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Published in Ken Addley, MCQs, MEQs and OSPEs in Occupational Medicine, 2023
Asbestos exposure is most associated with removal of lagging and insulation. Silica exposure is associated with an excess of tuberculosis. There is a synergistic effect with smoking rather than additive. Crocidolite is an amphibole asbestos.
Pleural tumours
Published in Anju Sahdev, Sarah J. Vinnicombe, Husband & Reznek's Imaging in Oncology, 2020
The relationship between asbestos exposure and MPM was established in a study which identified a definite or probable exposure to crocidolite in 32 out of 33 of the patients with MPM (4). Although other aetiological factors such as the simian virus 40 (SV40) and various genetic predispositions have since been proposed, the strongest link, by far, is with asbestos (5). MPM occurs more commonly in men (with a peak incidence occurring in the sixth and seventh decades), and a long latent interval, typically of around 30–40 years, between exposure and the development of MPM is characteristic. Occupations associated with a higher lifetime risk of MPM include those involved in the production of asbestos sheets, carpenters, plumbers, electricians, and painters/decorators. Non-occupational (environmental) exposure to asbestos is also known to occur and predisposes to MPM (6–8).
Respiratory medicine
Published in Shibley Rahman, Avinash Sharma, A Complete MRCP(UK) Parts 1 and 2 Written Examination Revision Guide, 2018
Shibley Rahman, Avinash Sharma
Patients are eligible for industrial injury benefit. Benign pleural disease involves plaques, diffuse pleural thickening, effusion and calcification. Benign pleural disease is usually asymptomatic and detected on CXR. Patients are usually not eligible for industrial injury benefit. Mesothelioma normally occurs >30 years and is almost always caused by asbestosis. High-risk asbestosis is crocidolite (blue asbestos). Diagnosis is confirmed by pleural biopsy.
The health effects of short fiber chrysotile and amphibole asbestos
Published in Critical Reviews in Toxicology, 2022
This concept was stated by Wylie et al. (1987), who reexamined using STEM and optical images seven crocidolite samples used by Stanton et al. (1981). Figure 3 reproduced from Wylie presents the tumor probability as a function of the log of the number of fibers per microgram for those samples that had sufficient fiber measurement data to determine what was called the index number – that is, the log of the number of particles longer than 8 µm with widths equal to or <0.25 µm. This figure illustrates the wide variation in the relationship with tumor probability. The correlation coefficient was r = 0.53 (r2 = 0.281). While significant, this represents a little more than 25% of the variation in the data. Stanton et al. (1981), including all index numbers, reported an r = 0.80. As Wylie states, “Stanton was aware of the limitations in the characterization of the mineral particulates.”
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
For the purposes of the present study, we counted elongated mineral particles as ‘fibers’ if they had roughly parallel sides and an aspect ratio of at least 3:1, counting such structures with lengths that were greater than or equal to 5 µm. The vast majority of asbestos fibers that we have identified in lung tissue samples have met these criteria.33 We found 65 cases of confirmed mesothelioma that contained talc fibers exceeding the range of our background population, including 48 men and 17 women. In 52 of these cases, the patients had elevated levels of commercial amphibole fibers (amosite or crocidolite) that are the most strongly associated with the development of mesothelioma.24,34-37 These cases typically had known exposures to asbestos either in an occupational setting or as a household contact of an asbestos worker (Table 4).
Comments on “Dimensions of elongated mineral particles with implications for pathogenicity and classification as asbestiform versus cleavage fragments”
Published in Ultrastructural Pathology, 2019
Roggli and Green write ‘It has been our impression that this distinction (between fibers and cleavage fragments) has little effect on the identification of amosite or crocidolite as asbestos but might have a considerable effect on the identification of noncommercial amphiboles, including tremolite, actinolite, and anthophyllite.’ As described above, length differences between the commercial and noncommercial amphiboles are likely due, in large part, to the handling and milling after mining. Amosite and crocidolite were largely used in construction applications and were not heavily milled. Tremolite, actinolite, and anthophyllite in the United States mostly occurred as contaminants of Talc and Canadian asbestos. These minerals were usually heavily milled for many of their commercial applications.