Document eyLZMJoLavX0XD99K7JbnEMG

' '*. ;' . !( -.V ', , a -1 `w .* i - J .*) .1 . I \* ^ _S .. J , U VI V,,> ^ -- u / , V t -1 w V> X . . i^ ^ V-.^ dviaifiC c. lawsuit ccr,corn;;: 3 ;fi : iiGSlfh c: >ry of d:c;r.:*.'!3 on t! it? darrje.'j o: .k.is v.ficoly L'coc: asir.-j. ' u. 10FtUi .Of O vl l V* * V 'J 'J w rch publioihcs e r.oxt few vvcs-ks its report on asbestos hazards Or C.'irisi.opfier \\'-1 Ufc /cV. w* v* wn? frn.icrly iScscarc;'. L-'cnuiv ut Jckaiwieiburi,'. >Ic is now c sy. ember oi *di 5o\'::0';'o JtidV of die Mecw.il iUiso.irch Coonoii'S Pneumoconiosis Unit, Pcnarth, Waics .? Figure 1 V/r,rid uiS'.i'ibuiion of asbestos usjse Figure 2 World diviributicn c; asbestos luinina' - ors*c. rorn the Creek for mi'.uc.i a br a. n;;::.- v c: found '.:: ' . :t Uvo mam ." . - j : c;::*yo* i P include . ar.:ph:b'.;c . , < i IT, C j < 1 0 ; u . 1 ' J i; ; }. ALnrm.r. w.ey uuicr ooo. puys.caUy chcrnicanv, tr.ccc minerals have two common features: they can be woven and arc resistant to flames. These properties were recognised by stone- a50 men -who used asbestos to manufacture 'i 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 lor beer; wine, medicines, and removing bacteria from drinking water. When coarsely woven and later combined with resir.s, asbestos formed friction materials ideal for the brake lining and clutch facings. It may be' bonded with asphalt and plastics for floor 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 ex p an j .o a o. : l;e wcrirl's asbestos orufi. . !.:s . ;00 *. 1 `i >> Jd 1CT7. T;:v. ;::.. ;rfiv of fi tiic *v*`..re " .. *.. a c u b o' Cd .* % or t c * r ' r */1. c v* is tour.'J ;r. .C.iLk.c, :>;;t on a r.mc;; s.:. scale Ike bk . -.-ocstos is .r.n.c-i .. o:.;inr:l site .*: wocov-ry n.-^v fi:: C;-- river m trie Ca ;;c Pro\ ince in At first it w-; difficult to fir..' the blue Acre. Then, ia 1CC0,. the Ca a-;. Naval Engineers wore looking for a cniiu.V material for Arc-proofing the skins of the German Navy. Chrysetiio hud proved rmst-ii. factory but the blue crccidoiitc was found t be far more resistant to corrosive fluids a:, sea-water. They decided therefore, to use thi: material in their ships and were followed b;. Britain, France and Italy. Factories to prepare the blue fibre were established in London. Paris, Hamburg and Turin. The blue fibre occurs hi banded ironstone, . was discovered truer in the Transvaal asso ciated with a brownish-grey fibre (amc-sitch and both these fibres wore then produced, commercially. Later, the blue-fibre was found in Western Australia and Bolivia. Several other similar fibres were produced commer cially on a small scale in Finland and the state of-Georgia in the USA. bat aniphibole fibres never accounted for more than 10 per cent of the total production. Figures 1 and 2 show where the asbestos is produced and where it is used. It cannot be disputed that asbestos has been extremely vnhrabm 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 have been saved by the insulation of passenger ar.fi naval ships, and by the removal of bacteria by filtration from potafcic fluids. However, con comitant with the increasing use of asbestes people began to realise that there were a number or health hazards to'those exposed tj tiic airborne dusL . ConoOo (cinyccrila) i;:e Sure 4 Pathological eturc of 4 isothclioma i! comof-ncd lu.15 l.5*U . ( - -- . .. dtnuiecktowt^uditxpotu*ufro_ TOuicmpAourorgoma 4 In 1900 a postmortem 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 titan 35 years of age, who had been work ing for 14 years, with asbestos textiles. A similar incident occurred in Normandy. Daring 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 Fac tories, considered the whole asbestos industry in Britain should be-studied. He conducted an investigation with an engineer named C. W. Price. They found that 28 per cent of the asbestos workers in the textile industry bad 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 were vr-porraw 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 essential product so that precautions in its use were by necessity not so strictly enforced. la Britain, there was a sudden call for gas masks with blue asbestos niters. When the War came, the ventilation c: the factories be came worse under black-out conditions, and ! C `U !<>: 'f.o' ro;:_ . Slutu:*, :..A the itut...,. bide .isbeite.'. Iro..! .South A(.;eo w.v: a top priority, as the fibre wi:j ro(;;:;:cd for si;i-tti;:g tkr naval vessels and Liberty under cui*s.`rnct:c:;. - Mcrewc.liur and 1;is colleagues warned the industry of the ci.infers, but accepted the f?e: tiiat iitlic coiiicl be improvt.d our;;:;; the He continued 10 cciiec: cviik ucc of cancer of the lung end 1547, hr ro;- irtcd that if par cent of ail death ce; tif cau s fur ir.eu w mentioned e;:e<t '.-sis, recorded that death w,1* due to cancer of iko luiip. By 10.52 i: 'eu per cent can in 103b over CO par cent. in. 1935. Sir Rickard Ball studied i!:e:a in dusty ceer.pn- tions in an asbestos textile factory cad con cluded that live incidence of carcinoma a: ti.c lung was ten times higher then expected. At this stage, a further hazard c: asbestos exposure was discovered. In South Africa we saw a series of rare tumours of the cl 1 ext w;a!. The chest is lined by a double layered mem brane called tl;e pleura (Figure 3); ibis separates the lungs from the chest wall, `i'o allow the two layers to move smoothly during respiration, they are lined by a layer of lubri cating cells called the mcsothnlium. These rare tumours were mesotheliomas arising from this tissue (Figure 4). Jn 1957, we diagnosed 1G of these tumours and by 65 had occurred. In the few cases in winch 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 -- ckrysotilc, 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 potted, were associated with exposure to asbestos dust and not necessarily with severe pulmonary scarring which was a feature cf the cancers of the lung in asbestos workers. Second, in some cases the exposure had boor, 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 end GOs. This was the first time that a specific type of nsbestos had been incriminatpd. To test ike nypoit,v.Si^. ifc <*< ...... these tumours occurred among those people working with the blue asbestos in Europe, anti not in places where the exposure had been to other types of asbestos. The latter were hard to find as, in the majority of industrial countries, the asbestos workers have been exposed to several types of fibre. It there:': ; became important to compare condition' the asbestos mining areas of the C Province in South Africa, with those :r:. Quebec, Canada and in the Svcdlosk e::e New StiruliM 7 ]f,7 -. Sunnnr.rv of 1P.HC finch'n.j3 on asbestos hazards1 1 Tiut ::[] types of asbestos produce pulmonary scarring if there has been excessive exposure to itu: dust. 2 Cancer of the Imr; occurs anion;' workers who have had excessive exposme to ail types of asbestos dust. 3 Cui.cer of the lung is far more common among workers who are cigarette smokers. (The two carcinogens, asbestos and cigarette smoke, appear to combine muUiplicatively in Die produed-m of lung cancer.) _ a Mesotheliomas of Lite pleura and the peritoneum (the lining of tiie abdominal cavity) arc more common among those exposed to asbestos than the genera! population. More than 1 COO eases nave 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 crocidoiitc mines in the Cape Province in South Africa. G la industry, crocidoiitc asbestos has been.definitely impli cated in the development of the mesotheliomas, and crocido- lite 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. Io two reports from tire United States it was staled that men who developed niesoDicIinm.-.j' .-.ere exposed only to chrysolilc or only u> r.mo.-iic. Pm: evidence of the amount and type of asbestos actually in th.i !m.g> c: these eases of mesotheliomas hn-> not been prodeced.^Tho risk of mesotheliomas is. on present evidence, generally agreed to be greatest with crocidoiitc. 7 Mesotheliomas have occurred in people who have had neighbourhood " ;;osme to asbestos dust cilhcr from living in close vicinity ;o mills and factories bufoiu the dust was controlled, or from the cleaning of protective clothing of relations who brought their overalls home before this prac tice was forbidden. 3 It was shown that asbestos fibres could be recovered free: 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 ambient air. , 3 There was no evidence that exposure of the general popu lation to the small 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 the Evaluation of the Carcinogenic Hisk of Chemicals to Man: Asbestos. 0i--0203560 tiic 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 Int..- In the major factories automation was in national ' Agency for Research, in Cancer creased. A great improvement being the wet (IAKC). In addition, it was necessary to estab 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 Hygiene 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 car-# The value they obtained was realistic and ried out during the period 2962-72 .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 chrysotilc, 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 bcc&tSg there . Effects of Asbestos" at the Now York have been several sensational reports about Academy of Sciences, no definitive new dat.-. the dangers of asbestos to the general popula have been published in the US relating tion, especially in the United States. In Octo- * .measured dust dosage and the incidence c: ber/November, 1973 a series of articles in asbestos-related diseases. ' The New Yorker, an American magazine, In the large textile factory whore Profe-sse - presented a highly prejudiced view, drawn Doll had found the high- incidence of car uncritically from the edits of a single investi cinoma of the lung, a further survey publish: gator. Fortunately, his alarming statements, in 1GG7 showed that the incidence et' car given in evidence in a recent legal case in the cinoma of the lung among those employe i States, were exposed to heavy criticism. This after 1D33 was no greater than the gcnorrl provided the court and the American public population. This indicated that if reasemabk with information from which they may be aide precautions were taken, asbestosis ;t:ul tk. to assess better the validity of the evidence. carcinoma of the lung associated with i: c.r.:` . Meanwhile, particularly in Britain, steps be controlled. In the same ye.tv. cm: M. .... were being taken to improve the working en Inspector of Factories published vironment. The asbestos industry in this coun arising from the use of A.-bes:;:.-". . try had formed the Asbestos's Research Coun gested that the use of cr;vM.:.:o. ' cil which, issued a serirs of Codes of Practice nr-bostos, should be controlled.:-. to ensure die safe use of asbestos, especially Act was amended, and by .' . iTure 5 Physical form tlie four types of . bestos . ajithophyllile . . crocidollte * chrysotile ' . smasite blue asbestos Into Britain had ceased, and it tcould only be stripped from existing installa tion under supervision of the Inspectorate of Factories. * The most remarkable improvement has been in the Royal Naval Dockyards, where a considerable amount of blue asbestos had been used as insulation and fire proofing on the warships, particularly the aircraft car riers. AU the blue asbestos has been removed from these ships, using sophisticated pre cautions, and has now been replaced by material containing a minimal amount of asbestos fibre. One frigate has been success fully iinulalrd withcul asbcM/xv - V/lia*. gives fi>w hk'C. nwjcMo:; tb:; prcpcrtics which c::n lead U> Ike <: v,,. nicut of these unusual t\z y:.l, we have* j;o proved a::swot but some have been discovered. V/neu .v.bnsics is in jected into the pleural cavity of rncm- thclioiiu'is develop two years letter. I; helc lhe asbestos ih'-y develop r.sbcttesi; ; :ri. in a few, cancers of ll.e Inn;,'. Ti'-cccferc, we have an experimental monel to tc:; /r.:: hypotheses. Ti;c fwsi. hypothesis wn> .0:- ward by ilr Joel; Kariruaton who found t! there were primitive oils end waves cssccir.'.ed v/ilh the blue asbestos, due to aiga-u c:.cuv: nn; at tiic lime of its original formation seme PIC3 million years ago. These waves conta.'-.cd smell quantities cf carcinogenic aroniutic hydrocarbons. A scries of experiments i;;;vc shown no difference in the number cf tumours produced by the oil containing fibre compared with fibre from which all the hydrocarbons have been removed. The second siw.m'.s;.: _ was that trace dements, particularly niVb... played a part in the tumour dcvclcprr.c.-.. Animal inoculation experiments have shown no association between trace element content and tumour incidence. ^ Recently,.we have published evidence indi cating that the physical form of the fore is an important factor in the development of the experimental mesotheliomas, the crocidoliic fibre having a particularly fine needled ike 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 bciug produced synthetically both as a substitute for asbestos and as "scaffold ing" for various composite materials. For some purposes from the engineering point of view the finer the fibre, the more successful the product. Our present experiments indicate that irrespective of the mineralogical nature all fibres less than 0*5 microns in diameter may produce tumours If inoculated into the pleural cavity of the rats. Thus manufac turers may be warned of the increasing hygiene risk as the fibre diameter is reduced. Asbestos information Association North America 16601 Street, N. W. Washington, D. C. 2C0S5