Document oDXXvXRdk9GmKmdQ1krLM5rdR

REPORT ON EFFECTS OF ASBESTOS DUST ON THE LUNGS and DUST SUPPRESSION IN THE ASBESTOS INDUSTRY PART I. PAST II. Occurrence ot Pulraooaty FtbcosU cthc? Pulmonary Affections in Asbestos Workers Processes giving rise to dust and methods for its suppression ' "".BT * `.`w*. E. R. A. MEREWETHER, M.D. H.M. Hrtfcat Inspector of Fadenei ' AND C. W. PRICE .. --*-*-->!.*, ta*f*cV a SStei. <, .............1 ........ /{ *1 . 7A y}'/ I l1 LONDON; PRINTED AND PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE. To be posch&tcd directly Iron H,M. STATIONERY OFFICE at U* Mbing addresses Adastrel How. Ktngsway, London, W.C.a; is<s. Ceorge Street, Edinburgh; York Street. Manchester; J. St Andrew'* Crescent, Cardiff; T$, Donegal! Square West, Belfast;............ or through any Bookseller. .... 1930 Price fi, 3d. Net : 4* PLAINTIFFS EXHIBIT WV-04369 PLAINTIFFSS JE M WV-04369 CONTENTS. NOT to BE lent P**r X. 1, Tkthoopctmh .................................... 2, Eneen or I b mtsxt Dust tiro* tsx Ld*o 1Rs*%iature of Aabio .............. a. Sion j thc XfrverjcATrew .............. TU Population at risk ... SeWiie-o oi Worker* for Examinatisa Th Clinical Examination and Standards adopted.............. ...................... ~ Rtdao&tapbi* EiarojaavVoi* ol tbe Luags ... ................. . -- . Itooua or raa Zksbiry ... ...* .............. ............................................... Aabeitou*--'tb* l'uUaorjir7 Fibrosis of Asbestos Workers ... -- Ha Asbestos Bodies .............. ........................ ......................... II* (aeidesea of Pulmonary Fibrosis 1b Asbestos Workers;.............. Effects of Ag tad Z*Bgib of EeaployueBt .............................................. , Effect of Work 2a Different Proeeuea >4' ... ... ... ; SeUim Dustlaa ?t Task** Astoteo Process** ... ' ... ... ... Cooftatratioo of Dust and length of Exposure nstry to prodvw* Fibroei* Disablement produced fe/ tbe Asbostea Pibrcett ... ...................... ... Pfogfew and Duration of tie D1m*m ...' .................................... AuMtai&a of (be Asbestos Fibrosis with Pulmonary Tuberculosis > Sooxetry ' .............. .............. *:... * ... ... ft. Factom &nTBHjNi*o rs* Pmskkt Bscosxjno* or vs* Assures Fasacoit ... . Punxnvs hlassnau................................... ... ........... .......... ?. Ts* Ocmocx . _ .............. ,, . ... p.ac & e : .7 ft f Id 11 I? 13 is IS IS is i? 17 IT Ix 11 %i * RcFeecxczs. Pm II. I, JsrrtOfitrtTios ......................... ., / ... . Piuuts -.......................... . ~ TaoiilaUoo ... ... ....................................' ... Sepsraiioe oi Proettass ... ........................ - it 19 ... ... go a Dtscainro* or Paoosau axe ?kivg.vriVK ileuses ... * ** Tmitu .- .................. . (a) Yarn and Cloth......................... Opsaias Csidlog i>> I .... .,, ,... tm Sttvpjilcj ve*d Grinding Card Sid* Waste Treatment Spinning tad Doubling ' Wtrpjog, Winding . . Plaiting ted Priding ... Wearing .......... -- * Cloth '`Picking," Examining, Afaaaorlog - so ... so ... 'SO r>* ... St ... ga ... {< - St - s< ... J8 ... S4 .w .*5S"e ifc . mmmmmmmsasmBaB Xo#-Tcxrtus ............................................... Piberliing or Opening (b) &!flbo*rd, Piper, SbeeU end Tile* (e> I&awiUioa KaUtiaU e&d Article* ... C0|)O(iti0& ................... .. gotMlidetcd Sheet* ...* ... fiettioos tad Bleb* ......................... UeUreiM* .............. . . ... <<?) BrWe end Clukb Ullage .............. () Tacking a&d /oiotlng*.............. I/) AabaMoa-eoveted Eiectrle Conductor* * Electrode* C*bU eaA Wutaf .,...................... JWd-CoU Wrapping ... .... (p) Wiaeallaae&tta .......................... . Heslded Ooodi ..) L.. .cm ~ .............................................. A C[u*a Of Wcikj, M*cBsssr uia 6*6*8 0. Scuiust 2Ucove&mos ... ' Kora ok Kmw Vcmutioir ix Actos Woxkb < )i . ?4fit 20 20 SO S7 27 S7 2? 29 20 it 30 30 90 30 30 30 31 it < 1< ,* II4 ' Thts Report *was laid -before PaTHamtnt on The 24th March, T930, "but has not been published as a Command Paper. The Right Boo. 0, R. Clyj*e$. M.P., HU Majesty's Secretary of State * " for the Home Department. Home Office, ntk iSarcK 1930. 8iH, I submit herewith a Report by Dr. . R. A. Merewether and Mr- C. W. Price on their inquiries into the health conditions of the asbestos industry. Dr. Mereweiher'e investigations on the medical side are of great scieaCihc value. [They e&u&Ub the facta that the inhalation of asbestos dust over a period of lycars results in the development of a serious type of fibrosis of the lungs, that the development of tbs disease varies in diroot proportion to the length of the exposure lo dust, and that susceptibility to the disease is not affected either by age or sex. ...................... The remedy for these conditions is to be found, as in the case of sc many industrial diseases, in the suppression of dust. The second part of the Report indicates that this point has only recently been appreciated. In the non-textile section of the industry, no serious difficulties arise as regards the application of exhaust ventilation. For the textile section, it is evident that a good deal of experimental work will have to be carried out before completely successful ventilating appliances are evolved effectively to remove ail the dust. - I have the honour to be. Sir, Four obedient Servant, GERALD BELLHO.USE, B.M. Chief Inspector of Factories. Report on Effects of Asbestos Dust on the Lungs and - Dust Suppression in the Asbestos Industry. . PART i. TEE OCCURRENCE OF PULMONARY FIBROSIS :AND OTHER PULMONARY AFFECTIONS IN ASBESTOS WORKERS. , . .. 1.--INTRODUCTION, v..; l*i^* This Report is based upon the data obtained id an extensive investigation daring ihe years 1928 and 1929. The inquiry was initiated by the Factory Department of the Home Office following the discovery in February, 1928, of a case of non-tubcrcular fibrosis of the luegs in an asbestos worker, of sufficient severity to necessitate treatment in hospital (Seiler's Case1}. Prior to this, this Departmentbad knowledge of only two deaths of asbestos workers, about whom there was expert opinion that the inhalation of asbestos lust had at least contributed to, if not caused, tba fatal outcome. The first of these, now referred to as the "Montague Murray Case/1 occurred in 1900, but all that is known concerning it Is contained in the evidence given by Dr. Montague Murray In 1906, before the Departmental Committee os Compensation / for Industrial Diseases'. Is this case post mortem examination confirmed the 1 clinical diagnosis of extensive non-tubercular pulmonary fibrosis. The second (Cooke's Cas*') occurred in 1924. Here, although Cooke4 and Stuart McDonald1 were of the opinion that the lungs showed a progressive dust fibrosis together with a chrome tuberculous infection, the etiological relationship .between' the inhalation of asbestos dust and fibrosis of the lungs would have been strengthened by the absence of a tuberculous infection, *' ' ' An early survey of the industry in 1910*11 by the Department did not dis* close any evidence of the existence of a serious fesaRb hazard in the industry, but some experiments on animals conducted in 1912 by Professor J. M. Beattie of Sheffield university for the Department showed that the Inhalation of asbestos dust will cause a mild degree of fibrosis. When, therefore, investigation of Seiler's Case showed that other industrial and infective causes of fibrosis could be definitely excluded, the necessity of deciding whether the supervention of this disease in as asbestos worker was an exceptional occurrence, or evidence of a grave health risk io the industry, was apparent and the investigation referred to was undertaken, , ,j'> . ........................................... :... 2.--Epfects of Irritant Dost Upon the Lungs. ! . The most important local effects which may follow the inhalation of dust include pulmonary and bronchial catarrh, asthma, bronchitis, fibrosis of the lungs, and secondary changes, such as emphysema, local or diffitte. These changes in the lungs, which may be looked upon as a measure of the effort* of the living tissues to repel or incarcerate the irritant particles of dust, necessarily > cause interference with the general efficiency of the lungs. The impairment of functional capacity may be slight or severe, and temporary or permanent, de* peodiag.on the variety of dost, and on other factors, such as concentration of dust and length of exposure. " . . * Moreover, individuals whose longs have been affected as the result of the inhalation of some dusts, Ehow an increased susceptibility to the supervention ' of respiratory infections, such as tuberculosis or pneumonia. : Fibrosis of the lungs is recognised to be the most important lesion caused by -the inhalation of dust, and the nroneness of workers with a dust &hrm\i io be affected'with pulmonary tuberculosis has been shown to be the main 'cause of the increased mortality rate from the latter disease in certain dusty occupa* ' as. v: * ui; . M . ' . At 6 This triad--exposure to dust, fibrosis of the lungs, and high mortality rate from pulmonary tuberculosis--was found to be common to a number of large and important industries, and in all of them the dust incriminated was free crystalline silica (SiO,). These features were not observed, however, in other industries in which, while there was exposure to siliceous dust, the silica was found to exist in the combined form as a silicate and not in the free condition. ".Thus, shortly, free silica came to be regarded as the pre-eminent cause . of industrial fibrosis of the lungs and as a notable factor m the production 1 of the excess mortality rate from pulmonary tuberculosis in certain industries, I Whilst the pulmonary fibrosis produced by free silica (Silicosis) has been, and is being, minutely investigated, the potentialities, as fibrosis producers, of dust other than free silica have not been fully explored, although it appears certain that some other inorganic dusts can, and some cannot, produce fibrosis i under the conditions met with in industry. i. That a serious, even fatal, degree of fibrosis can be produced by some of these other dusts has not been generally appreciated, although Badhatn in a thoughtful paper* has drawn attention to this point, in reporting a -fatal case of pulmonary fibrosis caused by dust of an prthoclase basalt containing no frea silica. .*<: * *.1 The Native of Asbestos.--The fibrous minerals commercially known as asbestos fall into the latter group, the silica being combined with metallic bases, mainly magnesium or iron and, to a leas extent calcium, sodium or aluminium. Tho term is & collective name applied to a variety of silicate .minerals which differ from each other in chemusl composition and physical properties but resemble one another in their finely fibrous nature and flexibility. Their value depends on the facility with which they can be split up into long and flexible fibres for spinning and weaving, on their resistance to neat and acids, and on their insulating properties with respect to heat and electricity. Varieties of asbestos possess tacae characteristics in differing degree. * ""1 ' J,*s ' * Practically speaking, ail that goes under the name asbestos in commerce Is either fibrous serpentine, or a fibrous mineral of the hornblende group, of which the most important are crocidolite, amosite and tremolite. Serpentine asbestos or chxysotfie is essentially a hydrated silicate of magnesium, containing little iron and practically no calcium. The hornblende varieties contain less mag nesium and usually more calcium, aluminium and iron--crocldolite and amosite being mainly silicates of iron. .. .............' '"*`".."7 $.--^Scores `Of -rat ItmsTrexrnw. < i ******4 i i. Asbestos is very largely used In industry, being an important constituent of many different products. The diversity of industries concerned made it essential that some restriction of the field of Investigation should be decided The manufacturing processes affected fall more or less sharply into two groups (1) those in which there is exposure to pure asbestos or asbestos mixed with a very small percentage of cotton or other vegetable fibre, and (2) those in which there is exposure to a mixture of dusts, of which asbestos U but one. * The former group comprises, in the main, the textile branch of the industry, a branch manufacturing insulating materials from practically pure asbestos, and some preliminary processes in other branches. . f ". ,. " , The latter group includes a number of processes in which the proportion * of astestes in the dust evolved ranges from a negligible quantity upwards. Since it is. impossible' to evaluate the effect on the lungs o? mixed dusts, of which asbestos dust is'only one component, until the action of asbestos dost itself was determined, the examination of workers for the purpose of this enquiry was restricted to workers employed in processes included in grsap 41), in oiiar words, to workers as nearly as possible exposed to the influence of pure asbestos dust. Furthermore, the effects of previous exposure to other irritant duste, such as that of free silica, bad to be excluded. 7 The Population at Risk,---The gross number of workers who may be exposed to the inhalation of asbestos dust to any extent is unknown, and, owing to the great variety of processes concerned, there are insuperable difficulties in ascertaining this 6gure. Nor, in fact, would enlightenment on this point be of any particular value. . ... -_ '* It is otherwise, however, with respect to the figure representing the number constantly exposed in the course .of their daily work to the influence of pure or almost pure asbestos dust. Some information on this point is very desirable to check the adequacy of the sample of workers examined, and to envisage the problem confronting the industry.. ,, ' White only a rough approximation is posribte, it is believed that about 2,200 is the present number of persons in this country exposed in their daily work to the inhalation of asbestos dust, either pure or admixed with a small Stson of cotton. It should not be overlooked that this figure does not a the considerable number of workers exposed to the influence of mixed dusts of which asbestos is but one, and commonly not more than 20 per cent, of the mixture. . . Of these 2,200, the sample examined cambered 963 {excluding *11 for reasons referred to later) or 16.5 per cent. . : ,. * Selection of Workers for Examination.--The selection of workers'for examination was not left entirely to chance, since it was early evident that the proportion of those employed 10 years and upwards in the industry was very small; therefore, in each factory those longest employed were preferred, since the importance of including a sufficient sample of this group is evident. Regard wa also paid to the other end of the scats so as to obtain information as to the length of exposure to dust necessary before effects are manifested, and also to the particular process on which the worker was engaged. .. u'-~u.y,v By 'balancing the component groups'of the sample in this way as the enquiry proceeded, it was felt that the maximum information would be obtained in the shortest time. .' / . It follows, therefore, that in respect of length of exposure to asbestos' dust, the component groups of the sample do sot bear the same relationship to each other as the corresponding groups of the Industry under review. The sub- joined Tables will make this clear. Table % shows the distribution according to length of employment (not necessarily in one factory) of 775 workers, the . toUlrmmbcr engaged on those processes fn several factories. ; Table 2 shows the sample of 363 workers distributed in the same way. ,1' * Tabes I. *- Tabi* 8 : *"*;**.... .>, T*r capbjtd. Kumber. ; fcrvenUs* 9tToUl Y*H eotplo7d. OH ............. 6-8 .............. 30-t .............. 18-W ... ... tCtp,io*tr ... .1.' 483 too M 84 . 1? ' *178 SI'S SS-3 * 3*1 8*8 ' ioo > 0-4 .............. 3-9 10-14 ... . ... . 13-19 ... ... J0*Bdo#r TcuU Nuober. 89 141 . 64 83 81 343 PfTCtattr* o!7oUl t U't .. `8 ns t.t 6*3 } ,x> '0 . ^0 ; > The enormous preponderance numerically of workers employed under five years is striking, as also is the very low percentage of workers employed 10 years or longer. *, .. Comparison of the two tables shows that the effect of the method of selec tion of workers for examination U that the number exasiobd is each successive fivt years employment group is a progressively greater proportion of the total miner which could have i>eea examined in each particular group. ,' r >** 1 With a soJiury exception all those examined were at work on the day ol examination. .. Thi Clinical Examination and Standards adopted.--The nature and purpose of the inquiry were explained to each worker whom it was proposed f**TM*138* individually, and hia qc her cooperation cbtai&ed. Each in. dividual'* previous industrial history, subsequent to leaving school, was noted m detail. This was essential in order to exclude, especially, the effect of pre vious work ia any of the numerous processes involving exposure to free silica dust, and, to a less extent, the effect of other dusts. Similarly, the in* dividual's medical history was scrutinised from childhood onwards, to determine the physical level on entry into the industry and any subsequent changes,. Particular attention was paid to accounts of pulmonary ailments, some of which, like asthma and bronchitis, are common enough amongst the general population, yet are also non-specific signs of irritation caused by the inhalation of dust, whilst others, like influenza and pneumonia, are occasionally followed by a degree of pulmonary fibrosis. War service, if any, was gone into, especially as to whether there was any history of the worker having been a gas casualty at any time. The family and persona! histor? is respect of pulmonary tuber culosis was enquired into, and tuso as to any dose association with known cases of this disease in friends r xtHUvts. In approaching the pertinent sokjeti of symptoms, groat care was taken to avoid leading questions, especially in eliciting information as to the existence of any undue shortness of breath. The actual'details of the physical examination do not call for comment, inasmuch as they followed the usual lines of s detailed examination of the chest, with observations of the senera! health and of tbs condition of the unner air passages. *... ( n V*.'.owY-`- Sefexcnce must be made, however, to the standard of normality adopted is assessing the state of the lungs. The appraisement of any departure from the normal necessarily pre-suppoees the existence of each a standard.; Every clinician has attained, as the result of experience, bis own clear conception of the normal chest, but it is not often that be finds it necessary to define this statejn so many words, in fact it scorns scarcely possible to do ao. and this for several reasons; the heart and lungs function efficiently within wide limits of applied strain, and, although vestiges of past disease may be present and apparent on examination, they will he unimportant if they will sever tax the organism beyond these limits, are son-progressive and do not predispose to other disease. Age itself has recognisable effects, bat for this reason alone, the chest cannot be considered abnormal. ""* ' *'*'< There is obvious disparity between the standard of physical fitness required for an air pilot and that required for life io&urtaoe at ordinary rates; in* dividual* reaching either standard cao be classed as " normal," yet many attain ing the latter standard have never approached the former. Thus, within limits, various gradations of normality may be distinguished, and corresponding standards constituted without inaccuracy, the precise status of eov standard being determined by the purpose for which it is established. far the purpose of this enquiry the standard adopted has been that evinced in any large group oi persons living under similar environmental conditions, opart from work fn dusty occupations, as those of the group being considered. This is neither a high standard nor a very low standard, but the average stan dard of normality displayed amongst the industrial population of this country. ..... Radicgravkio Examination of Ike Lnrtfs.--la addition a carefal radiographic examination of the chest was made in many {133) cases, the necessity lor which in investigations into the effects of dust upon the lungs has been emphasised repeatedly by various authorities. It was sot, of course, feasible to obtain technically sufficient radiograms of all the workers examined, derived as they were from factories 'scattered over the country,- some In districts remote from a radiological centre, Tbc mode of* selection was dictated by the needs of the situation, with the object of elocidating material points germane to-the investigation, e.g., the elucidation of complicating affections, in measuring the V 9 extent and progress of the lesions and locating the point at which the earliest radiographic signs appear, and finally as a check upon the human factor presented by toe examiner himself, *. 4.--Rasui/rs or Tffi Inquiry, To anticipate, examination of toe data collected in this investigation leads to the conclusion that toe inhalation of asbestos dust over a period of years resultsjn the development of a ierious type of fibrosis of the lungs. ./ . ...r ^ Asbsstosis--tAe Pulmonary Fibrosis of Asbestos Workers.---It is helpful to visualise fibresis of the lungs as if occurs (a asbestos workers as the slow growth of fibrous tissue (scar tissue) between the air cells of the lung wherever the in haled dust comes to rest. While new fibrous tissue is being laid down like a spider's web, that deposited earlier gradually contracts, this fibrous tissue is not only useless as a substitute for the air cells, but with continued inhalation of the causative dust, by iU invasion of new1 territory and consolidation of that already occupied, It gradually, and literally, strangles the essential tissues of the hmgs.: Is common with other essential organs of toe body the lunge have'a largo reserve of tissue for use in emergencies and to permit of a diminution <sf functional capacity due to advancing age or disease. .For this reason, and. v. because fibrosis of toe lungs Is essentially a local disease, It is only when toe fibrosis progresses to the extent of obliterating this reserve, that undue short-, ness of breath on any extra effort draws the worker's attention to the fact that bis health Is not what it should be, The other symptoms of the disease such as cough are equally unassuming, end are readily ascribed to some common and trivial causa. *. y- , Tro this point the progress of the disease is more rapid, since it is now encroaching on the remaining sound tissue of the lungs, already only just suffi cient to maintain him in his ordinary daily activities. Ultimately, no acute respirator infection has precipitated a fatal termination, a stage is readied when the lungs can do little more than maintain life, and the shortness of breath becomes extreme. * *;* In its main clinical features, therefore, toe disease resembles silicosis,4 si might be expected. It differs from silicosis, however, in the mode of distri bution of the fibrous tissue in the lungs, in its more rapid development, in ito radiological features, and, there is some reason for believing, in a lessened' susceptibility to the supervention of pulmonary tuberculosis, toe liability to which disease is so definitely an added hazard in silicosis/ Ths 'itsbsrios Bodies.-*!n"tb lungs of those exposed to asbestos dust, angular particles derived from asbestos,' and spicules of asbestos", arc found on microscopical examination, and also numbers of peculiar bodies described S Cooke anu HitlT and Stuart McDonald*. They are yellowish brown in colour, elongated, bead-like form, often with Bulbous ends. Cooke* and Boodhouse Glqynr independently demonstrated a mineral core in these bodies, evidently derived from toe asbestos fibre. Stewart and Haddow* have also demonstrated their presence in the sputum of asbestos workers. These'Bodies have not been found to occur in any other human affection. * They have been found is the sputum within & comparatively abort time after exposure to asbestos dust, and in toe absence of clinical or radiological evidence of pulmonary fibrosis, their presence cannot be taken at present as indicating anything more than previous tnbalatiofl of asbestos dust. The Incident* of Pulmonary Fibrosis in Asbestos Workers,--The extent of the risk to health associated with exposure to asbestos dust under present indus trial conditions. &fy sow Be considered Is detail. Of toe 374 workers of both sexes examined, 105 were found to have a diffuse Sbrosw of the Vanes attributable to toe inhalation of dust.. Ten of these, and one other In which there were earlier signs of the same noadiliom hire hew excluded from further consideration, inasmuch that it was felt that previous work in other dusty occupations, such as quarrying, and coal mining,.may have Been toe prime or a contributory factor in too development of pulmonary lessons found. .. , . v *3* & 1U Thus, 05 of 3C3 worker*, or 20.2 per cent. showed * definite fibrosis due to asbestos dust. An additional 21 were found with precursive signs of this disease, but those are given no weight in the general conclusions, which are.derived solely irons examination of the 5 cases of definite fibrosis. Of. the 13S radiographed, 62 presented radiographical signs of a disuse fibiosis, and in a* further 25 there wore suggestive radiological changes not definitely dlfiuse fibrosis. Is 10 of the former group and 3 of the latter the change were possibly referable to prior work in other dusty occupations or to other cause, and they arc therefore excluded, leaving 52 cases of fibrosis and 22 with signs suggestive of early changes in the lungs due to asbestos,--sufficient radiological confirmation. ' .* What inferences should he drawn from these figures!--Certainly not that 26.2 per cent, os roughly l in 4 of thoseat present, exposed toasbestos dust in their daily work have fibrosis of the lungs. As mentioned previously the sample examined is loaded with a greater proportion of workers employed 5 years and over than obtains in these sections of the industry at the present time (Tables ] and 2 above), and as shown in Table 3 below the incidence of fibrosis increases with the length of employment. Therefore in order to obtain an approxima tion of the general incidence rate of fibrosis in these sections of the industry a correction, muat he applied pa tots amount. Applying the sate* shown in Table 3 to the figures in Table 1, it appears that the general incidence rate of fibrosis of the lungs amongst those employed in these sections of the industry is rather less than 1 in 6, or, excluding those employed under 5 years, rather less than l in 3. * * */ ^ Further corrections would have been necessary if the sample had included an undue proportion of workers from the more dusty processes, but this was found not to be the case. Also no correction is required on account of differing ape distribution since, as will be seen later, the incidence of fibrosis is unacted thereby. Sex has no elect, ''/ y,' y * *:*, 1'.,1 *, *' < - These general incidence rates are convenient merely as affording a rough indication of the inherent risk associated with exposure to asbestos dust at toe present rime. They have no permanent value cither as an index.of the general risk of fibrosis in the industry from year to year* or as a measure of tie risk in. any particular factory or group of employees. This must be so since not' only wifi the distribution of workers in the industry according to process and length of employment vary from year to year in accordance with trade develop ments, but the increasing application or methods for the suppression of dust will have a cumulative effect in reducing the fibrosis incidence rate in future - " Zfoots of Age and Length of Employme&f.--Table 3 shows the distribution of the workers examined according to length of employment, and Table 4 their distribution according to age, together with the incicience rates of fibrosis in each case. . *- ' * . Tabic'S,--fnt&nfie of Fibrosis relate to Length of Employment, . Employe-d. s-9............. 10-14*. SO led o**r.,, ToUJi .... . - V.Kuobir ExaBtaod. 49 HI a< a 8J * 343 '/ * * Cams of Fibre*** . Ayrag ag Sa juri, ; Number, * *4 Group Of Gro*a Iccric&eo psr <&K ] MOU of Fibreiia. j Of Aiwa of i Fibml*. * r/^4 a* * ' * se ' > ? . tl . as>i ; '. * we . ' .17 *' . a-e*9 ' S**9 * 1 ae*8 * j 3*4 <1*# * 4'4 . \ '3$*0 <0*4 '44-J * SS'? 96" f, ,,> ; -set ' 30'J * | * <l'* ........... .. .. , , - > . n Taele 4.--fnc-identt of F&rvsi& relative to Apt. ... .. Ags Groups Nuccber Eioaiatd, 4 Jt , * ... 30-as... , 40.45............. SOssd **.,. '1 ,sa - "ISO : roo 47 - . .89 14 C uer * of Fiijrejit, Amts* Uagtfe f MDploj'toeol U ?sr&. HubW. Group fneidoe* pr . eeai. Of Gr*wp Uu tiiu I Sibredt. . Of etiti of ,, fttrotx ' tt * 14 ao . 31 n 0*3 90*0 63*8 ST*3 64-3 " '* .**' 8*1 - 11*5 0*7 16'0 . 8*7 ia*s M*t 16*8 . it*3 1 : TUfc 363 36 , i * M*S T't " 13*6 These tables indicate the outstanding importance of length of employment / (and hence length of exposure to dust), and tne negligible effects of age, on the production of fibrosis. .4 - .*1' . Thus age groups 30/39 and 50/59 (Table 4) hare incidence rates'o! 30 per s. eefifc. and .37.9 gcr cent, respectiivveelyr,. not a wide difference, since .the _groups indede -workers in various processes exposed to different concentrations of dust. Moreover, tho average length of employment in these two groups, excluding the cases of fibrosis, Is almost identical, but considerably less than the average length for all the cases of fibrosis (13.S years). . ..Sii'Zs . It appears also from the same Table that no special susceptibility to the development of .fibrosis is shown by-young persons, unless it is considered that the figure of S.7 years, the average-length 0$ employment of the cases of fibrosis in age group 20/29, has been shortened by increased.susceptibility of ages under 20. . As, however, the average age of this group at eases 0? fibrosis is. So.? years; and also because the establishment of fibrosis does not necessitate immediate retirement, from work, this is largely discounted.. r * Column 4 of Table i also shows a general irregularity which,* in itself, points strongly to the negligible effects of age in the production of SbsoeU. - Turning to the effects of length of employment a very different picture is seen. Table 3 shows that after 5 years' exposure,* the incidence rate mounts rapidly, and after 10 years increases almost in geometrical progression. *r,?. . Effect of Work *a different Processes.--There are* insuperable difficulties in ascertaining trustworthy figures of the precise incidence of fibrosis .amongst workers in particular asbestos processes. This is tho result of the common ,ipracticB3`fai`thg industry of boosing many processes is one room, and of workers transferring from ose process to another. These two factors, the Influence of dust from neighbouring processes, and prior work in other asbestos processes, operate to obscure the effects due to, work in any one process. * ?* . i'r- . By distributing the workers, however, according to the process in which efich has bees longest employed and grouping similar processes together, it is possible lo draw certain broad conclusions as to the relative eSecfc of work in ffifierent processes, la this way groups were obtained as follows :--. * ** T(!) Crushing, opening, disintegrating and! mixing- `` ' .g Carding. v '*w<- ' ?* ^ Spinning, twisting, doubling, plaiting, etc. t ' ' .! - ' (4 Insulating mattress making, Weaving and associated processes. ., ... ->k-x j *"f0 Miscellaneous processes and remaining unclassified workers. Vurv /. .The outstanding point'brought out.in this way is the relatively very low Incidence rate of fibrosis io group 3 (termed " spinners " for oohvenrence) as compared with each of the ether groups. There is some indication also* that amongst apinner* ' the disease takes longer to develop. Study of the radio grams, also, reveals further indwatrous confitaatoW of this. Moreover esin&a- tioos-of the dust emteut of the air in the fltlghbdurbood of these processes and in that of ethers in the various groups show that the evolutionV dust ia rrouu 3 is also relatively ipw {Table fif.. 0* J} i }.^`.j-W 4 '-ft U !< u 12 la fact, the history, and the medical and radiological features of the cases of fibrosis, together with the results of comparison of the dust counts, &U con tribute is some degree to the view ibaV with comparatively low concentration of dust in the neighbourhood of & process, the resulting cases of fibrosis amongst the workers in that process arc longer in developing and remain longer .in a milder stage. It follows, therefore, that in such cases the rate of accumulation of dost in the lung has not greatly exceeded the rate of elualn&Uoa, and a further point of great practical' importance emerges, namely, that In order to preveni-the full development of the disease amongst asbestos workers within the space of an average working lifetime, it is necessary to reduce the concentra tion of dost in the air of the workrooms to a figure below that pertaining to spinning at the time over which these cases were exposed. Not only does group 3 show the lowest incidence of fibrosis, but it forms the largest individual group in these sections of the industry--about one third. Relative Dustiness of Variates Asbestos ?rwiwi.--'While some reference here to the varying amount of dust evolved by the different processes is necessary, the causation of these differences and methods of suppression of dust are dis cussed in Fart II of this Export. Different asbestos processes do cause the evolution of different amounts of dust into the air of the workrooms, and, under present conditions, the difference between the least dusty and the most dusty processes is very pronounced. *' In scjmejjroceases the production of asbestos dual is insignificant; is a second group dust u continuously evolved but in relatively low concentration, as in spinning; m a third group the evolution of dust is continuous and in high con centration, as in dry cloth weaving; and in a fourth group modi dust is dissi pated in bursts of short duration, as in emptying the fibre from settling chambers By hand into bags. * *1 ' . Some additional data were obtained by means of a limited number of determinations of the dust content o! the axr at the breathing level of opera tives engaged ia various processes, with the aid of the Oweas'Jei Apparatus. The figures is Table 5 which were calculated from some $0 determinations, give a rough idea of the general dustiness of the processes concerned, and also of the effect of localised exhaust veutilatwa and damping in reducing the concentration of 'dust in some of them. The counts fo other processes are expressed proportionately to the spinning, plaiting and braiding group, taken as cnitv. or otherwise handling asbestos fibre, with a comparative figure of 2.34, The heaviest.counts of all were found in this groop, in sack filling by hand is a -eitliog chamber. The comparative figure here was 6.84, bat the record was dense, with much-i&iraprBg "together of the dirst -partides, with the result that the total dust count arrived, at was undoubtedly too low................... Next in order is dry cloth weaving without the application of localised exhaast ventilation, with a figure of 1.93. This is undoubtedly a dusty process, and although local exhaust venUlatiou reduces the count, at the breathing level of the weaver, much dust still escapes Into the workroom. . Weaving doth wet, not merely damp, reduces the dust count to a remarkable degree. Column Taslz 5.--Relative Dustiness of various Processes and Effect* of Localised Exhaust Featilation and T)awp Methods in steppresshif Dust. Wearing, -- SSgfflA-g* Cloth. Baad. t>*7. local xb,o,t\ sbWU j 411ml 1 ***}1 "*< wuhMt local whasM attoft. With beat OlhOBOt fmtiU itt&a, Wat. D*v, Kith local h*t**e attML WU ro i (7> * <3> ( ffl f * <T> 1 . jbjJ7 I'M i'06 -Sh - -81 | -91 MattNM Uaki& Opceieg Iioteddtitt HSfeTo,-ji local ukiBit toatiU Drr, vitx iilteit MOtUaMea. oxhonU vtttil. aVwa. r esr, lifcma WJ <rBl4latiml m * eim --QS-- yss <65 >s< . roea*>***r..?naoUt leciintj iXi *ik3**4*B,kftbTMtteUWUUea roia< roatUatioa afU* saattrMa eaki^ar .Mb. 13 7 for band (i.e., narrow) weaving, wet, is not accurate since the figure has been raised by dust from a neighbouring dry cloth loom. ' Mattress making without any precautions, such as exhaust ventilation, or damping.floors, tables and cloth, follows next with a figure of 1.83 (See footnote Table 5). Application of exhaust ventilation, and damping'reduces the figure considerably, hut it say be that the figures in columns $ and 10 are loo low, since counts for some subsidiary processes, such as buttoning, sewing, and cutting out, are not available. Xt will be observed that carding, although essentially a very dusty process, produced a comparative figure of only 1.17. This h due in part u> partial enclosure of the working parts of the carding machine, but is mostly the result of the application of local exhaust ventilation. . Moreover, the figure does not take into account the extremely dusty Operation of stripping, ..'1 < . Relative to the comparative numbers for the other different processes, the figure of 1 for spinning, plaiting and braiding is probably rather too high, owing to contamination by dust from neighbouring and more dusty processes. Samples of asbestos vaay much in chemical constitution and physical pro- [jcrties, and of tho three mam varieties, chrysotile, erociddite, ana amosiie, the atur two, Is the opinion of experienced workers, usually give rise to more dust than chrysotile in' the textile manufacturing processes, No evidence was feu*<3 x> indicate that any one of the three varieties is more, or less, potent than the others in producing fibrosis, other factors, such as concentration of dust, being equal. X peculiarity of the asbestos fibre is that it first fragments, longi tudinally, and apparently this process can go on Indefinitely, since there is no ultimate fibre comparable to a vegetable fibre such as cotton. /; -;j; . , Concentration of Dust and Length of Exposure Weeessarv to Produce . fibrosis.--From the data so far examined it seems clear that'fibrosis of the! lungs is & definite occupational risk amongst asbestos workers aa a class./ : Furthermore,, it appears that the risk falls moat heavily co those longest emy . ployed and on those engaged in the more dusty processes. >i * Some further cousvditaUon of these two impdrtatt factors, length of em ployment and concentration of dust, is desirable. Obviously, to some extent, they are interdependent, dace, assuming that'a specific quantity of asbestos dust must be inhaled to produce & generalised fibrosis, the fibrosis will result' from exposure for a period of time varying with the concentration of duet in the. air breathed. ;v.., .> . ^ _ . . Simson" reports' the case of an asbestos mill worker in South Africa,' xppsed for 12 months to a very dusty atmosphere, .who died from a rapid 'tuberculoma; sections of (belongs showed, apart from the changes due to tuber culosis, a moderately marked fibrosis. Barton Wood and Page** report the me of an asbestos spinner, employed 15 months, who died from a generalised tuberculosis, 8 months after ceasing work. In this case a little fibrous tissue was generally to be seen surrounding the asbestos fibres found.in the lung tissue, but there was co gross fibrosis. It seems probable, therefore, although further research is very necessary, that not only is a certain minimal quantity of tl* dost required for the production of a generalised fibrosis, but that inhala tion of the dust in high concentration results in the production of a more marked degree of fibrosis in a shorter time, than when the concentration is low. 1 Investigation of this important matter--ooncentration of dust and length of exposure necessary to produce fibrosis--from tho clinical side is beset with dsificofcte, one of the most confusing being that the existence of i dlmcaRy recognisable diffuse fibrosis is quite compatible with continued work la the industry, and, therefore, the cases of fibrosis discovered in such an investigation as this are in various stages of the disease, with the result that the point at which they first became recognisable clinically cannot be ascertained. - . Respite this, some'confirmation,of the hypothesis that'the IjengtlTof ex posure to asbestos dust necessary to.produce fibrosis varies inversely jrffb.iL* concentration of the dust in the air, within certain low and high limits/ to&y w? obtained. ... .. ' `t.T *: T> . ,*r <" Nf.T. JC* Table 0 shows the average age and length of employment of the cas of fibrosis in the groups of processes previously dealt with (p. II). Table $. FfOCMS. Cui f Fibrosis-, * .* > Average Age, Aversge Leoglh t : Zasployoaat 1. Crushing, ejecting, dsaiaUgriltag, aixieg t, Csrdi&g ,, ... ... ... ... 3, Spiaajeg, (siettBg, doubling, pltits&f. it. 4, MsUrm cuki&g ...' .......................................... 5, Wenvtog &<1 outdated processes .............. . 4. U(*cc)U&ou* processes ud rt&Bmfag ub* classified worktrs,* ToUU................. *............................. 43*1 S9 SJ -0 38*1 <3*8 42*1 io>9 v13*8 ih i$* * iS? , 13*3 13-6 The much.longer average period of employment of the cases of fibrosis in group 3 as compared with the other groups will be noted.' Thera is also least exposure to dust in group 8. It seems, therefore, that in this group a longer period elajssed before the fibrosis developed, or that it progressed less japidly.' . ' * * This is the more apparent if the incidence rates of fibrosis amongst workers employed in the processes in group 3 are compared with the corresponding rates for workers emptied in the more dusty processes comprised in groups 1. 2, 4, 5, taken together. l*bese rates are set out in Table 7,. .. ..v^ertiVn Table 7.-- Comparison leUeeen the Incidence Rotes of Fibrosis amongst Workers employed in Group 3 (less dusty processes) and the Incidence Rates amonys? Workers employed jm Groups I, 2, </, 5, taken together,(more ... ^ dusty processes). v ' ' wvU. < ..... .................. ... j 04. tut txn&tUK u 1044. 1542. S3cad over.,'. 1 J 1|1 *d .4 A yI 8 e -j r f" & w9&S 1*1 t 2 u 9 & J f 1 1 jt J I I2 6 s f secS" 3 ' taow sd i ^ ji 1 i * 6 9 i* !-. . Group 3... ... 1 30 Group* l, 2, 4, 6 | 47 (lakes together), 1 Per wot. 0 -- 40 ter eat. t 8' 30 Per mbu 2 *T n 0 -- 82 31 33-7 48 H 4B*e 14 For coat. . 4 36*4 3 Per coat! 4 sa*7 fi 37*1 13 n 84-e Group tatSptnoifijj, twiitSog, douWtog, plaiting,eto. Group* I,8, i, $*Crtuhisf,oifc,cording,autiroM asking toe aad fwmn. ifit It will be seen that, after 5 years' employment, the rates are consistently much higher amongst those employed in the more dusty processes, and, whereas the rate is high from about 5 years onwards in the more dusty processes, it.is sot until about the ISth year of employment is reached in the less dusty processes that the rate for the latter bceomes*high, and approximates to that reached after about 5 years' employment in the more dusty processes. .. .. - .. . }] Exposure to different concentrations of dust, together with the effect of the recognition of the cases of fibrosis in different stages of the disease, also afford art explanation' of the widely differing lengths of employment of individual eases of fibrosis, which ranged from 5 years to over -30, While no definite case of fibrosis clearly due to asbestos dust was found amongst workers with less than 5 vears exposure, the possibility of such cases occurring with 15 exposure to high concentrations of dust cannot be ruled out. Three cases were found with 3,^} aud 4j years work in asbestos, respectively, but iu eaon there was previous exposure to other dusts (see p. 10), Support for this view is provided by (1) Professor Beattie's experiments previously mentioned, which demonstrated teat the lungs of guinea-pigs ex- Efor 43 and 67 hours to asbestos dual showed " definite cellular protlon, though not very extensive, and this is certainly a preliminary stage in ihff production of fibrosis " s (2) Simeon's case mentioned above, and his report in the same paper on the lungs of a guinea-pig exposed by ha?rogordato to asbestos dust for 100 hours during a period o! 56 days. On the death of the animal (from causes other than asbestosis) some 32 months later, sections of the lungs showed a slight generalised fibrosis. Is commenting on the amount of fibrosis found, he states that " a comparison between the human cases and the experimental animal showed that the fibrosis was more rapid and extensive in the human cases than in the experimental animal," and again 7 the amount of fibrosis in two of the human cases was quite rapid, and if due to the presence of asbestos dust, the initial rate of production was rapid when compared with present day con-infective silicosis on the Sand (3) data from this investi gation, in which 21 of the 863 workers showed signs suggestive of commencing fibrosis (p. 10). Of these 12 had been employed for less than 7 yeare,'and 6, for between 4 and 5 years.. '.\H*: vy-*i ' V . To sum up, therefore, it appears probable that concentration of dust'and length of exposure as factors in the production of fibrosis are interdependent within certain limits. While it seems necessary for the production of generalised fibrosis of the lungs that a definite minimal quantity of dust must &e Inhaled, the lower the concentration of dust in the air breathed, the longer the lapse of time before the fibrosis is fully developed and within a certain limit, the higher the concentration of dost, the sooner the fibrosis becomes fully developed ana the more intense the involvement of the lung tissue.- * > ** a. * \ <i }. 'Ji .<> *.r- .. vJ -.sir If this hypothesis *is correct,* and the evidence, points to ic, the practical inferences are of very great importance, since it follows that the application of measures resulting in the reduction of the concentration of dust in the sir in the neighbourhood of dusty asbestos processes will cause, firstly a great in crease In urn length of time before workers develop a disabling fibresU, and secondly, the almost total disappearance of the disease, as .the measures for the suppression of dust are perfected. . * .! : .*4 . ., Disablement 'produced by fiU A sbestos Fibrosis,--Eegardiag the' amount of disablement produced by the development of pulmonary fibrosis in asbestos workers,-^fm*-a'wermber-t*f-years ibis se surprisingly slight, area saare-so than is generally the case in silicosis. This is partly due to the character of the disease, end partly to the nature of the work, which n the majority of these processes does not involve much physical exertion. The affected person may, and often does, continue at work with occasional intermissions, Utterly, due to exacerbations of bronchitis, until the condition is advanced, although he suffer* increasing inconveniences from shortness of breath, on exertion. Some-, times a terminal brondho-pneumoma, or other acute infection, commences while still at work, and there is no kng period of invalidism. ' .d * There is no doubt but that fibrosis of the type produced by asbestos can of itself lead to complete disablement and to a fatal termination, and this in the absence of a supersdded tuberculous infection. ... / Particulars hate bees collegid up la the end of 3$23 of JO cases in which an advanced degree of the asbestos fibrosis without tuberculosis was the primary cause 61 death. * In 3, the cause of death was verified by pest mortem examination and in the 10th, repeated clinical, radiological and sputum ex aminations confirmed the diagnosis. In an 11th case, post mortem examination showed that a lobar pneumonia had supervened upon lungs already the seat of a moderate degree of the asbestos Shrosis. . With one exception, all these deaths occurred 'in the years 1927-23. . The length of exposure to asbestos dust in these cases varied between 9 and 24 years. ITU *' Al s* It is not suggested that these few fatalities, in which the cause of death has fawn verifeetf by strict enquiry, are any criterion of the true effect of the disease on the mortality rates of asbestos wovkars. Others ate Vawwa ta.bMt occurred in which the existence of the asbestos fibrosis has been determined in jilt, but no post mortem examination has been possible. ' Proaresi and Deration of iht Disease,---The rate of progress and duratieii oi the disease varies within wide limits. \Yijh continued exposure to high concentrations of dust, the fibrosis may be folly developed in from 7 to 8 years, and may cause death after about 19 years, exposure, exceptionally in a shorter period. On the other hand, with exposure to less concentrations of dust, tbp Edod of maturation of the fibrosis may be extended to lb, 20 or 25 years. ere are definite indications,.derived from the industrial.histories and ex amination of workers, that a diminution in the concentration of dust in the sir breathed, either by change of employment from a highly dusty process U> one $m dusty, or the effect ofmethods taken for the suppression of dust, results in a prolongation of this period of maturation of the fibrosis, except in the late stages of the disease. While this is so, the existence of a clinically re cognisable degree of the asbestos fibrosis in any individual is an additional .adverse facta: in the prospects of recovery from any acute infection, of te Jungs, such as. pneumonia or broncho-pneumonia. . .*: Association of the Asbestos Fibrosis vfth Pulmonary Tuberculosis.--& previously mentioned (p. G), silicosis,* the fibrosis of the lungs due to the inhalation of free silica duct, has an unhappy association with pulmonary tuberculosis, in that there is a much increased Debility to the supervention of the latter disease amongst silicotics. It is of importance, therefore, both from {he point of view of the individual worker, and in its bearing upon the scope o! the preventive measure required, to enquire whether there is a similar liability attached to the asbestos fibrosis. "` U will be remembered that in this investigation the examination of workers was restricted to those at work at the time of the examination, and, therefore, a number of advanced cases of fibrosis, and a number of cases of pulmonary tuberculosis--with or without an asbestos fibrosis in addition--who had either given up work or who were off work temporarily, will have been aisttd. Moreover, the supervention of a tuberculous infection on a lung already the subject of fibrosis produces as increase in symptoms, previously unnoticed or disregarded, and induces the worker to seek medical advice. He is then appropriately advised to give up his dusty employment, migrates from the in dustry, and may or may not accept sanatorium treatment. - \ Thus there tends to be a drift of each cases from the fibrosis producing' industry. In fact, during the course of the investigation, information was obtained of a number ofjsersons, previously .employes Jo -asbestos, who were either at'home or In sanatoria, suffering from chest complaints. * <* *. Precise information as to the incidence of- pulmonary tuberculosis amongst asbestos workers cannot be obtained therefore, in the absence of periodical medical examinations in the industry, without prolonged enquiry involving the search of the records of local sanatoria, tracing workers known to have ceased work In asbestos, and examination of death certificates, and of the' sickness records of firms, where these are kept. Nevertheless, with these reservations, the data obtained in this investigation did sot disclose any outstanding sua&ptibiiity to pulmonary tuberculosis, either amongst asbestos workers as a class, or amongst the cases of fibrosis. ftunmery.--The outcome of this investigation is to establish the existence of & definite occupational risk is the asbestos industry. This takes the form of & distinct typo at fibrosis of tbo lungs, resembling silicosis is its main clinical aspects, but differing from that disease is the mode of distribution of the fibrous tissue in the lungs, in its radiological features, in the enhanced rate of development under average conditions in this country, and as far as the evidence goes, in a lower susceptibility to the supervention of pulmonary tuberculosis.' > *Tbe asbestos fibrosis results from the inhalation of asbestos dust, the proximate .causes being concentration of iuatia Abe-air breathed and length * Ta enftdie*i tad wdlelog&at <UU oOUuMd. ia tit* wtti t* l*wber*' 4A exposure to it. Thus the incidence rata is highest ia the most dusty pro: cesses aad'aiaongst'those'longest'employed. `Age and sex have ;no( apparent Jafl^ence on the production of the disease. i *; -.it.'i.ri 'J : , *. ' ' v,.v* * b ,, m* 5.---^ACTOXtS DSTERMiXItfG THE PRESENT SsfiOONiTIOM 0? .TBS ASBESTOS..., V;!'*'** >' -Fibrosis. 4 f; ' 'It is of iiterit'to consider why it is that this disease lias only recently attracted notice and become a problem in the industry, although asbestos .was known to) and worked by the auoienta. .... '""/rVu'C.' . . - Hl&y iactors contribute, to toU position, some dependent os the nature of the disease, home on the phenomenal, expansion of the Industry,' others on tie advance of medical science. * > /'* . ... . .'!* While asbestos ha been known and spaosodic&Uy worked for handled* of years, it is only in the post 40 years or so that it has been commercially exploited to any extent Hot only that, but it is less than SO years since the great crpan* aion of the industry commenced. Even after a number of years of steady expan sion, the industry is still comparatively small, and the workers employed in the . essentially dusty processes relatively few. .. * . .* . , * '4y V. . _ .The inkfdicus onset and anbfetrove signs and symptoms of the df&ase In jU'esrVier course, its covert advance by imperceptible^,stages, its points of resemblance latterly to fibroid tuberculosis, with which infection it is sometimes associated, and the migration of those affected from the industryt have all com bined to delay its teccgnitwa as ax'entity, axvd to obscair the causal agent,. V ' Knowledge of the effects'of specific dusts upon the lungs* has been greatly extended in the p,ast 20 years, but research has Seen mainly concerned with the more important and widespread risk associated with the dusts containing free silica, sfld enquiry into the effects of other dusts had to wait-upon those inmti- gallons. .V'T.:. ' . - 7; .1 //'T'. ^ 5\Yf ^*9-;$/ : -is-. . :.. A6.--TpxtEmmvx btXAsd&is:: v?'f'fhe necessary preventivemeama include,'first,''those dfrec4d^spSlcd3y: towards the suppression and control of.the dust evolved, in manufacturing pro- . cesses, which are examined m Part'll of this Beport, aid seeondfy,'measures directed towards those employed In the industry. * These latter include the control of the disease by periodical medical examine ' tics of the workers, by which those unfitted by health reasons are prevented from entering the industry, and cases of fibrosis and pulmonary tuberculosis are, . detected at the earliest possible moment.*. The ultimate aed only reliable test of toe effectiveness of the preventive measures adopted in the industry will be ' found in the statistics derived from toe records of* periodical medical crimina tion of tfco workers. .... They also include too education of the individual, as in other dangerous' tradantoaane^predation-of'toeei^t, ai&d-%odivs^exscsal xespoasfiality ia toe prevention and suppression of dust. r v.'i v The protection afforded.by respirators is only partial, and there is a*real u danger that toe use of them may give a sense of false security.. -Asbestos dust 1 floating is the air contains a majority of particles of'the order 2M, and under^ * many being only G.5* (*%.W into? in size. In practice, the discomfort of constant wear, and difficulty in speech, eto., render workers very unwilling to use this form' c! protection for any length of .time. - - Since, however, a high close respirator will trap a proportion of the large par- tides which can enter the long, they cannot be said to be valueless, out can only be recommended a ^second .line of defence, and not in substitution for otper preventive measures specifically directed to the control of dust as near as Cstole to its point of origin. Under very exceptional circumstances there may . scope for the use of the efficient type of breathing apparatus comprising a mask or helmet with a long tube, enabling toe wearer to breathe pure air from a distance. "* ,* Sy;.:M * * 4\ . *.w i J-Tm. Omiaot.^ :'x'` Trom consideration of toe nature of toe processes in the asbestos industry,* and other relevant matters, it is felt that the outlook for preventive measures is good. i,, That is fe ay tfaxti* tot spare of a decade, or thereabouts,' the effect of* IS energetic application of preventive measures should be apparent in a great reduc tion is the incidence of fibrosis. . 1 ' An immediate temporary rise in the incidence rate is probable, due to tie accumulated damage, partly a legacy of the war years, but with the passing of .tie peak, a steady fall should ensue. - . .. Much generous assistance has been received from many sources during the course _pf this investigation; these are gratefully acknowledged elsewhere. Special thanks are due, nowaver, to Dr. E; W. Twining of Manchester and Dr. hf. TaitersaB of Leeds for their indispensable expert assistance in the elucidation of the radiological features, to Dr. W. E, Cooke, Professor M. J. Stewart, and Dr. Roodhouse Gloyse, whose researches in the same field are well known, and to Dr. I. M. D. Grieve for information from an unpublished study of a group of asbestos workers. ......................... . *; *. ' ;*; ' .Reverences.............. ...............................% ' . . 1. Seiler, L E., Brit. Med, Jnl., 1928, II, 982. 2. Departmental Committee on Compensation for Industrial Diseases. (a) Minutes of Evidence, Appendices and Index, 1907. Cd. 3495, p, J27. .'-*.? {&) Report. 1907. Cd. 8495, p. U. % .. . t ...-ss*.... 8, Cooke, W. E., Brit. Med. Jnl., 1924, II. H7, ......... 4. Cooke, W. El, Brit. Med. Jnl. 1927, II, 1024. '' A McDonald, Stuart, Ibid. p. 1025. ,* - .i*! e; Sadkatn, C., Studies m Industrial Hygiene, No. 13, Report of the Director- . General of Public Health, New South Wales, 1927. * . .7. Cooke, W. E./and Hill. C. P., Jnl. Royal Micros. Soc. 1927, 232."* *'' 8 Cccke, W E., Bnt. Med. Jnl., 1929, II, 578. **" -W 9. Gloyne, S. Roodhouse, * Tubercle ", 1929, X, 404, . 50. Stewart, M, J., and Haddow, A. C,, Jnl. Path, and Bact., 1929, 2X211, V .11 Simson, F. W., Brit. Med, Jnl., 2628 I, oo*. . ............ ;rtiriw , . 12. Wood, W, Burton, and Page, D. " Tubercle ", 2930, 22. V.?^C:V ( ... .k. .. . .... ,, . i. ... .1.- 14 : v yi.,. . . PART II. i. M *-; " t' r- . ''! J Processes Giving Hiss to Dost and Methods for rrs Scpvrrbsios. 2 INTRODUCTION. The asbestos industry has developed greatly in recent years and continues to expand rapidly, mainly because of the demands of the motor, electrical engineering and building industries, and of the increasing attention, now paid to the insulation of steam plant to promote fuel economy................. ' Asbestos products may, for convenience, be dinded into seven main groups:-- /. : ' TertUet. V dk? 7"* i . ** : v* fe) Yarn and cloth. <>.. Nm-Ttxtiles. -' 4 4 Packing and jointings, . (/) Asbestos-covered ..electric conductors--electrodes, cables an< ". wiring, noils 'Jot .aiectetoxnaohimery.* * *,f`. -It* (y) Miscellaneous, including moulded electrical end other goods'etc *' Some factories ' make both textile and non-textile goods. So-*Ue< `Bbcrized'' asbestos, i.e., opened or brokeo-up materia) in a fine floeb-iik 19 condition, is manipulated, unmixed with other materials, in large quantities in the factories included in groups (a), (b), and (e), and to a much smaller extent in some of the other factories and workshops. . {a) Asbestos yarn H woven Into cloth for insulation mattress coverings, in sulating wrappings, filtering material, fire curtains, fire-smothering blankets 4 and firi-reristmg clothing, narrower woven material is produced for belting for conveyors. Brake linings and insulating tape, Some asbestos cloth is rubber-proofed for use in toe manufacture of steam packings and jointings. Besides iu main use for wearing, asbestos yarn is braided and plaited for use as packing, and also for insulating material. Spools of yarn are supplied to factones^n which electric cable or electrodes are mode, and polished thread for the completion of incandescent mantles. . .1' 1 (M Asbestos millboard and paper are manufactured from pulp containing short nhre asbestos, by a wet method, like ordinary millboard and paper, Asbeatos-ceraenfc sheets, tiles, gutters, pipes, etc., for building and similar pur poses are made from wet mixtures of Portland cement and snort fibre asbestos. A synthetic composition sheet is made from a rubber mixing, for use as jointing. Bituminous mixings containing asbestos are made for switchboard .panelling, and other mixings for floorii . . {c) Insulation materials ude fiberized asbestos; "magnesia," soiled containing about 15 per cent, of fiberized asbestos and S$ per cent, of magnesia, and other finely divined mixtures composed partly of fibenzed asbestos, used as inflating cements or plasters; fiberized asbestos stiffened Into thick sheets, like ah. ,, for lining bulkheads of .ships; shaped sections and slabs, moulded from fiberized asbestos or mixtures containing It, or built up of corrugated asbestos .per so as to enclose air cells; mattresses, made of asbestos cloth and filled with woerized asbestos, magnesia, or other filling. '!. **' r (d) Brake and clutch linings are chicly prepared from impregnated and heat-treated asbestos cloth, but also from moulded asbestos material, vv. r, . (d) Plaited and braided asbestos yarn, proofed asbestos cloth and com position sheet are used in making packings and jointings. 4 4 *+ ' *+t4.S4 , (/) Electrodes for welding work arc plaited with asbestos yarn or covered with a paste containing asbestos. Some electric cable and wiring required to withstand heat are plaited with asbestos yarn, field coils for electric machinery may be wrapped with asbestos tape.'**'* : *./ *_ `v- `; (?) Miscellaneous manufactured articles or products, composed wholly or partially of asbestos, include, in addition to moulded electrical and other goods,* asbestos putty and powder, rubber hose plaited with asbestos yam, and many others. * _ Apart Item manufacture, certain work is* carried oh in premises subject to the Factory and Workshops Acts, as well as in other premises, which involves us *>r manipulation of asbestos or products containing it. The insulating of boners, pipes, engines, and parts of ships is the most important. Much of this work is.done on board ship by contractors who employ a considerable outdoor iff. * 2.--PBtfJax*. The factories and workshops included in (a) to {g) number at least 160. of which IS are textile factories. This lou\ b Wed on Usts supplied by the District Inspectors. It docs not include the large number of works where there w incidental use of asbestos packing and joinring, asbestos-covered electric cable, or other finished goods, required for completing other manufactures. It*1-;- There is only one works in which the employees concerned with4 asbestos exceed 500. There are many small premises in which but a few employees, in some cases only one or two, are employed. A small " asbestos " department is fcasaf * number of important factories... K"" ' >:-w * ' >. . textile.departments are usually well housed in modern buildings. ''k few of the oder textile factories have been improved recently by'the addition of modem buildings, In one case a badly housed small concern is in process of - removal to newly constructed premises... r .. . The asbestos-cement sheet factories are modem premises oflarge ficor area, lofty and spacious, in the main, single storey buildings. The cable and electrode .factories are also modern and generally suitable.;. , .^ ,; 20 Some small works, more particularly those engaged in making boiler com* positions, are unsatisfactory. A few ere mere open-sulurf premises are difficult to keep clean, * Some .works are congested with plant and stocks of material This may result from inadequate accommodation or a temporary falhug-oS in the demand, but, the effect on cleanliness h bad. The dust evolved in manufacturing pro* cesses is more difficult, to control if the premises are unsuitable, particularly if crowded,with plant or material. Cleaning is not easily accomplished and the dust imore concentrated. * . , Vt * YenitiatUw.--The arrangements provided for ventilating asbestos works vary as in other industries. Bust removal systems, where used, effect & measure of general ventilation. A number .of workrooms in textile factories are ventilated by plenum systems, the air supply being warmed in winter. Over head extracting propeller fans are but little used now and would be unsuitable. In one mattress making room extraction fans connected to large overhead hoods arc used. Extractionby downward displacement, the air being drawn through openings in Use floor, or near floor level, has cot been met with, but has been considered for some weaving moms. This system, if designed of a capacity sufficient to effect a high standard of general ventilation, would tend to redues the dust in the general atmosphere at breathing level, and, with other safeguards, be a possible alternative to localised exhaust ventilation. . It $culd not be success ful without efficient heating, owing to the rapid change of air entailed. ' Separation of Processes.--In many works several processes are carried on in the same room. In the absence of effective means of preventing escape of dust into the air, many workers are subjected to a risk from which they would other wise be immune, or to a greater risk than that arising from their own work. In a few textile factories crushing and opening plants are placed close to spinning and carding machines. Spinning frames are installed close to looms and wet and dry wearing are carried on close together. la non-textile premises there,is more elective separation of dusty work and processes from non-dusty..; v . .5: .*"*'* < ~**. . 3.--DssctLtman or T&gcbsses a*b Pbsvjwtxvz MeascbssI'I r . , A complete account of manufacturing methods is not attempted. '.'Attention is mainly directed to the dust-producing processes, a description of which, in broad outline, has been deemed necessary to make dear the circumstances under which exposure to dust arises, and the character and object of the remedial measures already in use or here recommended.. Somewhat important changes are on foot which, it is confidently hoped; will greatly reduce exposure to dust In certain hitherto dusty processes. On the other hand, certain developments, e.g., speeding up of textile machinery, and -the increased use of asbestos in various industries, may intensify the dust problem, if adequate measures to deal with he Bust are not taken. .;'T > .. * >'!. Textiles. (a) Yam and Cloth, A The manufacture of asbestos yarn and doth proceeds on the whole like that of other textiles, but there are some important differences. Inherited and other asbestos material is freely handled in various operations, in gathering `waste," and in cleaning. Exposure, in some degree, to asbestos dust,,is common throughout all the factories, but steps have been taken, extending over many years, to deal with dust produced at various points, though the necessary degree of efficiency has, generally speaking, not been readied. Exhaust ventila tion plants used is,the best-equipped asbestos,factories for removing dust appear to he as efficient as those used m other textile industries, and to have been applied over a wider ffeld. As regards other safeguards against dust, e.g., substitution of mechanical methods for handwork for 'feeding the machines in preliminary operations, efficient enclosure of machines, and vacuum methods of cleaning, little development has been made. *#** ..f . Optnia?.--^Asbestos, suitable for yarn, has'usually to be crushed,'and in ill cases . opened *tory processes a"ref*ef^ffeibctoerd^iicbdv "m)_ aa.bcehfoi^nraee_r_yit, ibas.<urt^e.a_nd^tymamli1lom-r-- uc^caihri dnhina. g_n.adwTo*hKreks,e-'^fpereeppaarraa)i-- ing ito remove iron) and grading or sieving follow crushing, hat precede opening. 21 Material for yarn is sot usually treated in disintegrators, but in most factories these machines are used for nbeming waste asbestos yarn, etc. Crushing flattens out and breaks up the mineral without damaging the fibres. It is accom* * pllsbed either in a large edge rnnner, or in a small pan mill of the mortar mixing type. .The material is emptied upon the Scot close to the machine, the contents of several sacks sometimes being spread on the floor to obtain a rough " mixing. The crushed material is either taken from the machine by hand, or discharged m delivery slide, usually filled into sacks or skips and, if necessary, wrtable weighing marine. A few edge runners discharge upon short inclined lattices and the material falls automatically into the sack or skip. Edge runners give rise to dust of considerable amount where short fibre . is crushed; some are enclosed and hare exhaust applied. This is always neces sary. Pan mills are not enclosed and also give rise to dust, though less in amount. * u' ; <- Handwork, e.g., sack emptying idd filling, mixing, shovelling and feeding machine pans or lattice feeds, gives rise to dust, sometimes of considerable amount, and is done without exhaust. ' Application, of exhaust draught would be facilitated if feeding were done frodm a higher level so that sacks might he emptied under enclosed conditions, I.*. ina sack'aoptyiagapparatus. Automatic delivery and reversible bagging lattices eliminate dust produced in hand filling of ^cks, bat require to he efficiently enclosed with exhaust draught applied.' * - An open hsrettiag hand passing round &s electro-magnet is. used /or eparating loose iron, the asbestos being delivered to an elevator. Enclosed jparatus should be adopted. . . .........., ^ ,w . Enclosed rotarysieves {rotaries) or long oscillating frame sieves are used for to the'machine enclosures, otherwise unnecessary dust* is created, ..Some psetiiat* asieves are very d into sacks by '* ` '***"' * " enclosure with exl ,, 'deliveryand bagging lattices, also enclosed and exhausted, as used in some cases, are generally practicable. i -r, used for opeahag blending b/ crashed material is effected by spreading it evenly in layers on the floor over a considerable area--cotton may be added at this stage if required--and when feeding, taking a vertical cut through the mass. Admixture with a small proportion of cotton may ' be achieved Sr blowing it into the feed opening. The opened material is covered upon a lattice and collected either in a large container or in sacks, aatomaAic-bagging.UUicesh^iag.nsed.ia aQnift^aacft. Jfrftftha.nlfaldeeding under nclosed conditions, with exhaust draught applied to feeding lattices or other and that machine mixini retained, it should be d exhausted canopy and the mixture iea at a series oi enutes, delivery should be well enclosed and exhaust applied, as now done in some <jases; otherwise dust is evolved. . * r* \ Opened material sot required at once, may be stored in open bins in the workroom, involving emptying and filling sacks or skip which necessarily cause dust.. This storage m bulk should be avoided; alternative arrangements might be adopted which*avoid dost. ,y . Some material, e.g., long fibre waste from later processes,* is opened at enclosed lattice-fed teasers or wifleys, sot infrequently of primitive design, wore out, and emitting much dust, notwithstanding that a fan is e* integral part of the machine. These old machines should not bo used for asbestos opening. Bust may be emitted at feed points of modern machines, particularly when the feed is irregular. Exhaust is necessary * the feed lattice for i,hk reason and also because feeding itself causes dust. .* S^e material is either discharged upon a lattice for immediate collection, or blown into a chamber. The standards suggested for Crigbion machines should be adopted. . .v .* S3 Hopper lattice feeds are largely used with opening machines; the hopper Kps are about 3 kefc Q laches abovt Soot level. Much 2ust is produced in shovel* feeding as it is difficult to avoid scattering at the lip* An enclosed lattice, fed l or jest below floor level,with localised exhaust applied to the enclosure is more satisfactory. ;; . Single disintegrators, or two or three machines is series are used for break lag up textile or other asbestos waste, mow rarely for opening crushed asbestos Present arrangements for preliminary hand sorting of waste are unsatisfactory it should be accomplished at a covered bench, suitably exhausted. Whereas is *some cases, the indraught at the disintegrator feed openings caused by the rapid rotation of the rotor is not sufficient to remove dust, and because, at any rata, a*,soon as It is stepped, escape of dost may result from reversed air current*', fixbgfist should be applied here also. , . .. / Disintegrated material U blown into chambers, a blower fan being.in some cases connected to the delivery of the machine to create a stronger draught. Air pressure in tbo chamber Is relieved in diffami -ways, the sides may be covered with sacking, allowing much dust to escape, a " relief balloon " connected, or exhaust applied. Chambers connected with disintegrating aod teasing machines vary in size, some are little more than a Urge box, others are more roomy. Some, but not *11, are separated from the workroom. They are entered fob emptying, the material being filled into sack* or skips by hand after the machine i$ stopped or the flow of material diverted to another chamber. Work in chambers is very dusty and its elimination is most desirable. (See page 28.) * Carding.--Considerable developments hare taken place in recent years. One or two important new cardrooms bate been started. Many new machines, including some of foreign construction, have been installed.' * The machines, of large overall dimension*, are of the roller and dearer type. Modern, cards are of high das* construction and fitted with two doffor ?'linden supported on a carriage, which c&b be racked into or out of position. or fine yams, a breaker and a finisher, constituting a set, is used, connected by lattices, lap *Uver from the format being automatically fed to the finisher card. In esses where the sliver is collected is cans, a Derby doubter is used for prepar ing lap* for finisher cards. .* *- . - Single machines and breaker card* are equipped with hopper lattice-feeds supplied" from skips or sacks, handfuls-being dropped in, ana shaken apart os fed, or the sack emptied into the hopper. TEe asbestos falls intermittently upon a creeper feed which conveys it to tSe " lickac-ia " feed rbllen, between which point and the dofler the malarial is under enclosed conditions.. The material is combed from the open doflers of finisher cards, as a web or " sheet ", the sheets from the two doff&rs usually beingcombined at a con- denser, and the resulting sliver yam wound into spools. "Occasionally, combed web is collected without being condensed, the condenser7 carnage being with drawn. In other carding, the sliver may be obtained as a'lap. ' " Admixture with cotton is usually accompimhed by cording the two materials together, a cotton Up being mounted above the creeper feed,,and the cotton fed through the feed rollers with the asbestos. . .. : . 'ffce evoUUos of dust at cards is inevitable and a fine dust cloud may be observed ;a most cardrooms. Suppre&aUa of dust cannot be realised unless machines are maintained dean and in satisfactory repair, and there is effective enclosure of varies* parte. Above all, localised exhaust must be applied at well-defined pointsof dust emission, and improved stripping arrangements pro* vided. Wide spacing of machines is also desirable. * " Tba upper paste of modern machine# are usually provided with* well made vroodes covers and the lower parte are enclosed below in mete!/ The frames are well enclosed at the sides. A hinged metal cover, fitted in some cases, pre vents escape of dust produced by movements of the feed lattice, A curtain of fabric is less satisfactory. In older types, particularly, the wooden war* may sot fit satisfactorily, the cylinders may not be truly aligned with the frame anS other defect* may account for aide escape of dust, hot controllable by exhaust. Such defects should be- remedied. Creeper feeds, dofftrs .and condensate and competing lattices between breaker and. finisher cards are not enclosed. - Dust te evolved at doffer combs and at creeper .feada. ., ,u^ Localised exhaust ventilation was first applied to carding machines many years ago. Methods end apparatus have since been gradually improved and more powerful exhaust draughts are now used. One large firm have achieved .much success fay standardising their practice as regards points of application of exhaust draught, design of air guides, size of branch ducts to ak guides and duct velocity. Exhaust is applied at (a) the presser at the creeper feed; (5) feed roller at licxer-in; (e) top of cylinder; (d) each doffer, air guides or hoods being fitted at these'points with connecting branch ducts. Muff couplings, used on branch pipes, facilitate easy dismantling. Branch pipe sites and doct velocities are liberal. The improvement realised by applying powerful exhaust at each of the points mentioned, at all of which evolution of dost is important, shows that tfajs prffctice shoald be followed generally and gives point to the view expressed by some occupiers that carding cap be carried on practically dust-frcc. Apart from the above case, exhaust is applied in nearly all cases to the cylinders; In a moderate proportion to tiie creeper feed; in a few,,to one doffer--the top, and in one or two only, to the bottom doffer. But, apart from dust-emitting points not provided for, the results may be inadequate. Carding machines are occasionally installed and put into use without exhaust, this should'sever be done. Efficient results are not possible unless the exhaust draught is applied as r.taseW as possible to the dust-predudng points. Transverse air guides, with branch ducts connected at each end, are apparently more efficient thin pyramidal hoods of the usual type. Ducts of adequate diameter end high duct velocities are essential. ,, The usual air guide for the cylinder, provided to effect removal of dust boil luring carding, and stripping and grinding {though proved inadequate for stripping) 1$ placed a little above an opening in the crown of the cover. Two h' _nch euete, as above, and in addition a larger central branch duct {for use o-.ing stripping) are connected to it. The shallow space below tbe back of the afr guide is closed up during carding by a wooden hinged piece--thrown back for stripping--and the dust produced at the cylinder is prevented from escaping by inflow of air from the room, at the front. Tbe dust-laden air ia withdrawn at tbe side ducts. In stripping, inflow of air carrying some of the stripping dust takes place from below tbe lifted cylinder cover; the central branch duct, kept closed by a blast gate during carding, is then folly opened to proride a greater air volume. ......... la one factory, a circular doffer cleaning brush runs continuously above the doffer comb. A pyramidal exhaust hood is provided, but much dost escapes; uuless fully efficient exhaust is devised an alternative to this cleaning, if mUy necessary, should be found. The collection of combed web, previously referred to, is done without exhaust and dust is produced. Collection might be effected by exhaust drought as applied for removing side waste at condensers. .... ^otwithstanding the use of covers for card lattice feeds dusty conditions are proceed and exhaust draught should be applied at this point also. Strijfping *sw? *Ca5 " stripping *' or ctcantng'is done when tbe r riiine is opened oat -for grinding, which follows cleaning and talas place at e^h machine about once a week, but shorter and longer intervals also obtain. In one important factory the two processes are combined in one operation. BdHer and clearer cards most be opened out, i.e.. tbe lattice feed and breast, and .con denser and doffer carriages are drawn back, tbe cylinder covers are raised, and the various small rollers, which are cleaned and ground at a special machine, removed. 'Die cylinder is first cleaned, with the doffer carriage drawn baric r the carriage is then replaced and the doffers, run at a greatly increased speed, cleaned intorn.- Cleaning takes about ten minutes and is usually done in working hours,hutia one case, at least, after. The men press thaw *i strickles " .or fiat hand brushes about 12 inches long covered with card clothing^ against the wire* omred surfaces..1'Much of the debris is heavy and falls to the floor. .Dust is evolved in a dense cloud, eome being removed at the cylinder exhaust hood.' >Ia one case floor openings, beneath the machine, are connected .to the 'exhaust. Present exhaust arrangements are altogether inadequate, particularly so as regards the bottom doffer. Much du^t .is therefore carried into the /general atmosphere of the room. The cleaners wear respirators or " helmets.'* *-*-- *'*To`a few cases, more effective measures are taken, e.gM the opened-out machine is almost entirely enclosed with high canvas-covered .screens. Xn -tbe works where cleaning wkc place after working hours, an auxiliary exhaust System, with a hood for the bottom'doger, is brought,into use, .<.; Grinding which takes several hours, is an automatic process elected by abrasive covered rollers driven by the machine. The small amount of dust produced is chiefly of a metallic riaaracter. . ....... Is the factory where grinding and cleaning are combined, the duffer exhaust . arrangements &j& first reconnected. Machless dust is evolved and appears to be dealt with more effectively. This firm consider that hand gtrieklingbefore grinding should not be allowed. Their methods may, howmt, rat be generally applicable, A little stricklmg may be necessary after grinding to remove small peees of ddbris, / The trade recognise that present conditions are not satisfactory and experi- meats are being made with the object of developing improved appliances. In one case a revolving brush is being Irved, with independent exhaust draught applied by flexible connections; it is said to give promise of success. Toe brush is narrower thao the hand strickle and less dust is evolved at a particular moment. In another case, a vacuum fitting is under consideration. Previous use of vacuum stripping was given up because of rapid erosion of the metal pipe bends and other parta. tXaless.cSeeiive dust suppression is realised for stripping, s workers, other than strippers, should be excluded while it is in progress and for some time afterwards, ana.the room well ventilated.. ( .V.* ,j, : The machine for cleaning and grinding the smaller rollers, which'gives rise to much dust, , should be fitted with efficient exhaust arrangements--a straight forward matter--sad as completely enclosed as practicable to collect the heavier ddbrls, precautions which are sot always taken. The machine is either installed in Ihe carding room, or in a room adjoining. Independent machines should be provided lo deal with rollers of different lengths, otherwise inconvenient adjust ments, liable to be neglected, have to be made. ,s;i . .Cord Side Waste Treatment.---The irregular " selvedge " of carded .fibre, separated at the two sides of the finishing card, being unsuitable for silver yarn, is'removed by suction draught to i side-end '* machine, which prepares.it for farther use. - The material is blown upon perforated cylinders, the air escaping at the side and the material being discharged on the floor. The process produces dost, particularly when the feeding is irregular, the air then having & free path between*ihe cylinders.' The material should be delivered under section, and not under pressure, a ** psesriae '* machine: feeing upsuitable. Spinning and povbltnff,--*Yarn is spun at flyer or ring frames which may capry up to 80 spindles, 4.G on each side. Much.piecing is requited owing u> ths comparative weakness of the fibre. A fine metal thread is spun with asbestos, for brake linings and certain ether purposes. Mule spinning js not practised in this country. A large amount of doubling is carried on. . , Spinning, more .particularly ring spinning, gives rise to dust.-toallimooriy 'produced*hy Gve ** wHoool^ ,r out of the fibre owing to the rapid'rotation of the spindles, which'may run at speeds of I.7GG revolutions-pM* minute; and intermittently, when the yarn breaks. -Doubling is less dusty 'than spinning. `While Che amount bears so comparison with that produced in carding, and h less than that from dir weaving, the workers are continuously exposed to some dust, mote m some factories than is others, doubtless due to differences in working methods or materials. -Exhaust draught for its removal has not been applied hitherto, but experiments Us one factory have been so far successful that tin firm are prepared to equip all spinning'and doubling frames with exhaust ventilation plant, embodying (i) exhaust duels parallel with the frames, above the tin rollers, with shaped hoods at intervals, each to deal with a small group of spludks, and (ii).Xor more effective-concentration of the draught, panelling for tne ends aad lower parts of the frames beneath the spindles, capable of being easily removed when. necessary.. Such - safeguards may require somewhat wide* application unless special general ventilation is provided.- . V?arpUip*97arp beams are prepared in the usual way from creeling frames, a .small evolution of dost occurring * at ihe frames and beaming machines; localised exhaust*ventilation coaid hardly be applied effectively. 'A partaUw>ed- eff space, mechanically ventilated crosswise, with extraction at low level swould effectfarpiuvemroi.< -*.4 /- '*'5r- ......... ** - * .?* t-V-,r- 23 IPsntffa?.--Many winding machines are used, varying from makeshift types of primitive construction, at which the practice may obtain of holdingthe yarn . in the hand, to modern universal winders for winding " cheeses." vast may 4 he evolved to some extent, particularly in connection with the above practice, which could be eliminated. Application of exhaust draught will then probably not be necessary, except in particularises. ... * . Plaiting and Braiding--Plaiting and braiding, also carried on in engine packing ana electric cable factories, and done at machines of normal design, cause some evolution of dust, except where the yam is impregnated with *1 grease.*"^ 'While the amount of dost is sometimes less than is spinning, the difference is not material. But there is perhaps less exposure of the operative under ordinary working conditions and precautionary measures other than localised exhaust ventilation may suffice. ; ITeastop.--Looms vary greatly in size and general arrangement.: As many as 140 looms may be found in a single room, but this is exceptional. .The clear space between machines maynot exceed 28 inches. Some looms ere independently driven by electric motors. Cotton warp or weft is sometimes used. ' Thin'cloth, for mattress covers, filters] clothing, etc., is woven from a single warp beam nt a simple type of loom. Belting looms, for thick belting ah3 brake 'lining material are complicated, several warp beams, arranged in tandem Under the loom, or in some other convenient way, being required. These looms are narrow, but often very long. Tape looms are also narrow, unless several tapes are woven c ether when ee7*.l shuttles, in line, working in unison, are Used. Cloth is beamed at tho front m the usual way, but belting may be led under the bom, and coiled high above it, at the bade. //V* ,\V ^ ;, ."T;.;. * :Hbst weaving is dry,*1.* but some weaving is done wet; either w&rp or weft, and occasionally both being wetted, Wet weaving is accomplished more easily and a closer weave obtained, but rusting of heald fittings, and the subse- IiM&t drying entailed and the less satisfactory appearance ox the material are isadvantages. Thoroughly dry fabric is required for brake linings and rubber* proofed material, and wet woven cloth may be strongly objected to'oh this account . .. - V * Considerable evolution of fine dust occurs in dry weaving as a result of (a) the forward movement of the slay in " beating up/* this source being close to the operative, (b) the repeated contacts of the rising and falling warp threads with their neighbours, this source being the most important from a quantitative standpoint, {<?} the disturbance of " dust *' or " fluff " on machine parts, especially those in motion. --A fine dust cloud may be observed behind the heald* atmve the waxp threads. Much less dust is produced in wet weaving, "i * .-> u . Some ** diy " looms are now fitted with localised exhaust usually applied * deal with dust evolved by both {a) and {&}, in some cases (a) only, (a) flat horizontal "hood '' is fitted in front of the operative, just above the cloth, the opening faring towards the bealds; '(B) either an upright pyraaiid&l'hood, placed tmasversely, or horizontal flat hoods, one on each side facing each other, are fitted dose behind the healds. The second arrangement is the more effective for narrow looms, as the w scissors-like " action of the warp threads appears to displace most of the dust to the rides. The exhaust draught has ejected some improvement, but all the dust Is not removed, especially that produced by {3). It may be impracticable to apply the draught to all dust-producing points behind the healds, particularly at long looms, to greater success would have been -achieved with more powerful draught and larger air displacements, as is now being recognised. ... 1 l.$h* methods 'described for dealing with the dost created by {3} must be less successful at cloth looms of ordinary width. -.A few such looms in' one factory have `recently been equipped with large " bonnet M hoods, fitted transversely, dose down over the machine, covering-the slay, reed and heaids. The hoods are of hemispherical section, with extensions over the shuttle boxes. An * internal electric light fitting, and hinged sections, facilitate working. : A powerful draught, suitably applied, should prevent escape of dust, generated within. In another case, experiment i* said to have shows that a transverse iedined hood facing the operative, placed just below the warp near the front of the loom, can be more effective "rer'reducing fluit tcfflmrtratitjn -in the vrir breathed,.than present arrangements, aod the sow*design-ss to be substituted.."^ ' ' *e' 2 Application of efficient dust removal arrangements to weaving is clearly difficult. The expedient of installing individual machines or smaff groups of machines ia suitably ventilated small rooms or cubicles, as suggested under " Warping ' does not appear to hav* been tried, but might be considered if localised arrangements are not sufficiently effective. * long narrow sheds, for a single line of looms, ventilated as suggested, might be a possible alternative. Cloth Picking, S^tnining, Measuring,--There operations involve running out the rolls of cloth and fend to produce a small amount of dust* If carefully done, so that very little dust Is created, other precautions may be unnecessary... NoH-Tsxmss, * . inherited asbestos is not used in some of the son-textile factories and exposure to asbestos dust may be slight or* even negligible. Dost is evolved in factories or departments where such material is prepared for subseqncni use, or for sale, and also in departments where fiberized material or dry mixtures containing it are manipulated is preliminary manufacturing processes. Again, finishing processes, involving abrading or cutting at high speed, maybe a source of dust, bat such dust may contain only a small percentage of asbestos. The application of exhaust draught, where suggested in the soUovring description ot processes, is in most cases a straight!reward problem, comparable with many others met with in non-textile factories, &g., woodworking and grinding, where machinery similar to that described i w&ed. * < ' s Piberizing cr Oprasng.---Fiborizing U almost exclusively gained to works tn group (5).and (e). Much of the work is done under less supervision than In textile factories and unsatisfactory machinery- is more common, Primitive teasers (" devils ") are used in several mattress-making works, and chamber work sa also an unsatisfactory feature (see p. 22).. f . <* In some asbestos-comeat sheet factories, crushed material, from edge runners, falls Into worm conveyors below, which transfer it automatically to disintegrators. In one large works, the process U being entirely enclosed; the material from the edge runners, which are lattice-fed, will be discharged upon a conveyor and raised by an elevator to large overhead storage hoppers, fitted with automatic bagging lattices- Localised exhaust draught will be applied at feeding and demety points, where dust might escape. - . . . * Chambers have been eliminated in some Urge works, with beneficial results. The material, after being disintegrated or opened, is fan-handled, and blown to & hoppre fitted with bottom rotary delivery valves, the air bring re-circulated. The material is bagged at lattices. Direct supply to a manufacturing point is another improvement now bring tried. Such pneumatic conveyance should be practicable in many cases. Localised exhaust at feeding and discharge points of .these systems h necessary. , Vacuum methods for filling sacks may also be practicable. - ' If chambers are retained, the necessity for entering them'might be avoided, fcy providing chambers of small front to back dimensions fitted xvltbdow doors, at which sack filling would be done, localised exhaust ventilation being gpplied over the doors. ....... :, . ' fb> Millboard, Sapor, Sheets and Tiles. 1* ... The wet mixtures for millboard,* paper, *and asbestos-cement products are prepared in a beater, as used in paper nulls. Dry fiberired asbestos is emptied into the beater trough, the sacks being shaken to some extent. Evolution of dust occurs before the material becomes mixed with the circulating water. Occa sionally a sack is emptied before the water U turned on. Several sacks art required4 for a charge and the process Is repeated a number of times'daily, precautions are not taken at present but the dust might be avoided y fa) mechanical feeding under enclosed conditions, as appears to be done 1c some foreign works, (b) applying exhaust .draught, (c) feeding in small quantities sad in such a way that the material is wetted at once. ' - . . finishing processes on asbestes-ceraeot sheets include sawing 16 *izt, corru gating, pressing and drilling, .carried on in seme factories with the materia) moist as to prevent dust, and this practice should be adopted generally'.  2? Otherwise much dust is produced in sawing, owing to the rapid cutting speed, and localised exhaust is necessary though sot. applied. Similarly, turning, filing and smoothing of dry asbestos*cement pipes, at lathes, may require exhaust to remove the dust produced. . . Synthetic composition sheeting, sometimes made in a rubber department, is produced from dough consistingof fiberized asbestos and rubber, mixed with solvent in kneading machines. Dust is produced in feeding the mixer with asbestos, done in an open manner by band, from sacks or skips, the sacks being shaken out* or from an open lattice feed. Subsequent processes are dust-free, Exhaust should he applied at the feeding point. ,, ., (c) Insulation Staterials and Articles. r. Compositions*--" Magnesia," the most important insulating composition, is produced on a large scale by the principal manufacturers, by enclosed methods with pneumatic conveyance of the mixture to automatic sack fillers. 'Weighing and feeding the fiberized asbestos gives rise to dost for which exhaust is necessary. ... .. Fiberired asbestos or `` magnesia " is a component of many insulating com positions which may. also contain clay, kieselguhr, fossil meal, fiax, hemp or j"te waste and other materials. The proportion of asbestos in the final product v les widely. In many small works the materials are mixed " dry," by hand, in an open manner, involving sack emptying end filling, shovelling and1 weigh!og. Enclosed rotary mixers could apparently be used for sucK work with .xnanst applied at feeding points and the material discharged and bagged under enclosed conditions, if band work is retained, exhaust should,be applied. Consolidated Sheets.--Large sheets resembling thick mats, built up of layers of fiberized asbestos, are consolidated with silicate of soda, sprayed on in manu facture. The sheets may be backed on one face with millboard, resupplied without a backing, being faced when fixed with millboard or asbestos-cement sheets. u-' The sheets arc produced of the required site and shape at work 'benches; or built up oq the table of n machine, capable of slow reciprocating movement, and fed from a hopper above. 7a the former case, the fiberized material is taken in handfuls from skips and spread out in tbs form, the surplus being scraped away and falling about at the sides of the. work benches, and on the floors, a considerable quantity being scattered. Dust, produced in manipulating the dry fibre, before treatment with the silicate of soda, is largely avoided at the machine, tr^cieat localised exhaust should be applied .to the hand process with improved tvoch arrangements, to prevent scattering. ' ; "Band sawing oi piled sheets, causes evolution of much dust, owing to the jnsideraile depto of cut. Localised exhaust alone, not yet applied, may prove insufficient. ` - . Sections and Slabs.-^Moulded insulation is made chiefly in two forms, sec tions--semi-cylindrical and moulded hollow to suit various pipe sizes--and slabs, which are reclangular and solid. These products are ueualfy moulded wet, either by hand or mac&oeiy, from a paste or cream, prepared in & mixing machine or tank, feeding of dry material involves evolution of dust which might be avoidedby one of the methods suggested for feedingbeaters in millboard making. Section are made atone factory by a dry process, at a machine indifferently enclosed. Teed hoppers, filled from skips, deliver the asbestos to internal lattices which in tern supply a travelling hand, at which the section is roiled by hand. Revolving brushes which' clear the lattice and spread the material evenly on the band give rise to much dust, and dust is produced at the hoppers,*and in rolling and brushing away superfluous material Exhaust draught, not hitherto applied, is to be provided at the exposed brush and the machine is to. be more effectively enclosed. An. enclosed " feed '1 is a^o necessary,.h,*1. . The sections and slabs are trimmed to size with circular or band saws. "Much Bust is produced and exhaust draught is commonly applied, but is in some cases inefficient. Circular saws used in some cases in pairs, for trimming ends in one operation, can be fitted with exhaust hoods above and below the benches. n and band saws can be enclosed below the tables and inverted hoods fitted, the exhaust draught being applied as for woodworking machines. Efficient arrange* meats shouldbe readily practicable for all sawing work here. .. ........... *.. Mattresses.'--Mattresses are manufactured by practically all firms who produce insulation requisites, though only occasionally by some. Mattresses for large contracts are made in the contractors* premises, their outdoor sUfl taking necessary measurements and preparing rough plans. A mattress has sometimes to be made on site. `-Mattress making involves, broadly speaking, the sequence of processes associated with the making of domestic mattresses.* The work is almost entirely hand work, Lengths of asbestos cloth for covers are cut out on a wide bendi and sewn up, by treadle or power driven machines, to an extant depending on the method of Ming. Large mattresses may be sewn along one side only or both sides may be seamed and filling done from Both ends, Before filling, covers are turned inside out. Supplies of filling material, which usually, but may not, contain fiberired asbestos, are brought, in sacks or skips, from chambers,'or taken from open bins, in the room, kept supplied from the chambers, or from sacks of material supplied by outside firms, billing is done by hand, scoop or shovel, and quantities maybe weighed. The end filling of long double-seamed mattresses, referred to abovc^ necessitates the workmen mounting on the bench to empty the material from skips into the openings. After filling, the mattress is levelled or beaten, to make the filling lie eveniy within, the hand or a flat wooden beater being used. Finishing processes include final sewing, stubbing or buttoning, fixing on hocks, etc. *., , Some dost is produced at the cutting out bench, in opening out the roll of cloth, and at the sewing machine, but far more in taking material from bins or sacks, in weighing, filling and levelling. Beating of the cloth produces asbestos dust, the amount of which is largely increased li the filling contains asbestos. The work is largely done without regard to the necessity for suppressing dust. * All benches are entirely open. Localisedexhaust draught is not applied. : v; One firm have improved conditions considerably by the following pro* cautions:--- . ........ {a) Keeping floors and benches damp and spraying covers before filling. Hose connections and spray fittings are provided. ,t ft) Sob-division of department into several independent workrooms. (c) Exclusion during filling of all workers not so employed, the excluded workers proceeding to another section. .. , (d) Mechanical ventilation of each roan by cross ventilation, embody ing plenum supply (warmed when necessary) at one side and low level extraction at the opposite side, the air being changed between 10 and 29 rimes per hour. *(s) 'Enforcement of use, by fillers, of respirators. These precautions do cot include application of localised exhaust ventilation, without which mattress filling and beating mast involve some risk of inhalation of dust. For small mattresses, a wide double-sided canopied bench with exhaust draught applied at gratings along the centre line might be need, the filling material being supphed within tbe canopy. Such a bench may not perhaps be practicable for the making of Urge mattresses but the possibility should be explored. Otherwise at least tbe precaution* referred to above should be adopted. * . (d) Brake and Clutch Linings, . ... Before being impregnated, tbe dry asbestos doth, known as " grey,** may be calendered at squaring rolls and in all cases the colls are eased oat to separate them a little, so ensuring thorough treatment by the liquid. A little dust is produced in these operations but insufficient to render special precautionary measures necessary, Other preparatory work on " grey " arises in the making of special linings. Lengths of cloth are lightly hammered to ring shape, m templates, then cut with chisel or shears and the radial edges sewn together at e wire-stitching machine, ^4 used in Uok-binding. Dust-occurs in hammering and stitching. A canopied bench fitted with localised exhaust arrangements might be provided and the machine placed under exhaust draught. *. . >wer-drivftn squeezing presses and Sand saws. Cutting and sawiug exposeYnds of wire and leave rough fedges; trimming and smoothing, dona on grinding wheels aod limsners, are necessary to obtain exact size and finish. All the operations, except squeezing. Kace waste, and dost is created in some. The dust is heavy and sticky and ikeiy to fiy about than dry asbestos dust, The amount is considerable at sawing and grinding machines end localised exhaust draught, to remove it, has been applied--in some cases with much success--and is always necessary, , Inverted hoods are fitted at band Bavrs, just below the tables, the dust being drawn through the small openings in the table guides- A powerful draught is essential. v *v* machines 15 similar as reg&ras limsners, a noon oeing attea in une wiva ana at tne oatas of the band. A baffle plate to prevent dustbeing carried past the hood by the high linear speed of the band is a necessary addition. ...... Special linings and anti-friction bushes are moulded eom disinleetited impregnated waste. Some dust is created in the filling of moulds and efficient 1 -*1iiod exhaust draught may be necessary. The articles are shaped and finished ^ just described. Bushes are turned and bored in lathes, with production of waste and dust, but exhaust draught is not at present applied though possibly necessary,' ..a-n<* .... {) Packing and Joiatings. '" Engine packing is either (a) " cloth " packing built up from cloth, usually rubber proofed on both sides, handling of which does not cause dust, and (b) rope " packing made from yam. at braiding and plaiting machinery, as used is textile factories, (a) Negligible amounts of oust may arise ,at the spreading machine, from the unproofea cloth, and, in building op, from material proofed os one side only. {&) ** Cheeses " of yarn are first rewound on bobbins 2or the braiding and pfaitiog machines. Simpfe wiadiag mechanisms are used. Some little dust is produced; special preventive measures will usually not be nofutuirv. Flat packing, known as " grummet/* is made, on a small scale, from asbestos yarn, threaded on a needle and wound in and out by hand, as balls of .wool are wound. This apparently insignificant process causes sufficient dust to cover in a short time the hair and clothing of the workers and should be done at a canopied : mch provided with localised exhaust arrangements. ... . ' ' v " ^!) AsheStos-coveredElectric thmtetm. * '' > - ^ Electrodes.--Electrodes are either wrapped with yam, the usual method, or passed through paste containing asbestos "fibre, yarn being wrapped upon this coating. The former method U usually achieved by a small high speed stranding machine fitted with a flier carrying the spools or bobbins of yam, the wire travelling axially through the filer. Treatment with consolidating liquid, straightening and cutting to length follow, all done fit the stranding machine. Alternatively, single electrodes may be wrapped by a simple winding mechanism, hand-operated or power-driven. Taste-covered electrodes are also made singly at small extruding machines, a filer for feeding the yam being fitted behind the extruder, After drying, a short length of the covering at one end is ground away, leaving the here metal necessary for making electrical cc&Uct ft the holder, when In use. Small abrasive wheels, almost entirely enclosed, arc used.*; Small amounts of dust are projected from filers, though insufficient prob ably to require the adoption of special precautions. Much dust is produced is grinding ends and efficient exhaust ventilation Is essential; present apparatus, where provided, is capable of Improvement. The process would he unnecessary if bared ada were left in manufacture, and axperimania directed to this desirable end are being made and give promise of success. 30 Preparatory processes in paste making include (i) dry grinding of fiberizod asbestos by small vertical Ui6c grinding wheels, fed at tbc centre trod a hopper, above and discharged from the periphery into a bos below, and (ii) band mixing 01 the ground materials at a bench, involving emptying out of dry material into pane. Dust is produced, the amount being considerable in grinding. Little precaution is taken. The processes might be accomplished under almost entirely enclosed conditions, efficient exhaust draught being applied at points where diy material is exposed, e.g., in feeding. , ... Sowinding of yarn is sometimes necessary and primitive arrangements may be used, the practice referred to on page 24 being followed, and as a considerable ameaotpf dust is produced, the practice should be given up. . - Gable and Wiring,--tebtstoo>cc*et*d cable and vrimg constitute a small percentage of the output of the cable factories. The yarn isoraided and plaited on the conductors at machines, not reserved for " asbestos M products, similar to those previously described. Rewinding of " cheeses," as received from asbestos textile factories, is done at universal winding machines. The amount of duet evolved is small, and special precautionary measures are apparently not required, field`Coil Wrapping,--Field coils for electrical machinery are wound with asbestos tape by hand at ordinary work benches. The process dees not give rise to appreciable quantities of dust. > : ,w .* .' (g) Miscellaneous. ` . : Moulded (roods.--Some electrical insulating fittings are moulded from varnish-impregnated fiberized asbestos, preparea after thorough drying in a mixer and ground in an edge runner. Alternatively, impregnated scrap, ground, in a rumblsr, may be used. The preparatory processes on dry or practically dry material are intermittent, and involve sack emptying, shovelling, weighing, filling and emptying shallow trays. They are carried" on in an open manner without special precautions except that as regards grinding, hanging curtains may be used at the edge runner, and the scrap .rumbier is enclosed. Dust is evolved in the processes mentioned and localised exhaust ventilation should be applied to effect its removal, with, in addition, effective enclosure of some hand work, e.g., emptying of trays into machines could be done inside a cabinet provided with internal arrangements for securing the trays and an external liandlo for turning them over. Localised exhaust may be necessary for final trimming if done at abrading wheels. < Moulded articles made in otter trades may contain but a small proportion of asbestos, although a large quantity may be used. In one case the asbestos is sieved after drying, both operations being done in enclosed machines, and, in addition, dry mixing, done in rotary machines, and paste mixing, on open solfe, as in sews*t works, are also required. Processes carried on with some risk of exposure to dust include emptying of sacks into bins, filling of trays for drying, feeding at the sieve elevator hoppers, the dry mixer, ancT the rolls. Localised exhaust is applied at Xq) the elevator.hopper, (b) ihe storage chamber above an intermediate ragging point. (.-) the dry rntxer, and (d) the roils. More efficient arrangements appear to be desirable for {*) and (c) the feeding of the elevator might be done under enclosed conditions if a cabinet as mentioned above were provided into which the trays could be inserted. Localised exhaust is necessary at storage bins. Final trimming of rough edges is done under efficient exhaust draught. Other processes of comparatively minor Importance, e.gl, asbestos putty mixing, in which there is banding and feeding of dry material in preparatory processes, will call for precautions as previously described for similar work. 4.--Sacks. . *v>:i. :./ Xu a few cases sacks of sailcloth or other closely woven material 'are used inside the factories. Such sacks are much to be preferred W those made of the ordinary material, which is " leaky M and gives rise to dust m handling. 5.---CmKlKO Y WcsxS, IfaCHCKlKY KHZ SfcCXS, .... Some factories are kept in a more cleanly state than others, but higher standards and improved methods are desirable generally. Weekly cleaning by dry methods is general in textile factories, hut is mow effectively done -in some KA M casts than others. Casual cleaning may also be done during the wek* The dust which gathers in a week renders cleaning a very dusty operation. Young workers may be seen a carding machines brushing dust into the air .from the covers, etc., in considerable amount, near other workers- Some firms have instituted more frequent regular cleanings and more satisfactory methods by damping before sweeping. . Vacuum cleaning methods have not been adopted and such methods seem to be regarded as impracticable, but this can hardly be accepted. Portable vactmnf sets are constantly used with great advantage in other classes of works, e.g,, electric cable factories, by adult cleaners who keep the machines, plant; service pipes, etc., thoroughly clean. If vacuum methods are not adopted, well organised daily cleaning, by adults, using damp methods for floor cleaning, should be the rule in textile factories. A water supply with suitable hose and spray connections should be provided. Debris produced in asbestos-cement sheet works under moist conditions may become diy and cause general dusty conditions. Cleaning should be so frequently done as to prevent thia. The cleaning under machines such as looms and cards entails collecting waste of considerable value, done at present by hand. Vacuum collection should be possible*, in principle, it is already used for removing side waste at finishing cards. The sound principle of collecting card waste, through floor opening?, baa been adopted in one new factory, and might bo followed in others, with automatic collecting arrangements. V*' Sack cleaning is done in a few Urge works in enclosed machines, involving some risk of exposure to' dust in filling and emptying, notwithstanding the provision of localised exhaust ventilation. A type of " exhausted " machine which dees not involve such work is to be preferred. . /_' ;* . 6,--SOMWABT AKO RrCOM.KBXOVFiONS. . * ! Asbestos factories' and workshops cover a great .variety of processes. The premises differ widely in structural features and are congested in many cases with machinery or material. Processes arc largely carried on in close association. 'Dust is produced at many kinds of machines, in hand process work, and in simple incidental operations, particularly in emptying settlmg chambers, and in all handling of " fi&erizcd " asbestos.. , , .J ` *-> . In textile factories, pore asbestos dust is continuously produced, in differing amounts, at all the principal machines. Card stripping, a very dusty operation, -is -usually .effected ny.h&nd .strickles. Hand mixzng of different .grades and varieties, incidental to opening processes, is also dusty. In non-textile factories, pure asbestos dust is produced at opening machines. In feeding machines, in making insulating mattresses (a. dusty hand process), and in incidental hand work. Post, though rarely pure asbestos, is produced in finishing operations, e.g., sawing, grinding and other abrading of. asbestos products. , . . 1 The appropriate methods for suppression of dust may only be fully deter mined when the harmful effects of comparatively low concentrations of asbestos dust are duly appreciated. Very dusty processes will not fail to be resogaised, but in processes such as spinning and weaving, in which in other textile trades special methods for dust control are not required, due precautions are also neces sary/ The asbestos manufacturers are clearly confronted with the necessity of attaining conditions in their industry which will ensure much less dust in the atmosphere than can safely be tolerated in many comparable trades not using 1 asbestos. ,,, t1 Tbe principal methods for the control of dust are application of exhaust draught at dusl-producing points; ' (h) substitution of enclosed mechanical methods for hand conveyance, and for dusty band work generally; (c) effective enclosure of dust-producing machines and plant; <4 substitution of wet methods for dry. / 32 Each o theso has its particular sphere of utility, sad the particular indica tions for their adoption are put forward tnlsr alia In the recoiaeridations below. RECOMMENDATIONS. (i)'Application of Efficient Localised Exhaust Ventilation at dust-producing points. This measure, of the greatest importance where manufacturing and incidental prqpesses occasion escape of dust sot controlled by enclosure or other measures, is necessary for;-- (a) Dust-producing masAfnes, e.g.-- .* (i) Crushing, disintegrating, teasing and other opening machines; sieving machines; fibre grinding machines; dry mixing machines; rolls fed with dry mixings. (ii) Carding machines (to suppress dust from cylinder and defiers, caused by stripping and grinding, in addition to that pro duced by carding); card side waste exhaust machines; looms for dry weaving; stripping and grinding machines; other textile machines, if the dust evolved renders this preventive measure ' * necessary. ' (iii) Sawing, grinding, trimming, polishing and other abrading machines, used on dry asoestos products. . (3) Feeding and delivery lattices, or other conveyors, at machines or other plant; feed hoppers at elevators; bagging lattices; feeding of dry material at wet mixing machines. , (c) Chambers, containers, u cyclone " hoppers, or other enclosed space into which fiberiied asbestos or mixtnres containing it are delivered, or pass.' ' * * (d) Work benches, e.g. for mattress making, waste sorting. (e) Various band operations, e.g., sack emptying and filling, weigh ing, mixing. . This is the principal measure hitherto adopted, and is probably that most generally applicable. It bas been applied to some only of the above machines, and appliances, but not to hand vrork. The methods of applying the exhaust draught, and other associated factors, are becoming more effective, but there are few fully satisfactory plants. Special difficulties remain to be overcome in some cases, c.g., looms, mixing, mattress making. If not surmounted, an alternative, via., general ventilation of a high standard applied so as to draw the dust-laden air away from the worker, should be provided. *. (2) Substitution of enclosed mechanical methods for hand conveyance, and for dusty hand work generally. This measure-- (a) avoids depositing material in chambers, intermediate filling and emptying of sacks or Bkips, hand feeding of machines, and other incidenUl hand work; * *> (5) permits of final filling and weighing, under tbe least dusty con* ditions, of materials for dispatch; (c) renders exhaust draught more elective, or, in some cases* . unnecessary. ........... I It is already employed to some extent, and its further application, wherever possible, is greatly to be desired. iUr * . (3) EScctive enclosure of dust-producing machines and plant. (e) To prevent escape of dust not controlled by exhaust draught, or (b) to render its application more efficient. 33 (4) Substitution ol wet methods' for dry. To reduce the dust given off in certain processes end work, e.g., (a) 4 considerable amount of weavingj {&) mattress making, by wetting the covers before fitting, and by frequent wetting of.doors and benches; (e) final sawing, and other machine processes, in asbestos-cement sheet and rib factories, before the prepared material has bad time to dry? {<9 works* cleaning, by damping floors and benches, before brushing or sweeping.^ ' - This measure might bo adopted to a greater extent than at present, (5) Elimination of certain dust-producing appliances. , Certain appliances arc used in s few works, sometimes with a measure of precaution, but which emit much dust, difficult or impossible to control by e&cient enclosure or exhaust draught. They should not be retained unless effectively modified. {<3^ exposed doSer brush at carding machines; .. (3) card side waste exhaust machines, delivering under pressure; ; l,.. (c) certain willcys and teasers, particularly old machines. .. t; Abandonment of Settling Chambers in Manufacturing Processes, to the JT\ IT T ' otEer process; .-si', " * (b) spinning, doubling, plaiting and similar processes, from work not causing dust; ( ... (ff) mattress making, from all other work; (fl chambers, containing fiberised asbestos in bulk, and dust settling -mc chambers and apparatus, from any workroom. ,. . ... , .r :. The separation of mattress making should be adopted in existing works,' and other separation referred to, as far as practicable, '.. (S) Wide spacing oi dust-producing m&cbisas in sew factories practicable, in existing works. as ta? m This measure would bring about permanent reduction of dust concentration Is the air of the workroom os a whole, and provide improved cleaning facilities. (9) Use of tacks of close texture material for internal work. (10) -Efficient cleaning system with wide use of vacuum methods. (See also (4).) < * * (11) Storage ol asbestos and other goods to bo outside workrooms. (IS) Exclusion of young persons from specially dusty work. . ti'4 iVofr,--Particular protective measures of a medical nature are referred to in Part X, whore also the limited value of respirators as a safeguard in this industry is briefly discussed. < 4 f* .' Note on Exhaust Ventslation in Asbestos Works. Someexhaust plants are carefully designed and reasonably efficient, but some are ill-designed and inefficient; others, again, do act effect removal of dust to a sufficient extent. The draught may cot be applied as dosely as possible to tJie.dust-producing points, or may be too weak, The emission ol a visible dust cloud at a point where exhaust is applied is a clear indication of inadequacy. - Extensive alterations of existing plants may produce serious loss of efficiency. Exhaust provision for new ipaebipery and processes should, therefore, generally speaking, be made independently, while advantages result from deauag with manyjtust-producing points, by a single exhaust plant, a number of self-contained plants, with independent fans and settling apparatus, is often more effective. Exhaust ventilation applied on a large scale entails continuous removal of a considerable volume of air from the room. The supply of fresh air must be ample or the efficiency of the exhaust ventilation may*be reduced. In winter, the workers aro Viable to bring about this result by closing windows and doors. Plenum ventilation capable of supplying the volume extracted, the incoming air being warned, may therefore w desirable, where extensive exhaust plants are installed. Efficiency of an exhaust ventilation plant may be greatly reduced by in efficient dust-settling methods. Each fan should discharge into an independent settler. Settlers adopted in asbestos works include cyclones, large chambers connected with cyclones, large chambers enclosed with sacking or other filtering material, and bag filters. Cyclones and chambers are usually well separated from workrooms. Bag fillers are sow being commonly adopted, for small instal- Jations. These filters and " balloons " are sometimes placed inside workrooms, a bad practice. They ace best placed in freely ventilated rooms, effectively separated from workrooms. *' i ; Filtering fabrics for settling dust gradually become dogged; and as this effect increases the exhaust plant becomes more and more inefficient, the volume of air moved by the fan being reduced. Such settlers must therefore be kept clean. The usual practice is to beat the filtering material. Arrangements for shaking bags from outside, or automatic shaking apparatus are not provided. Asbestos dust does not appear to be so difficult to detach frem suitable filtering material as some dusts, but much dust is produced in beating. Efficient shaking arrangements, avoiding this exposure, should he provided if this method of settling is retained. Some firms strongly support the view that it should be given up because of the difficulty of maintaining the exhaust plant at the highest efficiency. The matter merits careful consideration, to particular, the efficiency of the exhaust plant should be kept under constant observation by a responsible person. Cyclones should be of adequate, dimensions. The oosabisatioR of -chamber and cyclone is used extensively, the fan discharging the air into the chamber, towVncfc the cyduneinlet is connected. The efficiency of this arrangement should remain practically constant. . . v.. ; E. R. A, MEREWETHER. CHAS. W. PRICE. 14th March. 1930. wiau-nSN soe v* v.w. u> NOT TO BE LENT References ID `notes arc frots an abstract of the article by fi.R.A. tercwether "A memorandum on asbestosis* published in i *2wrcle in thsto parts in 1933 and 1934. The abstract ^ia originally published in Bulletin of Hygiene and was reprinted is Pnewioconiosie Abstracts Section 3 Asbcstosis p. 140-143. 12) KBKEWSTHKR, B.R.A. Journal of Industrial Hygiene, 22, 1330, 198-222j 239-2S7. *3) Crated in a review of (21 by S, Roodhouse Gloyne published ii Bulletin of Hygiene and reprinted in Pneumoconiosis Abstracts Section 3 Asbestosia p. 132. M) KXO, W.8. and GLOfKE, S.R. Lancet 1930, Use. 1, 44S-8Abstracted by e.l. Collis in SwXZettn of Hygiene, Abstract rsprinted in Pneunooonioeie Abstracts Section 3 Asbestosis p ns. * St 16) rigger, E. et at Ayohiu Ce^r'berpotholoffie-and (kwerbehygiene, 2, *931, S58-90. Ctote is fxon an abstract of <5) which was originally published in Bulletin of Hygiene and was reprinted in P? eunceoniosU Abetracts Section 3 Asbestosis p.136. O) GJFSis and ucko. . Deutsche Medisinisahe Woahenechrift S3, 1132, 285-7. uote is from the abstract by S. R. Gloyne digitally published in Bulletin cf Hygiene and reprinted it PnranoconiooiB Abstracts Section 3 Asbestosis, p.138. {8} X-MZA, A.j, st cl Public Health Report, Washington, SO, 19)5, 1-12. Ouote is fro* an abstract by S.Rloyne, or .giniiXy publish*! in Bulletin of Hygiene and reprinted in Pneumoconiosis Abstracts section 3 Asbestoses p. 144. tI ) i I ;. 4t ' j f\ < j. , t w* -13- (9) HEREWETHER, B.R.A. TubsmU, 28, 1933 and 1934, 69-01, lOS'lS; 152-9. Abstract by S.R.Gloysio originally published in Bulletin of Hygiene and reprinted In Pneimocmiotris Abstracts section 3 Asfcestosis p.142., (W e&teRLXNE, p.s. Editorial. American Revieu of Respiratory Hseaee 238 (6) Dec. 1978, 975-8. Ol) NORBMMW, h. Seitschrift fur Krebsforacbung 47, 1938, 281 as quoted in {10). {12) Enterline op. cit. p. 975. 03) CLOWE, S.R. Tubercle, 27, 1933, S-lQ. fbatranted originally in Bulletin of Hygiene. Abstract repcinted in Pneumoconiosis Abstracts Section 3 Asbeatosls p. 144, {Hi Satfttlinn op. cit. p. 97*. . *15) LYHCK K.K. and SMITH, H.A. American Journal of Cancer, 24, 1935, 56-64. Author's .aagury of fncktHrial Hygiene, 27, 1935, p.83. <16> LYNCH, K.K. and cannon, w.n. 874-887. Dieeaees of the Chest, 24. 1948. ------ 07) Lynch and Cannon op. cit. p. 886. (18) Encerline op.cit. p. 977. 09) GWCXHM, 3. and HUSM2T2, K. IN Shapiro, H.A. ed. Pneumoconiosis : Proceedings of the International Conference, Johannesburg, 1969. O.U.9., 197C. p,742. ?2)} wsDLES, H., 575-6. .Deutsche Medizinische Vochenschrift, 69, 1943, 551 -14- (2}) . HOTTER, Donald The'dis&zaes of occupations, * Hcddar and Stoughton, $th d. 1S75, p.SS3. London* (221 Abstract appears in Bulletin of Bygiene, May 1944, p.362, (235 hyzss, h, Toetgradxate Medical Journal, ZS, 5949, p.637.. (Tsis vork was originally reported in a thesis for the degree of Doctor of Medicine at the University of Glasgow in 1945) (241 WOOD, V.B. and CLOCKS, S.R. 1393-5. Lancett Dec. 22, ig*<, (2S) Diagram from GiISOH, J.C. ' Vrooeedings of the Boyal Society of Medicine, 66, 1973, p,l4. <261 Mcnom, J.C. in Shapiro, H.A, ed. Pnemooonicsie : proceedinge of the international conference, Johannesburg, 1969. O.U.f. 1370, p. 201-203. (27) SIMSOK, F.K. p. 885. British Medical Journal, May 16, 1928, 1, . Document Ho. S. Exhibit "|4" sore RCfCRCwcrs on usscstosis which contain sonc otsojssjok or its ffcunortsmp ro fiiturtal hprosis. cancc*, mo7q* msoTHsuon* (7TM mo) KSfiEUtES, n, et. el lAientasa et Cancers Pulocnelras. level hadocina, 6, 1941, 97 Referred to by Leo end Selikoff (1979) (ismmxs, R, et el labeetosis end cancer cf the lung. Sera, Hop., ?3, 1947, 1820. four pB&afs from Canada, mainly concerned with asbestosis end tuberculosis. Soever, they "record brief details of two patient* who had asbestosis and lung :ancar."(4) Abstracted ins Journal of industrial Hygiene, 30, 1948. (from British Journal of Industrial ftedscine) :CSfl7f0,S. and CCICER.A.3. 'ulmonary asbestosis and carcinomas report cf a case with necropsy findings. Mexican fieview of Tuberculosis, 34, 1938, 143. "The case of e man uh had worked for 18 yoars ae a weaver in an asbestos 'act? ?, in whom tfjare wee a large tumour in the left lower lobe with extenaive ietatesas"(l) Referred to by tee* and Selikoff (1979) Interline (1978) a.orwE, s.a. "he morbid enetony end histology of asbestosis. TUBERClC. 14. 1933, 440-5, 493-7 J50-8. Refers to "horn - like changes in the pleura", (l) Referred to b* tea and Selikoff (1979) Abstracted In Bulletin of Hygiene, 1933. iOYNE, S.R. 'uo cases of squamous carcinoma of ths lung in asbestosis. Tubercle. 17. 1935. ."Soth had asbestosis, both had smell carcinomas. Ths author refrained from aiy u ;eapt to sake out a case for sn eetiological association of these two .ii*eases."(J) Referred to by tee ond 5elikoff (1979) Enterline (1978) Abstracted in Bulletin cf Hygiene, Mlfc. / iom:, S.R. case of oat cell esreindma of the lone occurrfno In *hT*<h<irrTe 17. 938, a, - Report of a third case in Britain, (l) Referred to by Us and Selikoff (1979) SUES, H.H. end ANGR2S7, A. rbnchiogenic carcinoma in association with pulmonary asbestosis. Report of two sees. American Journal of Anthology, 18. 1942, 123-135, "A table listing 10 reported cocas collected from the literature, in which carcinoma and asbestosis of the lungs was found, is presented. cent. /2 ie authors briefly ccnsidor the possible relationship between the two disease recesses, However they conclude that the date from 2 cases ere insufficient for statistical > evaluation* (4) Abstracted in Journal of Induetrial Hygiene, 24, 1942 .* iRBUfiCEfi, f. is coincidence of primary carcinoma of the lung end pulmonary aebeatosia. islyaia of the literature end report of 3 cases. American Journal of Pathology* ?, 1943, 7*?*- A review of the literature on the association of pulmonary asbeatoais end ircinoma,.,Xn this laboratory the association of tho two conditions Xa remarkably .gh* (3) there was no reliable answer to the question of whither asbestos was ivolved in the aetiology* (l) Referred to in Lae and Selikoff ,(1979) ADsfcractad in Bulletin of Hygions, U Journal of Industrial Hygions, 6, 1944, ISPG*" y,c, mcai-in its relotion to occupation and environment. >cletv for the Control of Cancer. 25. 1943, 63, Bulletin of the American "Asbeatoais cancer of the lung la the most recent newcomer among the occupiionai cancers of this organ,* Author as quoted by <2) Referred to by Entorline (1978) . ,ftPOiB, P. and RABIN, C. Notary neoplasms of the pleura. Archives of pathology, 11, 1931, 385, ... published an account of five primary neoplasms on the pleura, although is/ did not clearly establish tho relationship with asbestos exposure, (l) Referred to by Lee and Selikoff (1979) mt, a.j. .licn<de and asbeatosla, Oxford University Press, 1938, t Cxtendod the description (of pleural oabeetosis) in his text, (l) Referred to by Lea and Selikoff (1979) NCH, K.n, end CANNON, W.fl, ibestosie t Analysis of forty necropaied cases. 4-887. Pleeaeas of the Chest, /!* 1948, "One of tha outstanding fsaturos of disease encountered in advanced bastosis is pleural thickening and more or Isas ac&iesivs obliteration of the .aural apace" (S' "Apparently to the preesnt there are et least sixteen necropsied eases of rcinoaa of the lunga Xn asbeatoais, which, considering tho comparatively small tcropsy experience in the disease, aeeas excessive.,."( ) Referred to by Cnterlinc (1978) Abstracted in Journal of Industrial Hygiene, 31,, 1949. cont. /3 554 3. UKZ9ACX, A.3. snd WCOUft, H.W. Occupational cancer among asbestos worksrs, anatoeig. 2Q?t 1941, 357--*09. Virchows Archiv for pstholooia unO A esse history of one worker over the yottra 1921-1939...The author discussers the literature thoroughly end concludes that esbostotic fibrosis creates a local disposition.to cancer... (4) Abstroctsd In Journal of Industrial Hygiene, 24,19*2. LYNCH, ft,*'and SfitTH, V.A. Pulmonary eebsstoaia 3. Carcinoma of the lung in oobcato-oiiicosia. American Journal of Cancer. 24. 1935. "In flay 193S, Lynch and Smith published the first report of lung Careinoca in esbestA-alllcosie...* (l) "The pleura of the right lusg is thickened as a whale.***' {1} Referred to by Lee end Selikoff {1979} EnUrline (1978) Abstracted in Journal of Industrial Hygiene, ^17, 1935. L^CH, K.fl. and U.A. pl^pfrgry eabestosie ; a report of bronchial carcinoma and epithelial metaplasia. American Journal of Cancer. 36. 1939, 567-573. "The euthore report a second ease of esBesiosis with pulmonary cancer and cite 6 others f*ora the literature" (4) Abstracted in Journal of Industrial Hygiene, 22, 1940. flALLORY, T.9. CASTLEflAW, 8, and PARRIS,E.C, Pleaothelieaa of pleura and pericardium. Nay England Journal of Medicine. 236, 1947, 407. "Acaso of mesothelioma of the pleura and pericardium in an asbestos worker" (1) Referred to by Lee end Selikoff (1979) flCRE^THER, E.ft.A. ; aittl Report of the Chief Inspector of factories for he year 1947, Presented ...to Parliament ... January 1949, H.h.S.C, p.79-81. ",..a report by Pisrowsthcr,, in 1949, compart lung or pleural cancer in cases of asbestosis reported for compensation with lung or pleural cancer in cases of siliceele* This was clearly the most important single study in bringing about a consensus in Crest Britain.*' (2) t Referred to by Lee and Selikoff {1979) Enterline (1978) in bulletin Bf-Hygione KORDflAKH, IU Der SatufsUrBba der Asbesfcertteifcer. Zeitschrift fur Krabsfotschuno. 47. 1936,286. An account of two eases in Ceimany, which, like those previously reported, exhibited a long period between initial exposure end the appaoranee of the tumor, (0 "ft cause-effect correlation must be present here, even if 1 had been the only observer, us ora indead facing an occupational cancer which affects asbestos workers*. Author es quoted by (2) flefeneef t> By \ e*# frf ni*r.'mf f'/'y ' ) cont, /4 555 fijiiSb 4 ROBERTSON, H,, CndotheUowa of Vha pleura. Journal of Cancer Research. 6, 1W4, 3l7. Referred to by tee end Selikoff (1979) WEGtER, H.tf. Uber den Luncankrebs bei Aabestoso, OButseho Archly fur KMnirho M*rtir1ri"h 121 1934, 189, . "round a prevalence of of pulmonary carcinoma In 92 peataorte# repor ts cn. a^bastos workers described from'various parts of the world" (l) Referred to by Laa and Selikoff (1979) UEOU& K,, fAsbaetoa end cuiraonarv narnlneaal. nmitsehs PJadf rlnlsche litanhan.chHff *o 1943, 57S-6. ------------------------------------- ----------------- :---------- *~ "kfadler and kfelaa first noticed an association between asbestos and p2et/rs2 mesothelioma* Quota from a paper given by Gluckaan end Hurwitz in "Pneumoconiosis: Proceedings of the International Conference" ^ohannosburo. 1969. m1 "The author has collected the published autopsy records on asboatosla fro* arious countries end flnda that there have been fourteen instances of malignantdisease of the lungs end pleura in ninety two post mortem examinetione This ie in excess of the proportion of lung carcinoma in autopsies generally <2-6). ' There was often a long interval between cessation of expeauso sod the development of cancer, which in the authors view suet ntm be treated as an occupational disease." (2) end (4) Referred to by Enterline (1970) Lea and Selikoff (1979) Abstrocted_in Sulletin of Hygiene, ij , Hl#V Journal of Industrial^Vygiene, 26, 1944. UCOLER, H.W. "...in 31 cases of asbsstosis autepsied in Germany end described by Wedler in 1947 thewere two malignant tumours of the pleura. Referred to by tee and Selikoff (1975) full reference ?ot given. LZ,A, (Further observations on occupational carcinaaa -1c .a&heshos .workers). ArcMv fur GsverbooatholoQie und Geuerbshvolona. 11, 1942, 536-50. A record of 2 cases of asbestosis complicated by cancor of the lung. The author suggests there is a causal relationship between asbestosie end car cinoma. (3) and (4) Abstracted ln Sulletin of hygiene , t2, Journal of Industrial Hygiene,26, 1944, krrcRs, h. Asbestcsis, Postgraduate fledlcal Dournal, 25, 1949. /< (this work was originally reported in a thesis for the degree o hedicine at the university of Slesgou in 1945) UkAtJi* tar of coot. /5 556 .e *'ln the present series of thu patients with asbestosis also had primary csncor of the lung. This is all the more striking because so many of them were females" (0 Uyara refers to a case of "endothelioma of the pleura" ' Referred to by Us and Selikoff C7> Abstracted in Bulletin of Hygiene, WOOD, to,s; and GLQYNE, S,R. Pulsonery eabeetosis* e review of one hundred cases. Lancet, 1934, 1303 Reported two cases of lung earcinoaa soen et autopsy in 43 cases of asbestosis, (?) floferred to by Enterline ($978) Abstracted in Sulletin of Hygiene^fC?, MJS**. (1) Lee, O.K.K, and Solikoff, 1,3. Cnvironmental_9etearch, 16, 1979, 300 - 314, (2) Enterline, P.E. American Review of Respiratory, Oiseae*. 118. 1970, ?7S - 978, (3) Bulletin of Hygiene (4) Journal of Industrial Hygiene (5) Author etre