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Asbestos exposure and mesothelioma in South Africa
Abstract
Design. A multicentred case-control study.
Subjects and setting. 123 patients with mesothelioma interviewed by trained interviewers in study centres established in Johannesburg, Kimberley, Pretoria, Bloemfontein, Cape Town and Port Elizabeth.
Results. A convincing history of asbestos exposure was obtained in the overwhelming majority of cases (only 5 cases had unlikely asbestos exposure). Twenty-three subjects had worked on Cape crocidolite mines, 3 at Penge (an amosite mine), 3 on mines producing amosite and Transvaal crocidolite and 1 on a Transvaal crocidolite mine. Exclusively environmental exposure accounted for at least 18% of cases; 91% of these cases (20/'22 subjects) had had contact with Cape crocidolite. There was a relative paucity of cases linked to amosite and no convincing chrysotile case. Non-asbestos causes occur rarely, if at all; in South Africa.
Conclusion. The preponderance of crocidolite cases, followed by amosite and then chrysotile cases, is consistent with the view that there is a fibre gradient of mesotheliomagenic potential for South African asbestos (crocidolite > amosite >chrysotile).