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11 Exposure in some cases may be of brief duration and there is a long lapsed period (latent interval) between first exposure and diagnosis or death. This lapsed period may be from 20 to 40 years or more. Disease diagnosed today probably had its causation in working conditions which prevailed between 20-40 years ago, or longer. The tumor affects the pleura, grows slowly, doesn't spread readily to other parts of the body and it kills by slowly compressing the lung and vital structures associated with it. Peritoneal tumor is less common and is similar in its effects. The tumor can occur from about the age of 35 onwards but more than 50* do not develop until after age 60. Cigarette smoking does not seem to be a causative factor. According to a review of the epidemiology of mesothelioma from estimates of incidence presented by Alison and Corbett McDonald at the XVIII International Congress on Occupational Health in Brighton, in 1975, the incidence of niesothelial tumors is extremely high in three situations: among insulators, among those who work in or live in cities with shipyards and among those who work in or live in certain cities with large asbestos plants. The most definite association with mesothelioma is following exposure to crocidolite fibers from the Cape Province and Transvaal in South Africa and from UCC 010213 12 Western Australia. McDonald and McDonald concluded that there are indications in most types of exposure of a gradient in the mesothelioma inducing potential of asbestos fiber with crocidolite being the most hazardous, amosite less hazardous and chrysotile least hazardous. McDonald17 has recently demonstrated that cases from the chrysotile mines in Quebec, Canada, were due to crocidolite. Crocidolite was used for the Canadian army respirators and this fiber was processed at the site of the major Canadian chrysotile mine. Crocidolite was similarly used in gas masks in Britain. The Canadian gas-mask workers experience exactly 18 parallels that recently reported by Dr. J. S. P. Jones and colleagues of some 1,600 persons employed, 1939-45, on the same process using Australian crocidolite in Nottingham, England. McDonald calculates that the risk of mesothelioma after crocidolite exposure in the circumstances described would appear to be at least 50 times greater than that associated with chrysotile production. There is no evidence that the general public is at risk of developing mesotheliomas from the fibers measurable in the ambient air. Occupational histories are deficient in those studies which have attempted to correlate environmental measurements with mesothelioma incidence. The correlations between increasing UCC 010214 A00946 13 utilization of asbestos during and since World War II are more reliable, indicating the likelihood of occupational risk rather than public health risk. C. The Issues at Stake There appear to be three major issues at stake at the present time, viz: (1) Can asbestos products be manufactured safely? If so, (i) is there any risk to users of asbestoscontaining products and, (ii) do low levels of exposure constitute a public health risk? (2) Can substitutes be found for asbestos? (3) Who is going to provide the answers and make the decisions? 1. Manufacturing of Asbestos Products The uses of asbestos are myriad. Many of the uses of asbestos are probably unnecessary and continue because traditions die hard. It cannot be replaced by suitable substitutes as yet in many areas. There is satisfactory evidence in the world literature to indicate that asbestosis is a dose-response related disease. There is, furthermore, adequate evidence that a dose-reponse also exists for the carcinogenic properties of asbestos. The fibrogenic (ability to produce lung fibrosis) UCC 010215 A00 47 14 effect and the carcinogenic (cancer producing) effect of asbestos appear to be similar for all varieties in commercial use. The scientific opinion with regard to the proposed gradation of effect attributed to crocidolite, amosite, chrysotile, tremolite and anthophyllite in the production of diffuse malignant mesothelioma of the pleura or peritoneum, is divided. Although most observers believe that crocidolite, particularly that from Australia and the N.W. Cape Province of South Africa, is the most dangerous fiber, that amosite holds an intermediary position and that chrysotile presents the least hazard, some authorities do not accept this thesis. Having weighed the evidence presented by both schools of thought, I am of the opinion that crocidolite has greater mesothelioma producing potential than amosite or chrysotile and that its use should be strictly curtailed. In the United Kingdom the use of crocidolite has virtually disappeared and no raw fiber has been imported or handled in production since 1970. In reviewing the literature it is obvious that advances in the control of asbestos manufacture did not proceed at the same pace in the industrialized world. The Asbestos Industry Regulations, 1931, which came into effect in the United Kingdom in 1933, preceded the rest of the world by approximately 40 years (or more). Although it is difficult, if not impossible, to make comparisons of working conditions in different countries for the same type of industry, there are indications that the health experiences are different UCC 010216 A00943 15 in such countries due to the time lag between introduction of comparable control measures. One group of workers in a 19 South African factory described by Collins in 1967, worked in totally uncontrolled conditions. This paper is not suitable for statistical analysis, but the description given by Collins of conditions, in what he calls "an asbestos refinery", is horrifying. He states "The dust within the building resembled a dense fog, and could be seen escaping into the atmosphere through the entrance. Jets of dust escaped like steam from faults in the con duction systems between mills and cyclones, and dust lay thick on every beam and projecting surface." The insulation workers of the United States are perhaps the best studied and most widely quoted groups in present medical literature due to the prolific publication of results by the Environmental Sciences Department at Mount Sinai Hospital in New York. Chrysotile asbestos miners and millers 20 in Quebec have been equally well studied by McDonald. 21 Nicholson demonstrates quite clearly the problems which exist in attempting to define dust exposures for insulation workers where adequate dust measurements are lacking, while McDonald has been able to utilize information provided by the asbestos mining industry to derive a meaningful "Dust Index" for chrysotile miners in Quebec. The best documented study of asbestos workers (textiles) with regard to medical and dust-measurement data is that of the British Occupational Hygiene Society's Sub-Committee on UCC 0)0217 A00 94 9 16 Asbestos Standards which was published in 1968 and recommended a cumulative standard of 100 fiber/cc years for chrysotile 22 asbestos. In 1970 NIOSH reported that records of dust concentrations between 1930 and 1967 in one asbestos textile factory, and between 1948 and 1968 in another, were assembled in the Pennsylvania Department of Health. In a report presented at the Western Industrial Health Conference by Howard Ayer, it was disclosed that, using lung function as the most sensitive indicator of asbestos health effect, it appears that cumulative exposures below 50 fiber/cc years cause no reduction in FVC, and exposures greater than 200 fiber/cc years are usually associated with reduction in FVC. If this cumulative exposure were spread over 30 years, this would mean that concentrations less than 1.5 to 2 fibers/cc would cause no reduction in FVC,* and that concentrations greater than 7 fibers/cc would usually lead to a reduction in FVC as well as X-ray changes in loss or more of workers. The present standard in the U.S.A., and most of the world, is 2 fibers/cc and is based on the BOHS Standard for chrysotile. In the United Kingdom and certain other countries crocidolite is dealt with more stringently because of its association with mesothelioma. In October 1975 OSHA proposed a tightening of the standard to 0.5 fibers/cc and in December 1976 NIOSH recommended that it be 0.1 fiber/cc. The argument regarding the adequacy of the standard is dependent upon the "no safe threshold for a carcinogen" theory. There is qualitative evidence that the 1931 Asbestos Industry UCC 010218 A0095G 17 Regulations in the U.K. had the effect of markedly reducing the incidence of asbestosis and similarly reducing the excess deaths from lung cancer in the same factory studied by the BOHS. Some residual effect is still being seen in this factory because dust levels were still relatively high in many areas until very recently. Bearing in mind that the BOHS Standard was not published until 1968, that new Asbestos Regulations were not made in the United Kingdom until 1969 and that the 2 fibers/cc standard was not officially applied there until 1970, it is obvious that no conclusions can as yet be drawn with regard to the level of risk still attached to working in conditions in total compliance with this standard. Having attempted to review the main issues regarding asbestos manufacture, the answer to the question posed is obviously, that we do not know for sure, but the evidence is pointing towards the conclusion that, when adequately controlled the risk of asbestosis and lung cancer can be reduced to virtually nil. Dr. Roach24 has summed up the situation as follows: "A problem arises when it is appreciated that there is no exposure which can be said to be absolutely free of risk. There is no single threshold exposure held in common by everyone. There is, consequently, this gradually increasing risk in relation to exposure. The application of dust control to meet a TLV, an MAC, MAK value, or other similar hygiene standard will limit and control the risk but is unlikely to reduce it to zero. It has to be remembered that asbestos is very widely used and brings real benefits to the community at large. A standard could be made so stringent that the cost of dust control is prohibitive, that the production and use of asbestos ceases to be economic, production and use is discontinued and the associated benefits are lost. The benefits gained by reducing the risk of UCC 010219 A 00 D 18 asbestosis through reducing air contaminant exposure have to be weighed against the possible loss of direct and indirect benefits to the community from the use of the material." He goes on later to remark: "The air quality attained in industry in different countries does differ and, no doubt, will continue to differ. A wealthy country can afford to spend more money on air-contaminant control. Also, a country very conscious of the slightest risks to which its workers may be exposed through their occupation may be expected to have different standards from one which is not, where other health risks may be so much the greater. The benefits to the community from the use of inexpensive asbestos products have in some measure to be weighed in the balance against the benefits to the health of the workers that would accrue by reducing asbestos dust exposure." The further comments of Dr. Roach are of interest and I quote: "To derive hygiene standards for an air contaminant which provide a known degree of protection against a health hazard, it is necessary to have a body of data showing the amount of air contaminant to which people are exposed and the corresponding effects or lack of them in the people. It is also necessary to have a grasp of the consequences to industry and users of limiting and controlling emissions of the contaminant. Our present information is very imprecise, particularly in terms of the practical consequences of specific hygiene standards. In developing recommendations for a hygiene standard, the British Occupational Hygiene Society Sub-committee found that knowledge of the relationship between exposure and risk was not the greatest area of uncertainty. A much more difficult and contentious problem wa3 to decide on what, in fact, was an acceptable level of dust control. More information is needed, for example, on the expense of dust control. Where this is done by ventilation it is important to know what is the minimum amount and what kind of local exhaust ventilation and dilution ventilation is necessary to achieve a given degree of air cleanliness in a work place, since costs tend to climb as the cube of the air flow. Research is needed to determine the balance between local and general ventilation which produces a specified degree of control at minimum cost. By setting down the capital UCC 010220 AGO 52 19 cost, installation cost, running and maintenance costs, it becomes possible to grasp more firmly the consequences of adopting particular hygiene standards. This kind of information is needed throughout the field of asbestos dust control so as to be able to weigh up the costs of achieving high air cleanliness. This does not reduce the choice of an air quality standard to a mathematical equation, nor does it avoid the need to exercise wise judgment in the choice of standard. However, the judgment can become a little less arbitrary than at present." The second question posed under the above heading is in regard to the risk to users of asbestos containing products. Asbestos is used throughout industry and until recently, outside of the manufacturing industry, users took few, if any precautions. Because asbestosis is dose-related no immediate health hazard was apparent from this cause in users of asbestos products. The exception to this rule is in the insulation industry where the upsurge of cases became marked in the late 1950`s and early 1960's, probably as a result of the increase in asbestos usage under poor conditions during World War II. The process of spraying asbestos onto girders of high-rise buildings, spraying asbestos on the interior of buildings for heat ard sound insulation and the extensive use of this process in naval ship-building programs was probably one of the most hazardous uses ever. Mechanical operations such as the sawing, drilling or abrading of asbestos products will create dust and power tools create more dust than hand tools. The quantity of dust produced will also depend on the amount of asbestos in the product and the nature of other components. Most demolition processes, where asbestos-based ucc 010221 A 0 03 5 3 20 products are being removed, are likely to give off considerable amounts of dust. It has been shown that brief exposure to crocidolite asbestos can result in development of mesothelioma. Users of asbestos products are usually exposed intermittently and accumulate a smaller dose of dust in the same period of time as workers continuously exposed in manufacture of asbestos products. Mesothelioma may occur in the absence of asbestosis. Mesothelioma has occurred in plumbers, carpenters, electricians, etc., who were exposed in the vicinity of insulation workers or others using asbestos. It has also been reported in persons who have lived in close proximity to crocidolite mines and mills and factories or building sites at which crocidolite asbestos was used. From all the epidemiological surveys there are between 5-30% of cases of mesothelioma in which no evidence of exposure to asbestos can be found. It has been shown that nearly everyone who lives in an urban community has some amphibole asbestos fibers in their lungs. There has been a great deal of controversy as to whether asbestos brake-linings constitute a health risk in terms of exposure of brake service mechanics. The epidemiological surveys conducted on this population have been carried out very recently by the Selikoff group, and no other epidemiological evidence is available as yet. There appears to be some evidence of radiologic changes in brake-service mechanics in the group studied by Selikoff 25 but no evidence of frank disease. At the Annual American Industrial Hygiene Conference last UCC 010222 A00954 21 month, NIOSH presented data showing that the use of proper work practices would reduce the asbestos exposure of brake service mechanics to an extremely low level. (Approximately l/20th of the presently permissible OSHA level.) NIOSH will shortly issue a technical bulletin outlining acceptable work practices. The recommended work practices will be almost identical to in structions provided by Raybestos-Manhattan to all friction material customers for the past 2-1/2 years. There is obviously some risk attached to the use of certain asbestos containing products, but many give off no dust and others, once incorporated in machinery, etc., never again see the light of day. Great care should always be taken in the use of asbestos and materials containing it and the dust levels should always be below the minimum required. The main non industrial use of asbestos is in do-it-yourself building materials. There are also some domestic products which contain asbestos, such as some electrical appliances. There is negligible risk of fibers being dispersed from domestic products in normal use provided they are in good condition. To prevent the misuse bf asbestos products warning labels should always be affixed and work practices advised. In answer to the third question it should suffice to say that there is no published epidemiological evidence to support the hypothesis of a possible danger to the general public. The biological effects of asbestos have always manifested themselves in individuals or groups of individuals exposed to dust concentrations many orders of magnitude greater than UCC 010223 A0095b 22 levels measurable in the general environment. One major area of concern is the ingestion of fibers from water carried in asbestos cement pipes or from the filtration of wines, beers, spirits, beverages, etc., through chrysotile asbestos filters. This concern arises mainly because of the demonstration of an excess incidence of gastro-intestinal cancer in certain heavily exposed asbestos insulation workers and heavily exposed textile workers. It is interesting that the textile workers studied by the BOHS do not exhibit a similar excess mortality from GI cancer. If the use of chrysotile asbestos filters is discontinued this would be a retrograde step. The ingestion of chrysotile asbestos and other types of fibers in experimental animals has failed to produce mesotheliomas. From human evidence, only people with a severe exposure to asbestos dust have contracted peritoneal mesotheliomas and these tumors have not been found in any of the asbestos mining areas except those mining crocidolite, in spite of the very heavy dust exposure especially in those exposed to chrysotile. 2. Asbestos Substitutes The major health problem associated with asbestos exposure is mesothelioma. As has been stated earlier in this paper, asbestosis can be controlled and lung cancer appears amenable to similar controls, but because the latent period between first exposure and diagnosis of mesothelioma is long, and this malignant tumor's association with asbestos exposure is a recent discovery, sufficient time has not yet elapsed to determine the level of dust capable of producing this response. Some evidence UCC 010224 A0053 23 has emerged that mesothelioma is dose related, but more time is needed to determine this dose. The gradation of effect previously discussed becomes important in the context of prevention. The reasons for this gradation of effects are of importance and may determine the feasibility of using other fibrous materials as substitutes for asbestos. The theory developed by Timbrell can explain the gradations in biologic potential of the various types of asbestos. He suggests that long fibers are preferentially deposited in the respiratory bronchioles at bifurcations and that this may explain why fibrosis tends to be associated first with respiratory bronchioles and with long fibers. He also suggests that the characteristic "rectilinear" shape of amphibole fibers compared to the "curly" morphology of chrysotile fibers, allows the amphiboles to penetrate to deeper parts of the lung more efficiently than chrysotile fibers. A reasonable theory has thus been proposed to explain the reason for the development of mesotheliomas. It is based upon the ability of certain types of fiber to penetrate deeper into the lung than others and to reach the pleural cavity by direct penetration. Substitutes for asbestos are being sought although for most purposes none have been found as yet. Other fibrous minerals are being tried among them glass fibers and mineral wools. Animal experiments indicate that if such fibers were capable of reaching the pleura, i.e. had the same physical characteristics as amphibole asbestos fibers, they could produce mesotheliomas. The available evidence depends upon the implantation into the UCC 010225 A00957 24 pleural cavity by open surgical techniques, of the various materials tested to date. Both in Europe and in the United States epidemiological studies have failed thus far to demonstrate any carcinogenic hazard to workers in the man-made mineral fiber industry. This is a field of very active research and should hopefully provide answers in the near future which would prevent a repetition of the asbestos tragedy. 3. Who is going to decide? (a) Scientific Opinion "As long as there is any airborne asbestos dust in the work environment, there may be some small risk to health. Never theless exposure up to certain limits can be tolerated for a lifetime without incurring undue risks." (Roach)21* "With this discouraging picture of inadequate knowledge of risk, ill-defined exposure information, and limited enforcement of existing levels before us, one may well ask of what value a TLV is for asbestos, or for any carcinogen. Should such materials be banned from use in all forms? Asbestos is extensively used in industry for insulation, for inclusion in plastics and other products, for reinforcing high-stress materials. At present, nearly 1 million tons are used annually in the United States. For some uses, as in brake linings, it is difficult to find a replacement. A societal decision to ban the use of asbestos would create serious, if not insurmountable, difficulties. Moreover, we would still face control problems posed by the large quantities of asbestos in current use. Our only recourse at this time is to limit human exposures to asbestos and other similarly recognized carcinogens to the lowest possible levels, with existing technology. In the case of asbestos, a TLV can serve a purpose: Recognizing that it is, in fact, a Risk Limitation Value, however ill-defined that risk might be, it can serve to mandate implementation of available technology and rule out the small fraction of work processes in which available technology fails to keep up with the major portion of the industry. More, however, is required than the specification of a number. The specification of work practices and engineering controls offers an essential supplement to a numerical TLV if the latter is used at all. Application UCC 010226 AU0958 of many economically and technically feasible procedures can reduce exposure to levels much below existing numerical values. These should be mandated. Moreover, such procedures can be specified with joint government-union-management cooperation and can be monitored much more readily than can dust concentrations. TLVs and work-practice standards should be reviewed frequently with a view to achieving continued reduction in worker exposures. The specification of a proposed TLV can serve as a stimulus for the development of new engineering-control methods or to rule out marginal processes that cannot be controlled. As new engineering developments evolve, the lowering of a minimal standard can be undertaken along with the specification of additional protective work procedures. To a limited extent, this has taken place in the asbestos industry." (Nicholson).21 "Threshold and dose response are only two of the components in decision-making in environmental control and regulation. In addition to scientific data, with all of its present limitations, public health responsibility must incorporate "prudence" as a factor in judgment. This invokes such issues as "cost/benefit ratios" and "risk", as recently reviewed by Falk. The cost/benefit ratio, at best an elusive attainment, must clearly delineate the "cost to whom" and "benefit to whom." The quantitative contribution to this equation must virtually be entirely derived from data on man. The concept of "risk" - the summation of threshold and dose response - when applied to population, is indispensably but not exclusively based on human as well as on experimental data. Laboratory contribution to "risk" encompasses the entirely tenable concept of threshold as well as dose response when addressed to the subject of the conference: the hazards of environmental agents to man." (Kotin).2^ (b) Trade Unions "In the past, risk assessment has been largely the domain of academic, industrial, and government scientists who have usually waited as long as possible to share their information with workers. This discussion will focus on the need for risk assessment to be a process continually going on at two levels, Federal and local. The need for Federal involvement in the standard-setting process is obvious, with tasks including carcinogenic risk assessment itself, standard-setting, enforcement, and when necessary, further modifications if workers are not being adequately protected. The need for worker involvement has only more recently been recognized. During this Federal standard-setting process the involvement of workers or their UCC 010227 AUQ 26 representatives is critical to the design of an adequate standard, monitoring, and medical surveillance. Once set, workers must have an active and informed role at the local level in assuring that the standard is enforced." (Wolfe). ,, "To reiterate, the most difficult decisions to be made by government will not be scientific in nature. Social and moral decisions will be made that can channel and shape the development of our control technology, which itself will become a major determinant of our future welfare. In this process, labor's contribution is unique. Alone among American publics, the worker is most exposed to environmental insult both in the community and in the shop, while being most vulnerable to the economic consequences of control. He and his institutions are of necessity, therefore, in a position of forced objectivity. Thus his is a critical voice to be heeded. The participation of organized labor is not automatic. A positive effort must be made, an effort I call "positive public advocacy." This is an essential government responsibility, involving the public in decision-making processes such as the assessment of environmental risk." (Samuels).29 (c) Government and its Agencies "Because the Federal government has provided for a National Cancer Plan under the leadership of the Director of the National Cancer Institute, it must be this Federal agency that provides overall leadership for an effective integrated national program for prevention and control of occupational cancer. A splintering of responsibility for research and training can work only to the detriment of the worker. The NCI cannot retreat from its responsibility to provide regulatory agencies with information concerning risk of exposure to specific chemical, physical, and parasitic agents demonstrated to induce tumors." (Lassiter-OSHA).3 UCC 010228 A009RC REFERENCES ^Bell, D. & Elmes, P.C. (1968): "The Distribution of Asbestos Bodies Within the Lung." Biologische Wirkungen des Asbestes. International Konferenz 1968, Dresden, pp. 29-32. 2 Thomson, J.G. (1965): "Asbestos and the Urban Dweller." Annals of the New York Academy of Sciences, Vol. 132, Art. 1, pp. 196-214. ^Selikoff, I.J. and Hammond, E. Cuyler (1970): "Asbestos Bodies in the New York City Population in Two Periods of Time." In: Pneumoconiosis. International Conference, Johannesburg, 1969. Edited by H. A. Shapiro. 4 Ashcroft, T. and Heppleston, A.G. (1973): "The Optical and Electron Microscopic Determination of Pulmonary Asbestos Fiber Concentration and its Relation to the Human Pathological Reaction." Journal of Clinical Pathology, 26: 224. 5 Gross, P.; de Treville, R. ? Cralley, L.J.; and Davis, J.M.G.: (1968)-'Pulmonary Ferruginous Bodies." Arch. Path. .85; 539-546. ^Pooley, F.D. (1973): "Mesothelioma in Relation to Exposure." Biological Effects of Asbestos. IARC Scientific Publications No. 8. Editors: P. Bogooski, V. Timbrell, J. C. Gilson, J. C. Wagner, pp. 222-225. 7 Kiviluoto, R. (1965): "Pleural Plaques and Asbestos: Further Observations on Endemic and Other Non-occupational Asbestosis." Ann. N.Y. Acad. Sc. 132: Art. 1. pp. 235-239. O Burilkov, T. and Michailova, L. (1970): "Asbestos Content of the Soil and Endemic Pleural Asbestosis." Envir. Res. .3: 443. ^Gibbs, Graham W. (1972): "The Epidemiology of Pleural Calcification:" A Thesis Submitted to the Faculty of Graduate Studies and Research in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy, McGill University, Montreal. 10Elmes, P.C. (1972): "The Natural History of Mesothelioma of the Pleura." Journal of the Irish Colleges of Physicians and Surgeons, i: 117. UCC 010229 A 0 0 .o 0 i 1' 2 1Edge/ J.R. (1977): "Asbestos Related Lung Disease in a British Shipbuilding Population with Particular Regard to the Incidence of Bronchial Carcinoma in Men with Pleural Plaques. A Mortality Study." (Abstract). Amer. Rev. Resp. Dis. 115 (4) part 2, 212. 12 Leathart, G.L. (1968): `Pulmonary Function Tests in Asbestos Workers." Trans. Soc. Occup. Med. .18: 49-55. 13 Becklake, M.R.; Fournier-Massey, G.G.; McDonald, J.C. and Rossiter, C.E. (1968): "Relationship of Functional to Radiographic Change in Quebec Asbestos Workers." Biologische Wirkungen des Asbestes. Internationale Konferenz 1968, Dresden, p. 207. 14 Gilson, J.C. (1973): "Asbestos Cancer: Hazards (Abridged)." Proceedings of the Royal 66: 395-403. Past and Future Society of Medicine, ^5Selikoff, I.J.; Hammond, E. Cuyler and Churg, J. (1968): "Asbestos Exposure, Smoking and Neoplasia." J. Amer. Med. Ass. 204: 106-112. ^6Wagner, J.C.; Sleggs, C.A. and Marchand, P. (I960): "Diffuse Pleural Mesothelioma and Asbestos Exposure in the North-Western Cape Province." British Journal of Industrial Medicine, .17: 260-271. 17 McDonald, A.D. and McDonald, J.C. (1977): "Mesothelioma Asbestos-Fiber Type." Amer. Rev. Resp. Dis. 115 (4) part 2, 229 (Abstract). and 1ft Jones, J.S.P.; Pooley, F.D. and Smith, P.G. (1976): "Factory Populations Exposed to Crocidolite Asbestos - A Continuing Survey." Environmental Pollution and Carcinogenic Risks. IARC Scientific Publications No. 13. INSERM Symposia Series Vol. 52. ^Collins, T.F.B. (1967): "Asbestos - The Lethal Dust." S.A. Med. J., (July 15) pp. 639-646. 20 McDonald, J.C. (1973): "Asbestosis in Chrysotile Mines and Mills." Biological Effects of Asbestos. IARC Scientific Publications No. 8. Editors P. Bogovski et al. ^Nicholson, William J. (1976): "Case Study 1: Asbestos - The TLV Approach." Ann. N.Y. Acad. Sci. 271: 152-169. 22 British Occupational Hygiene Society (1968): "Hygiene Standards for Chrysotile Asbestos Dust." Annals of Occupational Hygiene, 13.: 47-69. ucc 010230 A 0 0 3 61' 3 23Peto, J.j Howard, S.; Kinlen, L.J.; Doll, R. and Lewinsohn, H.C. (1977): "A Mortality Study Among Workers in an English Asbestos Factory." Br. J. Industr. Med. (In the press). ^Roach, S.A. (1970) : "Hygiene Standards for Asbestos." Ann. Occup. Hyg. Vol. 13, pp. 7-15. ^^Lorimer, W.V.; Rohl, Arthur N.; Miller, Albert; Nicholson, William J. and Selikoff, Irving J. (1976): The Mount Sinai Journal of Medicine, ,43: 207-218. 2^Timbrell, V. (1973): "Physical Factors as Etiological Mechanisms." Biological Effects of Asbestos. IARC Scientific Publications No. 8. pp. 295-303. Edited by P. Bogovski et al. 27 Kotin, P. (1976): "Dose-Response Relationship and Threshold Concepts." Ann. N.Y. Acad. Sci. 271: 22-28. 28 Wolfe, S. (1976): "A Case for Worker Involvement in Risk Assessment." Ann. N.Y. Acad. Sci. 271: 410. 29 Samuels, Sheldon W. (1976): "Determination of Cancer Risk in a Democracy." Ann. N.Y. Acad. Sci. 271: 421. ^Lassiter, Donald V. (1976): "Prevention of Occupational Cancer - Toward an Integrated Program of Governmental Action." Ann. N.Y. Acad. Sci. 271: 214. UCC 010231 A00963 Go\\C -be*, l0 23. MEDICAL SURVEILLANCE OF PERSONS EXPOSED TO ASBESTOS. - Oil C INTRODUCTION. It is not my Intention to talk to you about the physical and chemical properties of asbestos and the various theories as to how it produces the "asbestos-related diseases". 1 should like to discuBS with you briefly the diseases associated with asbestos exposure and their natural history, the medical examination requirements in the present OSHA Standard, the defects in those requirements and my suggestions with regard to the essential components of medical surveillance of asbestos exposed persons. In order for the physician to Intervene at the inter face between the worker and the work and thus to prevent the development of seriously disabling occupational Illnesses, a complete data base needs to be established including medical. Industrial hygiene and personnel Information capable of assesment and application by the health team for the benefit of all concerned. THE DISEASES. The first transparency indicates what the pathological effects of exposure are in man. The ranking order of these five situations is Intentional and tends to indicate the diseases associated with the LEAST exposure through the UORST exposure. It is, however, easier to discuss the pathological effects in the reverse order. UCC 010232 A00964 WHAT ARE TOE PATHOLOGICAL EFFECTS OF EXPOSURE IN MAN? Exposure to asbestos at work or elsewhere nay result in five conditions: 1. The presence of asbestos in tissues without disease e.g., asbestos bodies in the general population. Z. The presence of asbestos in the tissues causing benign changes - e.g skin warts, pleural plaques. 3. The presence of asbestos in the tissues and the development of malignant mesothelioma of the pleura or peritoneum. 4. Asbestos in the lungs with tissue damage and the development of lung cancer. 5. Asbestos present with potentially fatal damage to the lungs (pulmonary fibrosis or asbestosis), but no cancer. UCC 010233 A0096S The second transparency lists two other conditions which have been associated with exposure to asbestos. These two conditions have been listed separately, because at the present time, there is insufficient published information regarding the presence or absence of asbestos in human tissue in these cases and the association has been established purely on epidemiological grounds. UCC 010234 A00966 There are two other conditions which have been detected in greater nianbers among asbestos workers than would be expected from a similar sanple of the general population: a. Cancer of the gastro-intestinal system involving oesophagus, stomach and colon and rectum. b. Cancer of the larynx. UCC 010235 AGO 9 6 7 WHAT IS THE EVIDENCE FOR STATING THAT ASBESTOS MAY BE PRESENT IX TISSUE WITHOUT DISEASE? Examination of material frcn randan autopsy series in several cities has revealed the presence of asbestos in lung tissue. The frequency of this finding depends upon the diligence of the search. Whm digested lung tissue is examined, prevalence approaches 1001. These findings can occur in the absence of any asbestos associated diseases. UCC 010236 A 00968 WAT ARE TOE BENICJJ CHANGES IN TISSUES FOUND IN TOE PRESENCE OF ASBESTOS AND WAT ARE THEIR SIGNIFICANCE IN TERMS OF PROGNOSIS? Warts on the fingers and hand, and a discrete reaction involving the parietal pleura, usually in more than one place and referred to as pleural plaques, are often found in people who have been occupationally exposed to asbestos. Pleural plaques are usually a radiographic diagnosis in an otherwise healthy person. Pleural plaques may calcify. Pleural plaques have also been described in people exposed by living in the vicinity of certain mines or tilling soil with a high asbestos fiber content. The above conditions are not in themselves disabling, although the pleural plaques may indicate a level of exposure sufficient to progress to more serious disease. The effect of pleural plaques on pulmonary function, although detectable in population studies, is modest and is mainly seen as small reductions in lung volumes. By contrast, X-ray changes may be very striking, particularly in the presence of calcification. Although the presence of pleural plaques alone does not appear to cause symptoms of disability, there is some evidence that they affect prognosis. They have been associated by some authorities with increased incidence of lung cancer and malignant mesothelioma has been reported as developing in the cells at the edge of the plaque. UCC 010237 A00963 WAT ARE THE CURRENT VIEWS REGARDING MALIGNANT MESOTHELIOMA? X. Epidemiologic evidence indicates a gradation of effect related to fiber type. Crocidolite, particularly fiber from the North Nest Cape Province of South Africa and from Western Australia, is con sidered to be the type of fiber most frequently associated with mesothelioma. Qirysotile is considered to be least likely to cause it and amosite has been allocated an intermediate status. Although anthophyllite has been associated with asbestosis, pleural plaques and lung cancer, no cases of mesothelioma have been attributed to it. 2. Cigarette sacking does not seem to be a causative factoT. 3. Exposure may be of brief duration and there is a long lapsed period (latent interval) between first exposure and diagnosis ot death. This lapsed period may be from 20 to 40 years or acre - disease diagnosed today had its causation in working conditions between 20 to 40 years ago or longer. 4. The tunor affects the pleura, grows slowly, doesn't spread readily and kills by slowly compressing first the ling on one side and then the vital structures in the center of the chest or the lung on the other side. Peritoneal timer is less common and is similar in its effects. 5. The tiaaor can occur from about the age of 35 onwards, but more than SOI do not develop intil over the age of 60. UCC 010238 Aa097c 6. Domestic or neighborhood exposure has resulted in the development of this disease. 7. Mesothelioma is not uniquely associated with asbestos exposure and in most reported series a small proportion (151-301) cannot be related to asbestos. UCC 010239 A0097 1 WAT ARE THE FEATURES OF ASBESTOS-ASSOCIATED MALIGNANT DISEASE OF THE LUNGS? 1. The risk of premature death from malignant chest disease seems to be con fined to those with high dust exposure, though sometimes of brief duration. 2. Asbestosis is no longer an inevitably fatal condition because improved dust conditions have resulted in a ''milder" form of disease, or in fact a Rib-clinical entity which is not always recognized. Less mortality from asbestosis occurring after longer periods of exposure to loweT concentrations of dust than in past years has resulted in survival of workers through the long latent period of lung cancer. ~ 3. The interaction of cigarettes and asbestos exposure as risk factors is of great importance. Non-smoking asbestos workers rarely get lung cancer. 4. The primary lung cancers in smoking asbestos workers do not differ in their effects from primary lung cancers in other people, and the results of treatment do not differ either.' 5. Although lung cancer is usually associated with asbestosis, tone authorities believe that this is not necessarily so. UCC 010240 A00972 J. DOES ASBESTOS HAVE OTHER CARCINOGENIC PROPERTIES? 1. Cancer of the gastro-intestinal tract involving oesophagus, stomach, colon and rectus, has been reported in excess in asbestos insulation workers and other asbestos workers. 2. An association has been found in some reported studies between an excess incidence of cancer of the larynx and asbestos exposure. 3. At present there is insufficient published information regarding the presence or absence of asbestos in human tissue in these conditions and the association has been established purely on epidemiologic gtounds. UCC 010241 A00973 WAT IS ASBESTOSIS AND HOW DOES IT AFFECT THE EXPOSED INDIVIDUAL? 1. Asbestosis is a fibrosis or scarring of the lungs and includes the associated thickening of the visceral pleura, but not that of the parietal pleura. 2. The lower (dependent) parts of the lings are affected first progressing as the years go by even after exposure ceases. 3. A diagnosis of asbestosis can only be made by examining the worker, all the available x-ray films, the pulmonary function test made over a period of time and the complete occupational history. 4. Other respiratory diseases such as chronic bronchitis, emphysema, asthma and certain chronic luig diseases can be mistaken for asbestosis. 5. From the time systems are first noted, most workers can continue with light work for 10 to 15 years and may live another 5 to 10 years after finishing such work. 6. Asbestosis is laiusual under the age of 50. Other conditions leading to the necessity for light work and retirement may precede it in this age group. 7 . Improving industrial conditions ewer the past 20 years have resulted in a type of asbestosis less severe than in the 1930's, 1940's and 1950's. At the present time life expectancy may not be appreciably shortened by this disease. UCC 010242 A00 9 7 4 MHAT ARE THE CLINICAL TESTS WHICH CAN BE USED IN THE DIAGNOSIS OF ASBESTOSIS IN LIGHT OF TOE BACKGROUND INFORMATION IN THE PREVIOUS SECTIONS? Asbestosis may be diagnosed using the following criteria: a. Obtaining a history of "adequate" exposure, b. Eliciting fine end-inspiratory crackles at the lung bases an auscultation, c. Finger clubbing (nay or nay not be present), d. X-ray changes - snail irregular and/or maided opacities (ILO U/C Classification), e. Pulmonary function changes indicative of restriction of ventilation or impairment of gas exchange, (Airways obstruction is not usually a feature of asbestosis, but has been reported in some studies.) UCC 010243 A0097b OSHA STANDARD FOR OCCUPATIONAL EXPOSURE TO ASBESTOS------ JUNE, 1972. MEDICAL EXAMINATIONS REQUIRED FOR: * PREPLACEMENT PURPOSES * ANNUAL PERIODIC EXAMINATION * TERMINATION OF EMPLOYMENT MEDICAL RECORDS TO BE MAINTAINED AND RETAINED BY THE EMPLOYER IN ACCORDANCE WITH THE APPROPRIATE OSHA STANDARD. UCC 010244 A 00 9 76 THE PRE-PLACEMENT EXAMINATION * DETERMINE THE SUITABILITY OF AN INDIVIDUAL FOR THE JOB AND THE JOB FOR THE INDIVIDUAL * ESTABLISH A MEDICAL DATA BASE FOR LONG TERM FOLLOW-UP * PROVIDES AN IDEAL OPPORTUNITY FOR THE INDIVIDUAL TO BE TOLD OF THE HAZARDS OF EXPOSURE TO ASBESTOS AND TO BE REASSURED ABOUT MODERN CONDITIONS AND ENGINEERING CONTROLS APPLIED THE PERIODIC EXAMINATION * REEVALUATE THE JOB AND THE INDIVIDUAL'S SUITABILITY TO CONTINUE IN THE SAME JOB * COMPARE MEDICAL FINDINGS WITH PREVIOUS RECORDS AND INFORM EMPLOYEE OF RESULTS * MEDICAL DATA, INTENDED PRIMARILY FOR PREVENTIVE HEALTH PROGRAM CAN BE USED AT LITTLE EXTRA COST FOR EPIDEMIOLOGY STUDIES TERMINATION AND RETIREMENT Follow OSHA asbestos standard requirements. Records are kept for use in the day to day medical supervision of employees, for the purpose of compiling statistics for management, and to fulfil statutory and legal obligations. Confusion arises when management requirements are different from those of the statutory authorities, or where there is significant difference of opinion regarding the definition of recordable conditions required for corporate versus statutory purposes. This is a matter which requires further clarification and the preparation of corporate guidelines will be undertaken by the Corporate Medical Department. UCC 010245 A 0 0 9 7.7 MINIMUM OSHA REQUIREMENTS FOR MEDICAL EXAMINATIONS OF PERSONS EXPOSED TO ASBESTOS. * POSTERIOR-ANTERIOR CHEST RADIOGRAPH, 14" X 17" * HISTORY TO ELICIT SYMPTOMS OF RESPIRATORY ILLNESS * PULMONARY FUNCTION TESTS : - FEV ( 1 second ). FVC UCC 010246 A00378 DEFICIENCIES IN OSHA REQUIREMENTS FOR MEDICAL EXAMINATIONS OF PERSONS EXPOSED TO ASBESTOS. * MEDICAL EXAMINATIONS: NO SPECIAL QUALIFICATIONS STIPULATED FOR EXAMINING PHYSICIAN; NO CHECK ON COMPETENCE, * CHEST RADIOGRAPHY: RADIOGRAPHIC TECHNIQUE NOT SPECIFIED TECHNIQUES FOR READING, INTERPRETING AND RECORDING RESULTS NOT SPECIFIED. * RESPIRATORY SYMPTOMS: FORMAT NOT STIPULATED * PULMONARY FUNCTION TESTS: PROCEDURES NOT STIPULATED TRAINING REQUIREMENTS FOR TECHNICIANS NOT STIPULATED CALIBRATION AND STANDARDIZATION OF INSTRUMENTS NOT STIPULATED. UCC 010247 A00979 There Is no cure for asbestosis, the outlook for the patient with lung cancer Is very poor and diffuse malignant mesothelioma of the pleura or peritoneum is invariably fatal within a short period of time after`diagnosis. In view of this gloomy future for the affected worker what can the physician now working in industry do to intervene or prevent undue suffering on the part of currently exposed individuals ? The basic role of the industrial physician in the case of asbestos is to institute an early warning system for the prompt and efficient recognition of the earliest biological effects of exposure. The hope is that speedy action will delay progression of pulmonary fibrosis or allow malignant condltoions to be diagnosed and treated sooner and more successfully. The system requires close collaboration of all involved in order to provide the best facilities for close observation of all "at risk" people. The next transparency outlines the logical sequence for the development of a medical surveillance program, starting with the preplacement examination and concluding with the termination medical. The methods to be employed will not be described in any detail, only the purpose and objectives of each type of examination. Through the intelligent and diligent use of carefully designed record keeping systems an invalluable contribution can be made towards the determination of dose-response relationships for asbestos exposure and the effects described, ultimately leading to the development of an acceptable industrial hygiene standard. UCC 010248 AUOc)