Amosite Fibers Research Articles

Measurement of Collection Efficiency of Amosite Fibers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMeasurement of Collection Efficiency of Amosite FibersJames W. Gentry, Kvetoslav R. Spurny, Helmut Opiela, and Gerhard WeissCite this: Ind. Eng. Chem. Prod. Res. Dev. 1980, 19, 1, 47–52Publication Date (Print):March 1, 1980Publication History Published online1 May 2002Published inissue 1 March 1980https://doi.org/10.1021/i360073a012RIGHTS & PERMISSIONSArticle Views30Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

FIBER DIMENSIONS AND ASPECT RATIO OF CROCIDOLITE, CHRYSOTILE AND AMOSITE PARTICLES DETECTED IN LUNG TISSUE SPECIMENS

Chrysotile, amosite and crocidolite fibers detected in autopsy tissue specimens from cases of mesothelioma and controls have been characterized by particle length, diameter and aspect ratio using a transmission electron microscope. The pooled information from such specimens reveals that the fibers of each mineral type detected in biological material have very different physical characteristics although in all samples fibers less than 5 microns in length are predominant by number while fibers over 25 microns in length are found very infrequently. Chrysotile fibers on average appear as the shortest fibers with the most fine diameter distribution, amosite fibers are on average the longest with the most coarse diameter distribution, crocidolite fibers on average have dimensions which are intermediate between both chrysotile and amosite. The percentage number of fibers of chrysotile, amosite and crocidolite detected with an aspect ratio less than or equal to 10 were 31.7%, 24.2% and 18.5% respectively.

Measurement of collection efficiency of amosite fibers

Abstract The collection efficiency of amosite fibers was measured for nuclepore filters as a function of NPF pore size and flow rate by four different measurement techniques – a gravimetric determination based on the activity of 57 Fe, a comparative fiber count using SEM, the use of a modified Royco with a variable flow rate, and a Climet. Comparisons of the four methods are made, and their appropriateness is discussed. Measurements indicate that the efficiency is a weak function of flow rate.

Dielectric characterization of UICC asbestos samples

The frequency dispersion of the dielectric coefficient and of the dielectric loss measured on suspensions of asbestos fibers in paraffin oil as functions of fiber concentration and temperature showed for Canadian chrysotile relatively large energy dissipation maxima which can be explained in terms of relaxation of transverse and longitudinal polarization with slightly different energies of activation. Amosite fibers, in contrast, were found to be dielectrically inactive compared with the large-scale effects exhibited by chrysotile. Chrysotile suspensions were slightly thixotropic at volume concentations of the fibers as low as 0.5%, while the amosite suspensions did not show thixotropic behavior up to fiber concentrations of 1.0 vol.%.

Measurements of collection efficiency of nuclepore filters for asbestos fibers

The collection efficiency of amosite fibers using nuclepore filters (NPF) was measured by two techniques: gravimetrically, using the activity of radioactively labeled amosite, and optically, with a Model 221 Royco. These studies employed an instrument with six successive NPF having descending pore sizes. Collection efficiencies ranged from 0.3 to 0.7. Electron micrographs indicate that fibers are able to penetrate NPF with pores less than 20% of the fiber length. A Royco was modified to increase the flow rate through the instrument. For NPF with large pores, penetration increased with velocity suggesting a greater degree of alignment.

The limit of detection of amosite in two forms of calcium silicate matrix

Preparation procedures are examined by which the length of amosite fibres may be reduced so that preferred orientation is removed thereby providing samples suitable for quantitative X-ray diffraction analysis. Grinding in methyl alcohol produced samples from which X-ray diffraction gave major peak intensities reproducible to within ±2%. X-ray analysis has been carried out on samples of either calcium silicate powder or a lagging material which consists largely of a calcium silicate matrix reinforced with rockwool fibres which contain known additions (≤ 10 wt %) of amosite. The limits of detectability of amosite in both of these matrix materials, based on three diffraction peaks 110; 060:310; 240, have been established. It is concluded that for a mixture of amosite in calcium silicate powder, the limit of detectability is 0.4± 0.1 wt % and for amosite in lagging material, the limit of detectability is 0.2± 0.1 wt %. These are discussed in terms of differences in the physical distribution of the matrix materials.

An examination of the fibrous mineral content of asbestos lung tissue from the Canadian chrysotile mining industry

An examination of postmortem lung tissue from 20 cases of diagnosed asbestosis from the Canadian chrysotile mining industry has shown that fibrous minerals other than chrysotile were present in many of the cases. Tremolite fiber was found in 11 of the cases, often in large amounts, and crocidolite and amosite fibers were found in 2 of the cases. Fibers corresponding to talc and anthophyllite were found in 3 cases. In 4 of the cases, fibers were not detected. Amphibole and other fibers were found to be present in larger numbers than chrysotile in 7 of the cases. No attempt has been made to relate the results to occupation and location where the exposures may have occurred. It is possible, however, that fibrous minerals other than chrysotile are active in the incidence of asbestosis in the Canadian chrysotile mining industry.

Emploi de la microscopie en contraste de phase pour l'identification des particules minérales fibreuses présentes dans le poumon humain

Optical microscopy remains the basic means for the study of particulate pollution. Very accurate measurement of the refractive index can be obtained by the use of the λ variation method in phase contrast microscopy. Results obtained on quartz dust and amosite fibres extracted from the human lung are discussed.

Chemical characterization of asbestos body cores by electron microprobe analysis.

Inhalation of asbestos may be associated with increased risk of developing malignant neoplasms. Some of the fibers become coated in the lung, resulting in "asbestos bodies." The occurrence of structures with the appearance of asbestos bodies in the lungs of urban dwellers the world over, individuals with no known exposure to these mineral fibers, has raised the question of whether the community at large may also have increased risk of neoplasia as the result of chance environmental asbestos exposure. Since other fibrous materials may also sometimes become so coated, epidemiology evaluation of the presence of asbestos bodies has been hampered by difficulties in obtaining absolute identification of the cores of the bodies found. Five fibrous silicates, consisting of four amphiboles (amosite, anthophyllite, crocidolite and tremolite) and one serpentine (chrysotile), constitute the asbestos mineral group. Chemically, they are diverse enough for unique identification. The electron microprobe analyzer permits microchemical analysis of particles in the sublight microscopic size range. Analysis of asbestos body cores requires particle selection, extraction from tissue matrix, a suitable conducting substrate, proper coating material, selection of optimal instrumental operating conditions and comparison of unknown cores with known fiber standards. In this investigation, asbestos body cores have been analyzed from tissues obtained from occupationally exposed individuals (known fiber exposure), laboratory animals (known exposure) and individuals with no known occupational exposure. Cores of bodies have been analyzed as amosite, chrysotile, chemically degraded chrysotile and cores of undetermined nature. Amosite fibers as cores of asbestos bodies show no marked chemical degradation even after prolonged biologic residence, whereas chrysotile asbestos cores are markedly degraded. Cores of asbestos bodies from the general population, from individuals with no known exposure, may consist of degraded chrysotile, synthetic silicate fibers and, in some cases, amphibole asbestos.

Formation of the Asbestos Body. A Comparative Study with Three Types of Asbestos

Abstract Asbestos bodies were produced experimentally in the lungs of hamsters by intratracheal instillation of three types of asbestos: soft chrysotile, harsh chrysotile, and amosite. Though some differences were noted, harsh chrysotile and amosite fibers were converted into asbestos bodies by the same successive steps that were previously described for soft chrysotile: (1) phagocytosis of asbestos by alveolar macrophages and other phagocytic cells and incorporation into phagolysosomes; (2) accumulation of iron micelles around the fibers, possibly by fusion of asbestos-containing phagosomes with hemosiderin granules; and (3) compaction of the micelles and clearing of the peripheral zone, to form a mature asbestos body. Formation of asbestos bodies seems to be a continuous process with old bodies growing in thickness and uncoated fibers being converted into bodies months or years after instillation of asbestos. Possible origins of hemosiderin granules are discussed. Striking hyperplasia of cell organelles was found, presumably indicative of their participation in the development of the asbestos bodies.

Formation of the asbestos body: A comparative study with three types of asbestos

Asbestos bodies were produced experimentally in the lungs of hamsters by intratracheal instillation of three types of asbestos: soft chrysotile, harsh chrysotile, and amosite. Though some differences were noted, harsh chrysotile and amosite fibers were converted into asbestos bodies by the same successive steps that were previously described for soft chrysotile: (1) phagocytosis of asbestos by alveolar macrophages and other phagocytic cells and incorporation into phagolysosomes; (2) accumulation of iron micelles around the fibers, possibly by fusion of asbestos-containing phagosomes with hemosiderin granules; and (3) compaction of the micelles and clearing of the peripheral zone, to form a mature asbestos body. Formation of asbestos bodies seems to be a continuous process with old bodies growing in thickness and uncoated fibers being converted into bodies months or years after instillation of asbestos. Possible origins of hemosiderin granules are discussed. Striking hyperplasia of cell organelles was found, presumably indicative of their participation in the development of the asbestos bodies.

The thermal decomposition of miscellaneous crocidolites

SummarySixteen samples of crocidolite asbestos from weathered zones in mines in Cape Province, Transvaal, Western Australia, and Bolivia have been studied by thermal analysis methods and their characteristics are compared with those of fresh crocidolite from Koegas-Westerberg given by Hodgson, Freeman, and Taylor (1965). New chemical analyses of these samples are reported.The effect of natural weathering on crocidolite tends to a removal of ¼ of the OH groups and an adjustment of the Fe2+/Fe3+ ratio to unity, but there are only minor changes in the physical characteristics of the fibre. The d.t.a. pattern of decomposition is not affected by weathering, but the endothermic peak corresponding to final decomposition is moved to higher temperatures as the Mg content of crocidolite increases. Mg-blocking of this decomposition is considered to be more important than Mg-blocking of the oxidation reaction at 400–450° C, suggested by Addison et al. (1962).D.t.a. and other evidence shows that the Transvaal crocidolite contains intergrown amosite fibres, and suggests that the Bolivian crocidolite is admixed with anthophyllite.