Document ybb7ndZoEMrzj3bxpxL9bxy5X

.1 f. . Arising from recent press publicity, sometimes ill informed and exaggerated, wide spread concern is being expressed by those, who process or handle asbestos u. asbawto.. goods regarding the possible health hazards. The object of this document !_ :o a-.a.v.p: to put the present situation in its proper perspective so that processors and Cfm asbestos materials may be given advice and re-assurance as required. For many years the only industrial disease known to be directly associated wi.r. asbestos was a fibrosis of the lung known as asbestosis. This disease was rightly assumed to be caused by exposure of the worker over long periods to high concen trations of asbestos dust and the first step in dealing with the situation was the intro duction of the Asbestos Industry Regulations, 1931. These Regulations .aid down certain rules covering the handling of asbestos fibre in the manufacturing aide o: the industry and the result was an immediate and significant improvement in v.-cr.ring conditions. Dust control measures were' introduced and since that time steady progress has been made in reducing the levels of dust concentration at all factory processes. The result of these efforts has beer, a steady and substantial fall in the incidence c: asbestosis where controls have been applied, leading to the view that the disease car. be eliminated by taking steps which are in line with modern industrial practice. Taking the asbestos industry as a whole, statistics show that the incidence of asbestosis aa* risen in recent years and is .still rising, which appears contrary to what has just been " said. The rise is due, however, almost entirely to the inclusion in the statist!-c s: ` asbestosis cases among workers in the insulation contracting industry which is not governed by the Regulations referred to, and where it w.as not at first realised that working methods and conditions needed to be controlled. In recent years some cases of cancer of the lung or bronchus associated with the asbestosif have been observed, particularly among older workers. It must be emphasised 0 at this increased incidence of cancer only occurs as a result of asbes tosis/ and' not directly as a result of asbestos exposure, if the latter has no: beer, sufficiently severe to lead to asbestosis. It therefore follows that if environmental conditions are controlled to a level at which asbestosis is eliminated then the asso ciated lung and bronchial cancer will also disappear. Although this association between asbestosis and lung cancer is a ser.ous matter, it has not been the subject of alarmist publicity because the industry has demonstrated conclusively that It is capable of control. The recent articles and comments ;n the press have been directed towards an entirely different health hazard, name.}, the possible relationship between asbestos exposure (without asbestosis) ana a rare torm of cancer known as mesothelioma. Mesotheilal tumours are found ir. t.-.e pleura or peritoneum and their exact relationship to asbe'stos is still under investigai.on. There . is no doubt that the main association is with crociaolite (blue) asbestos; any associa tion with chrysotTIe (white) asbestos (the type mainly used in asbestos textiles andasbestos reinforced plastic products) is much less definite. No connection at a.I has ASARCO ELP 0003104- pm-:m-icx:oNio.';is research uiiit Visit by Medical nnd Science Correspondents . ; : \ ]' Wednesday, 22nd February, I967 asbestos and cancer j i j ' i :' It is now accepted that there is an association between exposuro to asbestos . dust and the development of certain cancers. Theso nro cancers of the Inn/; nnd mesotheliomas of the pleura and peritoneum. There io evidence that there ia an . increased incidence of cancers of the gastro-intestinal tract; this has been . produced by German nnd American investigators. The cancers of the lung occur in workers with severe asboctosis - fibrosis of the lung due to asbestos dust. In contrast to this tho mesotheliomas can occur in people with minimal fibrosis and, in some cases, asbestos is found in tho lungs but insufficient to"cause any scarring of tho lung tissue. In these people the exposure to asbestos dust is relatively slight, and may be ns little ns throe months. In some cases, the exposuro has" been environmental, not occupational. Tho time between tho exposuro and tho development of tho tumour ir. usually moro than thirty yonrn. Those diseases are duo to tho r inhalation of asbestos dust. There in no known danger .through drinking water from j j nsbeotoo pipes, or boor that has passed through asbestos filtors. .J *i Asbestos is a generic term applied to a number ofi fibrous silicates. Four types"of this material are, and have been, used commercially in Britain. These are chrysotilo, crocidolito, nmosito and anthophyllito. Chrysotilo is by far the commonest type, tho total world annual production being more than J,.000,000 tons} tho main sources are the Soviet Union, Canada, South Africa, and Cyprus. Crocidolite (blue asbestos) is mined in South Africa and until recently in Western Australia - : the nsinuni prod.jction is about 150,000 tons; tho amount imported into Britain bag ' been reduced in recent years, and jo now 7,500 tons. Amooite is found only in South Africa where 100,000 tens nro produced annually, tho uso of this fibro is increasing in Britain and about 30,000 ton3 was brought in laot year. Anthophyllito io mainly produced from a small mino in Finland, with an annual production of 15,000 tons; . only a small amount of thi3 ia used in Britain. About 500 cases of cancer of the lung and mesothelioma are known to have occurred among people exposed .to asbestos . dust in the United Kingdom, This is hardly significant when one realises that more than 25,000 cases of carcinoma of tho lung are diagnosed .each year. .< vl 1 "' ! j On current evidence from South Africa, Australiajand Britain, it would . appear that crocidolito is mainly implicated in tho development of the mesotheliomas. .. However, cases have occurred in tho United States, Canada and a few in Britain in which tho people concerned appear to have only been exposed to chrysotilo. The ma.ior problem at the moment is to establish whether only ono type of asbestos ia responsible for the development of theso tumours, and if other varieties can be exonerated. Exposuro to only one type of asbestos is unusual in a manufacturing country such as Britain, therefore to find populations exposed to asingle typo of asbestos, surveys : have, to be undertaken in the mining areas. It i3 also hoped that information obtained . from animal experiments may be valuable in the assessment of this hazard. *j - * `" Members of the staff of this Unit have played a prominent part in tho . discovery and investigation of tho association between mesotheliomas and exposure to nobostoo dust. They wore concerned in tho original definition of the condition in South Africa, its recognition in Britain, and the development of tho international rosearch programme which is now in operation. JCW/y 16.2.6? Pnaumoconiosi3 Research Unit, Llandough Hospital, ... Penarth, Glamorgan. . r j. i: - ASARCO ELP 0003105 so far been established between mesothelioma and amositc, the type of asbestos used -most widely in the insulation side of the industry. The disease is very rare, there being only 500-600 eases on record in the world, compared with over 20,000 cases .of . lung cancer in Britain alone every year. Records at the London Hospital show that only S3 patients have died of mesothelioma over a period of almost SO years. About half the eases had had some contact with asbestos, in a further number contact was not .certain, and about a quarter had had no contact at all. Furthermore, the hospital in question serves an area which includes a large asbestos factory as well as the London Docks, so it is certain that a very large number of people have been exposed to some degree. '` So much for the facts. It now ccma.las to consider those processes involving the handling of-asbestos and asbestos products where a hazard might exist and, it possible; to assess the extent of the hazard with'a view to taking adequate preventive measures. In assessing any process, two main considerations raust'be taken into account -- the extent to which the process generates airborne dust and whether it is an occasional or a regular operation. For instance, processes covered by the present Regulations only come within the orbit of these Regulations If they involve the employment of any one person for more than eight hours per week. This is a very arbitrary boundary, however,', [{/A- and a better principle to adopt for dusty operations would be to protect the operator ) where the work is occasional and control the operation where the work is continuousy AM* The method to be adopted for occasional work would be .the wearing of an approved respirator by the worker coupled v/ith careful handling of the material; for continuous work, engineered control such as ventilation or damping v/ith the required degree of enclosure is recommended. Examples of processes which arc liable to generate significant amounts of dust are the handling of loose asbestos fibre, the sawing or machining of asbestos millboard and asbestos reinforced plastics, or the drawing of asbestos yarn through aper tures at high speed. The handling of asbestos cloth can also lead to the emission of dust In certain circumstances. The simplest method of controlling the operation is to apply damping where possible, otherwise ventilation and/or enclosure may be nec essary. Cloth may be'specially processed to reduce dust on handling. Simple -'opera tions such as the fitting of dry asbestos packings in pump glands and the cutting of sheet jointing materials containing asbestos are not considered hazardous, nor is the wearing of asbestos clothing. To sum up, asbestosis with or without lung cancer is not likely to occur except in conditions involving lengthy exposure to fairly high dust concentrations. The controls applied in the manufacturing side of the industry have demonstrated that jthe disease can be minimised and possibty eliminated by limiting airborne dust to a reasonable level. It follows that most uses of asbestos products and many operations upon pro cess materials are free of risk in this respect, while those evolving substantial amounts of dust can fairly readily be made safe by established methods of damping, ventilation or enclosure. The exact measures to be taken will vary with the circumstances and the Asbestosis Research Council is at present working on a Code of Practice which is being made as comprehensive as possible. In the meantime, every efiort will be made to deal with individual problems as they arise. Finally, whatever the connection between mesothelioma and asbestos exposure- in general, any association between this extremely rare disease and white asbestos, which has been widely used throughout the world for many years, is still very indefinite. February, 1967. ASARCO ELP 0003106