Document wjgEkvxdzG4nmoMny580y8vo

'mar .i INTEnXATTONAL CONTEDSyCS t on the BIOLOGICAL EFFECTS OF ASBESTOS Roport on Proceedings by Dr. X TAYLOR Departraent of Social Medicine, Queen's College, Dundee. November, 1964, ii . i i; A 17 90 v PLAINTIFF'S EXHIBIT CONTENTS I, Occurrence and the Major Use of Asbestos II. The Incidence of Asbostos and the Association of Asbestosis and Intra-thoracic Tumour.' III. Environmental Asbestos Exposure IV. Research Matters Arising from Asbestos Conference V. Clinical Criteria - Asbestosis and Radiological Appoarar.cos. VI. Colloaguos 1/orking in Asbostos Rosoarch Fiold VII. References Pago 1 10 A 1790b I. ' Occurronce and the Major Use of Asbestos rc,u. Serpentine -:-{?.VS0T IIS Asbestos t:CROC IDOLITE .AMO SITE Amphibolos TREliOEITE ACTINOLITE The important members of these groups are: i) VSGins - White asbestos, a hydrated magnesium silicate jrith the formula (3MgO 2Si02 2H20). Sp.g. 2.55 with a long fibre of tubular structure. . > rnoriROLTTE - Blue asbestos (N'i^O 3FoO Fo,,03 SSiO,, HgO). Sp.g. 3.37 viih a high resistance to acids and alkalies. ; .'''CiVIT?. - V.hitish-fawn, ferrous magnesium silicate (l.5flig0 5.5FoO Ho0). Sp.g. 3.45 the Ampkibolcs ail have 8 silica units with 7 mineral units and 1 wator molecule. 4 ; 790f; The annual world production of asbestos minerals has riser, iron 5CC- tons in 18S0 to over 3 million tons in 1S33, mainly from Canada (Chrysotilo and Crocidolito), South Africa (Amosito), and Russia (all three varieties); l thoao throo countries producing C3 per cent of tho world production, and oloven countries, including Finland, providing tho remaining 13 per cont of the world production. .. There arc many industrial uses for the manufactured products from asbestos minerals which follow from the chemical inertness and high thermal insulation properties of asbestos fibre. Because it is important to ascertain whether a clinical case has been exposed during a lifetime to asbestos in anv fora, it is necoauary to know tho industrial applications in detail. Tho following list includes the major usos:- 1. Asbestos Mining. 2. Asbestos Textile Manufacture (woven and non-voven), mattresses, curtains, safety-suits, pipe covers, filter presses etc. 3. Asbestos Cement Products (sheets, partitions etc.) 4. Asphalt and Vinyl asbestos floor covor'ings. 5. Roof coverings (in spray form). 6. Clutch and Brake Linings in the Automobile Industry. 7. Fillers for paints, caulking compounds, and in plastic rosins. There arc now over 3.000 industrial applications recorded. The hazard from Asbestos Bust arises in Industry in many environments: (a) Ship breaking and demolition yards. (b) Ship yard maintenance (dockyards). (c) Ship building yards. (d) Sawing, drilling and grinding of usboutoo products in brake lining works-. (6) Sawing, grinding, levelling of asbestos sheets. (f) '.'.'caving mills, especially in screening and preparation rooms, picking, stacking, carding, spinning, winding and weaving. _ (g) Spraying buildings to reduco fire risk. (h) The bagging of asbestos products - Insulation materials. (i) Demolition ami ronovul of pipe lagging in all industrial works. II. The Incidence of Asbestosis and the Association of Asbestos ond Intrc-Thoracic Tumour At this conforonco, tho nood for furthor epidomiological studies or. asbestos in ail countries vas strossed. Ihoro was vide divergence in tho fow opidomiological studios presontod on the incidence of asbostosis, and this was even r.oro apparent in tho figures presented front Canada, South Africa, the States and tho United Kingdom, on the association of asbestos with intro-thoracic neoplasms. In this respect, the Ministry of Labour, through the Factory Inspectorate^^ appear to be ahead, in that they have been collecting mortality data since 1924. With the size of scmplo now presontod, tho figures from England and Walos would appear to be tho most roliablo of all tho countrios roprosonted at this conference. In summary these are: Year 1924-194? 1924-1955 1924-1063 TABLE I Asbestosis (unc omplicated) 128 365 584 Asbestosis (Intra-thoracic tumour) 22 65 146 Tho proportion of asbostosis death cortificates which also record a thoracic tumour, has risen in both sexes disproportionately to the number of uncomplicated asbostosis, so that currently over SO per cent of males dying with asbostosis have also a neoplasm. Even who::. viewed against the steadily rising incidence of lung cancor in the population as a whole, there seems littlo doubt that the incroaso is a real one. Soiifcoff, (2) in the Now York area, and using data from the Asbostos Workers Union (total population 632) for the period 1942-1962, has recorded 45 deaths, 42 of these duo to carcinoma of the bronchus and 3 to pleural neoplasms (mesothe lioma), giving a death rate 6.8 times highor in asbestos loggers than in tho general U.S. white, male population. In the studies among asbestos workers in this series, it is interesting to note that cancer of tho stomach, colon and rectum was throe times as frequent as expected, thus focussing attention on the relationship between industrial asbestos exposure and carcinoma of the gastro-intestinal tract. Whilst x-raying tho large New York series, Selikoff('3)' noticed a high incidonco of ploural calcification amongst asbestos insulation workers, and tho suggestion nudo at this conferonca is that ashostoaia is perhaps tho most common cause of ploural calcification in industrial countries at prosont, ospocially if bilateral. Of 1,120 pipo loggers oxamined: /TABLE II ... . k .'790 0 --4-- TABLE TI liadiolnxical Examination of Pipe Loggers Lapsed Time Since Onset of Exposure 40 30 - 30 20 - 20 10 - 19 Number Exam ir. ad . $ 121 194 77 379 Grade Calcificaw: 57.9 3-1.5 10.4 1.1 He concluded that lapsed tine, since onset of exposure, is more important than total exposure. The common sites of pleural plaques diaphragm, costal margins, anterior and posterior-mediastinal, pericardium, inter-lobar fissures and even lung apices. Many plaques -were missed in the early days, (e.g. theso aro obscured by rib shadows)'. Two modifications of procedure have now brought many more calcifications to light: (1) Obliquo views aro always tuken v-.and Loft) (2) A higher penetration kilovoltagc is used if asbestosis _ is suspected. Pleural calcifications appear'to bo uncommon before 15 years interval or lapsed tine following first exposure. An average figure is 20 years. Ill, Environmental Asbestos Exposure This conforonco high-lighted a maxim well recognised ir. Industrial Health but insufficiently stressed in medical teaching - the importance of talcing a dotailed occupational history. Many cases in papers describing pleural calcification and pleural and peritoneal neoplasms could find at first, no association with asbestos. Careful histories, however, revealed chance environmental exposure to asbestos many years previously. Iioddcw '') in 1920, reported asbostos bodies in a nan not employed in asbestos, but living near an asbestos factory. At this conforonce Thomson^ reported the results of 500 autopsies in Cape Town and '500 in Miami, Florida. The result were similar in the two cities. 30 per cont of males and 20 pr cent cf females showoil asbestos bodies. In 0 por cent of tho males tlioro var. the possibility of occupational origin, but in 80 por cent of the positive tho presence of asbestos was regarded as tho result of contamination of the urban atmosphere. The origin of tho asbostos fibres was thought to be brake ar.d clutch lining disintegration, but this has now boon disproved and the problem remains unsolved, V.'hat is now required is a base line so that A 179 future trends nay be accurately followed. Th* eytont of tho probien: nay he v /larger --5-- larger xliri7\ v*c* ctnorcsiiii*^ prc^oriv* Aticng 37312 indiviwxi&* --r*wycd vr* Sarea around an asbestos nine in Finland, I-Svilnoto'''y found 499 cases of pleural calcification. In a control area, vithout an asbestos nine, no cases were found among 7,101 persons x-rayed. In this respect, concern .-.ay be felt for certain job categories. Pipe insulation workers undoubtedly sharo thoir exposure with other.trados -- electricians, pluabeirs, sheot-netai workers, boiler makers, fitaorc and ovon foremen. Perhaps =.. t'.io supervising engineer or urchiiuct should bo oxonined. In Belfast, where /7y thcro aro no asbustos factories, Slr.es' r found 42 cases of pleural mesothelioma in a population of 3/4 million in the period 1049-1963 (14 years). Between 19C6 and 1923, 1,000 tons per year of boiler conposition (S3 por cent asbestos) was imported f.r shipbuilding purposes and it is thought that the latent period of 40 years lias now produced the intra-thoracic tumours in Belfast. A positive history of exposure to asbestos at work vus obtained in 32 of tho 42 cases of pleural mesothelioma. Newhouse(' 8 )\ found S3 cases of mesothelioma from hospital records in London, 1C between (1917 - 1950) and 73 between (i960 - 1933). Tho interval between first exposure and torminal illnosn rangod from 16 to 55 yoars with a moan of 37 yours. A history of exposure to crocidolite was obtained in 53 per cent of cases and three main types of exposure were recognised: (l) Asbestos textile works (2) Laggers or pipe insulators (3) Exposure to dust brought home by relatives (d). Of the 3G patients with mesothelioma, with no positive occupational history and no. relatives living at hone who workod with asbestos, 11 lived within half a mile of an asbestos factory. Of the 33 casos found in London, 62 had ploural mesothelioma, an.l in 21 tho tumour was peritoneal in origin. Enticknap and Smithcr' ' .in 5-1- years (1958 - 1964) saw 52 cases of asbestosis at necropsy. Nineteen (36 per cent) had lung tumours and fourteen (27 per cent) had abdominal tumours, nine of which appeared to originate in .the peritoneum. The lapsed tine following exposure varied from 20 to 46 years and exposure time varied from 10 months to 32 years. Tho interesting feature of the peritoneal tumours associated with 'ndustrial exposure to asbestos was that associated lung- fibrosis and pulmonary changes arc below average in sevority (disability 10 - 30 per cent) and in some of those cases there was insufficient lung disability to qualify for asbestosis certification ( cusck). Jt was also suggested that the incidence of peritoneal tumours -t.'ht veil he very much highor but for: (a) me shorter life span of tho severely affected worker where* dust pathology predominates. v*>/ diifscult differential diagnosis from other forms f': 'lomimn neoplasm, i.o. Carcinoma of stomach, .-v::*.* le.s and many unclassified cases of tumour. 4 1 7 9; 0 --G -- IV. I-osoarch Matters Ariir.*' f.'f.J Asbestos C<~.r. Tnr-*:*..-;; '.(l) In future work, tho exact v.-n.; of asbestos dust `Bust be identified. Thoro is insufficient data correlating typo of duet and subsequent 'pathology. Animal experiments aust ha conducted with standard dusts. (2) Tho exact significance of particlo size is not known. Originally it was thought that only conrsc ' fibres were responsible for lung changes but tho conference felt that ultra-microscopic particles will also produce fibrosis (loss than 2 microns). The M.A.C. 5 million/n is not now accepted. This conference node it clear . that industry should aim at 1 million/m maximum and accept this figuro with reservations until our knowlodge in this field is extended. (3) Tho pathogenesis of asbestos is unknown. The following scheme asbestos fibre * macrophages lysis sclerosis -} fibresis -> carcinogenesis is thought to bo an inraunity reaction associated with gammaglobulin. The roaction is not now regarded as explosive in nature but is a slow, insidious, low grade, progressive fibrosis with early fibrotic changes around the bronchioles. Thoro is thickening of bronchiole walls ur.d of the pleura. In its early phase the lesion is not obstructive. Finally there is the formation of tlic asbestos body, a forriton (iron-j>rotoin complex) surrounding the- fibre and is laid down in concentric rings. Later tho asbestos body becomes fragmented. Asbestos bodies ore difficult to find, will require polarised light, may not be characteristic of asbestos only, and may contain metals other than iron. Small bir6fringent bodies seen in lung tissue have always been accepted as asbestos, but caution is r.ov required in interpretation. Electron-microscope studios are now proceeding at Cambridge. The conclusions are (a) that all asbestos bodies so identified nay not bo due to asbosaos, and (b) that there is difficulty finding asbostos particlos less than 10 micron without tho nncossary techniques. v-i) Asbestos fibres nay migrate from tho lung and liavo been feund in spleen and livor. This migration nay explain the presence of gastro intestinal malignancies, but again, fibres nay bo swallowed direct (ingestion of bronchial secretions). (l) There does appear to bo a direct correlation be two an asbestos dust exposure tine and tunour formation. Thero is, however, strong evidence reported by V/agncr in a large series of cases cf mesothelicnn that crocidolito is more dangerous than chrysotilo. In North Amori. a however, chrysotile has been associatod with peritoneal tumours. There havo boon no case.-! reported fren South Africa of tumour form.vi i,.;j where the exposure was to tinosiue only, but one tumour (peritoneal) has been reported by SoiikcTT with anosite. Vo/ The natural asbestos mineral;, as mined, always contain mineral oil (up A ; 79 | 1 v I''i b, i* \ i* 'id k'u * u I i Ii the ril-.'.-i icul fi.rld : :::. itor iNt.: ty Ilusor.rch Institute (Sr, I!urr i:i>'tr.R). no idonoc of bronchial care in. ;>1 curul nesntholi ur'.-is , peritoneal tumours and possibly gaatro--.:r;<i..tinai malignancy might bo explained by the fact that tho asbestos '.worker is sow in the so--cc.li.od "tumour formation period", i.o. 20 -- 40 years following tho first exposure. If this is tho pathology with asbestos fibre, then've shall require to look closely at fibre glass, a later development, now in.production IQ -- 12 years in Scotland. Personnel exposed to this fibre will not have arrived at the tumour formation period for a further 10 - 12 years in Scotland, but in Germany, where tho fibro glass process originated, a production time in tho region of 20 years is reported. (S) Thore .are largo differences both in morbidity and mortality of asbestos in the surveys in different parts of`tho world. Those discrepancies may be explained by the different chemical nature of tho minerals, but there is $,t tho sane time, au urgent need to standardise radiological findings and histology. (0) Therowere tod many small surveys presented at this conference without, the required statistical control, da overall epidemiological study is urgently required. (10) In malignant tissue arising from asbestos, tho characteristic lung histology is not easily interpreted. The loose, fibreus tissue is not particularly malignant-locking. Tho fibrous tissue is infiltrated with clefts lined with capillary and alveolar pseudo-epithelium, the whole picture being difficult to distinguish from adenocarcinoma. (11) In tho experience of tho M.il.C. Pneumoconiosis Unit, there is evidence that chest disease in asbestos workers detected by means of x-rays is more serious than pneumoconiosis or silicosis with similar radiological findings. (12) Tho average age at death when tho asbestos hazard was first recognised (190?) was 33 years. In 1934, the average ago at death is 57 years. It must, howovor, bo recognised that hoavily exposod people are st.:3 ' dying in 1964 in their 30's and 4C's. (13) There are two groups of asbestos workers in which the risk of asbestos and malignancy is high; (a) pipe 1aggers and demolition war . :\s, whore tho exposure will ho constant over many years, and (b) ashes to- sprayer, where the atmospheric concentration of asbestos is very high. (14) Thero is a vast improvement in dust control in lnr.70 manufacturing works whore tho asbestos hazards are now recognised an:" controlled, whore provontivo measures will eventually reduce tho r.L*;::i" ino i 1!. asbestojitfi. Small units, how.ivor, are still r.ot Uuut free and ar.. .; t. - -net to environmental control. In this respect, the effect of the ' combined with long working hour- at that A\) 7 9 1 2 V. Clinical Criteria - Asbestos:s Throughout tho conference there woro nany references tc signs and symptoms of asbestosis. Those nru:-- 1.Vaguo chost pains -- a vory curly symptom ' 2. Bypsnooa -- may bo first clinical symptom 3. Unproductive cough or bronchitis ir. an otherwise he-.l thy subjec with no previous chest history. 4. Loss of energy and generalIy off-colour. Early symptom, 5. There is little or no tendency to asthma. Lung function tests are not of great value in the early stages, other than to establish a base line, o.g. pro-employment examinations, 6. Basal rles - early sign. 7. Finger chubbing - noted in about 20 per cent of cases. 8; Pleurisy nay bo first indication of asbostosis, with or without associated ncoplasn. 9. Pneumonia nay also be first indication, as in S. 10. Peritoneal tumours nay often cone to light (a) Vague abdominal pain in any quadrant of abdomen (b) Abdominal discomfort. Indigestion is ar. early symptom and an employee complaining of vague discomfort is soon by the Fnc tary (c) Ancitos. Patient may report for a slimming diot, as happened in ono caso Enriiolor;-teal Ar.yjoarar.ccs 1. Basal distribution and commonly bilateral is characteristic of asbostosis. 2. The low grade, interstitial fibrosis gives rise to coarse, linear markings, more common in tho lower lobes on both sides, and spreading into tho niddlo lobes, described as "honey combin, 3. Pleural thickening (lung, diaphragm and pericardium). 4. Tho presence of calcified plaques. 5. An uneven right border of tho heart - "the shaggy heart" sign - pericardium thickening. VI, Kamoo and Units of Co? lentrnn?) UorhinfT in tho Asbestos Research Vi cl it l: )r* J C Gilyon M.R.C, Pneumoconiosis Research Vr.it, Glamorgan, Vales. i*T i u# C* As'above 3. Dr. T7. J. Saitfccr (Member of the Asbestos Research Council) The Cape Insulation and Asbestos Products Co. Ltd., London. (Medical Officer), r Dr. S. Holmes (Dust sampling and. counting techniques) Turner Asbestos Co. Ltd. Rochdale. O. Dr. C. G. AGdingley ( 'Royco' export) British Belting and Asbestos Co.' Ltd St. Peters Buildings, York Street, Leeds. O . Dr. Ross Hunt (physiologist and dust expert) As above 7. Dr. J. C-. Davis (Electron-microscope expert physicist) University of Cambridge, Cambridge. 0. Dr. J. C. McVittio .0 Dr. 17. D. Buchanan Ministry of Pensions and National Insurance, London. Ministry of Labour, London. 10. Dr, J. S. Harrington Chester Beatty Research Institute, Royal Canrer Hospital, London. ,11 Dr. K. E. Ayer Public Health Service, Division of Occupational Health, ) Braun. D.C. Tvuan. T,P. (lOoP,) Epidcniological Study in Lung Cancer ' in Asbestos Minors. Arch, Industrial Health. 17 : C:i-,-6~ ) y/nftiuir. rs , C.A.. Marcli.-.iu! . i\ (lOtiO) D: fi'n.-;,- l-lcur.-ii Mesothelioma and Asbestos Exposure in N.V/. Cu;.u Iravincu. B.J.I.M. 1? ; 2CC-A71 ) McCnughloy. ff.T.E.. Wulo. O.L.. Elmos. P. (lflGu) Exposure to Asbestos Dust and Diffuse'Pleural .Vesotheiio.r,.i. 2.M.J. 2 i 1307 ) Vagner, J.C. (1332) h'aturo. ) gftgnor, J.C., Mundny, D.E.. Harrington. J.S. (1062^ J. Path. Dact. ` 136 ISO 73 vrx kef i-i'CHCCS (1) Annual F.eport of Chief Inspector of Factories for the y-.-ur 1 355. Hor Majusty's otutj oner - Ofi'iae. Annual Aoport C. : 2C(j. (2) Sclikof f I..7.. Chnrg, J,. v . E.C. (19G--: 2 Journal of the American Ih.iical Assoc*..tien, April, p.22 (3) Asbestos Conference, No# York (1GS-1). (0 Hnddow, A.C. (1329) Lancet - 5 : 23C-231 (3) Thomson, J.G. University of Cane Tora Medical School, Capo Town Asbestos Conference (1364). . f (6) Kivilnoto, H. (1530) Pleural Calcification as x-ray _ign of :coii-occ upas i onai End or?.. s AnthupV.yllito--A..'.cs-,;osir'. Acta Audioi. fjuppl. 104 : , -37 (V) Elmos. P.C. (19;:- 1 Tho Aulutionship of Exposure to Asbestos and Pleural Mall nancy in Col fast. Asbestos Con .'or one o, New York (1964). (8) Newhouss. M.L. (: 36 :; Epidemiology of Mosotholial Tumour.-; in tho London Area. Asbestos Conferencej Now York (1964). (9) Entickr.nn. J.i). , Smither. T7.J, (lib :< Peritoneal Tueinurs in Asbestosis. 3.J.I.M. Ul : 20 Eurthor ?- fore near. - lAnor? mi A.-b^.stos not specificnllv .-'fa ><] be, in t..--. (e.) Lynch, IC.ut. , fsmjf.h, "!,A (1035) Pulmonary Asbestos!.^ Carcinoma of Lung in asbesios-3iiicosis. Auer. J. Cancer 24 : 56-6-1 (b) Ackerman, L.V. (1S5-;) Atlas of Tumour Pathology. Armed Forces Institute of Pathology, Washington. (c) Doll, R, (1955) Mortality fren Lur.g Cancer in Asbestos Workers. ,, 2 i 31--f.-'j (>) Braun, D.C. Tynan. T.D. (1S5B) Epidemiological Study in Lung Cancer 1 in Asbestos Miners. Arch. Industrial Health. 17 : C.'i-I-O.",:; () VAiftnor. -i.C,. SI.,.pry, , fl.A. . Mm-chr.r.d. E, (lOiiU) 1A f iu < l icUi`.ll Mesothelioma and Ashes to.-; Exposure in N.V/. Ca;n: 1 vine*:. 2.J.I.M. 7 : 2CC-271 vf) McCaughloy. W.T.E. . V/c.de, 0,L.. Elmes, P. (lGu) Exposure to Asbestos Dust and Dii'fuse 1 Pleural Mesothelioma. 3.M.J. 2 s 1397 (t) Wagner, J.C. (1932) Nature. 12B . i$o 00 V.'qgnor, J.C., liundav, D... Harrington, J.S. (1962) J. Path. Dact, 73