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Table 1. Proportional mortality from lung cancer and mesothelioma for selected male populations. Cohort Deaths Group No. men All causes % lung cancer % mesothetioma General population a Canada (1970) 82,052 5.3 0.03 USA (1970) 988,620 5.1 0.03 Finland (1970) 22,332 7.1 0.04 Italy (1970) 252,795 4.7 -- England - Wales (1970) 278,617 8.9 0.06 Chrysotile mining-mitling b Quebec (1936-73) 10,951 3,938 5.7 0.18 N. Italy (1932-70) 1.098 270 2.2 0 Anthophyllite mining-milling c Finland (1936-67) 900 216 9.7 0 "Asbestos" trades d Insulators 26,505 2,137 19.6 6.7 Asbestos factory 10,781 1,422 15.0 3.1 a Entire male population over 24 years of age [19, Table 13]. b [19, Table 12; 20, p. 525]. c [19, Table 12]. d Composite figures [19, Table 12]. At present, people are concerned about the possible health hazards associated with the quarrying of serpentine rock at Hunting Hill quarry near Rockville, MD, and its use as a surface material for roads, playgrounds, and parks. The rocks being quarried here are very similar geologically to those of the chrysotile mining localities of Quebec, except that they contain much less chrysotile - about 0.5 weight percent. Rohl et al. [29] from Mount Sinai Hospital reported chrysotile fiber abundances of 500 to 4700 ng/m$ of air sampled adjacent to roads and a parking lot paved with loose crushed stone from the Hunting Hill quarry. The highest figures were measured during "moderate" motor vehicle use. The Mt. Sinai figures are equivalent to 0.2 to 1.9 yms of chrysotile per cm3 of air or 0.04 to 0.4 "standard fibers" per cm3 of air. Air samples taken near the perimeter of the Hunting Hill quarry gave chrysotile mass concentrations of from 0.02 to 64 ng/mg or 2 x 10 to 5 x 10 3"standard fibers" per cros of air (U.S. Bureau of Mines, State of Maryland, and McCrone Assoc. , unpublished data). The present U.S. Government limits for "asbestos" content of air are 2 fibers/cmo (05HA) and 5 fibers/cm3 (MESA) where a fiber is defined as longer than 5 pm, less than 5 ym wide, and having a length-to-width ratio of 3:1 or greater. The publicity about the possible health risk because of dust emission from the Hunting Hill quarry and its rock products had caused the quarry to lose about 30 percent of its business by July 1, 1977. Montgomery County, MD, expected to pay about $2.3 million in its initial effort to seal the roads so as to reduce dust emissions and to remove loose stone from the parks The Council Reoort, Montgomery County, vol. 6, no. 22, July 1, 1977). Apparently, other mining and quarrying operations along the "serpentine belt" of the eastern U.S. from Maine to Alabama also will be considered health risks to the general public [29]. Rohl et al. [29] suggested that exploitation of crushed amphibolite rock also raises the possibility of contamination of the air by "asbestos"-like minerals. 59 2063104860

Discussion The cancer incidence among those employed in the chrysotile mining and milling industry does not appear to be excessive when compared to national populations (Table 1). However, the incidence of cancer among those employed in the "asbestos" trades is very high (Table 1); incidence of lung cancer being 3 to 4 times that of the average population, incidence of mesothelioma being 130 to 220 times that of the average population. The "asbestos" trades generally utilized a variety of "asbestos" minerals including amosite and/or crocidolite, sometimes mixed into a paste for lagging. If we consider that about 90 percent of all the commercial "asbestos" ever mined was chrysotile, and that there is a low incidence of cancer in the chrysotile mining industry, we are led to conclude that either amosite and crocidolite are very hazardous or that there is an additional factor relating to health risk in the "asbestos" trades which has not yet been discovered. Previously, I have discussed some reasons why these two minerals may be more chemically reactive than chryaotile. Definitive epidemiological studies of the amosite mining regions of South Africa and the crocidolite mining regions of South Africa, Bolivia, and Australia appear to be lacking; such studies are needed in order to understand the high cancer incidence in certain trades utilizing these minerals. It is important to point out that the "asbestos" minerals should be considered separately when analyzing their effects on the worker's health. Reasoning by analogy is dangerous; high cancer incidence associated with one form of "asbestos" in a particular occupation does not necessarily mean that there will be the same incidence when utilizing another form of "asbestos" in that or another occupation. Unfortunately, this type of reasoning has led many to assume that any amphibole in any environment will cause high cancer mortality. The operational problems in defining and characterizing fine mineral particles and the unknown health effects on humans by minerals not generally regarded as "asbestos" appear to be causing more and more investigators to accept rather broad definitions for "asbestos." The present analytical techniques used by the EPA and OSHA do not distinguish between amphibole cleavage fragments and the minerals geoscientists generally consider to be true "asbestos." In fact, if electron diffraction is not used expertly, many pyroxenes might be called "asbestos." For example, bronzite, a common orthopyroxene having the composition (Mg,Fe)aSieOa4, is very similar chemically to amphiboles of the cummingtonite- grunerite series, (Mg,Fe)zSie02Y(OH)g. Also, orthopyroxene gives an electron diffraction pattern similar to that of cummingtonite--both patterns possess 0.26 nm spacings between the diffraction row lines in the hoR reciprocal lattice net. A full interpretation of the patterns is necessary for positive identification. Similarly, calcic pyroxenes might be confused with amphiboles of the tremolite-actinolite series or with hornblende. Cumming- tonite (and possibly hornblende) is considered an "asbestos" health hazard by health investigators from the National Institute of Occupational Safety and Health (OSHA), as reported by Gillam et al. [10]. The Mt. Sinai group [29] suggested that crushed amphibole- bearing rocks (amphibolite) used as road-surfacing material may result in widespread "asbestos" contamination of community air. Along with the general use of broader definitions of "asbestos" is a trend toward setting lower and lower limits on the acceptable amount of "asbestos" permitted in the environment (at present the OSHA standard is 2 fibers/cros; the MESA standard is 5 fibers/cm3, but it will soon be changed to the OSHA value). A more stringent "asbestos" health standard is presently being proposed by the National Institute for Occupational Safety and Health (Reexamination and Update of Information on the Health Effects of Occu ational Ex osure to Asbestos, December 1976; document prepared by N OSH or transm ttal to OSHA, as requested by the Assistant Secretary of Labor). This document states (p. 92-93): "Evaluation of all available human data provides no evidence for a threshold or for a safe level of asbestos exposure." "In view of the above, the standard should be set at the lowest level detectable by available analytical techniques----." "Since phase contrast microscopy is the only generally available and practical analytical technique at the present time, this level is defined as 100,000 fibers >5 pm in length/m3 (0.1 fibers/cc)----." 60

es A definition of "asbestos" to include many amphiboles, chrysotile, and possibly other minerals that appear fibrous or acicular in the electron microscope coupled with a fiber- concentration standard of 0.1 fibers/cros should serve to shut down a large number of our hard rock mines and quarries. Also, nothing has yet been said about the effect of such standards on construction workers building highways, tunnels, bridges, or dams on amphibole- bearing rock, nor of the agricultural workers who are exposed to fiber-containing dust while working the croplands. If the present concept of low or "zero threshold" health risk and broad use of "asbestos" definitions continue, much of the crust of the earth could be considered a health hazard. A way of minimizing the effect on the mining industry of the present and proposed "asbestos" standards, yet still maintaining a good level of health safety, is presented by the Canadian studies of the Quebec chrysotile workers. Here J. C. McDonald and his colleagues G. W. Gibbs, A. D. McDonald, M. R. Becklake, J. Siemiatycki, C. E. Rossiter, F. D. K. Liddell, 0. A. El Attar, A. Harper, and many others [17-23] have undertaken not only to delineate areas of health risk in the Quebec environment but also to assess the exposure limits of rock dust where the incidence of cancer and other diseases is at an acceptably low level. No occupation can be considered to have a zero health risk. It would seem that similar studies in this field would be of value in the United States. References [1] Bates, T. F., and Comer, J. J., Further observations on the morphology of chrysotile and halloysite, Clays Clay Min., 6, 237-247 (1959). [2] Brulotte, Raynald, Study of atmospheric pollution in the Thetford Mines area, cradle of Quebec's asbestos industry, ~Atmos heric Pollution, M. M. Benarie, ed., Elsevier Sci. Pub., Amsterdam, 447-458 (1976). [3] Campbell, W. J., Blake, R. L. , Brown, L. L., Cather, E. E., and Sjoberg, J. J., Selected silicate minerals and their asbestiform varieties: mineralogical definitions and identification-characterization, U.S. Bureau of Mines Information Circular 8751, 56 pp. (1977). [4] Champness, P. E., Cliff, G., and Lorimer, G. W., The identification of asbestos, J. Microscopy, 108, 231-249 (1976). [5] Deer, W. A., Howie, R. A., and Zussman, Jack, Rock-formin Minerals, vol. 3, Sheet Silicates, Longmans, Green, and Co. Ltd., London (1 62 . [6] Ernst, W. G., and Wai, G. M., MSssbauer, infrared, x-ray, and optical study of cation ordering and dehydrogenation in natural and heat-treated sodic amphiboles, Am. Mineral., 55, 1226-1258 (1970). [7] Fears, T. R., Cancer mortality and asbestos deposits, Am. J. Epidemiology, 104, 523- 526 (1976). [8] Franco, M. A., Hutchison, J. L., Jefferson, D. A. , and Thomas, J. M. , Structural imperfection and morphology of crocidolite (blue asbestos), Nature, 266, 520-521 (1977). [9] Gary, Margaret, McAfee, Robert, Jr., and Wolf, C. L., Glossar of Geology, (Am. Geological Inst., Washington, D. C., 1972). [10] Gillam, J. D., Dement, J. M., Lemen, R. A., Wagoner, J. K., Archer, V. E., and Blejer, H. P. , Mortality patterns among hard rock gold miners exposed to an asbesti- form mineral, Annals. N.Y_ Acad. Sci., 271, 336-344 (1976). [71] Gilson, J. C., Asbestos cancers as an example of the problem of tomparative risks, Inserm Symposia Series, 52, IARC Scientific Publications No. 13, Environmental aion and Carc ; genic RTsks, 107-116 (1976). 61 2063104862

[12] Gross, Paul, Is short-fibered asbestos dust a biological hazard? Arch. Environ. Health, 29, 115-117 (1974). [13] Hemley, J. J., Montoya, J. W., Shaw, 0. R., and Luce, R. W., Mineral equilibria in the Mg0-Si0Z-H20 system:Il Talc-antigorite-forsterite-anthophyllite-enstatite stability relations and some geologic i.plications in the system, Am. J. Sci., 277, 353-383 (1977). [14] Huebner, J. S. and Papike, J. J., Synthesis and crystal chemistry of sodium-potassium richterite, (Na,K)NaCaMgsSisOa$(OH,F)2: A model for amphiboles, Am. Mineral., 55, 1973-1992 (1970). [15] Hutchison, J. L., Irusteta, M. C., and Whittaker, E. J. W., High-resolution electron microscopy and diffraction studies of fibrous amphiboles, Acta Cryst. , A31, 794-801 (1975). [16] Kogan, F. M., Guselnikova, N. A., and Gulevskaya, M. R., The cancer mortality rate among workers in the asbestos industry of the Urals, aig. Sanit. 37, 29-32 (1972). [17] McDonald, J. C., Cancer in chrysotile mines and mills, Biological Effects of Asbestos, Lyon, International Agency of Res. on Cancer, 189-194 (1973a). [18] McDonald, J. C., Asbestosis in chrysotile mines and mills, Biological Effects of Asbestos, Lyon, International Agency of Res. on Cancer, 155-159 (1973b). [19] McDonald, J. C., and McDonald, A. D., Epidemiology of mesothelioma from estimated incidence, Preventive Med., 6, 426-446 (1977). [20] Mc0onald, J. C., and Becklake, M. R; , Asbestos-related disease in Canada, Hefte z. Unfallheilkunde, 126, 2. Oeutsch-Osterreichisch-Schweizerische, Unfalltagung in er i$`nT~ pringer-Verlag, Berlin, 521-535 (1976). [21] McDonald, A. 0., Harper, A., El Attar, 0. A., and McDonald, J. C., Epidemiology of primary malignant mesothelfal tueors in Canada, Cancer, 26, 914-919 (1970). [22] McDonald, J. C., McDonald, A. 0., Gibbs, G. W., Siemiatycki, J., and Rossiter, C. E., Mortality in the chrysotile asbestos mines and mills of Quebec, Arch. Environ. Health, 22, 677-686 (1971). [23] McDonald, J. C., Becklake, M. R., Gibbs, G. W., McDonald, A. D., and Rossiter, C. E., The health of chrysotile asbestos mine and mill workers of Quebec, Arch. Environ. Health, 28, 61-68 (1974). [24] McDonald, J. C., Gibbs, G. W., Liddell, F. 0. K., and McDonald, A. 0., Mortality after long exposure to cummingtonite-grunerite (abstr.), Am. Rev. Resp. Disease, Supp., 115, No. 4, 230 (1977). [25] Nord, G. L., Jr., "State-of-the-Art" of the analytical transmission electron micro- scope, in Proc. 5 osium on Electron Microscopy and x-ray a lications to environ- mental and occupat oni al health a~es, Ann Arbor Sc~Publ., in press 1978). [26] Papike, J. J., and Ross, Malcoi., Gedrites: Crystal Structures and intracrystalline cation distributions, Am. Mineral. 55, 1945-1972 (1970). [27] Pott, F. and Friedrichs, K. H., Tumoren der Ratten Nach I. P. Infektion faser formiger Staube, Naturw., 59, 318 (1972). [28] Rendall, R. E. G., The data sheets on the chemical and physical properties of the U.I.C.C. standard reference samples, in Pneumoconiosis, H. A. Shapiro, ed., Oxford U. Press (1970). [29] Rohl, A. N., Langer, A. M., and Selikoff, I. J., Environmental asbestos pollution related to use of quarried serpentine rock, Science, 196, 1319-1322 (1977). 62

CS [30] Ross, Malcolm, Papike, J. J., and Weiblen, P. W., Exsolution in clinamphiboles, Science, 159, 1099-1102 (1968a). [31] Ross, Malcolm, Smith, W. L., and Ashton, W. H., Triclinic talc and associated amphiboles from the Gouverneur Mining District, New York, Am. Mineral., 53, 751-769 (1968b). [32] Ross, Malcolm, Papike, J. J. , and Shaw, K. W., Exsolution textures in amphiboles as indicators of subsolidus thermal histories, in Mineral. Soc. Am. special paper no. 2, J. J. Papike, ed., pp. 275-299 (1969). [33] Selikoff, 1. J., Hammond, E. C., and Churg, Jacob, Asbestos exposure, smoking, and . neoplasia, J. Am. Med. Assoc., 204, 106-112 (1968). [34] Seshan, K. and Wenk, H.-R., Identification of faults in asbestos minerals and applica- tion to pollution studies, in Proc. Electron Microscope Soc. Am., 34th annual meeting, G. W. Bailey, ed., 616-617 (ClaT-to-F's Pub. Div., Baton Rouge, LA, 197-6-T [35] Takeda, Hiroshi and Ross, Malcolm, Mica polytypism: Dissimilarities in the crystal structures of coexisting 1M and 2M1 biotite, Am. Mineral., 60, 1030-1040 (1975). [36] Veblen, D. R. and Burham, C. W., Triple-chain biopyriboles: Newly discovered inter- mediate products of the retrograde anthophyllite-talc transformation, Chester, Vt., (abstr.), Trans. Am. Geophys. Union, 56, 1076 (1975). [37] Veblen, D. R. and Burnham, C. W., Biopyriboles from Chester, Vermont: The first mixed-chain silicates (abstr.), Geol. Soc. Am. Abstracts with Programs 8, 1153 (1976). [38] Veblen, D. R. , Triple-and mixed-chain biopyriboles from Chester, Vermont, Ph.D. thesis, Harvard University, Cambridge, Mass. (1976). [39] Vigliani, E. C., Asbestos exposure and its results in Italy, in Proc. International Conf. on Pneumoconiosis, Johannesburg, Oxford U. Press, 192-196 (1970F- [40] Wagner, J. C., Berry, G. , and Trimbrell, V., Mesotheliomata in rats after inoculation with asbestos and other materials, Brit. J. Cancer, 28, 173-185 (1973). [41] Whittaker, E. J. W., The structure of Bolivian crocidolite, Acta Cryst., 2, 312-317 (1949). [42] Wones, 0. R., Physical properties of synthetic biotites on the join phlogopite annite, Am. Mineral. 48, 1300-1321 (1963). Discussion NOTE: Discussion of this paper was included in the General Discussion at the end of this session. 63