Document DvE8VkxwODaddZ1V2XBkmBVYM

Hemeon Study -- What the Companies Knew and Didn't Tell Exhibit No. T-106 Date: June 1947 Description: Report of Preliminary Dust Investigation for Asbestos Textile Institute by W.C.L. Hemeon, p. 3 "While the medical survey conducted by one plant recently shows only about three per cent of the employees with asbestosis, two other plants appear to have about 20 per cent of their employees affected. Medical supervision of workers in this industry is of utmost importance for the protection of both employee and employer, not to mention other considerations." Hemeon Study - What the Companies Knew and Didn't Tell Exhibit No. T-106 Date: June 1947 Description: Report of Preliminary Dust Investigation for Asbestos Textile Institute by W.C.L. Hemeon, p. 3 "Physical Testing (Dust Counts, etc.) - The "maximum permissible dustiness" for asbestos is commonly taken to be five million particles per cubic foot. This represents good attainment in the dust control program. It is emphasized, however, that dust elimination to this extent does not positively insure that no asbestosis will develop in some workers after a long working life (greater than 20-25 years)." [emphasis added] Hemeon Study - What the Companies Knew and Didn't Tell Exhibit No. T-106 Date: June 1947 Description: Report of Preliminary Dust Investigation for Asbestos Textile Institute by W.C.L. Hemeon, p. 22 "The information available does not permit complete assurance that five million is thoroughly safe nor has information been developed permitting a better estimate of safe dustiness." [emphasis added] Hemeon Study - What the Companies Knew and Didn't Tell Exhibit No. T-106 Date: June 1947 Description: Report of Preliminary Dust Investigation for Asbestos Textile Institute by W.C.L. Hemeon, p. 22 "It is nevertheless of the greatest importance either that such assurances be sought or a new yardstick of accomplishment be found for accurately measuring any remaining hazard in the dust zone below five million for the elimination of future asbestosis depends upon the degree of control effected now." [emphasis added] ETUJST DDCO Fifth .'1.ver.ua I PLAINTIFF'S * EXHIBIT . I f' REPORT CF ' PHZLEZZllEY FUST l.T.TSTICATIC:: FOR ITU IFSTITUTF 1SJ*7 3y W.C.I. Freor. Head Hr.grneer Juno 16, 1?L7 Industrial Hygiene Foundation. of Africa, "r.c. By John. F. McMahon Managing Director r* l ; / ! REPORT of preliminary dyst syryiy for ASEESTC'S TDCTILZ INSTITUTE June, 19-^7 OBJECT 0? I I! Y S T I r, A ? I 0 j This project was a preliminary investigation of the asbc-stcsis problem in textile plants of members of the Asbestos Textile Institute, with the immediate object cf defining the specific nature and the nagnitude of the problem in all its phases. From 3uch a definition, the char acter of a long-term project could be outlined. An original objective of moat immediate importance vas to facilitate the exchange cf information between member companies cn successful methods of dust control and other wise to promote a general improvement in that field. S U H MARY The fact3 upon which this report is based were obtained on visits during the pact three months, to all plants of Institute members (except one, who wished the visit postponed to a later date). Complete cooperation was extended at all plar.to. Dr. C. Richard Valmer, Medical Director of Industrial Hygiene Foundation, participated in visits to three plants nnd in development of the medical concepts of this report. The problem is seen to be composed of three aspects which are discussod in three sections of ths report and summarized herewith, os EHOrTHRIHG, MEDICAL, and PHYSICAL testing. c 0U -t C j'i IV3 Preliminary rust Survey for Asbcetos Textile Institute June, 19k7 Er..ctree ring. -- Mechanical methods vere seen in. use in cr.e or mere plants which effected practical dust control in all operations, bringing duct concentrations down to five million or lover vith cr.e or tve exceptions. It is proposed to prepare form! detailed descriptions of these methods for purer al distribution to members of Asbestos Textile Institute. Medical Supervision of Workerm. Only five plants h_ve had any lasdical x-rzy surveys of employees. In the others, therefore, there is a serious lack of inforraaticn as to the incidence of asbestcsi3. The lack is more serious, in a sense, because in nest of these plants r.o compensable cases of ashestosis have occurred to draw attention of top management to the problem While the nedical survey conducted by one plant recently shevs only about thro per cent of the employees vith asbestesis, tvo other plants appear to have abo 20 per cent cf their employees affected. Medical super-vision of vorkers in this Indus try is cf utmost im portance for the protection of both employee and employer, not to mention othc considerations. Therefore, it is strongly recommended that each plant insti tute a program of medical and x-ray examinations of all exposed workers as early as practical. Physical Testing (Dust Ccvr.t3, etc.) -- The "maximum permissible dustiness" for asbestos is commonly taken to be five million particles per cub foot, This represents good attainment in the dust control program. It is em phasized, hcvever, that dust elimination to this extent docs not positively in cure that r.o astestosis will develop in some workers after a long working life (greater than 20-25 years). Scientific evidence is obscure on this point. It i recommended, therefore, that studios be initiated aimed to develop another CO 4 -3 26 Preliminary June, 15`V7 Survey for Aerates Textile las yardstick, because it is suggested that vhsn control to lev five nil attained, present du3t count netheds nay net properly neasurs the rs hazard. . 13 --3 A details d surr.ary of rec is given at the er.d of this report. r.dations fo a long-to es 00462? Preliminary Dust Surrey for Asbestos Textile Institute, June, 19^7 I - s rc c i 1: z z 3 i :t g pt?T'CTT^'f >p* Practically all slant3 visited have had one cr acre dust ccur.t sur veys made cf their opera tiers ar.d these data were available fcr the present studs*. In addition, a fev samples vers taken, by the investigator in user plant. These records were studied ar.d a range of concentrations Judged to be cost representative selected for the summary given in Table I. Where relative ly extrero values appear it is or. indication of too fev data to perrit a closer estirnte. Figures in the last cclurr. are selected to indicate the ragnitude of readily attainable dust concentrations vith dust control measures new in corr.cn use; or Judged to be nest typical of an operation where no special dust control measures are employed, e.g., ring spinning. Discussion of Cor,centra tiers The available dust ccur.t data for operations in the preparaoi or. room are highly variable and reflect the poorer accuracy in sampling inherent in operations that are intermittent and miscellaneous in character. These figures are, therefore, considered much less reliable than these for other dcpartr_-er.cs. Eie figures for carding room, dustiness indicate.that with reasonably good enclosure and exhaust cf the machines, concentrations veil below three million are obtainable. Four cf the plants visited oxceed the five million limit materially. All the data for rule spinners exposure indicate a wide variation in dustiness, ranging from two to eight million, but the volume of data arc not CC452f Prcl izlr.-Tjj Dust Survey Jvtjs, 19-7. Asbestos Tex' .0 cee- < Mc--iil o CJ et*2 w &- $ a u^ -1 O o.js y- .C 30 U> o a o 2 r- 3 O *" l p 0. 'J (3 ! * vr i f-i WV Jf Ai pH >-j pH rr r- p* CO VO oi- E-- j* m "* CM t-t n O cu ai c CO CD pH 1 1r AA i A pH P 1 a| A _' --" / CJ 1 a> cm w 1 Ai CJ CM 1 CO Pi*- 1 o CO rH 1 rOH 1 CM CM CM riA CM lj Q o / 3 *;o5 S-J .( ^ -? z} CO i rH i CM CM' CM i pH i CM A i rH A 1t pf<\ rH CM a 1 pH t H"S -J- r- A i COr A AA -3* 1 i CM rH I A i CM A CJ 1 MO A opH A 1 t*i- rH i A pH A CM ii rH pH Ai A i A i A i pH rH rH pH A 11 CM 1 1 VO CM CM CM i rH I riCM CM I -*t CM c roH J <3 i*. C d P- P rH o Ti Ih d p. o cc W P pC cc c o. a c rH c cc to rp. to c p to c to C rH p* po* fff a C ph 3 *p ,i > <1 o^ oc a. pH * t* C/3 P= C-0462 0 Preliminary lust Curve- for Acbc Juno, 19*7. ^--V *----4- -^} great enough to yield a good average. Concentrations for ring spinning vary free: one to fire million although there is no strong indication, in the avails.ei; data of marked differences between this operation and rule spinning. There is a similar vide variation in data for twisting (two to eight nillicn), but there is sera Justification in these data for the opinion vidoly held that this is one of the dustier operations in the finishing end of the mill It is believed that occasional high values in both ring spinning and twisting reflect in sere cases the aarplir.g procedure. If the largo inningsr is maintair.ed in one location and there is a strand breakage in that irradiate vicinit* tho resulting whipping dust will be reflected in that single sarple cr.d would not; therefore, be representative of the worker's exposure. Lustiness in weaving operations reflects the use of water for dust control in sore plants and exhaust oysters in others. The lowest concentra tions of one to two million obtained in Plant A reflect highly efficient vet weaving methods there employed. Concentrations less than four to five million arc readily attainable by local exhaust methods as indicated by the results in ocveral olant3. The data for apoolir.3 and winding operations are included for com pleteness, but reflect miscellaneous operations and conditions. The duet re ported is often due to the effect of other machinery in the same room. These considerations therefore affect the reliability of these data, as in the caso of operations in the preparation room. 0043:0 Preliminary Duct Survey for Asbestos Jur.a, 19^7. :ile Institute / ExisTirs r.'sr ccmtpcl ipacttczs The following discussion cf dust control practices in the ir.du: is merely an outline. To he useful to those who are responsible for the engineering in each plant, they will need to hs set forth in the fern cf detailed specifications describing details of construction, 3pecii: for fihoet mstal contractors, for purchase of fans of proper ar.i design and operation of dust collectors. Preparation Highly variable practices prevail in different plants and the mis cellaneous character of operations vithin a single plant makes it impractical to formulate many general statements. Hovever, it cay ho said that such con trol as is realised results from the use of modem equipment that I3 veil en closed and which usually incorporates pneumatic conveycro vith ceiling con densers. The large movement of air involved in pneumatic transport serves the useful additional purpose of preventing the escape of dust from the primary equipment. Discharge of stock from ceiling condensers into bins, stock bc::es, or feed hoppers is a du3t usually not under control. Tho blending operation is another source which is often not satisfactorily controlled. Vith the ex ception of these two cormrxi operations, most of the dust control procedures re quired will be more or less specific for each plant. Cardin'? As has been noted, reduction of dustiness in carding to concentre tions of three million or lens is easily attained by good enclosure cf the machine and carefully designed exhaust. Moreover, experience of several 00 1 ' v 0 Preliminary Dust Survey for Asbestos Textile Institute, Juts, 13^7. companies proves that it dees not interfere seriously vith manufacturin' operations nor vith quality'of roving produced. Cur investigations indicate the superior advantages of having side walls of the enclosure of wood to facilitate snail clearance by rubbing con tact at the edge of the rain cylinder, thuo avoiding excessive air infiltra tion at that point. Wood covers have the advantage of resistance to crushing, vhich vc.o evident in installations vith sheet r.etal covers. . Connection of the enclosure to the exhaust system by mans of cham bers of ample dimensions, i.e., large croe3-sectional area is of major im portance to avoid localised high air velocities close to the vetoing in the rain cylinder. This detail vas not always observed. In viev of similar degrees of success, Judged by dust counts, be tween various installations, the best criterion of superior design as to de tails of exhaust from the rachinc was in the relative economy respecting velum of air exhausted per machine. Cur observations indicated rather ex treme variations as indicated in the following table of exhaust rates per carding set in five rerresentative plants: Plant Air Exhausted Per Set : A V. b s G H A > 15C0 cfm 22C0 cfn 3fiCO cfm 5UC0 cfm 2CC0 cfn It is apparent from this investigation that 2CCO-25CO cfm per set of breaker and finisher cards is ample exhaust capacity if the system is properly designed. 004S3u Preliminary Dust Surrey for Asbestos Tortile Institute, June, 1947 All five of the systems described in the table serve f'.fl 4 ,, s^4*y * * satisfactorily frem the viewpoint of operation, tut it dees not near. they would be equally satisfactory to others. ^^rirv^ Vi*'"' ^ ^ hau3t capacity (G) has a 'unique ir.terplar.t tunnel connection, so tha ,n x"-* -> heat fron another plant supplies replacement air without added cost. or winter discomfort. Plant II controls dust by completely housing each pair of cards in spacious room, exhausted at a rate of 2CC0 cfn. Sidewalls are easily ror.ov ed for repairs. Most plants would not prefer this arrangement. ,, As far as the dust count data can show, the card room, of Plant 3 vith 22C0 cfn is equal if not superior to that of Plant 2 with 3$C0 cfn, a recently installed sy3tcn. The fundamental features of best card dust control systems observ: are as follows: ' 1. Wood enclosure vith hinge ing arrangement. 2. Liberal clearance between worker rolls and curve of cover permitting air passage at lew velocity, 3. Large chamber connection on cover, to duct. 4. Duct branch not over 5", preferably 4". 5. No blast gate dampers in branch line. . 6. Exhaust influence over comb, either by extension of main cover or by separate hocd3. 7. Exhaust space under machine, not over 4" duct. 8. Enclosure and exhaust of food hopper, not over 4" duct. Two installations include an exhaust branch to prevent the escape dust originating in the qpace between the ring doffers and the main cylinder, -s W X.' Prgll.Tlr.arr - Jure, 15-7 Surrey for Asbestos Text'lc Ins Sol.---J.r-, Cr.g plant haa Installed ventilation for their ring a p innin.- frare a which management believes haa reduced dust in this operation. It consists in a aeries of exhaust openings under the frame, near the floor, running the length of each frame. Tire did nor permit demonstrating' to our cvr. satisfaction whether a measurable Improvement had been effected or not. 1hi3 should be done by a series of dust measurements with exhaust on and off. The vclumo of air exhaust is insufficient to effect a true local ex haust action, and if it is effective it must, therefore, be an effect of simple dilution. Twin tinInterest in control of dust from twisters is widespread in the in dustry and Plants A and B have installed an exhaust system like the one de scribed for the spinning frames in Plant A. Hero again the operators believe a marked improvement has resulted. Dust count data is needed that will measure the degree of improvement. Winders . IaJ*' Cop winders have been exhausted in Plants A and 3 with reports of beneficial reduction in dustiness. We do not have quantitative data on this point. The exhaust arrangement for Fester winders was developed man:' ycr.ro ago and io veil known. The tendency to elimination of this machine makes the problem one of little practical interest new. In moat plants, dust from other equipment, such as spinning a:.d twisting which arc commonly in the cams room, is of greater importance then, to that from winding onerstions. ' 004 Prcli-'xir.ary Dust Survey for Asbestos Textile Institute, Jura, 19^7 Weaving One plant haa a superior netted of suppressing dust ir. weaving by vet methods and duat count records indicate a complete superscalar, of duet. It ir.ro3.vcs a water spray head ncuntsd above the warp at the rear of tho 1 . hames3 with a mechanical screw arrangement for constant movement of `etc err head transversely to the varp. They believe it to to mere effective than ti system common in several plants wherein the varp is passed over vetted rolls It is apparently not practical to recommend ICO per cent vet roavi throughout tho industry. Moreover, vo are satisfied that it is practical to control dust in this operation ty local exhaust, where dry wearing is conoid ed ir.porotivefor special properties of the cloth. Or.e of the test exhauct armr.2omor.tB includes an exhaust opening directly' under the varp at the rear of tho harness frame with a slot exhaust opening carried by tho lay bear., th latter connected to the stationary part of tho exhaust system, either by flexible hose arrangement or by an all metal swivel joint. Duct Work Tho actual arrangement of duct work and exhaugt fan present no un usual problems where good practice In sheet metal fabrication is followed. T points are of sufficient importance to require emphasis.. Special care shoui be exercised in the fabrication to avoid, sharp projections on the inside tha create points of lodgement for fibers. Secondly, it must be designed to pro vide adequate transporting velocities. Velocities below 2000 fpm, in the experience of the industry, may permit settlement of material and gradual clogging. Therefore, allowing a margin of safety, Lhc design should provide for velocities of 3CC0 fan. 004S2U Preliminary Dust Survey for Asbestos lentil June, Ip1*! The problem of distribution of pi .2d c.ir flevs to the different branches of the system is of. importance in the design of all dus t o vW o u:j * systems. The U30 of dampers in brunches to adjust air flcvs is avoided ir. the test systems. Their function in effecting balance betvee.n b best attained in the original design. Design procedures to effe ct this obJective are available but vill not be elaborated at this point. lust Collectors Five plants in the survey employ the vcil-kr.cvn burlap dust house for filtering air fret: various exhaust eye teas. The favored filtering area is determined en the basis of one square foot for each air flcv of 2 cfn. Most arrangements are such as to permit cleaning by whipping vith a bamboo polo or a bug^- vhip by men vho remain cn the clean air oil of the filter cloth. In one system, the non are required to enter the dust side for clean ing purposes, and final cleaning is carried cut once weekly vith the use of a central station vacuum cleaner. Practices in different plants are variable as to frequency vith which the burlap filter is freed of its duct load by whipping While these dust collectors work veil, ve are not prepared to recom mend them to the exclusion of acme commercial types of filters having automatic shakers. Several engineering elements enter into the design of a dust collect or system, involving principally a proper estimate of pressure drop in all ele ments of tho system and especially that tlirough the filter proper (back pressure If the pressure drop eatirnte in the filter is incorrect, the oy0tem vill net operate properly. If the basic resistance of the filter, i.c., that irradiate - ly after shaking tho cloth, is subject to a constant increase over a period GO Preliminary Sust Survey for Asbestos Textile Institute, June, l$Vf of vcehs, tho system operation vill suffer. Apparently, cons of the oil ccTrrsrci.nl flat bag typ-o of collectors did exhibit that difficulty. Mod caticr.3 in. the design of such units have, however, been incorporated in : recent r.odels and these difficulties my have been eliminated. Two plants employ commercial collectors of the flat cag or eat. type. Another plant uses a cloth tube commercial collector and also cr.e vr.es e filtering element is of paper, vhich is replaced at intervals of several A study' of operating details of these ccomsrcial collectors is indicated in this study, including considerations of original cost and operating cost, Recirculation Several plants return air from the dust collectors to the voi'hrccm a conserve heat in the cold veather. We are not prepared at this point either to condone cr to condemn this practice except in caoes vhere there is obvious ly leakage of dU3t through the filter and consequent recontarn! nation of the air inside the plant. The practice is generally frowned upon vhere dusts that aro hazardous to health aro being handled. We believe there are certain, circumstances vhere the practice might be permissible provided adequate safe guards are incorporated in operating procedures. The large volumes cf air involved in dust control represent a tremendous problem ao to heat less uni toiler capacity vhich cannot be passed over lightly. 004537 Preliminary Tust Survey for Asbestos Textile Institute, Jure, 15^7 n - MEDT A ppL"cr*'p ~-V",rT;vd Every plant has connections vith a local sped?list in radio!337 vho is employed fer di23r.estic veri cn an irregular basi3, Three hare their own 2-ray ns.chir.ea used by the local specialist, tut only cne has a veilestablished schedule of periodic medical e.rsr.lnatioru?. Half of the plant3 have r.o positive infernatier, as to the incidence of asbestoois among their workers. The situation is these respects is in dicated in Table II. TABLE II. F-JZSE'rT Ty=L*Cl"vrCZl3 a:3 TACTIITTT3 AS TO JT3TCAL X-PAY EXAIIE .u< V/ltU', vS Plant A 3 C D E ** Cr - I J Recent X-ray1 Survey Made Y03 ' No Yes Yes No No No YcfT No Yes Periodic X--ray '.s Made No No . No No No No no Yes No No Have Cvn X-ray Machine Yea /-1 `. No c. No No ' No No ' No Yes ,)*?' No Yes H/ithin last few years, and results avt.ilr.blo to plant cr its physician Preliminary rust Survey for A3 be 3 tec Textile hz3ti.VJ.t0 Jure, 19^7 estt'attz} 0? asttstcsis The incidence of acbsstc3is among employees of those plants where employees vere examined in. recent years, shews a marked variation as indicat ed by the following : ' Plant A ha3 recorded cases diagnosed as asbestesis to the extent c ../* . about 0 per cent, ar.d in the past nine years leas compensated, on the average two cases per annum. Total textile employment about 4C0. Plant C on the basis of a recent systematic survey, estimates asbestesis incidence to be about three to four per cant. Plant D has results from an incomplete survey in which four oases vere found among those volunteering for examination with a total textile em ployment of around 150. They have compensated one case in about 10 year3. Three more are pending. Plant E with a textile employment of 3C0 finds five or six cases v-*N *annually that the pliysician believea show early changes duo to asbestos. Plant J has counted potential cases of asbestosis amounting in number to about 20 por cent, comparable with Plant A. The other plants have conducted no systematic x-ray aurvoys of their own and have no information as to incidence among their employees. "one of these has had cacc3 requiring compensation. While ve have no complete data on history of employment and labor turnover in the several plants, it is apparent that there is, at least super ficially, a marked inconsistency in this picture. Also, it is clear that 0043 3 Preliminary lust Survey for Asbestos Textile Institute, Juno, 19^7 a serious loci: of Information prevails gene roily cn this aspect of the probien. Tho story in North Carolina is vorth special rentier.. This state instituted 10 years ago, a systen cf periodic radical erarinatiens Tor all workers in dusty industries and, hence, all asbestos textilo workers have been x-rayed and clinically examined for a longer period, on a periodic b?.oi than any other asbestos textile plant in thio group. If the state exsninati finds that workers should discontinue their crpltyrant because of rapidly developing aobcotosio they have tho authority to effect this change. They al ese to it that workers who should receive vortesn'a ccrpcnsaticn due to dis abling asbestesio arc processed. So far as vo have been able to ascertain neither ovent has occurred to any e-rsplcyee cf tho two North Carolina asbsetr plants in this group. These observations suggest that there nay veil be a narked diverge in nodical procedures, interpretations, and attitudes respecting the diagr.es of asbestosis. There is a very 'urgent need for a concerted cooperative nodical effort to develop improved diagnostic procedures and university of interpre tation. Preliminary Dust Surrey for Asbestos Textile Institute, June, 19^7 i thpo?ta?:c:: c? pttictit ;idicai zx.\:cc:atii::s One of the r.03t important elements of a program cf protcoring health of workers in dusty occupatior.3 ic the periodic nodical examination. The lack of scientific information regarding all aspects of asbeutosis is serious. This cannot he ever-emphasized. The obvious procedure to help cverccno this deficiency is to enploy every tool new available that will threw more light or. the facte. The importance of the periodic radical x-ray examination can per haps best bo emphasized by stating that duet count investigations cannot, in the present state of knowledge, give U3 assurance as to the extent of cur suc cess in eliminating the hazard. Regular examinations serve to protect the worker by giving early in dication. of health impairment due to dust, and permit intelligent action to be taken to avoid further serious health deterioration. This is particularly true if the detection is early enough and there is no progression to late stage asbestosis. More important, for the long term, the accumulation of factual in formation regarding the health status of exposed workers, statistically inter preted in relation to duetir.sec studies end to mechanical developments in dust control equipment, will eventually indicate when the battle of aobestesis con trol is being von. This aspect of the problem is elaborated in the following section, . The inventory provided by such a medical program is Just e.s important to intelligent action in this problem, 03. material inventories are to the proper conduct of business, . GO 4641 Prelinir.ary -act Survc,7 for Asbestos Tcxtil June, 19^7 *1* 4-* * r*> / The question, os to vhother a plant should purchase its cvn r.equipnont io an econcnic one involving consideration of cost of local cnodical and x-ray facilities and of loss of enpicyce tine in travel, et: Diamcstic Far.el To further the objective of inprovensnt and unifemity in diagnostic procedures, a nodical section of the program is proposed in the fom of a ' J-EDICAL ASTZ370SIS PAIZL to be composed of outstanding nedical non in this field, and of the physician designated by each company as the cr.o respcnoible far it3 nedical and diagnostic vcrl:. The ccrpcsition, as to outside nodical personnel, of this panel vculd be dotomi.nod by it3 objectives: tho assentling of the best possible nodical brains and the mutual education in diagnostic procedures that cones fren exchanges of scientific experiences and infemotion. . The panel vould neet, perhaps send-annually, and consider the sig nificance of x-ray films and other clinical data brought to tho group by each participating physician. Dr. C. Hichard WaLzsr's services vould be available for the organization and other dotailo. C04342 Proliminar lust Survey for Asbestos JUT.C, i?47 u0*.7'r"kr"iTxOO'"p**T!'*:*\jT-i _J \rTmm\T'*u*-. T`-Lt vv.U.J3 There are two very Important questions concerning the phys -clcgicd nature of asbestos that have not yet teen answered hy any published investi gation: 1. What is the expectation cf agbestesis in workers exposed more than. 15-20 years to lev concentrations of asbestos dust? Among the 5"C-cdd workers vho composed the subjects in the U.S. Public Health Service study, there vers abnormally few vho had toon expeoed for mere than 15 years and practically none over 20 years, These facto seriously affected the conclu sions that could he drawn. 2. Is there a progression to advanced asbestosi3 after exposure e: an individual has been discontinued or has "been reduced to very low levels, due to action of dust deposits fren earlier exposure? This question is of very great importance to intelligent nodical supervision of workers in the so plants. It is virtually certain that statistical investigations of existing records would throw valuable light cn these questions. Hone of the plants visited during tills inquiry have sufficiently extensive and systematic records to provide satisfactory.answer to these questions, tut the medical department of Metropolitan Lifo Insurance Cnnpary, under Dr. A. J. Lanza, have x-rayo of a number of men obtained in the carl;' 1930*3 which could provide the nucleus of some useful information, depending on hcv many of the original group are available for re-x-ray. C0454G Preliminary Duat Survey for Asbestos Textile institute. Jure, 19-7 The moat outstanding store of inf errs. tier, is in the records the Division of Industrial Hygiene of the North Carolina Dope vho, in accordance with state lav have x-rayed workers in this, and other dusty industries, alnc3t annually for the cast 10 yesr3. A study of these records would undoubtedly cast such light on the question of progresslea. Through officials of the company members in North Carolina, ve already hav assurances of their full cooperation la any investigations, and although v have not discussed the natter with then directly as to details, there is every reason to suppose that the desired inforccaticn would ce .vale aval lab to us for the purposes described. In addition, a General x-ray and nodical survey of workers in or. or two plants with a long history of high order of dust control would be a great value for this purpose. 004 c.n Pro 1- ninery Bust Survey fcr its esc too Tor e Institute June, 15^7 HI - PH Y S I C A L olu.lT i.-.\-,v~. Lr .>.> Correlation bstveen development of nshestesis and seme pertinent measure of dustiness, e.g., dust counts, cc.n be developed by periodically shservir.g end. recording data on loth aspects -- periodic medical examinations of exposed vorkers together vith the periodically measured dust exposure cf each. Ecvever, to to useful for preventive purposes, theseprocedurcs have to be extesied into the past vhorever data i3 availab.c lhi3 vas the proced ure employed in the studies of the U.S.Public Health Service in North Carolina plants (Public Health Bulletin No. 2hl, 1939). The rain value of dust counts in asbestos plants is to obtain data on duct concentrations that can be censored vith that study, and thus lead to conclusions as to probability of developnor.t of asbestosis in the particular plant being studied. In that study, dustiness of different occupations vas measured in the usual nsnner, and also the incidence of asbcctosis by medical and x-ray examinations of the men employed. A statistical comparison of the tvo sets of data led the investigators to the conclusion that nev cases of asbestos!s vould probably not occur if dust control measures vere undertakento ensure that no dust expoourco exceeded five million particles per cubic foot (nsenured in the sane manner). 004 5s j Preliminary lust Sumey for Asbestos Jure, 15*^7 Having reached a degree cf dust control represented by the dust fact, develop in the future if dustiness is kept belev that level?" If there are factors, at present unknera, that vill indicate a need for still better dust control,vhat vill that licit he? The informtion available does not remit ccnolete assurance that five million is thoroughly safe nor has information teen developed- psmitti; a tetter estimate of safe dustiness. assurances he sought or a r.ev yardsticl: of accomplishment te found for ac curately measuring any rsminin the dust zone belcv five mi effected ncv. Measurement of Dustiness One basis of uncertainty as to applying present conventional d counting techniques to the measurement of aobsstos dust hazards belcv the five million level is sumarized in the question - - are the fibers cf ashes the causative agent or the nen-fibrous "cubical" particles that look like those of other industrial dusts? The noa-fibroua particles in nest textile operations comprise 60-95 per cent of the total dU3t seen in dust counting. While it is proven that asbestos dust is the cause of asbestos!s, there is no certain information as to vhat shape or size of dust is the causative factor. The correlation studies of the U.S.Public Health Service (O employed conventional duct count techniques which, in effect, related ir. of asbestosis to the number.of r.cn-fibrcu3 particles of a oize ranging f: bo five or 10 nicrons. For illustration, suppose the causative duct element is sene thin.-; different, e.g., fibers that aro leas than 50-60 nicrons long, and lass than 1-2 nicrons in diana tor. The conventional dust count nethed would be satis factory only if there were a fairly constant ratio between the tvo types of duct; it would, in that case, provide an adequate, index. Prsl'f~';-.orv Studies on Cuallties of Asbestos Eu3t With a view to eventual dcvelcpnent of supplementary netheds for measuring asbestos dust concentrations cn a weight basis, vo have conducted acne preliminary studies directed to the colorimetric detemination of total silica in the ninuto quantities of asbestos dust obtained in a typical atmos pheric sample. This requires development since it could provide a valuable tool for further investigation. Sub-rlcresconic ^articles and fibers. Another aspect of the dust examination problem on which preliminary work hag been don involved studies with the electron microscope. V'e posc-d the two following questions: ' 1. Ordinary dust particles, cue to three microns in diameter, corn- price r.cGt of the particles in the dust count. They look like ordinary in dustrial dust and vo refer to them as "cubical" as distinguished from "fibrous1 particles. The question is: arc these particles in fact nen-fibreus or are they bundles cf fibers? n '-i Preliminary lust Survey for Asbestos fCXtl-S -US" June, 191+7, 2. Secondly -- since the Unit of resolution of the nicrcscooe lense9 used in dust counting dcee not remit ceeir.g particles very much oral! than cr.e micron, one my ash if there are mny filers of great length, lut of such stall viith that they are invisible? Samples of atmospheric dust vere obtained for eriarJnation by the electron microscope, ly counting the small spec lean slide used vith this instrument, in the dust collecting zone of the electric precipitator. In erd to eliminate very large filers, the air leir.g oacpled v-ao caused to paoo firs through a glass spiral coated vith adhesive on ita interior. This subjected the dust particles to centrifugal force and the largest ones would le pre cipitated out, ruch as they eight be in the nasal passages of ran. Studies vith other industrial dust3 employing this spiral indicate that very rarely do cubical particles larger than three to five ricrcrs suc ceed in passing through the several turns of the spiral. ' In sacgjle3 obtainedvith this apparatus in a card rcon having a good dU3t control, vo obtained pictures, sore of which are reproduced in the attached Figure. They derenstrate first, that the cubical particles seen by a lew power light-nicroocope aro in fact bundles of fiber resenbling a life- size handful of partially opened fibers. . The picture further demonstrated that there are many fibers of con siderable length, com fully 50 microns, whose other dimension is only a fraction of a nicrcn; the fiber is therefore invisible in the dU3t counting nicrcocope. ' C0454u THIS CIRCLE 1 MICRON DIAMETER Preliminary lust Survey for Asbestos Textile Institute, June, 19V7 They Also shoved scre filers a few ri crons in length whose diameter is only 0.01-0.C2 ricrcr.s, although the cosoansat particlea are bundles cf filers about 0.1 ricrcr. in. width. In addition to the light these observer!0113 throw on the 3ub- nicroscope character of asbestos dust, they are cited to indicate the other qualities that night be pertinent to evaluation of dust exposure, to supple- nent the dust count technique now in use. 004S30 Preliminary lust Survey fer Asbestos Textile June, 19^7 Itute E^Eznrrr rusTms or st-ccic In investigations' of the type being presently considered, a primary air. cust be to develop irprcvensnts in dust control with the cinicuc of waste notion and expensive experimentation on. a plant scale. At the stage of developner.t of the industry, causes of dust are very often not obvious. An examination cf dust count records cade available to us, ccnbined with the few tests ve performed ourselves, provide numerous instances of variation, the cause of which is not apparent. We undertook recently to noasure the anount of dust in the roving of different sanufacturer3 by suspending a measured quantity of roving in aloo.be' , then caking a dust count in the sacs earner as with air samples. The resuic would bo expressed in nillicns of particles per yard of roving or per gran, etc and would be of great advantage in relating differences in dustiness to the causative factor. Such a measurement technique would be essential in apprais- I ing the actual value of oil. We do not have sufficient data on this effort on which to draw con clusions. There aro difficulties to be overcone, and the solution depends on core laboratory experimentation. Another test method vhich would be of value is a standardised mochanical abuse of roving in a snail vessel while sucking a stream of air with resulting dust as in the Gacpling for ordinary dust counts. A test of this Idnd, in conjunction with the dustiness index would be of value in evaluating the oiling practice, or it night taka tho place entirely of the procedure. _ previously outlined. GO 4A f* r Preliminary Dust Survey for Asbestos Textile Institute, June, 1$^7 CUTLER C5 r~CC::i2ZZD PrCCir.TES FOR ASEISTCSTSEri-oTZGATZCrS x. ET'Gr"?*:;: A. Disssrination of Existing Informticn Provide factual information to Institute Renters with least peso delay; prepare bulletins with design sketches on. scr.e or all ex several subjects listed belcv, to be distributed singly' as ready Additional field observations required in cany' cases. 1. Cardin? dust control: for various makes of machines 2. Dust in nrenamtion. miscellaneous operations 3. Wet weaving equipment 4. Exhaust fox' Drr weaving 5. Exhaust for winders, etc. 6. Design of duct work 7. Design of dust house B. Development of Dev Techniques for Dust Control In this category, the problem for which there are no present answers: like twisting, spinning, appraisal of operation, efficiency and cc3t of ccmsrcial dust collectors, etc. C046 Pro li:Jinnry Duct Purvey for Asbestos Text! June, 19!'T -0-3 tir.it:e 11. iimi This is urgently recommended to oil companies. Medical advice as to organisations. procedures vill "be given by the Foundation upon request. B. Crv.r.iettien of a Dtarrostic Panel far Aabostosis Arranged by the Foundation's Medical Director and organized to meet in Fittaburgh at suitable intervals for scientific reviev of diagnostic problems, reading of x-ray films, etc. Panel to consist of individual company physician or nodical consultants together with other nodical authorities to be determined. Designed to find answers to important questions concerning medical and physical nature of asbestesis; especially concerned with records of State of I.'orth Carolina, Metropolitan Life Insurnnee Company, etc. III. PHYSICAL TFSTTIC -- (Further Dust Studios) Studies cf physical and chemical characteristics of aGbestC9 du3t designed, in conjunction with medical studies, to provide more significant information concerning the nature of the dust exposure; to develop supplementary techniques for measuring remaining asheseesis hazard after reduction of dU3t to meet the present standard; to insure that effective control of dust has been attained. This ia a step by step program aimad at the elimination of asbestosis cases from the slants of Asbestos Textile Institute members. C- 0 4 6 5