Inorganic Particulates in Human Lung: Relationship to the Inflammatory Response
William S. Lynn in Inflammatory Cells and Lung Disease, 2019
The term asbestos encompasses a number of naturally occurring silicate mineral fibers in the serpentine and amphibole series.56 Chrysotile, the sole representative of the serpentine type of asbestos mineral, is a fibrous magnesium silicate consisting of a curled sheet which spirals around a central capillary. The fibers of chrysotile are typically curly or wavy (Figure 3A). The amphibole series has five recognized members: crocidolite (blue asbestos), amosite (brown asbestos), anthophyllite, tremolite, and actinolite. The amphibole minerals occur as double chains of linked silica tetrahedra which are crosslinked with various bridging cations, the identity of which is useful in the chemical identification of the various types of amphibole. For example, amosite contains iron (Fe+ +) as well as smaller amounts of magnesium and manganese, whereas crocidolite contains iron (Fe+ +, Fe + + +) and sodium as well as smaller amounts of magnesium. The amphiboles are typically straight fibers (Figure 3B). Asbestos may be associated with various contaminants, including trace metals such as nickel, chromium, cobalt, and aluminum, and various hydrocarbons (either as natural contaminants or as a result of processing and storage).56
Occupational and Environmental Lung Diseases
James M. Rippe in Lifestyle Medicine, 2019
Asbestos-related lung disease is a group of lung diseases caused by exposure to naturally occurring asbestos fibers comprised of magnesium silicate minerals. These fibers have desirable physical properties for industrial use, such as high tensile strength, flexibility, and resistance to chemical and thermal degradation, hence their prior extensive use in the construction, automotive, and textile industries.23 Chrysotile (also known as white asbestos) is the most common and only type of asbestos currently used in manufacturing in the United States, while the more toxic amphibole fibers, including crocidolite, amosite, and tremolite are still used in parts of sub-Saharan Africa, South America, and Asia.24 Asbestos fibers are highly carcinogenic and are known to cause lung cancer and malignant mesothelioma. Asbestos is considered one of the most important occupational carcinogens.24
Chrysotile and mesothelioma
Dorsett D. Smith in The Health Effects of Asbestos, 2015
The iron content of amphibole asbestos fibers is very important since iron catalyzes the Fenton reaction to convert nitric oxide to nitrite, which is toxic to living cells. It produces reactive oxygen species, which cause gene mutations and cell damage. Chrysotile is a magnesium silicate in contrast to the iron-rich amphiboles. The lack of iron in chrysotile greatly reduces its ability to cause the release of free radicals and cellular and genetic damage. (Mossman BT, Churg A. Mechanisms in the pathogenesis of asbestosis and silicosis. Am J Respir Crit Care Med 1998;157:1666–80.) Japanese investigators have correlated body iron content with the risk for mesothelioma. (Toyokuni S. Iron overload as a major targetable pathogenesis of asbestos-induced mesothelial carcinogenesis. Redox Rep 2014;19(1):1–7.)
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
In the case of particle and fiber toxicology, two main driving forces behind toxicity are the physicochemical characteristics of the particulate(s) and dose. Obviously, there are other influencing factors such as health status, age, genetic susceptibility yet the dose, morphology, and physicochemical properties are of primary importance. Chrysotile fibers within brake pads are bound within a phenolic resin, subjected to heat and pressure during the production process and high sheer stresses during the grinding of the surface and braking. Given these factors, it is entirely plausible that the morphological and physicochemical properties of chrysotile may be altered in comparison to the virgin chrysotile ‘asbestos’ fibers. Indeed, Weir and Meraz (2001) analyzed the particulates liberated from brake pads containing 50 ± 10% chrysotile. They found that the released material was mostly resin matrix yet some fibrous material, compositionally and morphologically consistent with chrysotile were also found, although the majority of which were bound to a resin matrix. Such findings have been noted in other studies (Lynch 1968; Hatch 1970; Rohl et al. 1976) and certainly indicates the possibility of modification such as bound resin particles which would alter the aerodynamic properties of the fiber.
The toxicology of chrysotile-containing brake debris: implications for mesothelioma
Published in Critical Reviews in Toxicology, 2019
Craig A. Poland, Rodger Duffin
Rather than being a single entity, “asbestos” is a collective term for a group of naturally occurring silicate fibers and are broadly classified into serpentine or amphibole. The serpentine group consists only of chrysotile asbestos, a flexible and flowing fiber of thin chrysotile fibrils that can be woven while the amphibole group consists of five different forms of “asbestos”, namely crocidolite, amosite, tremolite, anthophyllite, and actinolite. Crocidolite and amosite asbestos were used commercially to some degree including significant usage in naval and merchant shipping as insulation materials in the form of asbestos filled mattresses, lagging and prior to 1963, sprayed asbestos (Harries 1968). However, of the different forms of “asbestos”, chrysotile was the most extensively used worldwide (Virta 2006). The availability and useful properties of chrysotile, amosite, and crocidolite asbestos fibers promoted their use in many different environments and products. Their lightweight, fireproofing, and insulating capacity made them indispensable in the technological revolution at the beginning of the twentieth century. “Asbestos” fibers such as chrysotile found uses in brake and clutch linings, insulation for fuel tanks for the growing aviation industry, cement boards and roofing tiles in the building industry and even as “artificial snow” sold to the public.
Asbestos dust concentrations and health conditions of workers at asbestos-cement corrugated sheet production manufacturers in Vietnam: a nationwide assessment
Published in International Journal of Occupational Safety and Ergonomics, 2023
Hang Thi Le, Hoa Thi Dinh, Tam Thi Ngo
In Vietnam, asbestos used in industries is mainly chrysotile. Chrysotile is mainly used in the production of fibro-cement roofing sheets [9]. According to the report by the Vietnam Roofsheet Association, annually, fibro-cement roofing production facilities in Vietnam consume about 52,000 tons of chrysotile to produce an average of about 90 million m2 of roofing sheets [8]. To ensure safe production according to International Convention 162, since 1998, the Government of Vietnam has issued Joint Circular No. 1529/1998/TTLT-BKHCN-BXD dated October 17, 1998, stipulating measures to ensure health and safety for workers in the production of asbestos-cement roofing sheets in Vietnam. In 2001, the Government of Vietnam issued Decision No. 115/2001/QD-TTG intending to ban the use of asbestos since 2004. However, in 2004, the Government issued Decision 133/2004/ QD-TTG, which allowed chrysotile to be used under strict environmental and worker health monitoring [9].
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