Document Ev2aZX7N0NRepzw8oVbRnqgBL

^7 ft**. | HJXUSTEIAL JCfdEaB FOUIOATION OF AMERICA, 3UC, 4400 Fifth Avenue Pitt8burgh 13, ft.. REPORT OF FREL2J22TA3F EUST ET/ZSTIGA.TIOK FOR ASBESTOS TEXTILE IIISTITJTS JUTE, 1547 By W.C.L. Hereon Head Engineer f PLAINTIFF'S EXHIBIT MfctSeas*! June lO. 1947 ftduatrial Hygiene Foundation of Anerica, Inc. John F. McMahon * Managing Director 00899 A 77'^- REPORT of PRELIMINARY DUST SURVEY for ASEE5T0S TEXTILE INSTITUTE June, 19^7 O.B JE C T 0 ? m SSTI8A TIPS This project vas a preliminary investigation of the asbestosis problem in textile plants of nsmbers of the Asbe3toa Textile Institute, with the irmsdiate object of defining the specific nature and the magni tude of the problem. la all its phases. Fran such a definition, the char acter of a long-tern project could be outlined. An original objective of most 1mediate importance vaa to facilitate the exchange of information between comber companies on successful methods of dust control and other wise to promote a general improvement in that field. SUMMARY The facts upon which this report is based were obtained on visits during the past three months, to all plants of Institute cambers (except one, who wished the visit postponed to a later date). Complete cooperation was extended at all plants. Ur. 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 problem is seen to be composed of three aspocts which arc dlseussod in three sections of the report and summarized herewith, as ENGINEERING, MEDICAL, and PHYSICAL TESTING. 00899 Preliminary Dust Survey for Asbestos Textile Institute June, 1947 2. Engineering;. -- Mechanical methods vcre aeon in use in one or acre plants vhich effected practical dust control in all operations, bringing dust concentrations down to five million or lower with one or two exceptions. It is proposed to prepare formal detailed descriptions of these methods for gener al distribution to neuters of Asbestos .Textile Institute. Medical Su-csrvision of Workers. -- Only five plants have had any radical x-ray surveys of employees. In the others, therefore, there is a serious lack of information a3 to the incidence of asbestosis. The lack is nore serious, in a sense, because in most of these plants no compensable cases of asbestosis have occurred to drav attention of top management to the problem. While the medical survey conducted by one plant recently shews 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 inportance for 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 as practical. 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 em phasized, however, that dust elimination to this extent does not positively in sure that no asbestosis will develop in some workers after a long working life (greater than 20-25 years). Scientific evidcnco is obscure on tills point. It is rccoimacnded, therefore, that studies be initiated aimed to develop another 00900 Preliainary Dust Survey for Asbestos Textile Institute, Juno, 19^7 3, yardstick, because it is suggested that vhcn control bolcv five million is attained, present 'duat count methods may net properly measure the remaining hazard. A detailed summary of recommendations for a long-tern investigation ia given at the end of this report. 00301 Proliminaiy Duat Survoy for Aobcoteo Toztilo Institute, June, 19^7 4. I - SSClITESBIflO PRESENT STATUS OF DUST COKTEOL Practically all plants visited have had one or care dust count sur veys rade of their operations and theee data vere available for the present study. In addition, a fev samples vere taken by_the investigator in cost plants Thcae records vere stifled and a range of concentrations Judged to be noat representative selected for the oumary given in Table I. Vhere relative ly extreme values appear it is an indication of too fev data to permit a cioocr estimate. Figures in tho last column, are selected to indicate the magnitude of readily attainable dust concentrations vith dust control measures now in ccmnon use; or Judged to be most typical of an operation vhere no special dust control measures are employed, e.g., ring spinning. Discussion of Concentrations Us 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 those for other departments. The figures for carding room dustiness Indicate .that vith reasonably good enclosure and exhaust of the machines, concentrations veil below three million are obtainable. Four of tho plants visited oxceed the five million limit materially. All the data for mule spinners exposure indicate a vide variation in dustiness, ranging from two to eight million, but the volume of data arc not 00902. Preliminary Eust Survey for Aabcatoa Textile Institute, June, 1947. eoi fe Wf- & g0 fg,f ten- E a as 3 O3 0 aC><=3 g 0CJ Ob. e- Q {3 a H 0Ek WJS c COO 2 & cfCeJi 5 08 ?MQ *Sr6*aOP>004-(tn.J-aS> O0*~u0cl r30 O O1f 1 IrTf1S\ c~ KpH%l 7 t1- -pr3--1* 00 vKO1M O1s *1 OJ H 00* OP*-l t C(K-O14S CO *pH1> 1 i 1 ITS sV* C3 -7 1 OK1J* 1 ce 1 o1- trr1-\ O r1- oj OmtJ 1 C0O11 0HO1J OpOHtJ OJ b* CO O X rj 3S -*L* * Cr4O1 -O31*J OJ O-J* OIJ tHT1 \ 1 1 #>l rA tOr1s\ -Ot3-1Ji Kr1-\ UK**1SS c\or\ l -r3-1-t cu 1 Olf1J\ OtJ OJ (IT1-S Om0pH1J NO 1 <t*T1V- <rHT\ rHH 1 K1> 0H41 HIOl H(A1 HtT1V Htrtv 1 Om1J 1 O1J VOO1J HO1J -O3fJ Hi>00et4 & bpu. tcc 0TUC5l tco c2 tPo, pJ0S<a e5 ed w0. HS' tgo +0> *H >hpC4? J) * (4OO?-OPH4. CTv--CB4?* 5 00903 Prclininary Duot Survey for Asbestos Toxtile Institute, June, 1947. 6, grout enough to yiold a good average. Concentrations for ring spinning vary from ono to five Billion although there is no strong indication in tho available data of carted differences between this operation and mile spinning. There is a sinilar vide variation in data for twisting (two to eight aillicn), but there is sons Justification in these data for the opinion widely held that this is one of tho dustier operations in the finishing end of the nil! It is believed that occasional high values in both ring spinning and twisting reflect in soco casco the sanpling procedure. If the largo inpinger is m2re tained in ono location end there is a strand breakage in that imediatc vicinity the resulting whipping dust will bo reflected in that single carplo and would not, therefore, be representative cf the worker's exposure. Dustiness in weaving operations reflects the use of water for dust control in som plants and exhaust system in others. The lowest concentra tions of ono to two Billion obtained in Plant A reflect highly efficient vet weaving mthods there employed. Concentrations less than four to fivo Billion are readily attainable by local exhaust nethods as indicated by the results in several plants. 0 The data for spooling and winding operations are included for cas pictenesa, but reflect niscellaneous operations and conditions. The dust re ported is often due to tho effect of other mchinory in the sane roan. These considerations therefore affect the reliability of these data, as in the caso of operations in tho preparation roon. 00904 Preliminary Dust Survey for Asbestos Textile Institute, Juno, 19^7. 7 EXISTING PJST CONTROL FPACTTCES The following discussion of duct control practices in the industry is ecrely an outline. To to useful to those who are responsible for the engineering in each plant, they will need to be set forth* In the fora of detailed specifications describing details of construction, specifications for sheet metal contractors, for purchase of fans of proper capacity and for design and operation of dust collectors. Preparation Highly variable practices prevail in different plants and the mis cellaneous character of operations within a single plant makes it impractical to femulate cany general otatecents. However, it ray be said that such con trol as is realised results fron the use of nedem equipment that is well en closed and which usually incorporates pneumatic conveyors with ceiling condensers. 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 fron ceiling- condensers into bins, stock boxes, or feed hoppers is a dust usually not under control. The blending operation is another source which is often not satisfactorily controlled. With the ex ception of these two common operations, most of the dust Qontrol procedures re quired will be nor or less specific for each plant. Carding Aa has been noted, reduction of dustiness in carding to concentra tions of three million or less is easily attained by good enclosure of tho nachine and carefully designed exhaust. Moreover, experience of several 00905 Preliminary Duat Survey for Asbestos Toxtilo Institute, June, 19^7. 3, companies proves that it dees not interfere seriously vith manufacturing operations nor vith quality of roving produced. Our investigations indicate the superior advantages of having side- valla of the enclosure of vood to facilitate snail clearance by rubbing con tact at the edge of the rain cylinder, thus avoiding excessive air infiltra tion at that point. Vood covers have the advantage of resistance to crushing, vhich was evident in installations vith sheet.metal covers. Connection of the enclosure to the exhaust systen by mans of cham bers of ample dimensions, i.e., large cross-sectional area is of rajor im portance to avoid localized high air velocities close to the vebbing in the sain cylinder. This detail vas not always observed. In view of similar degrees of success. Judged by dust counts, be- . tween various installations, the bent criterion of superior design as to de- ' tails of exhaust from the machine vas in the relative econony respecting volume of air exhausted per machine. Our observations indicated rather cx- trece variations aa indicated in the following table of exhaust rates per carding sot in five representative plants: Plant ^ A `^0 ' . B CXt E G H y-"\ ` Air Exhausted 1500 cfa 2200 cfa 38OO cfa 5boo cfa 2000 cfa It is apparent from this investigation that 2000-2500 cfa per set of breaker and finioher cards is ample exhaust capacity if the systen is properly designed. 00905 Preliminary Dust Survey for Aobcatcs Textilo Institute, Juno, 19^7 o t All five of the systems described in the tablo serve thoir purpose satisfactorily from tho viovpoint of operation, but it does not mean that they vculd be equally satisfactory to others. Thus the plant vith high ex haust capacity (G) has a unique intsrplant tunnel connection, so that oxcess heat from another plant oupplics replacement air vithout added co3t, for heat, or vinter diaconfcrt. Plant H controls dust by completely housing each pair of cards in a spacious room, exhausted at a rate of 2GC0 cfn. Sidewalls are easily remov ed for repairs. Hc3t plants vould not prefer this arrangement, ^f As for as the dust count data can shov, the card room of Plant 3 vith 2200 cfn is eq^ial if not superior to that of Plant E vith 38CG cfn, a recently installed systen. Tho fundamental features of- best card dust control systems observed are as follows: 1. Wood enclosure vith hingeing arrangement. 2. Liberal clearance between vorker rolls and curve of cover permitting air passage at low velocity. 3* large chamber connection on cover, to duct. 4. Duct branch not over 5", preferably 4W, 5. No blast gate dampors in branch line. 6. Exhaust influence over comb, either by extension of main cover or by separate hoods. 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 of dust originating in tho space between tho ring doffers and tho main cylinder. 00907 Preliminary Dust Eui-rcy for Asbestos Textile Institute, June, 19^7 Spinning One plant has installed ventilation for their ring spinning fremss vhich management believes has reduced dust in this operation. It consists in ft series of exhaust openings under the frame, near tits floor, running tha length of each frass. Tire did not permit denonstrating to our own satisfaction whether ft measurable inprovezent had been effected cr not. Thin should be done by a series of dust measurements with exhaust on end off. The volure of air exhaust is insufficient to effect a. true local ex haust action, and if it is effective it rust, therefore, be on effect of simple dilution. Twisting Interest in control of dust fron twisters is widespread In the in dustry and Plants A and B have installed an exhaust system lilre tha one de scribed-for the spinning frames in Plant A. Here again the operators believe ft narked improvement has resulted. Dust count data is needed that will measure the degree of improvement. Winders ---------- j.. ... P Cop winders have beon exhausted in Plants A and B with reports of beneficial reduction in dustiness. We do not have quantitative data on this point. The exhaust arrangement for Foster winders was developed many years ago and is veil known. The tendency to elimination of this machine makes the problem one of little practical interest new. In most plants, dust from other equipment, ouch as opinning and twisting which are commonly in tho oaco room, is of greater importance than that from winding operations. 00908 / * '* I i Preliminary Dust Surrey for Aobeatbs Textile Institute, June, 19^7 11, Ucavtofl One plant baa a superior method of suppressing dust In weaving by vot methods and duct count records indicate a complete suppresoioa of dua t, I I v * w' It involves a water opray head notated above the varp at the rear of the- foS'* harness vitb a nechanical ocrev arrangement for constant eorerent of the spray head transversely to the varp. They believe it to be nore effective than the eyotca common in several plants vherein the varp is passed over vetted rolls. It is apparently not practical to recor=srd 100 per cent vet weaving throughout the industry. Moreover, vo are satisfied that it is practical to control dust in this operation by local exhaust, vhere dry weaving is consider cd imperativefor special properties of the cloth. .0ns of the best exhaust arrangements includes an exhaust opening directly under the varp at the rear of the harness franc vit.h a slot exhaust opening carried by the lay bean, the latter connected to the stationary part of the exhaust systen, either by flexible hose arrangement or by an all metal swivel Joint. Duct Work The actual arrangement of duct work and exhaust fan present no un usual problccs vhere good practice in sheet netal fabrication is followed. Two points are of sufficient importance to require cnphasia. . Special care should be exercised in the fabrication to avoid sharp projections on the inside that create points of lodgement for fibers. Secondly, it cast be designed to pro vide adequate transporting velocities. Velocities below 2000 fpn, in tho experience of the industry, nay permit settlement of material and gradual clogging. Therefore, allowing a margin of oafoty, the design should provide for velocitioa of 3C00 fpa. 00909 Preliminary Duot Surrey for Asbestos Tortile Institute, Juno, 19^7 12 The problem of distribution of planned air flows to tho different branches of the system is of importance in the design of all dust exhaust systems. Tho uoo of dampers in branches to adjust air flows is avoided in tho best system. Their function in effecting balance between branches is best attained in the original design. Design procedures to effect this ob jective are available but will not be elaborated at this point. Dust Collectors Five plants in the survey employ the vcll-kncvn burlap dust house for filtering air from various exhaust oysters. The favored filtering area is determined on tho basis of one square foot for each air flew of 2 cfm.. Host arrangements are ouch as to permit cleening by vhipping vith a bamboo pole or a buggy whip by men vho remain on the clean air side of the filter cloth. In one system, tho men are required to enter the dust side for clean ing purposes, and final cleening is carried out 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 dust load by vhipping. While these dust collectors work veil, ve are not prepared to recom mend them to the exclusion of some commercial types of filters having automatic shakers. Several engineering elements enter into the design of a dust collector system, involving principally a proper estimate of pressure drop in all ele ments of the syston and especially that through the filter proper (back preesurt If the pressure drop 00timate in the filter is incorrect, the system will not operate properly. If tho basic resistance of the filter, i.e., that immediately after shaking tho cloth, is cubjoct to a constant increase over a period 0 0910 Preliminary Dost Survey for Asbestos Textile Institute, Juno, 15^7 13 of veefcs, the systea operation vill suffer. Apparently, soce of the older commercial flat bag type of collectors did exhibit that difficulty. Modifi- . cations in the design of such units have, hovevsr, been incorporated in ncre recent rodels and thooe difficulties nay have been ellnine,ted. Two plants employ ccmsrcial collectors of tha flat bag or envelope type. Another plant uses a cloth tube commercial collector end also one whose filtering element is of paper, which is replaced at intervals of several weeks. A study of operating details of these cornsrcial collectors is indicated in this study, including considerations-of original coot and operating coat. Recirculation i Several plants return air fron the dust collectors to the workmen to ! i 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 ia obvious ly leakage of dust through the filter and consequent recontamination of the air inside the plant. The practice is generally frowned upon where duets that are hazardous to health are being handled. We believe there are certain circumstances where the practice night be permissible provided adequate safe- I guards are incorporated in operating procedures. The large volumes of air * I involved in dust control represent a tremendous problem, as to heat less and / boilor capacity which cannot be passed over lightly, / 00911 Prelisinaiy Dust Surrey for A3"beatos Textile Instivate, June, 1947 14, U - MEDICAL PHSSSNT 1-CTICAL FACILITIES AND PRACTICES Every plant has connections vith a local specialist in radiologr vho is enployed for diagnostic vorlc on an:irregular basis. Three have their own x-ray cachlnes used by the local specialist,* hut only one has a voil estahliohod echedule of periodic radical examinations. Half of the plants hare no positive Informtion as to the incidence of asbestosis anong their vorhero. The situation is these- respects is in dicated in TUlle H. TAPIS n, PRESENT PEACTICES AND FACILITIES AS TO MEDICAL X-RAY EXAMEiAHOKS HI VARIOUS PLANTS Plant A 3 C D E ? G H I J Recent X-ray^* Survey Made Yes No Yes Yes No No No Yes No Yoa Periodic X-ray Examinations Made No No , No No No No No Yes No No Have Own X-ray Kachin Yes t+ ( No. / '-'.xu: No No No No 'No Yes <) M No Yes Within last fcv years, and results available to plant or its physician 00912 Preiininary Eust Survey fer Asbestos Textile Institute June, 1947 15 eshkmsd hsheece or asbestoszs The Incidence of asbestosls among employees of those plants vhere employees vere examined In recent years, shove a marked variation as indicat ed by the following: . Plant A has recorded cases dlagnosod as asbeatoals to the extent of about 20 per cent, and In the past nine years ha3 compensated, on the average, two cases per annum. Total textile employment about hOO. Plant C on the basis of a recent systematic survey, estimates asbest03is incidence to bo about throe to four per cent* Plant E ha3 results free an incomplete survey in vhich fear cases verc found among those volunteering for examination vith a total textile em ployment of around 150, They have compensated one case in about 10 yoar3. Three more are pending. Plant 5 vith a textile employment of 300 finds five or sir cases annually that tho physician believes shew early changes due to ashentos. Plant J has counted potential cases of asbestosls amounting in number to about 20 cor cent, comparables vith Plant A. Tho other plants have conducted no systematic x-ray surveys of their cvn and have no information as to incidence among their enplcyees. Hone of thcoo has had caoc3 requiring compensation. Whilo vo have no complete data on history of employment and labor turnover in tho several plants, it is apparent that there is, et least ouperficiall7, a EarJcod inconsistency in thic picturo. Also, it is clear that 009j_3 Preliminary Dust Surrey for Asbestos Textile Institute, June, 19^7 16 a serious lack of information prevails generally ca this aspect of the problem. Tho story in North Carolina, is vorth special nsntlon. state instituted 10 yearn ago, a systen of periodic medical examinations for all vorhers In dusty industries and, hence, all asbestos textilo workers hare . been x-rayed clinically examined for a longer period, on a periodic basis, any other eabestoo textile plant in this group. If the state examination finds that workers should discontinue their employment because of rapidly developing asbestosio they hare tho authority to effect this change. Thaj also see to it that workers vho should recoire workman's compensation due to dis abling asbestosio are processed. So far as ve have been able to ascertain neither event has occurred to any employee of the two North Carolina asbestos plants in this group. These observations suggest that there nay veil be a narked divergence in medical procedures, interpretations, and attitudes respecting the diagnosis of aabestosis. Hiere is a very urgent need for a concerted cooperative nodical effort to develop improved diagnostic procedures and uniformity of interpre tation. .00914  Preliminary Eust Survey for Asbestos Textile Institute, Juno, 19 V? 17 IMPORTANCE OF PERIODIC MEDICAL EXAMINATIONS One of the nest important elements of a program, of protecting health of workers in dusty occupations is the periodic nodical examination. The lack of scientific inforcation regarding all aspects of aaheatosio is serious, TM cannot he over-emphasized. The obvious procedure to help overcome this deficiency is to employ every tool now available that will threw nore light on the facts. The irportancc of the periodic radical x-ray examination can per haps bc3t bo emphasized by stating that dust count investigations cannot, in tl;o present state of knowledge, give us assurance as to tho extent of our suc cess in eliminating the hazard. # Regular crani nations 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 end there is no progression to late stage asbestosis. More important, for the long tern, the accumulation of factual in formation regarding the health status of exposed workers, statistically inter preted in relation to dustiness studies and to mechanical developments in dust control equipment, will eventually indicate when the battle of asbestosis ccn- ' trol is being von. This aspect of the problen ia elaborated in the following section. The inventory providod by such a medical program is Just as important to intelligent action in this problen, as material inventories are to the proper conduct of buaincas. 009i5 ' Prclininary Dust Survey for Asbeatoa Textile Instituto, June, 19^7 Hie question as to vhother a plant should purchase its own x-ray equipment is an eccnenic one involving consideration of cost of local outside nodical and x-ray facilities and of loss of employee tiro in travel, otc. Dlamoatic Panel To further the objective of improvement and uniformity in diagnostic procedures, a cedical section of the program is proposed in the fom of a MEDICAL ASEESTCSIS IAIIEL to be composed of outstanding nodical nen in this field, and of the physician designated by each conpany as the one responsible for it3 nodical and diagnostic vorie. The conposition, as to outside nedical per3onnel, of this panel vould be dotemined by its objectives: the assembling of the best possible nedical brains and the mutual education in diagnostic procedures that cones frca exchanges of scientific experiences and infomation. The panel vould neet, perhaps acal-annually, and consider the sig nificance of x-ray files and other clinical data brought to the group by each participating physician. Dr. C. Richard Walnsr's services vould be available for the organizeticn and other details. 0091S Preliminary Dust Survey for Asbcstoa Textile Institute Juno, 19^7 19 STATISTICAL STUDIES OF MEDICAL EECORrS There are tvo very important questions concerning the physiological nature of asbestos that have not yet teen answered by any published investi gation: 1, . What is tho expectation of aobestosis in workers exposed core fogrt 15-20 years to lew concentrations of asbestos duat? Among the 500-old workers who composed the subjects in tho U.S. Public Eealth Service otudy, there ware 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 ov an individual has been discontinued or has been reduced to very lew levels, due to action of duet deposits fron earlier exposure? This question is of vexy great importance to intelligent radical supervision of workers in these plants. It is virtually certain that statistical investigations of existing records would throw valuable light an these questiono. Hone of the plants visited during this inquiry have sufficiently extensive and systematic records to provide satisfactory.answers to these questions, but the medical department of Metropolitan Lifo Insuranco Company, under Dr. A. J. Lanza, have x-rays of a number of men obtained, in the early 1930's which could provide the nucleus of some useful information, depending on how many of the original group are available for re-x-ray. 00917 Prolininary Dust Surrey for Asbestos TextHo Institute, Juno, 1947 20 The moat outstanding store of infomotian is in the records of the Division. of Industrial Hygiene of the North Carolina Department of Health vho, in accordance vith etato lav hare x-rayed vorbers in this, end other dusty industries, alnost annually for the past 10 years. A study of the30 records vould undoubtedly cast ruch light on tha question of progression. Through officials of the company renters in North Carolina, ve already have assurances of their full cooperation In any Investigations, and although vo he.vo not discussed the ratter vith then directly as to details, there is every reason to suppose that the desired information vould be rade available to us for the purposes described. In addition, a general x-ray and radical survey of verbsrs in cno or tvo plants vith a long history of .high order of dust control vould be of great value for this purpose. OOSig Preliminary Bust Survoj for Asbc3t03 Tortile Institute June, 1947 HI - PHYSICAL SI, SICNIITCANCS OF IUST COUNTS Corrolotion between development of asbestosis and sans pertinent measure of dustiness, e.g., iuflt counts, can be developed "by periodically observing and recording data on both aspects -- periodic radical examinations of exposed workers together vith the periodically measured dust exposure of each. Ecvcvcr, to be useful for preventive purposes, theoeprocedurea have to be czteoied into the past wherever data is availab.e This vas the proced ure employed in the atudies of the U.S.Public Health Service in North Carolina plants (Public Health Bulletin Ho. 2^1, 1938). The main value of dust counts in asbestos plants is to obtain data on duct concentrations that can be colored vith that study, and thus lead to conclusions as to probability of development of asbestosis in the particular plant being studied. In that study, dustiness of different occupations vas measured in the usual manner, and also the incidence of asbestosis by medical and x-ray examinations of the men employed* A statistical comparison of the two sets of data led the investigators to the conclusion that new. cases of asbestosis vould probably not occur if dust control measures vere undertaken to ensure that no dust exposures exceeded five million particles per cubic foot (measured in the sen0 manner). 00919 Preliidfiaiy Duat Surrey for Asbestos Textile Institute, June, 19^7 22 APPRMSAL OF EEKICEB 17JST HAZARD Hiving reached a degree of dust control represented by the duat count limit of fire Billion, it 1s then proper to ask: "What degree of assurance is afforded by existing knowledge that asbe3toaio will not, in fact, develop in the future if dustinea3 is kept below that level?" If there are factors, at present unknown, that will indicate a need for still better dust ccntrol,vhat will that limit be? The information available does not permit complete assurance that five million is thoroughly safe nor ha3 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 Billion for the elimination of future aabestosis depends upon the degree of control effected now. Measurement of Dustiness One basis of uncertainty as to applying present conventional duct "counting techniques to the measurement of asbestos dust hazards below the . five million level is summarized in the question -- are the fiber3 of asbestos the causative agent or the non-fibrous "cubical" particles that look like those of other industrial dusts? Ihc non-fibrous particles in most textile operations comprise 80-95 per cent of the total duat seen in dust counting. While it is proven that asbestos dust is the cause of asbes tosis, there is no certain information ao to what shape or size of dU3t is tho causative factor. Ihe correlation otudics of tho U.S.Public Health Service 00920 Preliminary Duot Surrey for Aobcetos TextHo Institute, June, 19^7 23. t-nployed conventional duat count techniques vhich, in effect, related incidence. * cf asbestosio to tho number of nen-fibrous particles of a size ranging from one to five or 10 microns. For illustration, suppose the causative dust element is something difforent, c.g., fibers that are less than 50-60 microns long, end less then 1-2 microns in dicaeter. The conventional duat count method vould he satis factory only if there vere a fairly constant ratio between the two types of dust; it vould, in- that case, provide on adequate, index. Preliminary Studies on Qualities of Asbestos East With a view to eventual development of supplementary methods for measuring aobestos dU3t concentrations on a veight basis, ve have conducted same preliminary studies directed to the colorimetric determination of total silica in the minute quantities of asbestos dust obtained in a typical atmos pheric cample. This requires development since it could provide a valuable tool for further investigation. Sub-ndcrcscoolc particles and fibers. Another aspect of the dust examination problem on vhich preliminary vork has been done involved studies vith the electron microscope. Ve posed tho two following questions: 1. Ordinary dust particles, ono to three microns in diameter, coapriae moat of the particles in the dust count. They look like ordinary in dustrial duat and ve refer to them as "cubical" as distinguished from "fibrous" particles. Ths question Is: ore these particles in fact nen-fibrous or are they bundles of fibora? 00321 Preliminary Dust Survey for Aoboatco Textile Institute,' Juno, 1947, 24 2. Secondly -- since the liait of resolution of the microscope lenses used in dust comting does not permit seeing particles very such scalier than one micron, one ray ask if there are cany fibers of great length, hut of such *^1 width that they are invisible? Samples of ataospheric dust were obtained for examination by the electron microscope, by mounting the stall specimen elide used with this instrument, in the dust collecting 20ns of the electric precipitator. In order to elininate very large fibers, the eir being oanpled was caused to pass first .through a glass spiral coated with adhesive on its interior. Thl3 subjected the dust particles to centrifugal force and the largest ones would be precipitated out, much as they night be in the nasal passages of can. Studies with other induetrial 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 obtainedwith this apparatus in. a card room having a good dust control, we obtained picturco, corns of which are reproduced in the attached Figure. They demonstrate first, that the cubical particles seen by a lew pever light-nicrescope are in fact bundles of fiber resenbling e. lifesize handful of partially opened fibers. The picture further demonstrated that there are cany fibers of con siderable length, some fully 50 microns, whose other dimension is only & fraction of a micron; the fiber is therefore invisible in the dust counting cicrcacopo. 00922 M TV h go to i 8 awt 3 0 3 u a a 8u o CO B H o B IX. 8H 8 d 00S29 Prolininary Dust Surrey for Aobeotos Textile Institute, Juno, 1^47 25 They also ohoved sons fibers a few dcrans in length vhose dieneter ie only 0.01-0.02 nicrons, although the connonoat particles are hurdles of fibers about 0.1 cicrcn in vidth. m$ In addition to the light these oboerrarion3 threw on the sub- nicroacope character of aciestos dust, they are cited to indicate the other qualities that night be pertinent to evaluation of duot exposure, to eupple- nent the duot count technique now in use. 00924 Preliminary Dust Survey for Asbestos Textilo Institute June, 19^7 86. 3BEEI5KT HJSIEBSS OF STOCK Ia investigations of the typo `being presently considered, & prinary ain cost `bo to develop improvements in dust control vith the minima of vasts cotion end expensive experimentation an a plant scale. At the stage of development of the industry, causes of dust are very often not obvious. An examination of dust count records made available to us, combined vith the fsv teats vo performed 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 alcohol, then making a dust count In th3 sane manner as vith air samples. The result vould be expressed in millions of particles per yard of roving or per sran, etc, and vould be of great advantage in relating differences in dustiness to the causative factor. Such a neecurement technique vould be essential in apprais ing the actual value of oil. Ve do not have sufficient data on this effort on vhich to draw con clusions. There aro difficulties to be overcome, and the solution'depends on more laboratory experimentation. Another test method vhich vould be of value is a standardized moch- anical abuse of roving in a small vessel vhile 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 valuo in evaluating tho oiling practice, or it might take the place entirely of the procedure previously outlined. 0092 Frolisinaxy Dust Survey for Asbestos Ibxtii Institute, June, 1947 oinmn: of kecch-sdb5d ppccziukss FOR ASB3STOSIS gflSS51GATIC!g x. mxnsssrBo A. Dlsnenination of Existing Inforratlcn Provide factual inforsatioa to Institutes renters with least possible delay; prepare bulletins vith design sketches on 3one or all of the several subjects listed bolev, to be distributed singly as ready. Additional field observations required in cany cases. 1. Carding dust control: for various rakes of rachines 2. Dust in oryparatlon, niscellaneous operations 3. Vet weaving equiprsnt k. Exhaust for Dry weaving 5. Exhaust for winders, etc. 6. Design cf duet work 7. Design of dust house B. Develorrent of ffev Techniques for Dust Control In this category, the problens for vhieh there are no present answers; like twisting, spinning, appraisal of operation, efficiency and cost of coraercial dust collectors, etc. 00926