DURABILITY OF CERAMIC AND NOVEL MAN-MADE MINERAL FIBERS

In vitro solubility testing is an important means of assessing the lik ely behavior of fibers that are respired and accumulate in the lung. T he problem has been that such tests often do not mirror the dissolutio n and removal mechanisms seen in vivo. Comparison of iron and silica s olubility values of various types of mineral fiber showed no obvious c orrelation. Treating a mineral fiber containing high levels of calcium with normal balanced salt solutions produces a precipitate of calcium phosphate on the fiber surface. This deposit was not seen in fibers i solated from the rung of exposed animals. New solutions have been deve loped and with variations in the methods of exposing fibers, results s imilar to those seen in vivo have been obtained. Suitable fluid phases have been examined in static and flow-through systems. The relationsh ip of solubility to biological activity is discussed.