Characterization of minerals in pleural plaques from lung tissue of nonhuman primates.

Authors: Anne E. Taunton, Mickey E. Gunter, Robert P. Nolan, James I. Phillips

Source: Periodico Di Mineralogia (2011), 80, 1 (Special Issue), 167-179

Summary:

To examine the hypothesis that secondary minerals precipitate in the lung after the inhalation of fibrous minerals, pleural plaques from 11 non-human primates (NHP) were examined using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and powder X-ray diffraction (XRD). Two NHPs served as controls, and nine were exposed to either low (1 f/cc) or high (1000 f/cc) levels of chrysotile, asbestiform grunerite (amosite), asbestiform riebeckite (crocidolite), or glass fibers. XRD analysis revealed apatite in pleural plaques of six NHPs, and SEM-EDS analysis found small quantities of apatite in three additional NHPs. XRD analysis identified calcite in one control NHP and one exposed to chrysotile (with talc present) and in the NHPs exposed to high doses of glass fibers, chrysotile, and grunerite. XRD analysis detected 2:1 expandable clays in NHPs exposed to high levels of glass fibers, chrysotile, grunerite and riebeckite. XRD also detected amphiboles in NHPs exposed to high levels of grunerite and riebeckite. SEM-EDS analysis revealed Mg-rich silicates in a control NHP and one NHP exposed to low doses of chrysotile. Asbestos bodies coating fibers were detected in NHPs exposed to high levels of grunerite and chrysotile. Iron-rich silicate fibers without coatings were identified in the NHP exposed to high levels of riebeckite using SEM-EDS. SEM-EDS also revealed Na-rich silicates in one NHP exposed to low doses of chrysotile. Because minerals other than exposure minerals were detected in many of the NHPs, the hypothesis that secondary minerals may form in the lung after exposure to fibrous minerals should be considered when addressing the health effects of minerals.