Document jgaDL4mxGZdpkaxqG378mga7Z

i+G**#1*!*#*" f:*< rKl jgffiygjgir>r^:<>..**?. Z^W''' '- V; ":'....... . V INTRODUCTION 06156341 SECTION I Mesothelioma before the Development of Industrial Use of Asbestos Mesothelioma is a malignant tumor of the lining of body cavities. It may appear in the chest (pleural) cavity, abdominal (peritoneal) cavity, or in the pericardium, rarely at other sites. It is a rare disease. It became more widely known when clusters of cases were found, in 1960, in persons working in crocidolite asbestos mines or living in the vicin ity of these mines of South Africa (Wagner, I960)'. Then it was iden tified irfother parts of the world in persons working with asbestos, and other varieties of asbestos than crocidolite were implicated. With time, mesothelioma has become considered by many as an "asbes tos-cancer", a tumor specifically caused by exposure to asbestos. This opinion, however, is not sup ported by facts. Although a majority of currently occurring cases can be -linked withexposure to asbestos, there is no doubt that there is a certain proportion oLcases where no link with asbestos exists, cases ~ ofmesoTfielioma which have another cause, known or unknown? Malignant mesothelioma was known to pathologists before asbestos was ever commercially mined and certain pleural lesions reported in the 19th century are now considered to have been meso thelioma (Suzuki, 1982)2, (Harris)1. Pleural mesothelioma was the subject of a publication by Porter et al. in 18964. In 1922, i.e. two years before Cooke's first clinical description of asbestosis was published, Klemperer and Rabin reported on mesothelioma and described two cases from North America and added three from the European literature (Suzuki)2.. Malignant mesothelioma has been found everywhere in 0.1% -0.01% of autopsies. Klemperer and Rabin discussed the disease again in more detail as an established and definite pathological entity in 1931$. It has been documented that mesothelioma linked with asbestos exposure has an exceptionally long latent period. It is believed that it may develop 20,30, up to 50 years after the first exposure to asbestos. Selikoff2 has not seen any case in which the period since first expo sure was shorter than 11 years. Thus the Klemperer cases, if related to asbestos, would have been due to exposures around 1900 or earlier, when the industry had hardly started its development, and some ` ' types'of asbestos were not yet even__ mined at all (amosite).-- ! *