World Trade Organization (WTO) measures affecting
asbestos and products containing asbestos
(See the document)
- Appendix 1 -
Review of the evidence published after 1976
points to the definite differences in biological effects and potencies of chrysotile asbestos
and the amphibole varieties |
There are no less than 25 reports from human studies alone, and they are presented here under two separate sub-headings:
|
A) Mortality and morbidity data |
Wagner, J.C., Newhouse, M.L., Corrin, B., Rossiter, C.E.and Griffiths, D.M. (1988).
Correlation between fibre content of the lung and disease in East London asbestos factory workers.
British Journal of Industrial Medicine 45(5):305-308.
"We believe therefore that chrysotile is the least harmful form of asbestos in every respect and that more emphasis should be laid on the different biological effects of amphibole and serpentine asbestos fibre".
Kleinerman, J. (1988). The pathology of asbestos related lung disease.
Proceedings, The Fleischner Society, Eighteenth Annual Symposium on Chest Disease, Montréal, Canada, 16-18 May, pp. 33-46.
"Most asbestos workers who develop mesothelioma are exposed to amphibole asbestos. Few mesotheliomas are found in workers exposed to chrysotile... The tremolite exposure is considered to play a major role in the development of the mesotheliomas in these cases".
Dunnigan, J. (1988). Commentary: Linking chrysotile asbestos with mesothelioma.
American Journal of Industrial Medicine 14:205-209.
Overview of evidence showing unlikeliness of link of mesothelioma with chrysotile exposure. Epidemiological studies from USA (Weiss, McDonald and Fry, Dement), from Britain (Newhouse, Thomas, Acheson) are analysed, and lung burden studies (Pooley, Wagner, Jones, A.D. McDonald) are also pointed to.
Hughes, J.M., Weill, H. and Hammad, Y.Y. (1987). Mortality of workers employed in two asbestos cement manufacturing plants.
British Journal of Industrial Medicine 44(3):161-174.
Mortality of 6,931 employees of two asbestos cement factories was studied. In one of them (plant 2), crocidolite was used along with chrysotile. There were 10 cases of mesothelioma in this study, 8 of whom from the plant 2. The case-control analysis found a significant relation between risk of mesothelioma and proportion of time spent in the area of making a/c pipes where crocidolite was used.
Gardner, M.J. and Powell, C.A. (1986). Mortality of asbestos cement workers using almost exclusively chrysotile fibre.
Journal of the Society of Occupational Medicine 36(4):124-126.
Three studies are reviewed of asbestos-cement workers using almost exclusively chrysotile in Great Britain and in Sweden. No asbestos-related mortality in meaningful excess of expected was found. The authors state: "This is in contrast with most studies of workers making similar products from mixed fibres containing mainly chrysotile but also amphiboles, crocidolite and amosite".
Berry, G. and Newhouse, M.L. (1983). Mortality of workers manufacturing friction materials using asbestos.
British Journal of Industrial Medicine 40(1):1-7.
Study of 13,400 workers (friction materials) showing no mesothelioma when chrysotile only was used, but 10 mesotheliomas when crocidolite was also used.
Thomas, H.F., Benjamin, I.T., Elwood, P.C. and Sweetnam, P.M. (1982). Further follow-up study of workers from an asbestos cement factory.
British Journal of Industrial Medicine 39(3):273-276.
Study of 1,970 a/c workers, showing no case of mesothelioma over 40-year period when chrysotile only was used, but 2 mesotheliomas when crocidolite was used during a 2-year period.
McDonald, A.D. and Fry, J. (1982). Mesothelioma and fibre type in three american asbestos factories - Preliminary report.
Scandinavian Journal of Work, Environment and Health 8 (Supplement 1): 53-58.
Study of yarns, cloth and packings, and also gaskets manufacturing, showing only 1 case of mesothelioma / 2,341 workers when almost exclusively chrysotile was used, and 18 cases / 1,429 workers when mixed fibre types were used.
Acheson, E.D., Gardner, M.J., Pippard, E.C. and Grime, L.P. (1982). Mortality of two groups of women who manufactured gas masks from chrysotile and crocidolite asbestos: a 40-year follow-up.
British Journal of Industrial Medicine 39(4):344-348.
Study of gas mask workers showing no case of mesothelioma when chrysotile only was used, and 5 cases / 757 workers using crocidolite.
McDonald, A.D. and McDonald, J.C. (1978). Mesothelioma after crocidolite exposure during gas mask manufacture.
Environmental Research 17(3):340-346.
Exposure to crocidolite in making war-time military gas-masks in Québec led to accumulation of 9 cases of mesothelioma out of 56 deaths (16%). High amounts of crocidolite (and some chrysotile) were found in their lungs. This compares with incidence of mesothelioma, 0.26% of deaths in the Québec (chrysotile) mines.
Weiss, W. (1977). Mortality of a cohort exposed to chrysotile asbestos.
Journal of Occupational Medicine 19(11):737-740.
Study showing no case of mesothelioma in millboard and paper manufacturing when chrysotile only is used.
|
B) Analysis of mineral lung content
|
Wagner, J.C., Newhouse, M.L., Corrin, B., Rossiter, C.E.R. and Griffiths, D.M. (1988).
Correlation between fibre content of the lung and disease in East London asbestos factory workers.
British Journal of Industrial Medicine 45(5):305-308.
The lungs from 36 past workers of an asbestos factory using chrysotile, crocidolite, and amosite were examined. Crocidolite and amosite lung contents were strongly associated with asbestosis, and with mesothelioma, whereas no such correlation was evident with chrysotile and mullite.
Wagner, J.C., Moncrieff, C.B., Coles, R., Griffiths, D.M. and Munday, D.E. (1986).
Correlation between fibre content of the lungs and disease in naval dockyard workers.
British Journal of Industrial Medicine 43(6):391-395.
Study showing increasing amounts of amphiboles in lung tissue with increasing severity of asbestosis, but no increase of chrysotile.
Churg, A. (1985). Malignant mesothelioma in British Columbia in 1982.
Cancer 55(3):672-674.
Study showing a 300-fold increase of amphiboles in lung tissue of mesothelioma cases, but no difference with general population with regard to chrysotile lung content.
Churg, A. (1988). Chrysotile, tremolite, and malignant mesothelioma in man.
Chest 93(3):621-628.
Churg maintains that of 53 cases of mesothelioma ever reported as caused by chrysotile, in fact 51 may be attributed to contamination by tremolite, crocidolite and/or amosite.
Jones, J.S.P., Roberts, G.H., Pooley, F.D., Clark, N.J., Smith, P.G., Owen, W.G., Wagner, J.C., Berry, G. and Pollock, D.J. (1980).
The pathology and mineral content of lungs in cases of mesothelioma in the United Kingdom in 1976.
In Biological Effects of Mineral Fibres, J.C. Wagner Editor, Vol. 1, International Agency for Research on Cancer, IARC Scientific Publications No. 30, Lyon:187-199.
Study in U.K. showing that patients with mesothelioma have a far greater number of amphiboles in their lungs, but same amount of chrysotile when compared to controls.
McDonald, A.D. (1980). Mineral fibre content of lung in mesothelial tumours: - Preliminary report.
Biological Effects of Mineral Fibres, J.C. Wagner Editor, Vol. 2, International Agency for Research on Cancer, IARC Scientific Publications No. 30, Lyon:681-685.
Same observation as above for patients with mesothelioma in North America.
Churg, A. (1982). Asbestos fibres and pleural plaques in a general autopsy population.
American Journal of Pathology 109(1):88-96.
Study showing that patients with pleural plaques have a 50-fold increase of amphiboles compared to chrysotile.
Wagner, J.C., Berry, G. and Pooley, F.D. (1982).
Mesothelioma and asbestos type in asbestos textile workers: a study of lung contents.
British Medical Journal 285:603-606.
In an asbestos textile factory that utilized mainly chrysotile with some crocidolite, less chrysotile and more crocidolite fibre were found in the lungs of 12 persons who had died of mesothelioma than in the lungs of controls without mesothelioma.
Wagner, J.C., Pooley, F.D., Berry, G., Seal, R.M.E., Munday, D.E., Morgan, J. and Clark, N.J. (1982).
A pathological and mineralogical study of asbestos-related deaths in the United Kingdom in 1977.
The Annals of Occupational Hygiene, Inhaled Particles V, 26(1-4):423-431.
Study showing a 100 fold increase of amphiboles in lung tissue, but similar amounts of chrysotile in referred pneumoconiosis patients.
Gylseth, B., Mowe, G. and Wannag, A. (1983).
Fibre type and concentration in the lungs of workers in an asbestos cement factory.
British Journal of Industrial Medicine 40(4):375-379.
The predominant asbestos type used in a Norwegian asbestos-cement factory (1942-1980) has been chrysotile (91.7%), with small admixture of amosite (3.1%), crocidolite (4.1%) and anthophyllite (1.1%). In the lungs of workers who had died of mesothelioma (4) or of lung cancer (3), the percentage of chrysotile fibres was 0%-9% whereas the corresponding proportion for the amphiboles was 76% and 99%.
Rowlands, N., Gibbs, G.W. and McDonald, A.D. (1982).
Asbestos fibres in the lungs of chrysotile miners and millers - A preliminary report.
The Annals of Occupational Hygiene, Inhaled Particles V, 26(1-4):411-415.
Lung samples from 47 workers of chrysotile mines in Québec who had died of various causes not related to asbestos were studied. Similar quantities of chrysotile and tremolite were found although tremolite admixture to chrysotile ore is extremely small. It indicates that tremolite persisted in the lungs while chrysotile was dissolved.
McDonald, A.D., McDonald, J.C. and Pooley, F.D. (1982).
Mineral fibre content of lung in mesothelial tumours in North America.
The Annals of Occupational Hygiene, Inhaled Particles V, 26(1-4):417-422.
99 case-control pairs of lung tissue specimens were examined from persons who had died of mesothelioma in North America. High content of amosite was found in 26 cases and 8 controls, and high content of crocidolite in 15 cases and 5 controls, while content of chrysotile was equal in cases and controls.
Gibbs, A.R., Jones, J.S.P., Pooley, F.D., Griffiths, D.M. and Wagner, J.C. (1989).
Non-occupational malignant mesotheliomas.
In Non-Occupational Exposure to Mineral Fibres, Eds. J. Bignon, J. Peto and R. Saracci. WHO/IARC Scientific Publications No. 90, Lyon:219-228.
The mineral content of the lungs from 84 cases of malignant pleural mesothelioma was estimated by electron microscopy and energy-dispersive X-ray analysis. These cases were chosen because the history of asbestos exposure was absent, indirect or ill-defined. The chrysotile counts in the lungs from these mesothelioma cases were similar to those in controls an in a previous series of mesotheliomas in which the majority had had direct exposure to asbestos. These findings confirm those of previous studies indicating that amphiboles are more important than chrysotile in the causation of malignant mesothelioma. The results confirm that some mesotheliomas develop in the absence of asbestos exposure. "It is possible that chrysotile might potentiate the effects of amphiboles, but we believe that it has either no potential (or a very low one) for mesothelioma induction on its own".
Albin A, Pooley FD, Strömberg U, Attewell R, Mitha R and Welinder H (1994)
Retention patterns of asbestos fibres in lung tissue among asbestos cement workers.
A study which showing different kinetics for amphibole and chrysotile fibres in human lung tissue. Amphibole fibre concentrations increase with duration of exposure, whereas chrysotile concentrations do not. The authors indicate that their study supports a former finding of a possible adaptive clearance of chrysotile, and conclude that their findings "support the hypothesis that adverse effects are associated rather with the fibres that are retained (amphiboles), than with the ones being cleared (largely chrysotile)."
|
