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Inorganic Particulates in Human Lung: Relationship to the Inflammatory Response
Published in William S. Lynn, Inflammatory Cells and Lung Disease, 2019
Victor L. Roggli, J. P. Mastin, John D. Shelburne, Michael Roe, Arnold R. Brody
Microscopic techniques employing visible light to study inorganic particulates include standard biological microscopy, phase contrast microscopy, polarized light microscopy, and dispersion staining.15 Many inorganic particulates exhibit the property of birefringence when examined under polarized light, and hence can be observed in tissue sections. In addition, mineral samples suspended in a suitable refractive index liquid can be identified on the basis of their morphologic features and characteristic dispersive staining as observed with polarized light.16 However, inorganic particulates must be extracted from their organic tissue matrix in order to employ the latter technique. In addition, particulates in biological residence acquire a surface coating which modifies many of the optical properties of the minerals.15 Although a number of studies have employed light microscopic techniques for identifying and quantifying inorganic fibrous mineral species, especially asbestos, in lung tissue,17, 18 these studies are hampered by the fact that many particulates resident in the human lung are beyond the resolution of the light microscope.19, 20
Updated Italian cohort data continues to confirm lack of mesothelioma risk in pooled cohort of international cosmetic talc miners and millers
Published in Inhalation Toxicology, 2022
A. Michael Ierardi, Elizabeth A. Best, Gary M. Marsh
Since 1976, the cosmetic industry has relied upon the J4-1 analytical method to determine the potential presence of asbestiform minerals in talc; this method incorporates X-ray diffraction (XRD) to detect the presence or absence of amphibole mineral, followed sequentially by optical microscopy and dispersion-staining color to determine potential fibrous morphology, if the mineral is in fact detected in the initial XRD step (CTFA 1976 b, 1976a). The U.S. Pharmacopeia (USP) has also published an analytical method to determine the “absence of asbestos” in talc used for pharmaceutical applications using either the infrared spectroscopy (IR) technique or XRD as a first step, and then optical microscopy if either of these two initial procedures returns a positive result (i.e., tremolite or serpentine minerals are detected) in order to confirm the potential presence of asbestos fibers (USP 2007, 2020). Additional efforts to develop analytical methods that can reliably identify potential asbestos fibers in talc are underway by the Talc Methods Expert Panel associated with the USP, as well as a federal Interagency Working Group, which made a white paper publicly available in December of 2021 (IWGACP 2021).