Document O19D1bd4k96p2kZ6dBJ7k2xZv

Carcinogenicity of Amosite Asbestos Irving J. Selikoff, MD; E. Cityler Hammond, ScD; and Jacob Churg, MD, New York Few data exist concerning the comparative neoplastic potential in man of the several kinds of asbestos, in particular, there has been no evi dence concerning whether the amosite variety is carcinogenic. The matter is of practical im portance, since amosite use in the United States has sharply increased. The mortality experience of a group of 230 men previously employed in an amosite asbestos factory was studied during the years 1960 through 1971. Total deaths were more than twice the number anticipated: 46.4 were expected, and 105 occurred. Some 14 deaths were due to asbestosis. Both lung cancer and mesothelioma were found in considerable ex cess. Two or three deaths from lung cancer were expected, and 25 occurred. There were five deaths from mesothelioma. Occupational exposure to amosite asbestos can be associated with serious cancer hazard; its continued industrial use re quires rigorous control. Possible differences in the disease potential of the several common, commercially avail able varieties of asbestos fiber (.chrysotile, amosite, crocidolite, anthophyllito) have been sought, since the use of asbestos might be guided accordingly.1 Experimental studies were undertaken to seek such information. These have not indicated any critical differ ences; mesothelioma can be produced easily by intrapleural inoculation of various types of asbestos.2 There is less information concern ing experimental lung cancer.3 Submitted for publication Feb 7, 1972; accepted March 17. From the Mount Sinai School of Medicine, Gty University of New York, and the American Cancer Society, New York. Reprint requests to Department of Community Medicine, Mount Sinai School of Medicine. City University of New York, Fifth Ave e 100th St, New York, NY 10029 (Dr. Selikolt). Few data exist concerning the compara tive neoplastic potential of the several kinds of asbestos in man. Some information is available for chrysolite,4 crocidolite,3 and anthophyllito.5 ..However, there has been no evidence to indicate whether or not the amo site variety is also carcinogenic. In large part this has been the result of epidemiological diiftculties. Since there is often admixture o: fiber varieties under in dustrial circumstances, the experiences of employed populations are not always readi ly attributable to a single fiber variety. Dili gent efforts have been made to investigate the occurrence of disease in the Transvaal in South Africa, th-- only area in which amo site is mined, and where populations ex posed only to a'ionite could be identified. Environmental studies in this area, reported in 1964, showed no instance of mesotheli oma in amosite miners and only isolated instances of carcinoma of the bronchus, al though asbestosis was found.7 This survey has since been complemented by a study of miners in the area. No attempt was made to study the Bantu workmen who are in the majority, since labor turnover is very high, and ". . . records kept are such that follow up of individuals over a period of time is impossible."* The fate of white miners em ployed between 1954 and 195S was investi gated. Unfortunately, the records turned out to be imperfect and incomplete, since the white work force in these mines was unsta ble. Only 147 white miners could be fol lowed at all, and only 20 of these were observed for rrore than 20 years after first exposure to asbestos. Among these 20, there was one instance of lung cancer and none of mesothelioma. Elsewhere, comment is made Arch Environ Health--Vol 25, Sept 1272 CHEV BB 0003215 186 AMOSITE ASBESTOS & CANCER--SELIKOFF ET AL removed and analyzed. They were invariably amosite. 5. We have extracted mineral fibers from the lungs of individuals in this cohort who had died. Large numbers of fibers were present Electron diffraction and electron microprobe analysis showed them to be amosite,11 except for the occasional chrysotile fibril expected to be present in the lungs of urban dwellers in this area.12 Results Hie mortality experience of this group of workmen, 1960 through 1971, demonstrates that a serious health hazard was associated with this industrial use of amosite. Table 3 records expected and observed deaths. Total deaths were more than twice the number anticipated: io.4 were expected and 105 occurred. This excess death rate was limited to two categories: cancers of various sites and asbestosis. Fourteen deaths were due to asbestosis. when virtually none was expected. That amosite can result in asbestosis has been previously recognized.17 2I3n4 5p6hysiological studies of a select group of workmen at this particular factory from 1954, serious pul monary insufficiency had been demon strated.13 Both lung cancer and mesothelioma were also found in considerable excess. It was anticipated that 2.4 deaths from lung cancer would eventuate; 25 occurred. The calcula tion of expected rates disregarded smoking habits, since the smoking habits of individu als not examined by us are not accurately known. In prospective studies from this point on, smoking habits will be taken into account.14 Mesothelioma caused five deaths: two pleural and three peritoneal. Each has been histologically verified in material obtained during operations in two instances and at autopsies in three. In one case, there had been prior chrysotile exposure; in four, only amosite asbestos exposure had occurred. Parenthetically, additional instances of meso thelioma have occurred among men working in this plant, other than in the cohort re ported here. It may be of interest that more deaths from cancer of the stomach, colon, and rec tum have occurred than expected. The in crease is only threefold, however. As with similar previous experiences, further obser vations are required before this association can be regarded as clearly established.18 This investigation has been supported in part by research grant ES 00358 of the National Institute of Environmental Health Sciences. US Department of Health. Education, and Welfare. Field investigations were carried out by Dorothy Perron. Shirley Levine, Rayla Margolies, and Charles V. Nolan. References 1. Whipple HE fed;: Biological effects of asbes tos. Ann NY Acad Set 132:706-721. 1965. 2. Wagner JC, Berry C: Mesotheliomas in rats following inoculation with asbestos. Brit J Cancer 23:567-581.1969. 3. Smith WE. Miller I* Churg J: An experimen tal model for study of co-carcinogenesis in the respiratory tract. Oak Ridge. Tenn, Atomic Energy Commission symposium series 21. 1970, pp 299-316. 4. McDonald JC, McDonald AD. Gibbs GW, et al: Mortality in the chrysotile asbestos mines and mills of Quebec. Arch Environ Health 22:677-686, 1971. 5. Wagner JC. Sieges CA, Marchand P: Diffusa pleural mesothelioma and asbestos exposure in the North Western Cape Province. Brit J Industr Med 17:260-271.1960. 6. Kiviluoto R. Muerman L: Results of asbestos exposure in Finland, in Shapiro HA (ed): Proceed ings of International Conference on Pneumoconiosis. Johannesburg 1969. Capetown. South Africa, Oxford University Press. Inc. 1970. pp 190*191. 7. ShiU-Crcmcr GK: Asbestosis in South Africa: Certain geographical and environmental considera tions. Ann NY Acad Sci 132:215-234,1965. 8. Sluis-Cremer GK: Asbestosis in South African asbestos miners. Environ Res 3:310-319,1970. 9. Wegner JC: Asbestos cancers, editorial J Nat Cancer Inst 46:v-ix, 1971. 10. Sclikoff IJ, Bader RA, Bader ME, at al: Asbestosis and neoplasia, editorial. Amer J Med 42:487-496. 1967. 1L Longer AM. Rubin I. Selikoff IJ: Election microprobe analysis of asbestos bodies, in Shapiro HA (ed): Proceedings of International Conference on Pneumoconiosis. Johannesburg 1969. Capetown, South Africa, Oxford University Press, Inc, 1970, pp 57-69. 12. Longer AM. Selikoff IJ, Sastre A: Chrvsotils asbestos in the lungs of persons in New York City. Arch Environ Health 22:348-361,1971. 13. Bader ME. Bader RA, Selikoff IJ: Pulmonary function in asbestosis of the lung: An aiveolarcapillary block syndrome. Amer J Med 30:235-242, 1961. 14. Selikoff IJ. Hammond EC, Churg J: Asbestos exposure, smoking, and neoplasia. JAMA 204:106 112.1968. 15. Selikoff IJ. Churg J, Hammond EC: Asbestos exposure and neoplasia. JAMA 188:22-26, 1964. Arch Environ Health--Vol 25. Sept 1972 CHEV BB