Toxicology and Applied Pharmacology 2018 June 27 [Link]
Asbestos mineral fibers have been associated with the development of a variety of diseases in humans and experimental animals, including asbestosis, lung cancer, and mesothelioma. Asbestos includes several mineral types divided into two mineral groups, serpentine and amphibole forms. Chrysotile is the serpentine mineral classified as asbestos, whereas the amphiboles include amosite, crocidolite, tremolite, actinolite and anthophyllite. There are a number of mineral fibers that occur with asbestiform morphology and that have been associated with various asbestos-induced diseases. These include the Libby amphiboles (associated with a vermiculite mine northwest of Libby, MT), erionite (in Turkey and North America), fluoro-edenite (in Sicily), and perhaps balangeroite (in Italy). In addition, each of the asbestos minerals occurs in a non-fibrous form, and these may occur as cleavage fragments that satisfy the definition for a fiber, i.e., particles with an aspect ratio of at least 3:1 and roughly parallel sides. Cleavage fragments of non-asbestiform minerals have not been associated with asbestos-induced diseases nor are these minerals regulated by the Occupational Safety and Health Administration. Finally, there are a number of other mineral species which can occur in human lung samples that satisfy the definition for a fiber as given above. These similarly have not been associated with asbestos-induced diseases. All of these various minerals satisfying the definition for a fiber can be referred to as elongated mineral particles (EMP). It is the purpose of this presentation to discuss the role of scanning electron microscopy (SEM) equipped with an energy dispersive x-ray analyzer (EDXA) in the detection and classification of EMP in human lung samples.