Document gE2YweV8LejyvLDvrq2Ov4DVQ

in itsf i iai Memorandum Oat# January 16, 1^6 To W. T. Birg*. Lmtr No. Prom J. W. Weil Subject Seperately you will be receiving from Jacob Towioh his report on the rc.hc;.: background of the asbestos problem. I think you will find it useful o.-d provocative. 1 would like Jacob to be my representative in further corporate deiibc:oto-. on asbestos. Would you pleese moke sure that he is involved with ycur coordinating task group and that Bruce Klein keeps him closely involved He and Tom Thompson will work together to avoid overlop or conflict, so that Tom stays informed. I believe Jacob con be a useful contributor to this multi-foceted prorU-i r ( believe if can also be good experience for his development. i JWWral cc: J. W. Armstrong B. Klein S C. N. Menz J. W. Tawiah T. E. Thompson THE BENDIX CORPORATION CORPORATE ENGINEERING STAFF SOUTHFIELD, MICHICAN T* r 1-1-7 i, HEALTH-HAZARDS OF ASBESTOS A REVIEW OF THE MEDICAL LITERATURE Prepared By: Jacob W. Taviah December 11, 1975 t executive summary HEALTH-HAZARDS OF ASBESTOS A. CURRENT MEDICAL XNOVLZDCZ 1. Nature of Asbestos-Related Diseases Present medical knowledge associates asbestos with three primary diseases: Asbestosis; Bronchogenic (lung) Cancer; and Mesothelioma, a rare form of cancer. All three diseases affect the lungs and in the case of mesothelioma, the abdominal cavity may also be affected. Asbestosis can cause death but it is noc. always fatal, bronchogenic cancer is fatal and mesothelioma- is the moat- deadly of cheer all. 2. Is there a safe exposure level? There is general agreement that the risk of developing one of the asbestos-related diseases is positively correlated with the intensity and duration of eI xposure to asbestos dust. '. * However, there is no conclusive proof of a safe threshold level of exposure. If and when such a threshold level is determined present indications are that 'it will vary from type of asbestos fiber to type of asbestos fiber; from occupation to occupation; and frer. disease to disease. 3. What is the relationship between esbestosis and lung cancer? There are reported cases of lung cancer victims showing symptoms of asbestosis, but if an individual does not smoke, asbestosis does not lead to lung cancer. The medical evidence is that asbestosis do occur irrespective of one's smoking habits while an excess risk of lung cancer has chus far been only associated with cigarette smokers. 4. What ere the relative risks followina exposure to only one variety of asbestoa? All comecrcial forms of asbestos esuse asbestosis, bronchogenic cance: and mesothelioma. However, the risk is greatest with croeidolice, le with aaosite end perhaps, still lass with chrysotile.'10 ' 5. What is the mechanism of disease causation in asbestos-related diseas Existing evidance appear to Indicate that extracellular processes and the physical features of fibers constitute a major part of the causat of the lung discuses associated with exposure to asbestos dust. The fiber diameter appear to be the controlling factor in the causation < disease. -2- The association of "asbestos-caused" cancer with cigarette sr.o>i-~ coupled" with the physical nature of the process of disease causation as preeenc studies indicate; perhaps, permits the speculation that * asbestos fibers or other fibers of similar physical dimensions, once in. the lungs act only as a mechanical confactor in enhancing recenticinhibiting clearance and modifying the distribution of inhaled insol- ' uble cigarette smoke particles which are proven to be carcinogenic. It nay be inferred, therefore, that other insoluble particulate matter of similar physical dimensions as asbestos may be equally cocarcinogenic as asbestos. 6. What other causes of mesothelioma are there? There have been reported cases of mesothelioma that cannot be linked to asbestos but there are no known other cuases of the disease other than exposure^ to asbestos dust. 7. Can asbestos cause other diseases? Yes. Them m ample evidence of on association between pleural, plaque; and all types of exposure to asbestos, and to all types, of asbestos fiber. Asbestos is not the only cause of plaques but it is the: c-as* common. (33) '* 8. Is it possible to detect asbestosis earlv enough to permit a curP> With regular x-ray examinations it is possible to detect the onset of asbestosis to at least permit its control. However, the latent pcrioc of asbestos-related diseases is estimated to be about 20 years, d*' B. COMMENTARY There is no doubt that the inhalation of substantial amounts of asbestos c lead to increased rates of various types of lung disease, including two fc of cancer. The medical literature is full of solid evidence linking asbci to disease. Eliminating the emission of asbestos dust into the working environment appears to be'an obvious way of dealing with the problem. Th: however, may not be the most feasible approach in light of economic consi< atioas. -It then becomes necessary to examine what other alternatives cxi There is strong evidence to indicate that all the diseases associated wit asbestos is exacerbated by cigarette smoking. In fact, the evidence is c there is no excess risk of bronchogenic cancer in asbestos workers who dc not smoke. In this case It appears that asbestos is merely a catalyst ti causation of bronchogenic cancer end the priawry carcinogen Is cigarette An alternative solution to die problem that perhaps would be economical! attractive to all concerned may thus be a requirement that workers in th asbestos industry be non-tmokeri. This option becomes even more attract when recognition is taken of the fact that existing evidence, even t)ou? inconclusive at this time, indicates that other fibers with certain phy; dimensions (below i yim diameter) Irrespective of chemical composition t have the seme effect as asbestos. A 3- In the self Interest of Bendix the apparently physical nature of mechanism of disease causation of asbestos fibers should be careful! considered fh our search for alternate material for our brake linin- composition. * P.S: SLIETEERAATTTUARCHEMREENVTIEAWFEODR. SUPPORTING DETAIL AND BIBLIOGRAPHY O0FF TOP ksuical * ATTACH*!?:? A HEALTH-HAZARDS OF ASBESTOS ' A REVIEW OF THE MEDICAL LITERATURE ASBESTOS-RELATED DISEASES Three primary diseases are known to be caused or induced by the exposure to and Inhalation of asbestos fibers in industrial environments. They are; asbestos-bronchogenic (lung) cancer; and mesothelioma, an extremely rare font of cancer which affects the lining of the pleural (lung) cavity or cite peritcnal (abJor.-icavity. Asbestosis This is the most common of the three asbestos-related diseases. It is one of the lung diseases classified as "pneumoconioses." Among others are silicosis, frost crystalline silica dust; byssinosis from cotton dust, talcosis from talc; and antbraeosis frost coal dust. Asbestosis is a non-malignanc fribocic lung condition which shows a high frequency of-occurrence in populations exposed, to asbestos dust, if the dust con centration ir high duration of, exposure is long. 4 When an asbestos fiber is inhaled into the body and it is not eapturs and eliminated by the normal cleansing mechanisms, two different actions can occur. It can be encapsulated with iron-rich protein - in which cas it is then referred to as an "asbestos body" or "ferruginous body." Or, it can remain in a naked state-vneoated. For all intents and purposes, the asbestos fiber if coated is harmless. On the other hand, if thu fiber remains in a naked state in the lung, then an almost uncontrolled growth of cells may begin, resulting in the formation of collagen, or scar tissue. When collagen forms in the lungs, it alters the normal tissue so that it no longer functions properly. When this biological reaction occurs, the body's vital capacity is greatly reduced and the oxygen-carbon dioxide exchange function within the lungs is altered. The overall effect is poor ventilation and labored breathing,-which are signs of asbestosis. Other physical symptoms of asbestosis are rales - unusual sounds produced in the chest cavity, end finger clubbing. Asbestosia has bean shown in numerous studies to cause death but it is not nacessarlly always fatal. All the commercially significant varieties of asbestos; chrysotile, amosite, crocidolite and anthophyilite, have been shown to cause asbestosis. <4'9) However, there it considerable evidence to suggest that tiie risk is greatest with crocidolite, less with amosite and perhaps still less with chrytotile.C10**** While exaet dose-response relationships are not well established, th is general agreement that thera exists a positive correlation betwee intensity of exposure and the frequency of occurrence of asbestosis. 3 3 lt i -2- Studies indicate that pulmonary fibrosis is augmented in asbestos workers by-cigarette smoking. (13' It has also been shown that the risk of death from asbestosis say be increased by cigarette smokinr Bronchogenic (lane) Cancer: A high frequency of bronchogenic cancer greater than that expected on the basis of the general male population h..s been shown to be manifested among persons who have had exposure to asbestos in indus trial settings. (15-18) Studies (19-25) have shown that all types of asbestos can give rise to an excess of bronchogenic cancer under some circumstances. It has been forcefully demonstrated th.it the risk of bronchogenic cancer is greatest with crocidolite, less with amosite and perhaps, still less with chrysotile. Evidence from studies using dust exposure assessments has generally shown that the excess, risk of1 bronchogenic cancer is related to dose and duration- of, exposure*,, Perhaps the most significant conditional- factor^asso ciated with the excess risk; of bronchogenic cancer related; to indus trial exposure to asbestos is the requirement of cigpsea&os: smoking* Existing evidence indicates that non-smokers do not show any excess risk of bronchogenic cancer regardless of their exposure to asbestos* (26, 27) * The biological mechanisms involved in the development of bronchogenic cancer and mesothelioma are not yet clearly established. However, evidence based on studies thus far conducted on this subject permit.* reasonable speculation on a probable course of events. In a study, conducted by M. F. Stenton of the Laboratory of Pathology, National Center Institute, Bethesda, U.S.A., various structural forms of asbestos, fibrous glass and aluminum oxide were tested for carcinogenicity on the pleura (lung) of rats. Results from all three materials indicate Chat carcinogenicity is related primarily to fibrous structure rather than to physicochemical pro perties. A comparison of the dimensional distribution of fibers in those samples of asbestos and glass producing high and low tumor incidenca indicate that carcinogenicity may be related to libers below 2.5, v m (micron) in diameter and between 10 to SO -r in length. Another study by V. Tlmbrell *29^of the MRC Pneumoconiosis Unit, Llandough Hospital, Fenarth, UK. concluded that "extracellular processes and the physical features of fibers appear to constitute a major part of the etiology (causation) of the lung disease! associated with exposure to asbestos dust. Including the cancers. The biological exposures which different types of asbestos fibers produce when Inhaled teem to be governed largely by the aerodynamic properties of the fibers. The physical characteristics of the fibers which form the basis of these suggested expla nations are fiber disaeter, fiber length and fiber morpho logy, the central parameter being fiber diameter." 3* Further evidence supporting the thesis of physical processes *s etiological (causation) mechanisms of asbestos-related cancers is presided by Dr. Edward A. Kartell of the National Center for Atros* pheric Research. In two articles published in 1974 and 1975, Dr. Kartell asserted and provided evidence to support the following: "Airborne 210?b is concentrated on small Aitken particles which accumulate on tobacco trlehomes. Tobacco curing and the combustion of triehomes in burning cigarettes produce insoluble partieles of high ^lOpj, radioactivity which are inhaled and deposited in the bronchi of smokers. ' The subsequent ingrowth of 210po results in high local alpha irradiation which may account for bronchial cancer among smokers." The significance of this finding is that coupled with the cited evi dence of the physical nature of the causation of asbestos-related cancers, and other related facts, the suspected carcinogenicity of asbestos (or fibers of an appropriate physical dimensions) may be subject to reinterpretation. It has been observed by Selikoff et al (26,27) chac bronchial car^ioms deaths among asbestos workers who smoke cigarettes are about eightriiw that expected for cigarette smokers in general, whereas there were no excess bronchial carcinomas among asbestos workers who did not smoke, thus follovs that asbestos is not a primary carcinogen. It is indeed cocarcinogen. It may be concluded, therefore, that it Is likely that an accumulatior of the small asbestos fibers (or other similar fibers) in the lungs e>i the workers acts only as a mechanical cofactor in enhancing retention inhibiting clearance, and modifying the distribution of inhaled insol> alpha-emitting radioactive particles from cigarette smoke which are p to be carcinogenic. ' Mesothelioma Mesothelioma Is the third asbettoe-related disease. It is an extreme rare form of cancer which effects the lining of the lung cavity and f the abdominal cavity. Meeothelloma Is by far the most serious of th three diseases because at the present tine, once it is dlegnosed, it inevitably fatal -- there is no known treatment. Death usually occu within 16 months after .diagnosis. Although there ere reported cases ox mesothelioma that can not be 1 to asbestos, asbestos remains the prime suspect as the carcinogenic According to P. C. Eimes * \ the tuwor usually starts in the pleur* (lung), but a small proportion starts in the peritonewr. (ebdbr.en). 1 either case,-pain is usually the first symptom, followed later by breathlessness and loss of weight. The time course of the disease is short, "averaging 13-1* months for the pleural cases and six months : the peritoneal." Even though the evidence Is not conclusive, it appears that cigarette smoking aggravates the occurence of mesothelioma. The causation of this disease in so far as it relates to the role cl asbestos, is similar to bronchial cancers as previously described. to 4 *4 references 1* Merewether, E.R.A., And Price, C.W. Report on Effects of Asbestos Oust on the Langs end Dust Suppression in the Asbestos Industry." Her Majesty's Stationery Office, London, 1930. 2. Sayers, R.R., *nd Dreesen, W.C. "Asbestosis." American Journal of Public Health, 29, 205; 1939. 3a. Johns-Hanville Corporation, "Asbestos and Health" Environmental Facts,' Asbestos, Kerch 1974. 3b. Selikoff, I.J., Churg, J.f and Hammond, E.C., "The Occurrence of Asbestosif Among, Insulation Workers in the United States," Ann. N.Y. Acad. Sci. 122, 139; 1965. (4- through? 9 were presented sfc,IARC Conference on Biological. Effects o.A*te**eesr,, Erases^ ISiSIjs . 4. McDonald, J.DV, "Asbestosis in-ChryMine** and- Mills" 5. Sluis-Crener, C.K., and duToit, R.S.J., "Amosite and Crocidoiite Mi rune and Killing as Causes of Asbestosis." * 6. Ahlman, K. et al; "Anthophyllite Mining and Hilling as a Cause of Asbestosis. 7. Smither, W.J., and Levinsohn, H.C., "Asbestosis in Textile Manufacturing." 8. Cooper, K.C., and Miedema, J., "Asbestosis in the Manufacture of Insulating Materials." 9. Enterline, F.E., and Weill, H., "Asbestosis in Asbestos Cement Workers." 10a. Timbrell, V., "The Inhalation of Fibers." Proceedings of the International Conference on Pneumoconiosis, Dept, of Mines, Republic of South Africa, 1969. * 10b. Report of the Advisory Committee on Asbestos Cancera.to the Director of the International Agency for Research on Cancer, October 6, 1972. 11. Wagner, J.C., and Skidmore, J.V., "Asbestos Dust Deposition and Retention in Rats.*1 Ana. X.Y. Acad. Sci., 132, 77, 1965. 12. Vagner, J.C. "Asbestosis in Experimental Animals," British Journal of Industrial Medicine, 20, 1, 1963. 13. Veits, V., "Cigarette Smoking, Asbestosis and Pulmonary Fibrosis." Ar*r. Rav. of Respiratory Diseases, 104, 223-227, 1971. REFERENCES PAGE 2 14. Auerbach, 0. et el, Seokiitg Riblts end Age In Relation to Pulmonary Clianm Rupture--of Aveoler Septum*, Flbrosi*. end Thickening of Walls of Small /vrte end Arterioles." New England Journal of Medicine 269, 1045-1054, 1963. 15. Doll, R., "Mortality from Lung Cancer in Asbestos Workers." British journa Industrial Medicine 12, 81, 1955. 16. Selikoff, I.J., J. Churg, and E. C. Hannond, "Asbestos Exposure and Kw-opl.-.? J. Am. Med. Assoc. 188; 22-, 1964. 17. Elmes, P.C. and J.J.C. Simpsone, "Insulation Workers in Belfast - Mortali*.v 1940-66" Bridie J. Ind. Med. 2f, 22S-43&* 1971. ' 18. Newhouse, M.L., "A Study of the Mortality of Workers-in Asbetos* Factcry.'' Brit. J. Ind. Med. 26, 294-301, 1969. (19 through 26, 28, 29, 32, and 33 were presented at 1ARC Conference on Biological Effects of Asbestos, Lyon, France, 1972) 19. McDonald, J.C., "Cancer in Chrysotile Mines and Mills." 20. Webster, I., "Malignancy in Relation to Crocidolite and Amosite." ^ 21. Meuncan, L.O. et. al., "Mortality and Morbidity of Employees of Authophvlli Asbestos Mines in Finland." 22. Newhouse, M.L., "Cancer Among Workers in the Asbestos Textile Industry." 23. Selikoff, I.J., et al; "Cancer Risk of Insulation Workers in the United Sta 24. Bohlig, H. and Rain, E., "Cancer in Relation to Environmental Exposure." 25. Pooley, F.S. "Mesothelioma in Relation to Exposure." 26. Selikoff, I.J. and E.C. Hamaond, "Relation of Cigarette Smoking to Risk of Death of Asbestos-Related Disease Among Insulation Workers in the United States*1* - 27. Selikoff, I.J., E.C. Hsasnond, and J. Churg, "Asbestos Exposure, Smoking at Neoplasia." Journal of Aaar. Med. Assoc. 204, 106-112, 1968. 28. Stsaton, M.F., "Some Etiological Considerations of Fiber Carcinogenesis." 29. Timbreil, V., "Physical Factors aa Etiological Mechanisms." REFERENCES FACE 3 30. Kartell, E.A., "Radioactivity of Tobeceo Tridiones end Insoluble Cigarecrc Smoke Particles," Mature,. 249, 5454, 215-217, Kay 17, 1974. Mk. ' 31. Kartell, E.A., "Tobacco Radioactivity and Cancer in Smokers," American ScientiST; 63, 404-412, July-August 1975. 32. Elmes, P.C., "The Natural History of Diffuse Mesothelioma." 33. Jones, J.S.P. and C. Sheers, "Pleural Plaques." * A % > T* r /" 1lTHE BESDIX CORPORATION CORPORATE ENGINEERING STAFF SOUTHFIELD, MICHIGAN HEALTH-HAZARDS OF ASBESTOS A REVIEW OF THE MEDICAL LITERATURE Prepared By: Jacob W. Taviah December II, 1975 executive sugary HEAL7H-HAZARDS OF ASBESTOS A. CURRENT METICAL KNOWLEDGE 1. Nature of Asbestos-Related Diseases Present medical knowledge associates asbestos with three primary diseases: Asbestosis; Bronchogenic (lung) Cancer; and Mesothclicmn, a rare form of cancer. All three diseases affect the lungs and in the case of mesothcliov.i, the abdominal cavity may elan be- affected. Asbestosis can cause death but it is not *iways~,fatale bronchogenic cancer is fatal ant mesothelioma is the most deadly of char all. 2. Is there a safe exposure level? There is general agreement Chat the risk of developing one of the asbestos-related diseases is positively correlated with the intensity and duration of el xposure to asbestos dust. * However, there is no conclusive proof of a safe threshold level of exposure. If and when such a threshold level is determined present indications are that 'it will vary from type of asbestos fiber ro type of asbestos fiber; from occupation to occupation; and frer. disease to disease. 3. What is the relationship between asbestosis and lung cancer? There are reported cases of lung cancer victims shoving symptoms cf asbestosis, but if an individual does not smoke, asbestosis docs net lead to lung cancer. The medical evidence is that asbestosis do occur irrespective of one's smoking habits while an excess risk of lung cancer has thus far been only associated with cigarette smokers. 4. What art the relative risks following exposure to only one variety of asbestos? All ccenereial forms of asbestos cause asbestosis, bronchogenic cance: and mesothelioma. However, the risk it greatest with eroeidolice, le with amotlta sad perhaps, still less with chrysocile.'10 ) 5. What is the mechaniam of disease causation in asbestos "related diseas Existing evidaaco appear to indicate that extracellular processes and the physical features of fibers constitute a major part of the causat of the lung diseases associated with exposure to asbestos dust. The fiber diameter appear to be the controlling factor in the causation c disease. M il