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Experimental Asbestosis
Published in Joan Gil, Models of Lung Disease, 2020
We believe that these views have been reinforced by our studies on the asbestos fiber tremolite (Wagner et al., 1982). Tremolite is an amphibole asbestos with fibers that have dimensions varying from large flakes to very fine fibrils. Following inoculation of the range of size of this material, we were only successful in producing mesotheliomas with the very fine material (diameter less than 0.3 μm). These findings, taken with the results of our collaborative investigations with epidemiologists and mineralogists, have been confirmed on a worldwide basis (Beck and Bignon, 1984). The very fine tremolite fibers are associated with mesotheliomas in humans, the fibers with a diameter of more than 1 μm are associated with pulmonary fibrosis and carcinoma of the lungs. The coarser fibers, which occur in many parts of the world as a contaminant of agricultural soils, are associated with the production of large calcified pleural plaques. The large flakelike particles that occur in some regions as a contaminant of talc do not cause lesions in humans or experimental animals.
Acute Lung Injury In Children Due To Chemical And Physical Agents
Published in Lourdes R. Laraya-Cuasay, Walter T. Hughes, Interstitial Lung Diseases in Children, 2019
Two main groups of fibers are found, serpentines and amphiboles.417 The only serpentine, chrysotile (white asbestos), is the most common type (90% of all asbestos used) and is used in textile manufacture and related industrial processes.418 It is made of spirals of curved fibrils and, when inhaled, is deposited on proximal branching points of the tracheobronchial tree.417 Although chrysotile is cleared more rapidly than the other asbestos fibers from the tracheobronchial tree, it is more cytotoxic because of its high magnesium content.417 The amphiboles are used primarily in insulation applications. There are several, including cro-cidolite, amosite, anthophyllite, and tremolite.419 They are rectilinear fibrils of various dimensions that penetrate deeply into the lung.417 Fibers differ somewhat in fibrogenic potential, but even greater differences exist with regard to oncogenic potential so that crocidolite and amosite are associated with mesothelioma more often than the other fiber types.419 Tremolite is a common impurity in talc and other minerals417 and may be responsible for some lung disease associated with these agents.
Assessment of the physicochemical properties of chrysotile-containing brake debris pertaining to toxicity
Published in Inhalation Toxicology, 2019
Matthew S. P. Boyles, Craig A. Poland, Jennifer Raftis, Rodger Duffin
The role of amphibole contamination of chrysotile in the risk of MM (the so-called ‘amphibole hypothesis’) is a hotly debated topic. The hypothesis hinges on the observation of significantly higher proportion of amphibole fibers in the lungs of MM suffers despite higher levels of exposure to chrysotile (Roggli et al. 2002). Furthermore, study of MM incidence in Canadian chrysotile mines and mills where there is a <1% contamination of tremolite found the relative ratio of tremolite to chrysotile fibers in the lungs of workers is directly related to their risk (Mossman et al. 1990). Amphiboles are widely considered to be much more potent at causing MM than chrysotile (Berman and Crump 2008; Hodgson and Darnton 2010). As such, where amphiboles are present as a contaminating element of chrysotile, the overall MM generating potency of the mixed exposure would likely increase. Conversely, an absence of amphiboles would suggest a reduced potency (although we do not suggest removed), thus requiring heavy exposure to generate a significant risk of MM.
The health effects of short fiber chrysotile and amphibole asbestos
Published in Critical Reviews in Toxicology, 2022
In contrast, the amphibole asbestos class of fibers is formed as solid rods/fibers (Skinner et al. 1988; Whittaker 1960). The structure of amphibole is a double chain of tetrahedral silicate (Si4O11)6− with the silica on the outside of the fiber, which makes it very strong and durable. Crocidolite and amosite were the only amphiboles with significant industrial uses (Virta 2002). Tremolite, while not used commercially, has been found as a contaminant in other fibers or in other industrial minerals (e.g. chrysotile and talc). Due to the structural matrix of amphibole fibers, they have negligible solubility at any pH that might be encountered in an organism (Speil and Leineweber 1969).
Talc and mesothelioma: mineral fiber analysis of 65 cases with clinicopathological correlation
Published in Ultrastructural Pathology, 2020
Victor L. Roggli, John M. Carney, Thomas A. Sporn, Elizabeth N. Pavlisko
Talc is a hydrated magnesium silicate which belongs to the phyllosilicate family.12 Deposits of the mineral may be found in association with amphibole minerals, tremolite or anthophyllite. In some circumstances the latter may have an asbestiform habit.7 Because of its unique properties, talc has an abundance of industrial applications. Consequently, talc is the most abundant non-asbestos elongated mineral particle identified in human lung tissue samples.2,16,30,31 In our laboratory, tremolite is the most common asbestiform mineral identified in our control cases and correlates to some extent with the concentration of talc fibers in lung tissue samples.7,21