Quantitative Assessment of Asbestos Fibers in Normal and Pathological Pleural Tissue-A Scoping Review

Our plain-English summary of Quantitative Assessment of Asbestos Fibers in Normal and Pathological Pleural Tissue-A Scoping Review, by Y. Caraballo-Arias, P. Caffaro, P. Boffetta, et al (Life, 2022).

The study

• Authors: Y. Caraballo-Arias, P. Caffaro, P. Boffetta, F.S. Violante
• Journal: Life
• Published: 2022;12(2)
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: pleural mesothelioma is a rare cancer in the general population, but it is more common in subjects occupationally exposed to asbestos. Studies with asbestos fiber quantification in pleural tissue are scarce: for this reason, we aimed at undertaking a scoping review to summarize the evidence provided by studies in which asbestos fibers were determined by electron microscopy (SEM or TEM) in human pleural tissues, whether normal or pathologic.

Materials And Methods: A scoping review of articles that quantified asbestos fibers in human pleural tissue (normal or pathologic) by electron microscopy (SEM or TEM), in subjects with asbestos exposure (if any) was performed.

Results: The 12 studies selected comprised 137 cases, out of which 142 samples were analyzed. Asbestos fibers were detected in 111 samples (78%) and were below the detectable limit in 31 samples (22%). The concentration of asbestos fibers detected in the positive samples was distributed from as low as 0.01 mfgdt (millions of fibers per gram of dry tissue) up to 240 mfgdt. However, the minimum concentration of fibers overlaps in the three types of tissues (normal pleura, pleural plaque, mesothelioma) in terms of magnitude; therefore, it is not possible to distinguish a definite pattern which differentiates one tissue from the other.

Conclusions: The studies included were heterogeneous as to the representativeness of the samples and analytical techniques; the possibility of false negatives must be considered. It would be desirable to systematically search for asbestos fibers to fill the knowledge gap about the presence of asbestos fibers in normal or pathological pleural tissue in order to better understand the development of the different pleural diseases induced by this mineral.

In plain English

This scoping review looked for published studies that counted asbestos fibers in human pleural tissue (the lining around the lungs) using electron microscopy. They found 12 studies, published from 1974 to 2001, covering 137 cases and 142 pleural samples, and described them as case series. Asbestos fibers were detected in 111 of 142 samples (78%). Most studies reported both chrysotile and amphiboles. The highest concentration reported was 240 million fibers per gram of dry tissue, in pleural mesothelioma tissue; the article gives the lowest as 0.01 million in its abstract but as 0.016 million, in pleural plaque, in its discussion. Minimum concentrations overlapped across normal pleura, pleural plaque and mesothelioma tissue, so no clear pattern distinguished them. No pleural mesothelioma tissue sample was negative for fibers. Fibers were not detected in 22 of 50 pleural tissue samples (44%) in two studies and in 9 of 26 pleural plaque samples (35%) in two other studies. The authors noted that the studies were highly heterogeneous and that false negatives were possible. They recommended systematically searching for fibers in pleural tissue.

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: Scoping review of published studies; the authors judged the included studies to be case series
• Who was studied: 12 studies published between December 1974 and February 2001, together covering 137 cases (autopsy or biopsy) in which 142 human pleural tissue samples were analyzed. The PubMed search was run on 30 September 2021.
• Exposure: Asbestos fibers (chrysotile and amphiboles) measured by electron microscopy (SEM or TEM) in normal pleura, pleural plaque or fibrosis, and pleural mesothelioma tissue. Subjects had occupational, environmental, unknown or no known asbestos exposure.
• Main results:
  • Asbestos fibers were detected in 111 of 142 pleural tissue samples (78%) and were not detected in 31 samples (22%)
  • The highest concentration in positive samples was 240 million fibers per gram of dry tissue, in pleural mesothelioma tissue in one study
  • The article's abstract gives the lowest concentration in positive samples as 0.01 million fibers per gram of dry tissue
  • The article's Discussion gives the lowest concentration as 0.016 million fibers per gram of dry tissue, in pleural plaque tissue in one study
  • Maximum chrysotile concentration was 5.1 million fibers per gram of dry tissue in pleural tissue, 89.7 in pleural plaque, and 240 in pleural mesothelioma
  • Minimum fiber concentrations overlapped across normal pleura, pleural plaque and mesothelioma tissue, so no clear pattern distinguished one tissue type from another
  • No sample of pleural mesothelioma tissue was negative for asbestos fibers in any study
  • Asbestos fibers were not detected in 22 of 50 pleural tissue samples (44%) in two studies
  • Asbestos fibers were not detected in 9 of 26 pleural plaque samples (35%) in two studies
  • Of the 137 cases, 48 had a diagnosis of pleural mesothelioma (35%) and 38 had pleural plaques or fibrosis (28%)
• The authors' conclusion: The authors concluded that the included studies were heterogeneous and that false negatives must be considered. They recommended that, whenever human pleural tissue and pleural plaques are available, asbestos fibers be searched for systematically and accurate occupational and/or environmental exposure information be collected.
• Limitations the authors state:
  • The included studies were highly heterogeneous, which the authors said prevents firm conclusions
  • Methods for determining asbestos fibers were not standardized across studies
  • Some studies did not report when asbestos exposure began, how long it lasted, or latency
  • There was a high risk of inappropriate samples, because pleural tissue is technically difficult to obtain except at autopsy

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Asbestos Exposure, Fibers Per Gram, Pleura, Pleural Plaques, Mesothelioma.

Related studies

• Quantitative Assessment of Asbestos Fibers in Normal and Pathological Peritoneal Tissue-A Scoping Review — Y. Caraballo-Arias, C. Zunarelli, et al. (2022)
• Quantitative assessment of asbestos fibers in some normal and pathological extra-abdominal tissues-a scoping review — F. Graziosi, P. Caffaro, et al. (2023)
• Quantitative Assessment of Asbestos Fibers in Abdominal Organs: A Scoping Review — Y. Caraballo-Arias, F. Roccuzzo, et al. (2023)
• A trial on the quantitative risk assessment of man-made mineral fibers by the rat intraperitoneal administration assay using the JFM standard fibrous samples — S. Adachi, K. Kawamura, et al. (2001)
• Response to: Pleural mesothelioma, and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment — P. Boffetta (2016)
• Pathways affected by asbestos exposure in normal and tumour tissue of lung cancer patients — S. Ruosaari, T. Hienonen-Kempas, et al. (2008)

Browse return to medical research.