Intrapleural administration of vitreous high duty ceramic fibres and heated devitrified ceramic fibres does not give rise to pleural mesothelioma in rats.

In order to determine whether they are potentially carcinogenic to the pleural mesothelium, three samples of ceramic fibre have been administered to rats by the intrapleural route. These samples were a high-duty grade refractory ceramic fibre (manufactured by Thermal Ceramics Ltd) in the as-manufactured vitreous state and two devitrified samples produced by heating the same fibre for 2 weeks at 1200 degrees C and for two weeks at 1400 degrees C. The mean lifespans of the groups of rats treated with vitrified and devitrified ceramic fibres were not significantly different from that of the control rats. In these studies none of the treated or control rats developed pleural mesothelioma, making it unlikely that ceramic fibres of this type, whether vitreous or devitrified, are potentially carcinogenic to the pleural mesothelium.