'S when the body is again infected with this gem. The chilihoc 1 reset!:.. con sists of cr.e or ncre isolated nodules of tubercvlssi - somewhere in the lung and another focus in a lymph node situ-ted at the root of the lung. Such ncdulss of infection tend to heal with a deposition of lime salts which renders them easily visible in an x-ray film. In the gypsum workers these ncdulss healed with an excessive der:ri- ticn of lime so that they were unusually large. The incidence of such infectious lesions was no greater than that in any group of individuals. . The other type of tuberculous change, the "adult lesicn" generally occurs in the upper portion of the lung. It also normally tends tc heal but occasionally it spreads and gives rise to wide spread manifest clinical tuberculosis with symptoms and possibly fatal-termination. Five or possibly seven in this series of gypsum workers showed evidence of a previous adult type of tuberculosis, but in every case the lesion had completely healed without exhibit ing the slightest tendency to spread. If a corresponding number of mc-n exposed to pure silica dust were in question, it is safe to assume that some of these adult types and possibly evon the child hood types of tuberculosis would have shown evidence of spread and progression. .. Following Is u list of the individual v.ovlz..n., ~rou: to csc*.;rszi~ ::, t o{:ct hr r w:i _h the4 " T'\ unt Cr.lv. 7 to 21 Yc-sri 1ST, Zloved 7 yrs. 8 yrs. 11 ri 12 rt M 14 tl 16 n 12 u 21 ti Kane Frank Lanke A. Ferris C. Brown F. '.Vs. ter street a. a '*r Fred. hanks r<-- . 11. Clnstead Carl lutz F. TJrtel Case Jlc. 46.................... , 43.................... .... 41......................... O7 X-' i-- TP 47 .#. T' 22.................... ..... . . ?1 .0.................... ' *2 19.................... .... . . p. 43.................... r* f Corzple o :i .. r.. 2 E-uhr St or.e Dressers * cl (vr:.rl:ev*=r2 Fo Coupler.,: 11 "part ) C. Rinehart tiire ) 40.................... .... * Fo Fibrosis ? Tub e reals. 10 11 S 11 c 11 DM 10 11 11 II C us=in-3 1 Laboratory Tester _ 101 . . 22 I'ir.ors E. Casslano 77 . . C. Kelson (rushc-r) 76 . . t Jeroue (Loade:* Hard Coal) . 61 . . 4. Dcrsaogolla C2 - S. Scopano (Pig Iron Loader 2 years) 57 . . . . Pi - Pi er-hyserrn . . f2 -Fi apices .* * * i~ * TT. *1 - -2 12 years 12 t) 12 (I 12 Tl 12 ii 12 it 12 -15 * 16 it 17 ti 17 u IB u 12 n 1 it 24 n 25 rr 5 it 7 it 8n 8 ii 10 ii 10 ti >i'UT v1 *^ r 22 P.lnc-rs (Continued) C:t^ ::r. " 76 ... . . . FX D. Faolucci A. Paolucci A. Frigonl 74.................... 63.................... 64.................... * P1 * F1 F1 Primary complex,1 Primary complex,?. K. Paclucci A. Ferrari r. _>-.,~pii ~ * X1,1'. Il P. Tad.de i I Cxpci'.c* k5M?T 17 .a.4^>. w 67.................... * F1 Large Hear- - 68.................... . f2 no . . ?-> i ^'"S * * * F1 r/- J * 0 P1 ^ * Large He a: 80.................... P1 73.................... IOC.................... Pi Ca1_ _ficati ". Apex G. Cafero ,66.................... J. Callarisn *" - * " - - . Cure P. Malta . 75.................... nc 24..................... 96..................... *1 ' F1 * P1 Emphysema 19 Board Plant Only L. Eeicenrlch _ . 52 .... . F1 - ' J '/ 0 OCiS ~ 116 r 11'* (2 yrs. outside) E. Green 54..................... 53..................... 25..................... F1 Primary complex,P.t. and FlX Lt. Ditto . f Ditto Wm. Acars 5G..................... Y.'irdrs tern 37 * * * . 0 ' S. Davidson 35..................... P2 Calcified - both apices 10 ye nrr, 10 11 10 11 10 n 11 n 12 it Xcr*. If M. V. 14 '1 15 ii 16 tl 22 11 T. Pei-fit t E. Bumstead I. Davis S. Davis LI. Allen R. Harris Y. Greene 7. V. Seatur V/. Allen Alien . Did: ' 0n2v (ContinueG) v -1 i * 52 ... . Fi Primary 3 . . . . . F1 comp11lex,Lt 2 . . . . . . FX 50 . . . .. . . f2 26 ... . wD . . . 51 ... . 71. . . . . 33 ... . . . PX . . PX 7 . . . 5 11 C 1! 6 II 10 II 11 It 12 n 6 V/ a re he us e Only R. Valens Fred Bernard __ Vim. Shepard John Smith (Bates Packer) A. Beckwith T. Joslyn - . ` X * T"t * *1 11 . . . . 10 ... . . . f2 51 ... . 17 ... . . . PX 16 ... * - T?., Primary Complex, Lt. 5+5 n 5+25 it 9 Warehouse and Cccvrat icr.o Elsewhere in F lent Yin. Farnsv7orth E. Dinehart 5. . . . 13 ... . plex,Rt.+ Lt. 7 1/2 1 yrs . Put aka ' 9 ... . . . f2 8+3 yrs. 9 +1 11 E. Earl A. Hansel 7 . ". . . . . f2 93 . . f2 * * ' -f * -* . I P Vi^rehc-.y:e f.na Oecnnpa ti onr Elrewheve in Plant. (Cent.) r 1,/2-rOl *'ll -p* j. Remains 10 + 19 n Mil::e Marrah 12 10 ti Chas. filler 15 + 7 ii Burt Smith Case No. ^ r\ 15.................... Primary C plsx Rt.+ . . Pi 6................ 8.................... Fi Primary C: plex Rt.+ 1 c ;*e ers t * (r 12 <i 12 u 15 it 15 it 15 it 15 rt 16 tr 17 ir 20 it 21 n 25 It i? trip cellanerus with Ccca s icr.al'Work in Ware ho * * c ^ ^ *r ^r fa ^ ^ 6 **V r. * Monette (Mason, boil ers and flues) m 0 Miller (Carpenter) D. Bowden 84. ... . 67.................... 85. .... E Eoden s. Fosdicl: 3 5.1.four ' 83.................... F1 91.................... ?1 4.................... n tr. Freiday - Z-- * ? ar.dir s. Christorhero 89.................... 92.................... 0 Primary Co: plex Ft. - Kami H. Holm L!. J. Eordan . G Lehman - * 90................ P1 (Isolated ?E ( . ` S3................ * P1 (both roots. 97................ *2 Ow RW . . F2 Primary Com- plex, Rtl 90 . Qk/ n 10 it 19 Miscellaneous - No Warehouse Exposure D. Tillet * Nvth A Eurr L. Park 94................ p2 So.................... *1 20. ... . Fl .2211 *1 1*. .t S *1 -* > x ~ ~ :r --. . .'u., 4* s.` i J vhousc ---rrecrruunrc (Cent. ) Ew.ui eyed ] * c. r- e> Case Mo. 11 years 11 t) E. Newton Kent 44 t 1 * A2 F1 11 It Ed. Hale 99 Fo Primary Comple: Rt. lo tl C. Manetta 50 *1 T n B. lanni (Mine 7 3rs.) 61 -nt**- IT > - ^ -v . .r a 23 " -- t -- --C \ -- -.SO I"* w I'i J 55 - 4 ?r --- ---------- -- c v, w j rs . j 60 * ?2 Cld lurerculosis 14 tl A. Schulk 82 Fi 15 tl 15 11 \ n Cj It 21 ri B. Cater. (Mine 12 yrs.) K. Stevens Xj w OG jTl J. lanni (Mine 12 yrs.) 72 6 39 65 F2 Pi F2 F1 - 26 rt 30 ft Schulte (Mine 11 vrs.) . Steen 53 * IS s 2 Ft Primary Complex,. Rt. and Lt. From this analysis of the x-ray and cli.nl it V. ould appear that gypsum dust inha led in hi gh con ^P e-*. -** ^X QCs'l^e* s#- a long as 20 to 25 years does not produce changes in the lung' v.hic'n a3'e Inc cure title with normal function. It cannot he maintained ` that this dust has no effect oh the lungs for only 13 of the 101 men examined show wliat could be interpreted as negative lung roentgenograms, but thure was r.o clinical evidence that gypsum i:.:silation had produced disability. When silica dust is also present in the Industrial atmos - !.; ** . .iero with the gypsum dust this substance has not excited the reaction \W>-'. * g* -- - V - w ' ^ v.' i- V ~ . 4 1 r *v * J.* x--; -r. * 2. U -- ^ w C I' v t (* ^ ^ .... v- to hav-j brought at out changes in th.ei lunge demons t rat It by x-ray but such changes could not be discovered. Two explanations have sug gested ther.seIves: either that the gypsum by virtue of its physical properties clumps the silica particles in the air into aggregates too large to be inhaled or that gyp.-urn chemically modifies the tissue reaction to silica. In the absence of any data on the subject it seems more libel'* that the former ervlanatior :. s~ be the rrorer cr.e. Ou .< W k. . :o prer. r-s autopsy material from r.er. ex posed as long as possible to mixtures of silica and gypsum, so that chemical analyses of their lungs n_ght demonstrate i.ev, much silica actually penetrated their tissues. Opportunity for such a study , c o* ccurse , qu i t e f or tu: t ous. The investigation has also der.or.strated a complete lach ` of pregresrire tuberculosis among the gypsum workers who '.-ere exam ined. This finding substantiat-es the view that little silica has been inhaled, for ar.y group exposed to silica for as much as 20 years should contain 10 to 15 with active tuberculous lesions. It has been claimed that gypsum dust protects against tuberculosis. H. L:aer.dl (Zeitschrift fur Tuberlcv.lcse 1921,XXXV, 104) quotes riss&k, without citing the source cf his figures, to the effect that of 40,824 deaths" among lime and gyjsun workers cr.ly 17 or C.4l were due to tuberculosis ar.d that among 4C0 employees in one gypsum plant {presumably German or Austrian) no death from tuberculosis had occurred in 17 years. Exam ination of the" death records in Oakfield and tlx nearby towns might demonstrate whether the incidence of deaths from tuberculosis or other respiratory disease was equal to or below that for other industrial 'communities. Tv;o cases of ac :ivc- tuber n; lot-Jr i:. gyy -:r:. Calrfiels hove cr:;.o to ovr cttcr.ti(\ sc the.*. v.-. 1: J. t W M occur. FATHOLCGY - Lack of material forbids any elaborate discus sion of the tissue changes produced by the Inhalation of gypsum in pure fora or in combination with silica or other substances. Animal experiments are in progress bvt the exposure period has not been sufficiently long to hacar:, an (pinion as to she nature of the reaction. One autopsy on a gypsum worker was obtained through the efforts of "r. Daniels at Oahfield. This man was not employed by the U. S. Gypsum 3c. but by a competitor for a period of 6 years, presumably in various capacities but his occursti :;;al history was not obtained lr. detail. Yo n-ray films had been made of his chest prior to hir death so that a comparison between roentgenogram ana - _ pathological lesions *,vas not possible. Presumably the picture would have shown an accentuation of the linear markings, as there was a rather narked accumulation of dust along the lymphatic ' vessels accc... anying bronchi, blood vessels and the connective tissues between the lung lobules. These structures were pigmented by the dust and slightly thickened-by the formation of a small amount of new connective tissue but there was no.fibrosis and no' nodules such as occur ir. silicosis. There were nodules- in the lungs and lymph nodes cf "childhood tuberculosis" which had healed with very extensive calcification. Death occurred from coronary arter ial disease which could not be associated with dust inhalation. The character of the pulmonary changes was that of the reaction pro duced by many non-irritating dusts, like soft coal and marble. This report discloses t) .t umcr.p the 101 lor.7 ter:.. .r.pi epees of the U. o. vypou.-.: Osmpi.-.p v.i.o havc- Veer. examined. t is no cose of definite silicosis nor one of active p'jLT.or.ary' tuber culosis. These findings were somewhat surprising in view of the fact that in some portions of the plant, notably near the mixer over the #12 Facker, there were total dust counts as high as 11 billion parti cles per cubic foot of air with a free silica content 'which night be as high as 3 billion particles. The fact*that no silicosis occurred in the group of 6 men employed exclusively in this part of the plant, and that the one nan who had worked on this particular machine for 10 years showed a normal chest, throws sons doubt upon the existence of a haoara under the conditions encountered in this gypsun plant. As nr. explanation the hypothesis was suggested that the tendency of gypsun to forn aggregates clumped the silica particles - _..to masses too large to be inhaled in significant quantities. Never theless it must r.ot be taken for granted that with further exposure cf 10 or more pears these men would remain free from, disease. The occurrence of an "F" classification in so many of the roentgenograms suggests that 'with continued exposure sone of these men might ulti mately develop serious pulmonary damage. . ' As far as gypsum dust is concerned nothing has bsen . observed which would disturb our original feeling that this dust would prove to be quite harmless. Probably it is responsible for certain changes in the x-ray pictures of the lungs but there is nothing to indicate that these changes are associated with physical disability. Tr&ces of active pulmonary tuberculosis are wanting and .* ^ J^ crieuce quoted fror: Ocrro-ry r-v .'c:;:coc. The evidence cvv-c in fection is present the oust inhuloc in this i doc-c not tc-r.d to csv.se it to become active for 18,'j of the pictures shoved well healed foci of childhood tuberculous infect ions and 5fj of them disclosed healed adult tuberculosis. however, it cannot be claimed that such infection never becomes progressive in r.en with gypsum exposures. For these reasons it is of utmost importance to select for test c^ses individuals without active tuberculosis cr obvious silicosis in order that unfavorable precedents may not be established ' ' that in the gypsun industry. If it can be dlsccvered/perchance such con ditions exist among the group of cases scheduled for trial, we would urge that they be settled by compromise and that the test be based upon the typical case. "v ASST. DIRECTOR \ [ yxir^'fv {