Document YjqjQO2gyzRpNJK9gMO7xk6eN

FILE NAME: OWILL DATE: 1997 OWILL100 DOC#: OWILL100 DOCUMENT DESCRIPTION: Letter to the Editor, Medical Journal - Asbestos-Related Cancer and the Amphibole Hypothesis Letters to the Editor \< \n J OOJ . 1997, Vol. 87, No. 4 Asbestos-Related Cancer and the Amphibole Hypothesis 1. The First Documentation of the Association An annotation' and a paper2 pub lished in a recent issue of your journal must have confused readers on the subject of the association between exposure to asbestos dust and diffuse mesotheliomas of the pleura and peritoneum. It is important that this situation be clarified, as misrepresentation can affect the use and control of these materials in many coun tries. As the original discoverer of the development of mesotheliomas in people exposed to asbestos dust,3 1 would appre ciate an opportunity to try to clarify the situation. In 1957, in the Cape area of South Africa, we established that mesotheliomas of the pleura were occurring in people living in the vicinity of mills processing blue (crocidolite) asbestos and in people milling and mining the material. The main paper was published in 1960, and in 1963 we confirmed that the tumors were occurring in the crocidolite mining area, but not in the amosite or chrysotile areas of southern Africa. Southern Africa was American Journal o f PuKHr* Ae*r Letters to the Editor the ideal area for these investigations, as the three main types of asbestos were produced in the same amounts by a similar labor force. In an international study, we set out to see whether the role of crocidolite could be confirmed in other countries. Over the years, our initial hypothesis has held. The vast majority of mesotheliomas are associated with expo \ sure to crocidolite asbestos. A small number of cases have been recorded following exposure to other forms of amphibole asbestos: amosite, tremolite, and anthophylite. No mesotheliomas have been shown to have occurred in chrysotileexposed workers, unless the exposure has been intense and for more than 20 years. / In addition, there must be tremolite contamination of the chrysotile. Two other facts are of great impor tance: 1. The majority of these tumors occurred following prolonged exposure to large quantities of fiber. This situation rarely exists today. 2. There is a "natural" incidence of these diffuse mesotheliomas. At least 10% of these diffuse mesotheliomas occur without exposure to asbestos dust, and sporadic cases of these tumors were reported before the widespread use of , asbestos. J. Christopher Wagner, MD FRCPath, FFOM Correspondence should be sent to J. Chris topher Wagner, MD, FRCPath, FFOM, " Foxstones," 59 Coombe Valley Rd, Preston, Wey mouth, Dorset, DT3 6NL England. References 1. Cullen MR. Annotation: The amphibole hypothesis of asbestos-related cancer--gone but not forgotten. Am J Public Health 1996;86:158-159. 2. Stayner LT, Dankovic DA, Lemen RA. Occupational exposure to chrysotile asbes tos and cancer risk: a review of the amphibole hypothesis. Am J Public Health. 86:179-186. 3. Wagner JC. Historical background and perspectives of mesothelioma. In: Jaurand M-C, Bignon J, eds. The Msothlial Cell and Mesothelioma. New York, NY: Marcel Dekker; 1994:1-15. Vol 78 in Lung Biology in Health and Disease. 688 American Journal o f Public Health April 1997, Vol. 87, No. 4