An analysis of factors associated with the cytotoxicity of natural and man-made mineral fibers

Natural and man-made mineral fibers possess physical and chemical characteristics that have been associated with cytotoxicity. Among these are fiber length, fiber width, fiber aspect ratio, and surface chemistry. This study correlated measurements of these characteristics with their respective effects on colony forming ability of 3T3 fibroblasts in vitro. These correlations and measurements were used to develop a model for predicting the cytotoxicity of mineral fibers.

A proprietary treatment that reduces the toxicity of both natural and man- made mineral fibers was tested. This proprietary treatment covalently binds a hydrophobic coating to the fibers' surfaces causing them to behave in a hydrophobic manner. Colony forming ability assays were performed on treated and untreated silicon carbide whiskers (SiCW) and crocidolite asbestos. The coating significantly decreased cytotoxicity as measured by colony forming ability. At the highest dosage levels, the fiber coating decreased the cytotoxicity of crocidolite asbestos and silicon carbide whisker by 35% and 60% respectively. A preliminary transformation assay indicated that the coating technique may reduce the fibers' ability to transform cells.