09:30 - 12:30, 3 hours, International Conference Hall
Plenary Session 4
Medical Aspects: Surveillance and Treatment of Asbestos-related Diseases
4-A: Asbestos and Non-asbestos Agents in Mesothelioma Pathogenesis and Immunology
Chairs: Yasunosuke Suzuki and Iguchi Hiroshi
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Yasunosuke Suzuki, Steven R. Yuen, Richard Ashley
Mount Sinai School of Medicine, the U.S.A
ABSTRACT:
To identify and characterize asbestos fibers associated with the induction of human malignant mesothelioma, we have investigated type(s), number and size of asbestos fibers detected in the lung and mesothelial tissues taken from 168 cases of human malignant mesothelioma (including 164 males and 4 females; 156 pleural and 12 peritoneal; definite or probable; autopsy or biopsy samples). Their occupational history was diverse including asbestos insulators, pipe fitters, electricians, shipyard workers, sheet metal workers, Navy service men, power plant workers, boiler men, brake lining mechanics, fire fighters, family members of asbestos workers, etc. For the tissue sampling, a bulk tissue digestion, or ashing technique of tissue sections, or both were used. A high-resolution analytical election microscopy was used for the identification of asbestos fibers. Results were as follows: (1). asbestos fibers were present in almost all of the lung and mesothelial tissues in these cases. The average number of the fibers in these tissues was much greater than that found in the general population. (2). The most common types of asbestos fibers in lung were either an admixture of chrysotile with amphiboles, amphibole alone, and occasionally chrysotile alone. In the mesothelial tissues most asbestos fibers were chrysotile. It was suggested that such a disproportion of asbestos types between the lung and mesothelial tissues was caused by chrysotile fibers' strong capacity to translocate from the lung to the mesothelial tissues. (3). In some cases, the only asbestos fibers detected in both lung and mesothelial tissues was chrysotile fibers. (4). The majority of the fibers in these tissues were short (< 5ƒÊm in length). thin (< 0.25ƒÊm in width). It was concluded that to determine the types of asbestos fibers associated with the induction on human malignant mesothelioma, both lung and mesothelial tissues must be investigated and that short, thin asbestos fibers should be included in the list of fiber types contributing to the induction of the tumor.