ASBESTOS IDENTIFICATION FROM HUMAN TISSUE

Human tissue analyses for asbestos are generally more of a challenge as compared to the analyses of mined minerals or products. Mined minerals and the products that they are made into generally have the typical morphologic and chemical appearances when analyzed by electron microscopy. However, once these fibers enter the bodies of humans or animals they can be significantly modified. Fibers that enter the bodies of humans general enter via the lungs, gastrointestinal system or in females, genitally. Once inside these structures they interact with enzymes, chemicals and a variety of molecules. Then the fibers interact with macrophages which either completely engulf the fibers or partially engulf them with the fiber extending beyond the cell membranes of the macrophages. Conditions within the cells and lysosomes of the macrophages can and do modify the surfaces of these cells. It is the surface of the fibers that are observed and analyzed chemically and structurally. The typical example of such effects are the dissolving and breakdown of chrysotile type of asbestos by the leaching of magnesium. Leaching of magnesium results in magnesium levels as measured by energy dispersive spectroscopy (EDS) equal to talc or for that matter anthophyllite. It will then have to be analyzed by selected area electron diffraction (SAED) to observe the internal structure of the arrangement of atoms within the crystalline structure of the fiber. Amphibole type asbestos is more resistant but undergo similar types of leaching and breakdown on the surface of the fibers. On the other hand interactions of molecules with fibers which attach or are added to the surfaces of the fibers change the analysis of the structures in some cases significantly making it difficult to analyze without performing all criteria and even then identity of fiber type can be in question. The alterations of both chrysotile and amphiboles and how it effects their identification will be discussed.