Analysis of asbestos fibers in lung parenchyma, pleural plaques, and mesothelioma tissues of North American insulation workers

Our plain-English summary of Analysis of asbestos fibers in lung parenchyma, pleural plaques, and mesothelioma tissues of North American insulation workers, by N. Kohyama, Y. Suzuki (Annals of the New York Academy of Sciences, 1991).

The study

• Authors: N. Kohyama, Y. Suzuki
• Journal: Annals of the New York Academy of Sciences
• Published: 1991;643:27-52
• Cited by: 67 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos fibers and ferruginous bodies (FBs) in lung parenchyma, lung cancer tissues, pleural plaques, and pleural and peritoneal mesothelioma tissues from 13 North American insulation workers were analyzed and quantified using an analytical transmission electron microscope and a polarized microscope. Diseases from which these workers suffered included asbestosis, lung cancer, and mesothelioma. They had been occupationally exposed to materials containing chrysotile and amosite; their pathological diagnoses, occupational and cigarette smoking histories, and clinical summaries have been reported. Large numbers of FBs were found in the lungs and small numbers found in extrapulmonary sites. Most of the FBs had cores of amosite fibers. In all instances, lung parenchyma and lung cancer tissues showed chrysotile and amosite fibers in high concentrations (63.1 x 10(6) and 150.2 x 10(6) fibers/g dry tissue as mean values, respectively). Crocidolite fibers were seen in seven of the 13 cases, but in much smaller numbers. Other amphiboles were rarely found. In pleural plaques and in pleural and peritoneal mesothelioma tissues, amosite fibers were markedly fewer in number, whereas chrysotile fibers were seen in similar numbers as in the lungs. No significant differences in the size distribution of asbestos fibers were seen in the different sites. However, the mean widths of chrysotile fibers were thinner than those of amosite fibers. These results strongly suggest that translocation of inhaled asbestos fibers from the lung to other tissues, such as the pleura and the peritoneum, occurs frequently, and that chrysotile may be more actively translocated from the lung, compared to amosite or amphibole asbestos. The likelihood of translocation seems to be strongly related to the thinness of the fibers. Translocated chrysotile fibers may play an important role in the induction of either malignant mesothelioma and/or hyaline plaques, since the asbestos fibers detected in both these sites were mainly chrysotile.

In plain English

This study measured asbestos fibers and asbestos bodies in 33 tissue samples from 13 insulation workers in the United States and Canada. The workers had been exposed to materials containing chrysotile and amosite. Their diseases were asbestosis, asbestosis with lung cancer, pleural mesothelioma and peritoneal mesothelioma. Using electron and light microscopes, the authors examined lung tissue, pleural plaques and tumor tissue. Chrysotile and amosite were found in the lungs of all 13 workers, at mean concentrations of 63.1 million and 150.2 million fibers per gram of dry tissue. Crocidolite was found in seven lungs at much lower levels. In pleural plaques and mesothelioma tissue, chrysotile was found at concentrations similar to those in the lung, while amosite was much less common. Chrysotile fibers were thinner than amosite fibers. Tremolite was rare in the lungs and not detected in plaques or mesothelioma tissue. The authors concluded that inhaled fibers frequently move from the lung to the pleura and peritoneum, that chrysotile seemed to move more readily, and that this chrysotile may play a role in mesothelioma and/or plaques. They noted that their fiber-size data had considerable statistical variability.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Tissue burden study: laboratory analysis of autopsy/pathology tissue samples by analytical transmission electron microscopy and polarized light microscopy
• Who was studied: 33 tissue samples (lung parenchyma, pleural plaques, lung cancer and mesothelioma tumor tissue) from 13 insulation workers in the United States and Canada, drawn from a large prospective study of insulation workers. The cases were 3 asbestosis, 3 asbestosis with lung cancer, 2 pleural mesothelioma and 5 peritoneal mesothelioma. Exposure began mostly in the 1930s and 1940s.
• Exposure: Occupational exposure as insulation workers to materials containing chrysotile (mainly Canadian) and amosite (South African)
• Main results:
  • In lung parenchyma, chrysotile and amosite were found in all 13 cases. Chrysotile ranged from 15 x 10^6 to 196 x 10^6 fibers per gram dry lung (mean 63.1 x 10^6). Amosite ranged from 7.27 x 10^6 to 415 x 10^6 (mean 150 x 10^6; 150.2 x 10^6 in Table 3).
  • In the lungs, crocidolite was found in 7 of 13 cases at a mean of 11.4 x 10^6 fibers per gram dry lung. Anthophyllite was found in 3 cases (mean 1.9 x 10^6) and tremolite/actinolite in 3 cases (mean 2.5 x 10^6).
  • The mean ratio of amosite to chrysotile concentrations in the lungs was 4.8. In plaques and tumors the ratio was about 0.06.
  • Chrysotile was found in pleural plaques (mean 44.6 x 10^6 fibers per gram dry tissue, 10 samples) and mesothelioma tumor tissue (mean 49.4 x 10^6, 7 samples) at concentrations similar to the lung. Amosite was much lower in these tissues (means 2.53 x 10^6 and 3.3 x 10^6).
  • Asbestos bodies (ferruginous bodies) were found in the lungs of all 13 cases, at a mean of 1.69 x 10^6 per gram dry lung, and most examined cores were amosite. Concentrations in plaques and mesothelioma tissue were about 0.1% of those in the lung.
  • Fiber size distributions for each fiber type did not differ significantly between sites. Chrysotile fibers were thinner than amosite fibers in all sites; in lung parenchyma the geometric mean widths were about 0.03 and 0.11 micrometers.
  • Tremolite was rare in the lungs and was not detected in hyaline plaques or mesothelioma tissue.
• The authors' conclusion: The authors concluded that inhaled fibers frequently translocate from the lung to the pleura and peritoneum in insulation workers. They concluded that chrysotile seemed to be cleared from the lung to other tissues more readily than amosite and that fiber width seemed important. They also concluded that translocated chrysotile may play an important role in mesothelioma and/or hyaline plaques, and that tremolite did not appear to contribute to mesothelioma in these workers.
• Limitations the authors state:
  • The fiber-size data are subject to considerable statistical variability because the number of fibers counted was limited.
  • The route by which fibers move out of the lung was not fully worked out.
  • No tissue digestion method is perfect for recovering all fibers.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Parenchyma, Pleural Plaques, Mesothelioma, Insulator, Ferruginous body, Lung Cancer, Peritoneal Mesothelioma, Chrysotile.

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• North american erionite-associated mesothelioma with pleural plaques and pulmonary fibrosis: a case report — C.R. Kliment, K. Clemens, et al. (2009)
• Asbestos, asbestosis, smoking, and lung cancer. New findings from the North American insulator cohort — S.B. Markowitz, S.M. Levin, et al. (2013)
• Malignant pleural mesothelioma: overview of the North American and European experience — J. Kukreja, M.T. Jaklitsch, et al. (2004)
• Biopersistence of refractory ceramic fiber in human lung tissue and a 20-year follow-up of radiographic pleural changes in workers — J.E. Lockey, V.L. Roggli, et al. (2012)

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