ABSTRACT
Groups of rats, 24 male and 24 female, approximately 8 weeks old, were dosed by a single intrapleural injection with a saline suspension of refractory alumina fibres (Saffil fibres ICI plc) either as manufactured or after extensive thermal ageing; or one of two aluminosilicate ('ceramic') fibres with different diameter distributions. Similar groups were dosed with a suspension of UICC chrysotile A asbestos or saline solution to serve as positive and negative controls respectively. Rats were maintained to 85% mortality and all decedents and terminal sacrifices were closely examined for the presence of mesothelioma. Malignant mesothelioma was diagnosed in ten rats, seven dosed with asbestos and three dosed with aluminosilicate fibre B. No mesothelioma was detected in any rat dosed with Saffil fibres or aluminosilicate fibre A or in negative controls. The results support the predicted inert nature of Saffil alumina fibres and provide further evidence for the importance of fibre dimension in the induction of mesothelioma. The implication of the results for inhalation exposures is discussed.
Subject(s)
Aluminum Oxide/toxicity , Aluminum Silicates/toxicity , Pleural Neoplasms/chemically induced , Animals , Asbestos/toxicity , Female , Hot Temperature , Male , Mesothelioma/chemically induced , Peritoneal Neoplasms/chemically induced , Pleural Neoplasms/etiology , Rats , Rats, Inbred StrainsABSTRACT
Evidence for the lack of toxicity of various bioglass formulations has been deduced from studies carried out, both in vivo and in vitro, in several different centers. Recent studies of the authors, described here, include testing of solid bioglass implants in the soft tissues of rats and rabbits for time periods of up to eight weeks. Two new techniques are described for the toxicological testing of particulate biomaterials. These tests, which involve rat peritoneal macrophages in culture and a mouse pulmonary biomaterial embolus model, indicate the biocompatibility of bioglass powders. Thus, the surface activity so critical in bone adhesion is without toxic effect in non-osseous tissues in contact with solid bioglass implants. Should wear occur and produce particulate bioglass, the material should be eliminated without consequence.
Subject(s)
Biocompatible Materials/toxicity , Ceramics/toxicity , Drug Evaluation, Preclinical/methods , Animals , Bone Cements/toxicity , Cell Division/drug effects , Cells, Cultured , Chickens , Cricetinae , Humans , Inflammation/etiology , Mice , Papio , Prostheses and Implants , RatsABSTRACT
Groups of rats were exposed by inhalation to atmospheres containing a refractory alumina fibre (Saffil Fibres, I.C.I.) either as manufactured or in a thermally aged form. Similar groups were exposed to UICC chrysotile A asbestos or clean air to serve as positive and negative controls respectively. Exposures continued for 86 weeks after which the animals were maintained to 85% mortality. Pulmonary reaction to both forms of alumina fibre was minimal; chrysotile asbestos provoked the expected progressive fibrosis. Pulmonary tumours (both benign and malignant) were confined to rats dosed with asbestos. The results support the predicted inert nature of these alumina fibres.
Subject(s)
Aluminum Oxide/toxicity , Aluminum/toxicity , Lung Diseases/etiology , Animals , Asbestos/toxicity , Asbestosis/pathology , Dose-Response Relationship, Drug , Female , Lung/pathology , Lung Diseases/pathology , Lung Neoplasms/etiology , Lung Neoplasms/pathology , Male , Rats , Time FactorsABSTRACT
Two commercially available grades of the refractory fibre SAFFIL were administered to rats by intraperitoneal injection and the tissue reaction was compared. Although the fibres differed considerably in surface properties and porosity the tissue reactions were identical and consisted of a mild chronic inflammatory response with a small amount of collagen present. The reaction was quite distinct from the marked fibrosis induced by chrysotile asbestos. As the reaction to all fibres tested had stabilised after 6 months, a longer observation period is unnecessary.