Document dQqmneB77qjrbp8YeOLQkaDm9

FILE NAME: Raybestos-Manhattan (RBM) DATE: 1937-1948 DOC#: RBM094 DOCUMENT DESCRIPTION: Interim Report on Experimental Asbestosis at the Saranac Lab with Relevant Correspondence \s /K ' 'W / April 26, 191$ President, Ken:;hey -v. Mat.hison Conpany, Arr.bier, Penna. Dear Mr. I'uehleck: You and t'r. Rohrbnch are the only rafiber3 of fh~ yrrmn '1 th rhon I have co'^unlcntecl concerning the Inn^ndiiHr ronort upon Dr. Gardner's eyprlrnnin. You Till bn interested to Jcnow that Mr. Pohrbnch lihcvrlse favors a review of the report by a srjall co"nitteo prior to Its being released to the entire group. I nn in rgreenent with you and hr. hohrbnch. but I nrs not entirely clear an to bon the nf-tter should be handle'-1 noohnnicnl.Ly. Since it rra the osbertor. textile manufacturers; who underwrote the or.p<>rir>onts, norhner it n!Ufht bo nnyrop^into for tho or^sldont of the Textile Manufacturers; An sedation to npooint a onnll committee. Sincerely yours, V B ;y Vandiver Brown, Secretary. cc fir.J. F'.D.Rohrbnch \/ Raybestos-Manhattan,Inc. Bridgeport, Connecticut. \ \ \, \ e t t 's i t f i r t Q * oopy for * lir. Vrjvlittcrc Broun, Secretary J nhn Rinvilia Corporation copy for Hr. O.H. Cilley, U.S. Asbestos Division - Hanheim, Pa. V ' 1 leon lG f6, ;> 1Q tet? 3foj& Jrjmoxy Hf - >>&;* r' ----i > ' * ; leroy tt. Gardner, n.P. D irector, iO c-.r-n::.c hoooretory f o r the Study o f Tu'ocrculocifj of Uio clurr !.. Trudeau Foundation, ffmnoo halle, lieu XnrSi* .: - U Dear Doctor Gardner, Reolylnif to yoar le t t e r o f January 12th u&itic to ho 'ncm ittea to aoii a curtrcy o f the f ilc o o f tanga eoployec, tabula alvino that Doctor kmnn hn thorn fllna ln Me poocsocloa and I t touIg ho oatlcfoecopy for you fco cjmaino then? ana system atically record any ctaAjoc or other inform Cion that you t;ish to obtain. ' -!i: -, v::: ' , 'H." There arc also odp filas at Kiinhoin Clint tatto been- taken of /v; prospectivo orsloynoc tiio have? cartel in other itufiSries^ttinfe v. ary tetto dunt hesor rivi theno aro In poescanion tX the ^ffico /A at hpnheln, Fa. ol if you vans to look at sons of -tane, -V will you pionco contact:- Mr* 0*n* Gilley, Aipir&snt General United Sr.ateo Arborton D ivision- o f RnybntOi?-Rnnha ten, *n?#* Sanheia, *?cnncy2^',nS,n` A and ho u lll ta very iati to how Choo to you* Of coureo i t i s nnderntnoa that cur nrr,o trill not "oe in nny uny In tfco ozncintsion or in your report o f !0 For r ootor of your rcoordo a*l the ffctronolitan Sec**-**J CoOTonv i t io olrir.ht, but -econ cenerai publication* XotiTD very truly, 3, Pirronon, Pro old one *,* n/y Div-trof-:'Akttv/f' a H \1\M- The Saranac Laboratory FOR THE STUDY OF TUBERCULOSIS OF THE EDWARD L. TRUDEAU FOUNDATION Sa r a n a c La k e , N.Y. January 31, 1944 Mr. Sumner Simas on, President; Raybestos-Manhattan, Inc Room 1G25 120 Broftdmay, 'dev; Yorl: Dear Mr. Simason: I appreciate very ouch your letter of the 19th i'hich averted my on my return from a recent trip. I am grateful to you for your offer to co oper? te in the matter of reviewing; films of your employees. I expect to see Dr. Lanza on Monday and -ill ash him to g'ive my access to those films in his possession. I do not believe that it mould be profitable for us to review the pre-employment films that are at Manheim as ve are particularly concerned now -ith the evolution of asbestosis. I shall, of course, refrain from mentioning* the names of any particular employer in publication but simply acknowledge my indebtedness to a group of companies who have made such a study possible Vfith best wishes, Sincerely yours, L U S :R K Leroy U. C-ar;ner, M. D. Dir?ctor n \~VsP hQ n 1 r t h e Sa r a n a c l a b o r a t o r y OF THE EDV/k RD u . TRUDEAU FuUNDi.TlON Sa RANAC LacCE, 1. Y. Leroy U. Gardner, iu. D. Director July 26, 1946 Mr. Ernest Muehleck, President Keasbey and Mattison Company Ambler, Penna. Dear Mr. Muehleck: Your letter of July 23 is at hand to disturb an already guilty conscience. I by no means have forgotten my obligation to prepare the report of our studies for your industry. Every time I see a case of asbestosis or have occasion to examine tissue from a few of the animals that are still being sacri ficed after injection with asbestos dust, I realise that I have not fulfilled my part of the bargain. My intentions are the very best, but it has not yet been possible for me to do any writing on the subject. I am besieged by an influx of European visitors who are arriving here to find out what has been done during the war. Official delegations are coming from everywhere to consult us on aluminum therapy in silicosis and various other industrial disease problems. It looks now as if I will not be able to take, any vacation, as I had hoped to do as soon as the war was o v e r . A Therefore, I see,little chance of my devoting the necessary tv/o months to the preparation of your report until the winter.// I trust you will forgive me and realize that I very much want to do this, but simply have not yet been able to fulfill my intentions. Sincerely yours, LUG L U G :LB C C : Mr. Vandiver Brov/n ft H ) f.c1 :0 Ex ec u tiv e Of f ic e s J o h n s -Manville C o r p o r a t i o n T W E N T Y TWO E A S T F O R T IE T H S T R E E T N E W Y O R K 10, N.Y. April 19, 194-$ Mr, J. F. D. Rohrbach, President, Raybestos-Manhattan,Inc., Bridgeport, Conn. Dear Mr. Rohrbach: / By an interesting coincidence I received your letter of April 15th on the same day that I received advice from Saranac Laboratory that a report on Dr. Gardner1s asbestos dust experiments would be submitted within approximately one month. You and Mr. Simpson will recall that our con tract with Saranac provided that the results of Dr. Gard ner's experiments would not be published unless approved in advance by the asbestos textile group which financed the experiments. I shall be interested in yours and Mr. Simpson's ideas as to how we should proceed after the report has been received. Should we convene a meeting with representatives of the entire group or . should a small committee be appointed to review and make recommendations? The latter would probably be preferable as it is my recollection they were approximately ten contributing companies. As you are probably aware, Dr. Lanza became a Trustee of the Trudeau Foundation following Dr. Gardner's death and he was instrumental in securing the services of Dr. Kenneth Lynch, of Charleston, South Carolina, for the purpose of reviewing Dr. Gardner's experimental data and notes and preparing the forthcoming report thereon. Please convey my regards to Mr. Simpson. Sincerely yours, VB:y Vandiver Brov/n, Secretary. . \ A The Saranac Laboratory FOR THE STUDY OF TUBERCULOSIS OF THE EDWARD L. TRUDEAU FOUNDATION Sa r a n a c La k e , N.Y. January 12, 1344 Mr. Sumner Sinpson Rebestos-M anha t.tan Company Bridgeport, Connecticut CU* i Dear Mr. Sinpson: I am getting material togeth our monograph on asbestos.is. Among other thi would like to include a section dealing with appearances in human subjects. Moone has eve ported a comprehensive survey of serial films over a period of years on the same individual I have written Vandiver Brow ask permission to review the films of his emg at Manville and I am wondering whether you wo permit me to review those of your group at M? I would ho oe to be able to get at such a stud latter part of February. I won't be able to before because I am scheduled to leave for th tomorrow. It is, of course, our purpos describe the evolution of the X-ray shadow pa no reference to individuals wo"la be rwde. V have been seeing films with Dr. Lanza and Dr. I have made no attempt to systematically recc successive changes for the purpose of descripI I hope that it may be possib to grant us this favor. With very best wishes, Cordially yours, L W C :RH Direc Lor Bridgeport, Conn April 15, 19AS Mr. Vandiver Brown, Secretary Johns-Hanville Corporation 22 East Clth Street Hew York 16, Hew York , / < . *. ,> ;/ My dear Mr, Brown: Mr. Simpson end I have discussed the work Dr. Gardner did at the Saranac Laboratory and have reached the conclusion that the in- ` dustry cou^d not possibly got a report on the work that was done under Dr. Gardner^ direc tion for a long tens of years.. 'v'. Do you consider this matter closed or do you think there is any chance of getting' .* some report through other staff members of the ' Saranac Laboratory? Very truly yours, JFDRsG President Bridgeport, Conn. Sept. 27, 19o7 lir. Vandiver Brov.n, General Attorney Johns-Danville Corporation 22 East 4 Jth St. Hew Xork City My dear Mr. Brown: I am enclosing copy of a letter re ceived from Dr. Chas. E. Iiyde, who is the ohysician for the DuPont1s Fairfield factory. I am also syncing a copy of the letter to Dr. Gardner. I saw Dr. Gardner this cummer at Lake Placid, and ho stated he v;as very much interested in the results he had obtained, but, of course, it was too curly to toll anything definite, but he does think the outlook is somewhat promising. He made one remark when I asked him to obtain more information and advise you, and that was that the- Harvard College Laboratory had sent him an asbestos sample vhich upon in jection caused immediate death of the animals. This was a little bit strange. Ho did not know .exactly where this cample came from, and 1 ask ed him to endeavor to find out. I expect in a few weeks, wo may have some information as. to this sample, and as soon as received, I will ad vise you promptly. Sb:G Very truly yours, Enclosure President E x e c u t iv e Of f ic e s ; : J o h n s -Manville C o r p or a ti o n TW EN TY -TW O EA ST F O R T IE T H S T R E E T N E W Y O R I1, N .Y . September 29, 1937. Mr. S. Simpson, President, Raybestos-Manhattan, Inc., Bridgeport, Connecticut* Dear Mr. Simpson: I wish to acknowledge receipt of your interesting letter of September 27th. I have heard nothing from Dr. Gardner concerning his experience with the asbestos sample sent him by the Harvard College Laboratory which, upon injection, caused immediate death of the experimental animals. I agree with you that this sounds strange. The sample in question must have come from Russia, which I am sure you will agree ex ports poison in a variety of forms. Anyhow, I trust it wasn't from Canada. In regard to the copy of your letter from Dr. Hyde, referring to the work being done by certain people with aluminum dust as a counter-agent to free silica, I be lieve you will be interested in knowing that these experiments were conducted by two Canadian doctors and a metallurgical engineer. A preliminary report on the subject was presented before the Academy of Medicine at Toronto on June 15, 1937 and printed in the Canadian Medical Association Journal. If you'or anyone in your company is interested, you can obtain a reprint of this report from Air Hygiene Foundation. In fact, I am surprised you have not already received one, since obviously news of this character must be welcome to the eminent industrial sponsors of Mellon Institute. I With kindest personal regards, I a m ' v Sincerely yours, v Lr V VB:y Vandiver* Brown, General Attorney. \ f.' /\ OP X v/ Che re i.'to if b C Muy G, IU*. Juaian itohell CkV> ^14.J i*v.,J*I>lj CW * i 1v* Dear hr. Mitchell; I r.ra very grad inceda to "nave? the opportunity of examining Dr. Garc.nerTs report on recent invar tig- liona of the effect of fine a s m s tos cuat as comparer v,ita longer fiber oust. As he s',ya, if the hypothesis constructed on the bata of this oxpc rilento Lion provea tenable, our .i w i m s icea that the finer the duet the more harmful till have to be revamped. It all goes to show that the only thing that c; r: yet be positively statua la that in the i m a m sufficient exposure to astra to s beast till cause asbestos!a, but v.hat conati tutor sufficient ex posure still reami nei subject to leex of complete .ano?;lebge It might be well us a forward-looking program for the asbestos factory to begin to think more about precautionary near urns in departments v.hero the oust is coarser, although even apparently leac xn amount. As Dr. Gardner says, Ihu-c are things about asbe.stasis which have not been satisfactorily explained os yet. One that re na ins with me and ny locai material is, v.hy the scvane e old esses thov, so cucii evia cnee of pure- silicosis. I have not been able to get any evidence that any of the asbestos used here may have had free silica in it, but, unless asbastosis under some conditions shots the? feature of .silicosis, it must have had. I think that this question, that is whether local eases nave not Lean expos t-d to free silica in aCoition to si lies.,ter, is very im portant for the- loenx. incus try to clear. I do rut tnin.c that Dr. Gardner's experi icnts ve any practical cosring on whether there is such a thing as asbestosis. Mr. Jcfsores suggestee to me that conclusion, out of the extract from Dr. A. J. Ireland in the South African Mining^ sne Engineering Journal of Jan. 15, ideo. All I can conclude Irosi this extract is that ap parently unuor the conditions existing there, the exposure is insuf ficient. Yi'antc-ver those conditions may be- it night bo v.ell to ascer tain, if possible. only mechanical. I get stimulation from the South African report to again rc."nina that no m e can xnov. \diot the hr.arci here is until the seme sort jf examination of workers is cone here. I shall be glad to talk these ms Iter." over with -uu rt -nv venient tine. " * Sincerely yours T h e Saranac Laboratory for th e Study of T uberculosis of THE EDWARD L. TRUDEAU FOUNDATION POST OFFICE BOX 551 7 CHURCH STREET Sa ranac La ke,N.Y. May 19, 1958 Mr. S. Simpson Raybesbos-Hanhattan, Inc. Bridgeport, Conn. , Dear Mr. Simpson: ` Tliank you for allowing me to see the copy of Dr* Lyn c h 's comments on my report. I have also been curious about his cases of asbestosis. He has sent me sections from some of them which I have felt indicated a silicotic rather than an asbestotic type of fibrosis . I have always been suspicious that the men whom he has autopsied may have had some previous or coincident exposure to free silica, producing a nodular rather than a diffuse typo of fibrosis. I am of course sorry that he feels that our experiments have no practical bearing on whether there is such a thing as asbestosis. This is a matter of opinion and I trust that others may find the information which we shall furnish to be of more use. D r . Lynch comments on the findings as to the lack of progression. He fails to bear in mind that after a fibre becomes coated to produce an asbestosis body, the mechanical irritation is minimized. This might very well explain the failure of continued irritation. I am well acquainted^that Dr. Lynch has some very positive ideas but feel that I am justified in differing from him from time to t i m e . Sincerely yours Bridgeport, Conn M a y 17, 1918 Dr. Leroy U. Gardner, Director The Sari;nuc Laboratory for the Study of Tubercuio:;is 7 Churchy Street Saranac La&o, K. Y. Hy dear Dr. Gardner: Enclosed find copy of n letter from Dr. Kenneth U. Lynch, v.ho is the doctor in charge of our spinning plant at North Charierton, 8. C. I thinii as a matter of Informa tion I should pass this on to you. If there are any questions you would line to as* Dr. Lynch, would suggest that you correspond with him direct. Very truly yours, G Enclosure President ^ tv-iiLo^C*j (j^A'Vvv'VN X \ Bridgeport, Conn. May 17, 19L8 Llr- Julian Mitchell Mitchell & Horlbecic Charleston, C. C. liy dear Julian: I have yours of May 14, and am sending a copy of Dr. Lynch*s letter to Dr. Gardner, and. also a copy to Vunciver Bvoan, of Johns-Manvilie, so they will have a com plete file of the asbestos dust question. Very truly your -[ 'y - ~ \ _` " Ex e c u t iv e Of f ic e s J o h n s -Manviijle C o r p o r a t i o n TW EN TY -TW O EA ST F O R T IE T H STR EF.T N E W Y O H K , N .Y . May 18, 1938. Mr. Sumner Simpson, President, Raybestos-Manhattan, Inc., Bridgeport, Connecticut. Dear Mr. Simpson: Thank you for yours of the 17th and for the attached copy of a letter from your Charleston doctor commenting upon Dr. Gardner's second progress report. It seems to me Dr. Lynch has made a very thoughtful analysis of Dr. Gardner's report. However, it all comes down to this: V<e cannot draw any con clusions upon the basis of the experiments to date other than that any conclusions would be premature and, in spite of Dr. Gardner's references to the apparent trend of the results thus far developed, it is quite evident he feels the same way. Very truly yours, VB:y ^an<f& Browriy General Attorney. / 'r'; V / / 2i> J brio Report,, Conn. May So, lyoB Dr. Leroy U. Gardner, Director The Saranac uaboratory for the Study of Tuberculosis 7 Church Street Saranac Lake, N. Y. My clear Dr. Gardneri CONiILaNTIAL Very glad to get your letter of May IS, in rei'erence to Dr. Lynch. I want to say I an pinning rny faith to you, and am quite positive it will not be very long belore you convince Dr. Lynch that your findings, whatever they nay be, are correct. I d o n 't thinx Dr. Lynch had any particular experience,other than general medical practice,with dust problems until he became connected with our North Charleston plant, and he seemed to be about the only one in that vicinity that was willing to learn something about our cast problems. While he has some positive ideas, 1 believe that he wi_i be subject to your proof, for I under stand. he has u great aoul of confidence in Dr. Lans.a and yourself. Very truly yours. B: G 7>? l. December IB, 1939. Dr. Leroy U. Gardner, The Saranac Laboratory, Saranac Lake, New Yonc. Dear Dr. Gardner: I have received yours of December 14 th and the very interesting 'Interim Report on Experimental Asbestosis" which was enclosed therewith. . As usual, I plan to distribute copies of your report to the various members of the group which has been sponsoring these experiments - ten in number. For this purpose I will require four (4) additional sets of the illustrations and I will appreciate your furnishing them at your earliest convenience. The matter of financial support for another year of experimentation will have to be considered by the group and for that reason I cannot, of course, give you any definite advice at this time. With very best regards, I am Sincerely yours, VB:y Cc Mr. Sumner Simpson, Raybestos-Manhattan Inc., Bridgeport,Conn. Vandiver Brown, General Attorney. $ ? /4$- E x e c u t iv e Of f ic e s J o h n s -Manville C o r p o r a t i o n TW ENTY TWO EAST FO H TIETH STH EET NEW YOHK, N. T. December 26, 1939. Mr. Sumner Simpson, President, Raybe stos-Manhattan,Inc., Bridgeport, Connecticut. Re: Asbestos Dust Experiments Dr. Leroy U. Gardner_____ Dear Mr. Simpson: Enclosed is a photostatic copy of an "Interim Report" submitted by Dr. Leroy U. Gardner in connection with the asbestos dust experiments he has been conducting during the past three years with the assistance of your company. You will note Dr. Gardners statement at the conclusion of the report that the experiments are not yet complete and that an additional sum of $5,000 will be required to finish them. Dr. Gardner, in. his letter transmitting the report, says "I sincerely trust that^ the companies who have sponsored this worx may feel dis posed to help us to finish it." May I have, as soon as possible,an expression of your company's position as regards the continuance of these experiments and its willingness to share in the expense thereof for an additional year? ^ '' f Sincerely, VB: y M rridiver Brown, General Attorney. \ /O '7' .A-.U-  f o l IL, i ii*-UnS> Interim Report on Experimental A 3bestosi3 at the Saranac Laboratory The original purpose of these experiments was to reproduce in animals an advanced stage of asbestosis whose progress could be followed anatomically and in x-ray films. There were two major objectives - one, to establish a better correlation between the various shadows seen in x-rays and the pathological changes in the lungs, and the other to determine in how far associated infection was responsible for the severer manifestations of the disease. Upon the basis of previous experience with pure free silica, it was thought that the reaction to inhaled asbestos would develop most rapidly if the inhaled fibres were exceeding ly fine. Accordingly Canadian chrysotile was ground in a steel ball mill until practically all of the material was reduced to 2 microns or less in maximum diameter. This ground fibre was placed in a hopper and churned to liberate dust in the atmosphere of an 8x8x8 foot animal room. It has not been previously reported to the sponsors of the experiments and in fact the writer was until recently unaware that one volume of unground fibre was being added to every three volumes of the very fine asbestos to facilitate agitation of the material in the hopper. Thus there has been a limited amount of long fibre asbestos liberated in the atmosphere however the quantity is comparatively small as the paddle, moving freely in the hopper, does not fracture much of the coarse fibre. The average concentration of fine asbestos dust inside the animal cages ranged about the wall of this room has been 145 million particles per cubic foot of air. (It should be noted that this figure is 29 times that set by the U.S.Public Health Service as the maximal permissable concentration of asbestos dust in industry). Exposed to this concentration for 3 hours a day, 6 days a weekwere 80 guinea pigs, 8 rabbits, 20 white rats and 17 cat3 . beginning with the fifth month of the exposure, sample guinea pirs were sacrificed at intervals. The last group was killed on Sept. 25,1939, thirty months after starting the ex posure. As shown in figure 1, there is barely enough change in a thin microscopic section to be visible on magnifIcation of 2 or 3 diameters. Still higher magnifications (not reproduced here) reveal that the reaction is not.fibrous in character, but more cf the nature of a chronic inflammation. 4 1*17 o <i'f, /v/, - /a! Figures 2A and 3A show the less advanced changes after exposures of 12 and 20 months respectively. Figure 2B demonstrates for comparison the very much greater reaction obtained after a 12 months asbestos exposure in a previously reported experiment. In that instance the average atmospheric dust concentration was only about one-third that in the present experiment, but the fibre was longer in that case. This experience seemed to demonstrate that, contrary to the behavior of quartz, asbestos dust would not become more irritating as the size of the particles decreased. This conclusion could not be maintained, however, until it was proved that the particular lot of asbestos was capable of producing fibrosis in the lungs of guinea pigs. The only way to be certain of this point was to try another inhalation experiment as previous experience had shown that injection tests are not applicable to asbestos dust as they are with quartz. Accordingly, in the fall of 1938 another dust room was taken over for an experiment with unground asbestos of the same l o t .' After some experimentation a suitable dust, containing a high proportion ofihirly long fibres was secured by affixing both to the sides of the dU3t hopper and to the rotating paddles a series of steel wire brushes. The sheering action of the opposing sets of wires broke the asbestos into lengths that could be inhaled. Inside the cages the average atmospheric concentration of fibres that could be expected to be inhaled into the lungs was 37.5 million particles per cubic foot of air. On the same 8 hour daily schedule 100 guinea pigs, 20 white mice and 6 cats were exposed in this room. The guinea pig3 have been sacrificed at intervals, the last group being killed on November 3, 1939, one year after starting the exposures. As shown in figure 313 there is much more reaction to the long fibres than to the finely ground material from the sane lot, even though the concentration in the air was only about one-fourth as great. Higher magnifications show that the longer fibres are beginning to cause fibrosis rather than the chronic inflammation produced by the fine material To learn more than could be inferred from mere in spection of microscopic sections about the quantities of dust inhaled into the lungs, representative proportions have been subjected to chemical analysis. For the fine material these tests were not started until the lth ronth of exposure,when it came to be appreciated that the anticipated fibrosis was not developing. In the long fibre experiment they were made earlier but only a few of them will be reported here as they have no basis of comparison. In the following figures it will be noted ,,that in neither series is the weight of inhaled material 'sufficient to affect the per cent of ash very much. Magnesium silicate cannot, of course, be determined as such and the amount of available tissue in each lung precluded determination of both magnesium and silica. There fore only the latter was done. It is to be understood that in the table the Si02 values are merely an index of the relative amounts of asbestos present in the different lungs. The values shown by the figures for 1 month's exposure to long fibre as bestos- begin to approximate those for a normal guinea pig. It will be noted that 3 or in some cases 2 animals' lungs were analysed after each interval of exposure. The results for each is given to indicate the degree of individual variation. Table Long Fibre Asbestos Period -=? Exposed Dry Lung Tissue Ash % Ash % Si02 % Si02 1 mo* 4.35 0.04 1.10 4.33 0.09 2.11 4.37 0.04 0.93 8 m o . 4.72 0.10 2.21 4.92 0.09 1.90 4.34 0.07 1.58 12 mo. 4.87 0.25 5.20 fpt ... 15 mo. 5.02 5.16 0^20 0.31 4.09 5.99 20 mo 24 mo* 30 m o . Short Fibre Asbestos Dry Lung Tissue Agh /o Ash % Si02 % Si02 5.02 4.58 5 .16 5.00 4.76 4.95 5 .86 6 .34 5.42 5 .50 5.35 6 .55 0.51 0.46 0.54 O'. 49 0.43 0.53 0.85 0.90 0.78 0.78 0.96 1.27 10.25 10.08 10.54 9.96 9 .00 10.60 14.46 14.07 14.48 14.20 17.89 19.46 4< The above figures prove that with both long and short fibre dusts significant quantities are entering the lungs. The comparisons at the 12 montiainterval indicate that more short fibre enters the lung than long. This of course would be ex pected in view of the more ready penetration of the fine dust and the fact that its average concentration in the air wa3 four times as great. The proof now seems conclusive that grinding asbestos to this degree of fineness destroys its capacity to irritate the lungs. 1 . It has been shown that long fibre asbestos v/ill produce significant changes in guinea pigs lungs within a period of one year. 2. It has been shown that on grinding same of the same lot dT asbestos it is no longer capable of causing the same effect in 30 months . 3. It has been proved by chemical analysis that the failure to react is not due to failure of the fine material to penetrate into the lungs. 4. It has been shown that about one-fourth the atmospheric concentration of long asbestos fibres has much greater effect upon the lungs than a concentration 145 million per cubic foot of exceedingly fine particles.. This evidence strongly suggests that the irritation from asbestos is not chemical but mechanical in nature. Attempts to prove this hypothesis have taken various directions. It has been shown In a series of injection experiments that no fibrosis results when asbestos is injected into other organs of the body than the lungs. Chemically active quartz, however, causes fibrosis wherever it comes in contact with connective tissue cells. It has been shown that, in animals, asbestosis docs not progress after cessation of exposure. The reverse is true in the case of chemically active quartz. The smooth covering deposited upon the surface of an asbestos fibre that forms the asbestosis body after two months contact with the tissues would tend to minimize mechanical injury. It seemed probable that the lungs rat' er than the other organs should be mechanically injured by asbestos because the lungs move rapidly and constantly. To test this theory the lungs of four dogs were Injected with a heavy suspension of long fibre asbestos, by means of a tube in the wind pipe, material was care fully introduced in both lungs * Then one lung was collapsed by cauterizing the inside of its stem bronchus with silver nitrate so- that<% V no longer moved in respiration. Thus we had what was thought to be effective doses of asbestos in either lung but only one would move to produce the mechanical injury and resultant fibrosis. The animals survived their treatment with no apparent ill effect. A month ago two of the dogs were killed on the first anniversary of their injection. In each case one lung was well collapsed and there were asbestos fibres on each side. However, there was neither fibrosis nor asbestosis bodies in either lung of both animals. Apparently we were misled by a report in the literature that dogs were susceptible to the action of asbestos. The result was disappointing but the method of attack seems reasonable if it can be applied in guinea pigs. V/e are now trying to overcome the technical difficulties in volved in working with such a small animal. The matter of species susceptibility is a puzzling feature which need not be discussed here. Hone of the rats, rabbits or cats exposed to the short fibre asbestos have re acted. The S cats, now exposed to long fibre dust for 13 months, are being kept in the dust room until their exposure reaches two years before comparative x-ray and anatomic studies are begun. The guinea pig/ continues to be a reliable animal with which to experiment. While the experiments have demonstrated that it is not possible to accelerate the rate of reaction in the body, and the anticipated results have not been realized, it is felt that the effort has been extremely profitable. As pointed out in a previous report to the sponsors, they have shown the innocuousness of finely ground asbestos, which' is of real practical significance. They probably explain the lack of asbestos is in the mills at Thetford. They may help to define the hazard in other plants where very finely ground material rather than fibres constitute the major element in the dust. They serve as a guide to engineers who must control the hazard in plants,indicating that their efforts must be directed parti cularly toward the fibrous material in the air. In view of the probability of fulfilling the original purpose of these experiments, it is hoped that the sponsors may agree to renew their appropriation for another year. For the past 12 months the Laboratory has assumed the obligation of operating a second dust room for the asbedosis work. The ex pense is somewhat over ')5000. In addition it has carried on various collateral injection experiments, such as those upon the dogs and others not mentioned in this report. It h a 3 secured an appropriation for an inhalation experiment upon the tir effect of glass wool, which may prove a useful control to the mechanical theory of the action of asbestos. It is hoped that you may find these accomplishments sufficiently valuable to be willing to continue the work* Respectfully submitted, Leroy u. Gardner, I.I.D