SURFACE-CHEMISTRY AND BIOLOGICAL PATHOGENICITY OF SILICATES - AN X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY

We extend our electron spectroscopy for chemical analysis studies of t he chemistry of silicates to provide direct surface chemical informati on on the interactions involved in silicate-induced lung and tissue pa thology. A total of five fibrous and non-fibrous silicate minerals, pr imarily amphiboles, have been studied: anthophyllite, tremolite, cummi ngtonite, hornblende and actinolite. We have followed the 'inlattice' surface chemistry of these materials and monitored features such as th e simultaneous presence of four- and six-coordinate (with respect to o xygen) structural aluminium, and the presence of iron in the M4 octahe dral positions. In vitro experiments involving contact of the silicate with cultured murine Ehrlich cells have identified modifications in t he surface chemistry of Al, Mg and Fe in the silicates and changes in cellular iron content.