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ejbjstrial irrc-rr^ r Ukco Fif th Aver.ua ' Pittsburgh 13, Pa. s PLAINTIFFS Li lEXHIBIT... REPORT OF prele Hilary lust iutzsttgatii FOR as: T*g<M I IX"Tw*1**--*^? JUUE, 1947 By W.C.L. Per.?on Head Eng: no 6 r Jur.o 16, 1?L7 Industrial Hygiene Foundation of America, Ir.c. 5y John F. McMahon Managing Director r 04 /. ! REPORT of PRELIMI^LAFY DUST SURVEY for ASEESTOS TEXTILE INSTITUTE June, 19-vY OBJECT OF INVESTIGATION Thio project vas a preliminary investigation of the ashestosi3 problen in textile plants of members of the Asbestos Textile Institute, with the immediate object of defining the specific nature and the magr.itude of the problen in all its phases. From such a definition, the char acter of a long-tern project could be outlined. An original objective of most immediate importance was to facilitate the exchange of information between nenbsr cenpanies cn successful methods of dust control and other wise to promote a general improvement in that field. SUMMARY 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 plants. Dr. C. Richard Vainer, Medical Director of Industrial Hygiene Foundation, participated in visits to three plants and in development of the medical concepts of this report. The problen is seen to be composed of three aspects which arc discuscod in three sections of the report and summarized herewith, as Ei:orZZRi::G, MEDICAL, and PHYSICAL TESTING. Preliminary Dust Survey for Asbestos Textile Institute June, 19 ^7 '. Engineering. -- Mechenical methods vere seer, in U3e in one or more plants which effected practical dust control in all operations, bringing dust concentrations devn to five million or lover with one or tvo exceptions. It is proposed to prepare formal detailed descriptions of these methods for gener al distribution to renters of Asbestos Textile Institute. Medical Surervisien of Workers. Only five plants heve had any medical x-ray surveys of employees. In the others, therefore, there is a serious lack of information as to the incidence of astestcsi3. The lack is more serious, in a sense, because in most of these plants no compensable cases of asbestosis have occurred to draw attention of top management to the problem. While the medical survey conducted by or.e 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 im portance fer the protection of both employee and employer, not to mention other 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 ag practical. Physical Testing (Dust Ccunt3, etc.) -- The "maximum permissible dustiness" for asbestos is commonly taken to be five million particles per cubic foot. IMo represents good attainment in the dust control program. It is em phasized, however, that dust elimination to this extent docs not positively in curs that no asbestosis will develop in some workers after a long working life (greater than 20-25 years). Scientific evidence is obscure on this point. It is recommended, therefore, that studios be initiated aimed to develop another 0046 Preliminary Pus b Survey for Asbestos Textile I: June, 1JU7 tute, yardstick, because it is suggested that vhen control bolcv five million i3 attained, present du3t count methods nay net properly Treasure the remixing hazard. A detailed sumary of reccnnendntions for a long-tern invest!33 tier* is given at the end of this report. 004627 Preliminary Dust Survey fcr Asbestos Textile Institute, June, 19-+7 I EN5I 1: I XxTi 'J ppzstut status cf lust cc::tt:ol Practically all plants visited have had one or more dust count nurveys rade cf their operations and these data were available for the present study. In addition, a few samples were taken by the investigator in --zz~ plants These records were studied and a range of concentrations Judged to bo nost representative selected for the summary given in Table I. Where relative ly extreme values appear it ic an indication of too few data to permit a closer estirate. Figures in the last column are selected to indicate the magnitude of readily attainable duet concentrations with dust control measures now in ccnn.cn use; or Judged to be nost typical of an operation where no special dust control measures are employed, e.g., ring spinning. Discussion of Concentrations The available dust count data for operations in the preparation 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 departments. The 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 mule spinners exposure indicate a wide variation in dustiness, ranging from two to eight million, but the volume of data arc not C 0 4 5 2 r; Prclizj-r.ur-j' LU3t Survey for Achesto 3 Textile Institute Jure, 19J.7. ew- 1<-3 p* cCpo4 EH 5 E 0 0 U- CO1 fc 3 Ed H2i i-3 c. CwcL>O<=Or4!. E- c0 0 fc-4 B ciHs2 b- 0 Mz 0pP< U3 g NwP0H3 tIOcodj Praans* ^O843 rH 6*a>0-1->3t>-.+c3HJ 0 +h> uOCl r~- 3 r0H O a CrOV1 20: 1 nN1O f~1 i -a* rXH"1N iH -5 r4- -31" CO vmO4 CN -a1 CM1 M 0cu 0IT cK1*1 1 CrNHO"1N CrNHO1"\ 1 Vw -7 O U* Ed Q O .< -'j . .( t cu1 1 00 1 -ra1- rO--1J O1J 1 COO1J 0rOH1J r0Ht OJ 0rH31 --Cl3rM1\" CM rCHM1 CM1 mrH1 I K** ~rHlit\ r--1 mN"4V CnO1 C<v OrHJ -a1- 1 jr-HI CM CnM1 eIT1N- OmJ 0rH \o 1 0IPl-. rrnHH1 HnI CrHM1 K\ rH1 rnH1 ^nH1 rnH1 1 tr* O1J 1 CM1 VCOM1 rCHMt 1 A tlT--1 \ CM 1 CeM1CM 1 1 JCM-1 c: <hp0rt u Pa, O pU. O'Tc*<H.?<s ccc cc cwc2H CnO. tCo r3H0 4*^ tcHf 4MaHG-H> P <>tCHol >'J *> WG fO rH 0 0CU -'nTcCtji to P 004520 Preliminary Dust Surrey for Asbestos Textile Institute, June, 19^7. 6. great enough to yield a good average. Concentrations for ring spinning vary from one to five million although there is no strong indication in tho avails.ole data of marked differences between this operation and rule spinning. There is a sinilar wide variation in data for twisting (two to eight million), but there is sera Justification in these data for the opinion widely 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 casco tho aampling procedure. If the large impinger is raintair.ed in cr.o location and there is a strand breakage in that immediate vicinity, the resulting whipping dust will be reflected in that single sample and would not, therefore, be representative cf the worker's exposure. Dustiness in weaving operations reflects the use of water for dust control in sore plants arid 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 oevera.1 plants. The data for spooling and winding operations are included for com pleteness, but reflect miscellaneous operations and conditions. The dust re ported is often due to the effect of other machinery in the same room. These considerations therefore affect tho reliability of these data, as in the case of operations in the preparation room. C-0 4 U~ J'v n Preliminary Dust Survey for Asbestos Tortile Institute, June, 19^7. EXIST!?."! r.'ST cc?:t?oi ??ACTICT3 The following discussion of duct control practices in the industry is rerely an outline. To be useful to those who are responsible for the engineering in each plant, they will need to be set forth in the fern of detailed specifications describing details of construction, specifications for sheet netal contractors, for purchase of fans of proper capacity and for design and operation of dust collectors. Preraration Highly variable practices prevail in different plants and the mis cellaneous character of operations vithin a single plant calces it impractical to fomilats cany general statements, Hovever, it ray bo said that such con trol as is realised results fren the use of r-edern equiprent that 13 veil en closed and which usually incorporates pneuratic conveyors vith coiling con densers. The large covenant of air involved in pneuratic transport serves che useful additional purpose of preventing the escape of dust free the prirary equipment. Discharge of stock fron ceiling condensers into bins, stock bc::es, or feed hoppers is a du3t usually not under control. Th3 blending operation is another source vhich is often not satisfactorily controlled. Vith the ex ception of these two common operations, nest of the dust control procedures re quired will be noro or less specific for each plant. Card? rt Ao has been noted, reduction of dustiness in carding to concentra tions of three nillion or less is easily attained by good enclosure cf the machine and carefully designed exhaust. Mcreov9i'f experience of several CO Prciir.ir.nry Dust Survey for Asbestos Tortile Institute, Jure, 12'*7. companies proves that it docs not interfere seriously' vith manufacturing operations nor vith quality of roving produced. Cur ir.vesti(rations indicate the superior adventures of having aid vails of the enclosure of voed to facilitate small clearance by rubbing cor. tact at the edge of the main cylinder, thuo avoiding excessive air inflitre, tion at that point. Wood covers have the .advantage of resistance to crushi vhich va3 evident in installations vith sheet r.etal covers. Connection of the enclosure to the exhaust system by means of era bero of ample dimensions, i.e., large cross-sectional area is of major im portance to avoid localized high air velocities close to the vebeing in the main cylinder. This detail va3 not alvays observed. In viev of similar degrees of success, judged by dust counts, be tween various installations, the boot criterion of superior design as to do tails of exhaust from the machine vas in the relative economy respecting volume 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 representative plants: ' Plant `f A BE G HA Air Exhausted Per Set 1500 cfn 22C0 cfn 38CO cfn 51*00 cfn 2000 cfn ! j \ \1 It is apparent from this investigation that 2000-2500 cfn per so of breaker and finisher cards is ample exhaust capacity if the system is properly designed. Preliminary Dust Survey for Asbestos Textiio Institute, June, 19^7 All five of the systems described in the table serve their purpose satisfactorily fren the vicvpoir.t of operation, tut it dees not mean that they vculd be equally satisfactory to others. Thus the plant vith high ex haust capacity (G) has a unique interplant tunnel connection, so that excess heat from another plant supplies replacement air without added cost, for heu or winter discomfort. Plant II controls dust by completely housing each pair of cards in spacious rocn, exhausted at a rate of 2CC0 cfm, Sidewalls are easily remov ed for repairs. Most plants vculd not prefer this arrangement. As far as the dust count data can show, the card room, of Plant 3 vith 2200 cfm is equal if not superior to that of Plant E vith 3SCO cfa, a recently installed system. The fundamental features of best card dust control systems observe are as follows: 1. Wood enclosure with hingeing arrangement. 2. Liberal clearance between worker rolls and curve of cover permitting air passage at lev 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 hood3. 7. Exhauot 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 apace between the ring doffers and the main cylinder Preliminary Dust Surrey for Asbestos Text.!io Imti Jure, 1?17 > Spinning One plant has installed ventilation for their ring spinning frenas which management believes has reduced dust in this operation. It consists in a series of exhaust openings under the from, near the floor, running the length of each frame. Tine did not pemit demonstrating to our own satisfaction whether a censurable improvement had teen effected or not. Thi3 should be done by a series of dust measurements with exhaust on and off. The volume of air exhaust is insufficient to effect a tru3 local ex haust action, and if it is effective it must, therefore, be an effect of simple dilution. Twisting Interest in control of dust fren 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. Here again the operators believ. a narked improvement has resulted. Dust count data is needed that will measure the degree of improvement. Winders f i. h ;* Cop winders have been exhausted in Plants A and B with reports of beneficial reduction in dustiness. We do not have quantitative data on this point. Tho exhaust arrangement for Foster winders was developed many years ago and is well known. The tendency to elimination of this machine makes the problem one of little practical interest new. In most plants, dust from other equipment, such as spinning and twisting which are commonly in the came roon, is of greater importance than that from winding operations. 0 nU t/ qJ wT Preliminary Dust Survey for Asbestos Textile Institute, June, 19*7 1 Weaving One plant haa a superior cethcd of suppressing duat in weaving 'ey vet cothcds and duat count recordo indicate a ccr.pletc suppression of dust. , i It involves a water spray head, counted above the warp at the rear of the hamos3 with a mechanical screw arrangecent for constant covenant of the spray head transversely to tho warp. They believe it to be core effective than the system ecmen in several plants wherein the warp is passed over vetted rolls. It is apparently not practical to recorxrend ICO per cent wet weaving throughout tho industry. Moreover, wo are satisfied that it is practical to control dust in this operation by local exhaust, where dry weaving is consider ed ir.porativefor special properties of the cloth. One of the best exhaust arrangocents includes an exhaust opening directly under the warp at the rear of tho harness frace with a slot exhaust opening carried by tho lay bear., tho latter connected to the stationary part of the exhaust systec, either by flexible hose arrangecent or by an all cetal swivel Joint. Duct Work The actual arrangecent of duct work and exhaust fan present no un usual problccs where good practice In sheet cetal fabrication is followed. Two points are of sufficient icpcrtar.ce to require eephasis. . Special care should be exercised in the fabrication to avoid sharp projections on the inside that create points of lodgecent for fibers. Secondly, it cust be designed to pro vide adequate transporting velocities. Velocities below 2000 fun, in the experience of the industry, coy percit sottlccent of material and gradual clogging. Therefore, allowing a margin of anfety, the design should provide for velocities of 3C^0 fpn. 004533 Prclimir.ai-y Dust Survey for Asbestos Textile- Institute, June, 1>U7 The problem of distribution of planned air flews to the different branches of the system. ia of. importance in the desist of all dust oxhaust systems. The uso of dampers in branches to adjust air flews ia avoided ir. the tost systems. Their function in effecting balance between branches ia test attained in the original design. Design procedures to effect this ob jective are available but vill not be elaborated at this point. Pu3t Collectors Five plants in the survey employ the well-known burlap dust house for filtering air from various exhaust systems. The favored filtering area is determined on the basis of one 6quore foot for each air flew of 2 cfn. Most arrangements are such as to permit cleaning by whipping with a bamboo pole or a buggy vhip by men who remain cn the clean air side of the filter cloth. In cr.e system, the men are required to enter the dust side for clean ing purposes, and final cleaning is carried out once weekly with the use of a central station vacuum cleaner. Practices in different plants are variable as to frequency with which the burlap filter i3 freed of its dust lead by whipping. While these dust collectors work well, we are not prepared to recom mend them to the exclusion of aom9 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 pressire. If the pressure drop estimate in the filter is incorrect, the system will not operate properly. If the basic resistance of the filter, i.c,, that immediate ly after shaking tho cloth, is subject to a constant increase over a period CO Preliminary Dust Survey for Asbestos Textile Institute, June, l$bT i of weeks, the 073ten operation, vlll suffer. Apparently', Gone of the older commercial flat bag type of collectors did exhibit that difficulty. Modifi cations in the design of such units have, however, been incorporated in rare recent r.odels and those difficulties nay have been eliminated. Two plants employ commercial collectors of the flat bag or envelope type. Another plant uses a cloth tube corroercial collector and also one whose filtering element is of paper, which is replaced at intervals of several weeks A 3tudy of operating details of these commercial collectors is indicated in this study', including considerations of original cost and operating coat. Peciroulation / Several plants return air fron the dust collectors to the vor-mrocm t conserve heat in the cold weather. We are not prepared at this point either to condone or to condemn this practice except in cases where there is obvious ly leakage of dust through the filter and consequent recontamination of the air ir.3ido the plant. The practice is generally frowned upon where dusts that are hazardous to health are being handled. We believe there are certain circumstances where the practice night be permissible provided adequate safe guards are incorporated in operating procedures. The large volumes of air involved in dust control represent a tremendous problem as to heat loss and boiler capacity which cannot be passed over lightly. C 0 4 aO kaJ Preliminary Dust Survey for Asbestos Textile Institute, Juno, 19^7 H - MEDICAL PHESUIT MEDICAL FACILITIES AMD PPACTICES Every plant has ccmecticr.3 vith a local specie list in radio10,37 vho is c nplcyed for diagnostic work on an irregular basis. rijivo ovn r-ray machines used by the local specialist, tut only one has a weli estatlis hod schedule of periodic radical examinations. Half of the plants have no positive inform tier. as to the incidence of asbes;tosis among their workers. The situation is these respects is in- dicated in Table II. TABLE II. PRESENT PRACTICES AID FACILITIES AS TO MEDICAL X-RAY EXAMi..u--J-L'i vV*j`-LrL*.T-L^'-Tw*O0 "*'T * Plant A B C D E F Cr I J Recent X-ray^ Survey Made Yes No Yes Yce No No No Yes No Yes Periodic X-ray Examinations Mado No No No No No No No Yes No No Have Cvn X-ray Machine Yes No No No No No ' No Yes v 1 * ', No Yes Vi til in last few years, and results available to plant cr its physician Preliminary 3ust Survey for Asbestos Textile Institute June, 19^7 ESTH'ATZD I 0? asttstcsis The incidence of astestC3is among employees of those plants vhere employees vere examined in recent years, shevs a narked variation ns indicat ed by the following: Plant A ha3 recorded cases diagnosed as asbestesis to the extent of kXv-' about 20 per cent, and in the past nine years has compensated, on the average, two cases per annua. Total textile employment about ^00. Plant C on the basis of a recent systematic survey, estimates asbest03is incidence to be about three to four per cent. riant S has results from an incomplete survey in which four cases vere found among those volunteering for examination with a total textile em ployment of around 150. They have compensated one case in about 10 years. Three more are pending. Plant 5 with a textile employment of 3C0 finds five or six cases \! annually that the physician believes 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. Tie other plants have conducted no systematic x-ray aurvoys of their own and have no information as to incidence among their employees, irons of these has had caec3 requiring compensation. While we 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 C04S3 <r> Preliminary Eust Survey for Asbestos Textile Institute, Juno, 19^7 a serloua lack of information. prevails generally cn this aspect of the problem. The story in North Carolina io vorth special mention. This state instituted 10 years ago, a ayston of periodic nodical examinations Tor all vorkors in dusty industries end, hence, all usbcsto3 textilo workers have hocn x-rayed and clinically examined for a longer period, on a periodic baoi3, than any other asbestos textile plant in this group. If the state examination finds that workers should discontinue their employment because of rapidly developing aobeotosio they have tho authority to effect thia change. They also eee to it thse workers who should receive workman's compensation due to dis abling asbestosis are processed. So far as wo have been able to ascertain neither ovent has occurred to any employee of tho two North Carolina asbestos plants in thia group. These observations suggest that there cay well be a narked divergence in medical procedures, Interpretations, and attitudes respecting the diagnosis of ascestosis. There io a very urgent need for a concerted cooperative nodical effort to develop improved diagnostic procedures and uniformity of interpre tation. CO / - . : r< Preliminary Dust Surrey for Aobestes Textile Institute, June, 15^7 i. :dic ittdtcai sx.M-inrATic::s One of the r.03t important elements of a program of protecting health of workers in dusty occupations ie the periodic medical examination. The lack of scientific information recording all aspects of asbestosis is serious. This cannot he ever-emphasized. The obvioua procedure to help overcome this deficiency is to employ every tool new available that will threw more light on the facte. The importance of the periodic medical x-ray examination can per haps hoot ho emphasized by stating that dust count investigations cannot, in the present state of knowledge, give U3 assurance as to the extent of cur suc cess in eliminating the hazard. 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 dustiness studies end to mechanical developments in dust control equipment, will eventually indicate when the battle of aobeutosis con trol is being won. This aspect of the problem is elaborated in the following section. The inventory provided by such a medical program is Ju3t as important to intelligent action in this problem, 03. material inventories are to the propor conduct of business. Preliminary Dust Survey for Asbestos Textile Institute, June, 19V7 The question C3 to.whether a plant should purchase ita cvn x-ray equipment io an economic one involving consideration of cost of local outside nodical and x-ray facilities and of loss of employee tiro in travel, etc. Diagnostic Panel To further the objective of improvement and uniformity in diagr.osti procedures, a nodical section of the program is proposed in the form of a MEDICAL ASmSTCSIS FAIZL to be composed of outstanding medical men in thi3 field, end of the physician designated by each company as the one responsible for it3 medical and diagnostic work. The ccmpcsition, as to outsido medical personnel, of this panel vculd be determined by its objectives: the assembling of the best possible medical brains and the mutual education in diagnostic procedures that comes from exchanges of scientific experiences and information. The panel would meet, perhaps semi-annually, and consider the sig nificance of x-ray films and other clinical data brought to the group by each participating physician. Dr. C. Bichard Walmer'e services would be-available for the organization and other details. C045 O Preliminary fust Survey for Asbestos Tex June, 1947 X-*-w Wl wutC STATISTICAL STATE'S CT .MTTICM ~ICCT"3 There are tvo very important questions concerning the physiological nature of asbestos that have not yet been answered by any published investi gation : 1, What is the expectation of asbestosis in workers exposed nore than 15-20 years to lev concentrations of asbestos dust? Among the 500-cdd workers who composed the subjects in the U,S. Public Health Service study, there were abnormally few who had been exposed for nore than 15 years and practically none over 20 years. These facts seriously affected the conclu sions that could be drawn. 2. Is there a progression to advanced asbestosis after exposure ca an individual has been discontinued or has been reduced to very lev levels, due to action of dust deposits from earlier exposure? This question is of very groat importance to intelligent nodical supervision of workers in these plants. It is virtually certain that statistical investigations of existing records would throw valuable light on these questions. None of the plants visited during this inquiry have sufficiently' extensive and systematic records to provide satisfactory.answcis to these questions, but the medical department of Metropolitan Lifo Insurance Compary, under Dr. A. J. Lanza, have x-rays of a number of men obtained in the early 1930*3 vhich could provide the nucleus of some useful information, depending on hew nary of the original group are available for re-x-ray. 004543 Prclir.ir.-ry Du3t Surrey for Asbestos Textile Institute, June, 19^7 Hie most outstanding store of information is in the records cf the Division of Industrial Eygier.e of the North Carolina Department of E vho, in accordance with state lav have x-rayed workers in this, and otho dusty industries, clnc3t annually for the past 10 years. A study of the records would undoubtedly cast much light on the question of progression Through officials of the company members in North Carolina, we already h assurances of their full cooperation in any investigations, and although have not discussed the matter with then directly as to details, there is every reason to suppose that the desired informticn would be made avail to us for the purposes described. In addition, a general x-ray and medical survey of workers in or two plants with a long history of high order of dust control would be great value for this purpose. Co4S Pro 1'nt nary Bust Survey for asbestos Textile Institute June, 1947 HI - PHYSICAL Correlation between development of nsbestesis and sons pertinent measure of dustiness, e.g., dust ccunt3, can te developed by periodically ob serving and recording data on both a3poct3 -- periodic medical examinations of exposed workers together with the periodically measured dust exposure of each. However, to be useful for preventive purposes, theseprocedures have to te ertenied into the past wherever data i3 availab.e This was the proced ure employed in the studios of the U.S.Public Health Service in North Carolina plants (Public Health Bulletin No. 241, 1938). The main value of dust counts in asbestos plants is to obtain data on duct concentrations that can bo compared with that study, and thuo load to conclusions as to probability of development of asbestosis in the particular plant being studied. In that study, dustiness of different occupations was measured in the usual manner, and also the incidence of asbcst03is by medical and x-ray examinations of the men employed. A statistical comparison of the two 33ts of data led the investigators to the conclusion that new cases of asbestosis would probably not occur if dust control measures were undertaken to ensure that no dust exposures exceeded five million particles per cubic foot (measured in the same manner). CO 4 5 Preliminary Punt Survey for Asbestos Tortile Institute, June, 15^7 APPPATSAL C? '"I'JTTD TT5T -AZAPP Haring reached a degree cf dust control represented by the dust count Unit of.five million, it is then proper to ask: "What degree of assurance is afforded by existing knowledge that asbe3tosia vill not, in fact, develop in the future if dustiness is kept b9lcv that level?" If there are factors, at present unknown, that vill indicate a need for still better dust control,vhat vill that Unit be? The information available dees not permit complete assurance that five million Is thoroughly safe nor has information been developed permitting a better estimate of safe dustiness. It is nevertheless of the greatest importance either that such assurances be sought or a new yardstick of accomplishment be found for ac curately measuring any remaining hazard in the dust zone below five million for the elimination of future asbest03is depends upon the degree of control effected nov. Measurement of Dustiness One basis of uncertainty as to applying present conventional duct counting techniques to the measurement of asbestos du3t hazards below the five million level is summarized in the question -- are the fibers of asbestos the causative agent or the non-fibrous "cubical" particles that look like those of other industrial dusts? The non-fibrous particles in most textile operations comprise 80-95 per cent of the total dust seen in dust counting. While it is proven that aobestoo dust is the cause of asbestosis, 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 00434 5 fM Preliminary Dust Surrey for Asbestos Textile Institute, Juno, 19^7 employed conventional duot count techniques vhich, In effect, related incidence of asbestosis to the number of ncn-fibrcu3 particles of a size ranging free: cr.e to five or 10 microns. For illustration, suppose the causative duot element is something different, e.g., fibers that aro less than 50-60 microns long, and less than 1-2 microns in diameter. The conventional dust count method would ta satis factory only if there were a fairly constant ratio between the two types of dust; it would, in that case, provide on adequate, index. Preliminary Studios on dualities of Asbestos Eust With a view to eventual development of supplementary methods for measuring asbestos duot concentrations on a weight basis, we have conducted seme preliminary studies directed to tho colorimetric determination of toto.l silica in the minute 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-nlcrcsco-oic ^articles and fibers. Another aspect of the dust examination problem on which preliminary work has been done involved studies with the electron microscope. Ve posed the two following questions: 1. Ordinary dust particles, cue to three microns in diameter, com prise moot of the particles In the dust count. They look like ordinary in dustrial dust and we refer to them as "cubical" as distinguished from "fibrous' particles. The question is: are these particles in fact non-fibrous or are they bundles of fibers? Pre limine ry Dust Survey for Aa bos too Textile Institu June, 19^7* 2. Secondly -- since the limit of resolution cf the microscope lenses used in dust counting doss not pemit ceein.g particles very much smaller than cne micron, one may ask if there are cany fibers of groat length, but of such snail vidth that they are invisible? Samples of atmospheric dust vere obtained for examination by the electron microscope, by mounting the small specimen slide used vith this instrument, in the dust collecting zone of the electric precipitator. In order to eliminate very largo fibers, the air being sampled vao caused to pass first through a glass spiral coated vith adhesive on lt3 interior. This subjected the dust particles to centrifugal force and the largest ones vould be pre cipitated out, much as they might be in the nasal passages of man. Studies vith other industrial dusts employing this spiral indicate that very rarely do cubical particles larger than three to five microns suc ceed in passing through the several turns of the spiral. In samples obtainedvith this apparatus in a card room having a good dust control, ve obtained pictures, some of vhich are reproduced in the attached Figure. They demonstrate first, that the cubical particles seen by a lew pever light-nicroocope are in fact bundles of fiber resembling a lifesize handful of partially opened fibers. The picture further demonstrated that there are many fibers of con siderable length, some fuller' 50 microns, vho3e other dimension is only a fraction of a micron; the fiber i3 therefore invisible in the duat counting microscope. 004640 THIS CIRCLE 1 MICRON DIAMETER Preliminary Dust Survey fer Asbestos Textile Institute, June, 19^7 They also shoved sore fibers a few nicror.3 in length whose diameter is only 0.01-0.C2 microns, although the comonsat particleo are bundles of fibers about 0.1 micron in width. In addition to the light these oboervarion3 threw on the subnicroscope character of asbestos dust, they are cited to indicate the other qualities that night be pertinent to evaluation of dust exposure, to supplenent the duct count technique now in use. G04650 Prcllrir-.ry Su3t Survey for Asbestos Textile Institute Jure, 19^7 r~. iyEErsrr rusTrms or stcc:: In investigations' of the type 'being presei^ly considered, a primary aim must be to develop improvements in dust control vith the minimum of waste notion and expensive experinsntation on a plant scale. At the stage of development of the industry, causes of du3t are very often not ob-.*iouo. An examination of dust count records made available to us, combined vith the fev tests ve perfeme d ourselves, provide numerous instances of variation, the cause of vhich is not apparent. We undertook recently to measure the amount of dust in the roving of different manufacturers by suspending a measured quantity of roving in alccke1, then making a dust count in the same manner as vith air samples. The resulu would be expressed in millions of particles per yard of roving or per gram, 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. Ve do not have sufficient data on this effort on vhich to draw con clusions. There arc difficulties to be overcome, and the solution depends on more laboratory experimentation. Another test method vhich vould be of value is a standardized mech anical abuse of roving in a small vessel while sucking a stream of air vith resulting dust as in the sampling for ordinary dust counts. A test of this kind, in conjunction vith the dustiness index vould be of value in evaluating the oiling practice, or it might take the place entirely of the procedure, previously outlined. C04 6 Preliminary Dust Survey fcr Asbestos Textile Institute, June, lS^+7 OUTLET CF rTCCCEFDZD PF.CCTDVFES FOR ASHFST03IS nrrQyg x. st:geef?i:'3 A. Dissemination of Existing Infcmatic.n Provide factual information to Institute members vith least possible delay; prepare bulletins vith design sketches on some or all of the several subjects listed be lev, to be distributed singly as ready. Additional field observations required in many cases. 1. Carding dust control; for various calces of machines 2. Dust in rrcnarr.tion, miscellaneous operations 3. Wet weaving equipment 4. Exhaust for Err; weaving 5. Exhaust for winders, etc. 6. Design of duct work 7. Design of dust house B. Develorment of Nev Techniques for Dust Control In this category, the problems for vhich there are no present answers: liko twisting, spinning, appraisal of operation, efficiency and co3t of corrmrcial dust collectors, etc. C04S52 Preliminary Due L'urvey for Asbestos Textile Institute June, 1911-7 II. MEDICAL A, T:i"tituticn of Periodic Medical rx3.rtiro.tio:'~ This is urgently recommended to all companies. Medical advice as to organisation:: procedures vill "be given by the Foundation upon request. B. Orvonination of a Pin.-rostic Panel far Asbostogis Arranged by the Foundation'3 Medical Director and organized to meet in Pittsburgh 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 vith other nodical authorities to be determined. C ::istir.-n Medical Pccords Designed to find ar.svors to important questions concerning radical ar.d physical nature of aobestosic; especially concerned vith records of State of North Carolina, Metropolitan Life Insurance Company, etc. III. PHYSICAL TuSTSIS -- (Further Dust Studies) Studies cf physical and chemical characteristics of asbestos dU3t designed, in conjunction vith medical studies, to provide more significant information concerning the nature of the dust exposure; to develop supplementary techniques for measuring remaining astestesis hazard after reduction of dust to meet the present standard.; to insure that effective control of dust has been attained. This is a step by step program aimed at the elimination of asbestosis cnees from the plants of Asbestos Textile Institute members. 004S53