Document 2NrRQpzkRwzBjBDxXJVVD4Qj5

AIA-55 jN'cw Scic:i;ist 7 ;; * \ ***", .</ - 1 J <x*\ ^ d 'V-fc'' -J "n :a:it few weeks its report on asbestos hazards 'vising in * ',,i *V C I..lit concern;.': 3 tit j iioslfh ry of uis;i ::' 3 00 + ? i`j dcnne.'j o; Il.'fis v/ie'e, u.IOmJ /\ 1C-'Cy ! \J \ <1 l C \ 'J C V O rc *) p u L) 1; Or Cl'rh :.o nn^r ig nzr wnr- for;.". Asbosiosi ;sec L-cilo-.v in Jc!:n;.;;c:-bi-ir7- Ke is now n incrr.bcr of the 5d>'::ti'.c stuff of the Mcdiwil iU'-senrch Cotiiwa's Pneumoconiosis Unit, Penarth, Wales ?i Figure 1 World distribuiion of asbestos usage Figure 2 V/orlJ Uijtrlfiuticn of asbestos mining As rom the Creel for un-'ut. j is ^ c r p^i ci i } r ** r,ri f1. nil' ;.' 'c r found l':r ' \\ :v/o . j - j : Cni-y-on : cir.-i tii amphibei: ci' include -TmilO (Lilia nrr.c;j:o . : W*"s; .. y;,;, c (w i,;; . Althea; outer no:.. pruyslcally an< chernicaii;yt there iHKicrais iici^vvec two common features: they can bo woven and arc resistant to flames. These properties were recognised by stone- age men tv ho used asbestos to manufacture cooking utensils, and were appreciated by the Egyptians who used asbestos cloth for the ceremonial trappings in Royal cremations so that the ashes of the corpse could be readily retrieved. From this early period, asbestos materials were regarded as curiosities until the late 1870s. From then on the value of asbestos in the industrial age began to be realised. The ancient mines in the Alps, Cyprus and the Ural Mountains were re opened and huge new deposits were dis covered in the Province of Quebec in Canada. As the demands increased, mining engineers remembered reports of a blue fibrous mineral seen near the Orange river in South Africa. * Initially, asbestos was used for fire-proofing and heat insulation, but other uses were rapidly discovered. Mixed with cement the asbestos acted as a scaffolding in making roofing tiles, 'wall boards, plaster boards, pressure piping, guttering and ceiling tiles. Finely woven asbestos produced an ideal filter To? beer, wine, medicines, and removing bacteria from drinking water. When coarsely woven and later combined with resins, asbestos formed friction materials ideal for the brake lining ami clutch facings. It may be bonded with asphalt and plastics for fioor tiles, roofing materials, and more recently, for a diverse range of products. This bonded material was used in the covering of the nose cones of space-craft, where an outer covering of asbestos overcomes the intense heat of re entry into the earth's atmosphere. With this wide industrial potential, a rapid C.^pvir.o.or; Of [:.';e world' !.:s cccurra-'. 'am ICO '.ev.es ore; *1 J J w J - - . iC-72 7 the v;:;.:e ;t or is ioend in .-r.iLi-.c, 'u scale tl;e bl - ' 0 C 510 5 original site .r,' (iibCovi, river in the Ce ;;e Pr.r, irv At first it wss difficult to fir.,I ,t rvr.ke. ;* the blue fibre. Thou, in 1CCD, ike Gera-.-. Naval Engineers were looking fov a itfiufi,' material for fire-proofing the ships of the German Navy. Chrysctile had proved unsetl. factory but the blue crccidoiite was found t bc fur more resistant to corrosive fluids a;, sca-water. They decided Lherefore, to use ifiu: material in their ships and were followed b;. Britain, France and Italy. Factories to prepare the blue fibre were established in Loudon, Paris, Hamburg and Turin. The blue fibre occurs in banded ironstone, . was discovered later in the Transvaal asso ciated with a brownish-grey fibre (amcsitci. and both these fibres wrre then produced commercially. Later, the blue fibre was round in Western Australia and Bolivia. Several other similar fibres were produced commer cially on a small scale in Finland and the slate of Georgia in the USA. but amphibole fibres never accounted for more than 10 per cent of . the total production. Figures 1 and 2 show where the asbestos is produced and v.-lierc it is used. It cannot be disputed that asbestos has been extremely vnluab'e in saving lives and improving the quality of existence for a large part of the world's population. One only has to consider the part played by asbestos in fire control and the reliance of vehicles on asbes tos lined brakes. Countless human lives Iinvu been saved by the insulation of passenger aid naval ships, and by the removal oC bacteria by filtration from potable fluids. However, con comitant with the increasing use of asbestos people began to realise that there were a number of health hazards to" those exposed to the airborne dusE. . pure 4 Pathological eturc of _ isothclioma ' lUAQ i>3fe4 p^ure due to tufnouf Tdiucrpnnoruotgomf% 4 In 1900 a post-mortem on an asbestos worker in London showed that" he had died from scarring of the lungs, not due to tuber culosis. He was the last survivor of ten men, less than 35 years of age, who had been work ing for 14 years, with asbestos textiles. A similar incident occurred in Normandy. During the next 30 years, sporadic cases were reported from among the textile workers in Europe and America, and the workers in an asbestos mill at a mine in South Africa. In 1923, Dr E. R. A. Merewether, the Chief Medical Advisor to the Inspector of Factorics, considered the whole asbestos industry in Britain should be-studied. He conducted 211 investigation with an engineer named C. W, Price. They found that 28 per cent of the asbestos workers in the textile industry had evidence of pulmonary fibrosis ("asbestosis"). This report was published in 1930. In 1931 legislation was brought in to improve the factory conditions, and allow for initial and periodical examination of the people em ployed in dusty processes. Then, in 1935, cases of carcinoma of the lung occurring in workers with severe asbestosis wer*t London and South Carolina. However, before the suspicion that the tumours were caused by exposure to asbestos could be more fully investigated, Germany and Britain began re arming and asbestos became an csseutial product so that precautions in its use were by necessity not so strictly enforced. lu Britain, there was a sudden call for gas masks with blue asbestos niters. When the War came, the ventilation of the factories be came worse under black-out conditions, and AIA-55^ re. lb::! ;d r..:d the i.. tut..... :: bole ashcsler. Iroi.t .South /hues wot ,, top priority, as the fibre wes re<;;i;: ed for subbing the nuva! vessels and Liberty j.np; under cuustriictio::. - McrcwcliuT red his colleagues warned the inausl ry of ike (Lingers, but receptee- t!:e fee: that iitlic could bo improve;', our;::;; the War. He continued to cciiect cviib ncc of career ;.f the lung and in 1947, hr rw-irte;! that id par cent of nil rb-nlh certifier.!i-s fur men oh mentioned a; heliosis, recorded tiir.t death v.v* dun to cancer of die lung. By 1932 it liu per (c;;L 2*10 iti wdL' ovc.ii' 'jo ''c.. coni, i;', ii/jo. Sir Richard Doll studied those in dusty occupa tions in an asbestos textile factory and con cluded that the incidence of etneinora.a 3: ti.c lung was ten times higher ikon expected. At this stage, a further hazard cf asbestos exposure was discovered. In South Africa we saw a series of rare tumours of the chest wail. The chest is lined by a double layered rm-m- brane called the pleura (Figure 3),- this separates the Sungs from the chest wall. To allow the two layers to move smoothly during respiration, they are lined by a layer of lubri cating cells called the mcsothelium. These rare tumours were mesotheliomas- arising from this tissue (Figure 4). In 1937, we diagnosed 1G of these tumours and by 1SG1, 5 had occurred. In the few cases in which lung tissue was available asbestos fibres were seen. Epidemiological studies revealed that the majority of these cases had been asso ciated with the asbestos mining area of the Cape Province where the blue asbestos (crocidolitc) was mined. ' South Africa produces all the major types of asbestos -- chrysotilc, crocidolitc and amosite. We had been studying all the asbes tos fields and the mesotheliomas were only associated with people living and working in the Cape asbestos fields. There were ether important facts. First, these tumours, unlike the carcinomas of the lung previously re ported, were associated with exposure to asbestos dust and not necessarily with severe pulmonary scarring which was a feature of the cancers of the lung in asbestos workers. Second, in some cases the exposure had brer, for only a few months. Third, there was a very long period between initial exposure and the occurrence of the tumours. In some cases, people who had been born on the Cape asbes tos fields and left in early childhood developed these tumours in their 50s and GOs. This was the first time that a specific typo of asbestos bad been incriminated. To test 'die *TiV.l*b' Vf uw , *, - 4 - these tumours occurred among those people working with the blue asbestos in Europe, and. not in places where the exposure had been to other types of asbestos. The latter wore hard to find as, in the majority of industrial countries, the asbestos workers have bee;-, exposed to several types of fibre. It there:'; : became important to compare ccadit.e:" the asbestos mining areas of the C Province ir. South Africa, with those :r:r Quebec, C-r.udu and in the Svcdlosk e::e AIA-55NcwG03 StirutiM 7 Mr.rrli If,7; Suniinr.rv of JAHC fiiulinjs on asbestos hazards* 1 Tii.it .:!] types of osbestos produce piileicn.-iry scarring if there hns becti excessive exposure to inn dust. 7 C.\i;tvr of the iuir; occurs among workers who have had excessive exposme to ail types of iishestos dust. 5 Cancer of the lung is far more common among workers who arc acurettc smokers. (The two carcinogens, asbestos and riravette- smoke, attpear to combine multiplicative!)' in Hie produedon of king cancer.) _ -! iUercikeiior.iar of tile pleura and the peritoneum (the lining of tiie abdominal cavity) arc more common among those exposed to asbestos ihar. the general population. More than 1 GOO eases have been reported in people exposed to asbestos. 5 There is no evidence of an increased rate of mesotheliomas among miners, and those living in the vicinity of the mines, in any mining area except the crocidolitc mines in the Cape Province in South Africa. "_ _ G In industry, crocidolitc asbestos has been,definitely impli cated in the development of the mesotheliomas, and crocido- litc asbestos has been identified in the lungs of asbestos workers with mesotheliomas from Germany, Italy, Britain, France, Holland, Sweden, South Africa, Australia, Canada and the United States. Id two reports from the United States it was stated that men who developed mesotheliomas wore exposed only ro chrysolilc or only in .-un.r.uc. p.u; evidence of die amount and type of asbestos .'.ctu.dly in the king, o: these eases of mesotheliomas ha> not been produced. The risk of mesotheliomas is, on present evidence, generally agreed to be greatest with crocidolitc. 7 Mesotheliomas have occurred in people who have had neighbourhood - ;;osiue to asbustos dust either from living in close vicinity to mills and factories bcfoie the dust was controlled, or from the cleaning of protective clothing of relations who brought their overalls home before this prac tice was forbidden. 8 It was shown that asbestos fibres could he recovered from the lungs of the majority of individuals living in urban communities. However, there was.no evidence to suggest that anyone had developed disease from exposure to the ambicat nir. . 3 There was no evidence that exposure of the general popu lation to the smalt amounts of asbestos fibre in beverages, drinking water, food or pharmaceutical preparations in creased the risk of cancer. * These findings include both those from the Advisory Com mittee to the Director of the IABC and the IAHC Working Group on tiic Evaluation of the Carcinogenic Risk of Chemicals to Man: Asbestos. 0 I-0205560 Hie USSR. For such an undertaking, inter for insulating which had not been covered national support was required and this was effectively in the earlier regulations. They also . obtained from the International Ur' a modified the methods used in spray insulating. . Against Cancer (UICC) and later; the In: In the major factories automation was in , national ' Agency for P.esearch in Cancer creased. A great improvement being the wet (IARC). In addition, it was necessary to cstab- processing of the fibres for textile produc lish a good working relationship with the ; tion. Unions and the asbestos industry. This study In 1968, a subcommittee of the British Occu was based at the Medical Research Council's pational Ilygierie Society produced a report Pneumoconiosis Unit, which was experienced on the concentration of dust which had to be in the epidemiology of occupational disease. met to prevent the occurrence of asbestosis. , A considerable amount of research was cor-. The value they obtained was realistic aud ried out during the period 1962-72 .and in acceptable to industry, but only because.of order that the findings could be summarised the tremendous improvements that had occur ' they were `discussed at a meeting under the red in ventilation during recent years. The aegis of the IARC, at which more than ICO figure applies only to chrysotile, the most com experts on various facets of the problem took monly used type, and was based on very . part. After this meeting, an Advisory Commit limited data, though on all that was available tee drawn from this assembly presented its at the time. -' conclusions to the Director of the IARC. The The New Yorker articles contain mud: Proceedings and the Report of the Committee ill-informed criticism relating to the deriva will be published within the next few weeks tion of this hygiene standard--the limitations (sec the summary above). of .which were clearly stated in the original These findings, which summarise the state ` article. It is surprising that nearly ten years of our scientific knowledge about asbestos- after.the Conference on "The Biological related hazards, are given here bccattSg there . Effects of Asbestos'' at the Now York have been several sensational reports about Academy of Sciences., no definitive new data the dangers of asbestos to the general populs- have been published in the US relating tion, especially in the United States. In Octo- ' .measured dust dosage aud the incidence c: bcr/Noveinber, 1973 a series of articles in asbestos-related diseases. The New Yorker, an American magazine, In the large textile factory where Pro fosse : presented a highly prejudiced view, drawn Doll had found the high- incidence of cr- uncritically from the edits of a single investi cinoina of the lung, a further survey publish: gator. Fortunately, his alarming statements, in 1567 showed that tiie incidence ef car given in evidence in a recent legal case in the cinoma of the lung among those employed States, were exposed to heavy criticism. This after 1933 was no greater then the gemor.-i provided the court and the American public population. This indicated that if reaso.oabk with information from which they may bo aide precautions were taken, asbestosis and ;h. to assess better the validity of the evidence. carcinoma of the lung associated with it cm:', Meanwhile, particularly in Britain, steps be controlled. In the same year, the M were being taken to improve, the working cn- Inspector of Factories published ' viroerncr.t. The asbestos industry in this coun arising from the use of A.-beMeV. ",. try had formed the Asbestesis Research Coun gesfed that Elie use of ere. : cil which ixv.md a series of Codes of Practice a^i estos, sltotnd hi: contro-lei. . to ensure :i:e safe use of asbestos, csccdni'y Act was amended, and by A. . AIA-55 itutc 5 Physical form tile four types of . bestos aiithophyllUe . rrco'doKte chrysolite ' . scnosite fully i:nu!aicJ without - V/hat. gives live Idvc rSwiAts thu r prcrcriics which c::;i Ic^d f-> the d v... nicut uf these unusual ti:r;:o::Az y:.:, wa have no proved answer In:: some hove been discovered. IVncn ashes ,'cs is ;n- jee'ed into the pleural cavity of rau,, r.wso- thclioiiK'iS develop two years later. I: rat- hale liic asbestos tii-y develop r.zbcztos:: . ::d. in a few, cancers of the inn". Therefore, c have an experimental model tn tc:; varfone hypotheses. The firs;; hypothesis was p-1. ,er- ward by ilr jack ifar:r.;eta:i who found th.r. there were primitive oil." end waves associated with the blue asbestos, due to algae occur: bn; at the time of its original forma'.rir. seme ~fC j million years ago. These wanes contained small quantities of carcinogenic aromatic hydrocarbons. A series of experiments have shown no difference in the number cf tumours produced by the oil containing fibre .compared with fibre from which all the hyohu carbons have been removed. The second i.ir<'.:ws.iv was that trace elements, particularly nhm.. played a part in ths tumour dcvdoprr.c.-.. Animal inoculation experiments have shown no association between trace element content and tumour incidence. _ Recently, wc have published evidence indi cating that the physical form of the fibre is an important factor in the development of the experimental mesotheliomas, the crocidolitc fibre having a particularly fine r.cedlcdikc blue asbestos into Britain had ceased, and it 'could only be stripped from existing instajla'tion under supervision of the Inspectorate of shape (Figure 5). We were also able to pro duce the tumours with other fine fibrous materials.-This is important as a number of these were betug produced synthetically both Factories. * as a substitute for asbestos and as "scaffold The most remarkable improvement has ing" `for various composite materials. For been in the Hoyal Naval Dockyards, where ' some purposes from the engineering point of a considerable amount of blue asbestos had view the finer the fibre, the more successful been used as insulation and fire proofing on . the product. Our present experiments indicate the warships, particularly the aircraft car* that irrespective of the mincralogical nature riers. AU the blue asbestos has been removed all fibres less than 0*5 microns in diameter from these ships, using sophisticated pro* : may produce tumours If inoculated into the cautions, and has now been replaced by pleural cavity of the rats. Thus manufac-. material containing a minimal amount of turers may be warned of the increasing asbestos fibre. One frigate has been success' hygiene risk as the fibre diameter is reduced. Ksoestos Information Association North America 1660 L Street, N. W. Washington, D. C. 2C3s5