Quantitative Assessment of Asbestos Fibers in Abdominal Organs: A Scoping Review

Our plain-English summary of Quantitative Assessment of Asbestos Fibers in Abdominal Organs: A Scoping Review, by Y. Caraballo-Arias, F. Roccuzzo, F. Graziosi, et al (La Medicina del Lavoro, 2023).

The study

• Authors: Y. Caraballo-Arias, F. Roccuzzo, F. Graziosi, N. Danilevskaia, S. Rota, C. Zunarellli, P. Caffaro, P. Boffetta, M. Bonetti, F.S. Violante
• Journal: La Medicina del Lavoro
• Published: 2023;114(6):e2023048
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Quantification of asbestos fibers has been mainly performed in the lung but rarely in other organs. However, this may be relevant to understanding better translocation pathways and the oncogenic effects of asbestos on the human body. Electron microscopy is the best technology available to assess the type of fiber, dimensions, and distribution of asbestos fibers in different tissues and as a biomarker of cumulative dose.

Objectives: This scoping review aims to summarize the findings of the studies in which asbestos fibers have been quantified by electron microscopy, occasionally associated with X-ray microanalysis, in normal and pathological tissue of ten abdominal organs.

Methods: A scoping review has been performed by searching articles that quantified asbestos fibers in abdominal organs by electron microscopy (Scanning- SEM or Transmission- TEM).

Results: The 12 selected studies included 204 cases, and 325 samples were analyzed. The colon and rectum, kidney, bladder, and abdominal lymph nodes were the organs with at least ten samples available with quantification of asbestos fibers. Asbestos fibers were detected in all the abdominal organs considered: the highest value (152,32 million fibers per gram of dry tissue) was found in the colon and was identified using STEM with EDS.

Conclusion: The studies included were heterogeneous in terms of exposure and cases, type of samples, as well as analytical techniques, therefore we cannot confirm a specific pattern of distribution in any organ, based on the low homogeneity of the exposure status. The colon is the organ in which the number of fibers is the highest, probably because of exposure arising from both internal distribution of inhaled fibers and ingestion. Additional studies of the number of asbestos fibers in abdominal organs should be made to achieve better representativity.

In plain English

This article was a scoping review. The authors searched six databases on 26 April 2023 for studies that counted asbestos fibers by electron microscopy in ten abdominal organs: stomach, colorectum, small intestine, spleen, bladder, kidney, gallbladder, liver, pancreas and intra-abdominal lymph nodes. They included 12 studies published between 1981 and 2021, covering 204 cases and at least 325 samples. Asbestos fibers, mainly short ones, were reported in all ten organs. The highest value, up to 152.32 million fibers per gram of dry tissue, was in colorectal tissue from exposed or possibly exposed workers, in a study by Ehrlich et al. The highest kidney value, 86.9 million fibers per gram, was in the unexposed group. Fiber counts overlapped between exposed, possibly exposed and unexposed subjects. The authors concluded they could not identify a distribution pattern in any organ. They said they did not know why colon counts were highest, and speculated that fibers swallowed in water and food add to inhaled ones. They noted wide variability among the studies.

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, following the PRISMA extension for scoping reviews; six databases searched on 26 April 2023
• Who was studied: 12 studies published between 1981 and 2021, together comprising 204 cases and at least 325 autopsy or biopsy samples from ten abdominal organs (stomach, colorectum, small intestine, spleen, bladder, kidney, gallbladder, liver, pancreas, intra-abdominal lymph nodes)
• Exposure: Asbestos fibers measured in tissue by electron microscopy, including chrysotile and amphiboles (amosite, tremolite, crocidolite, anthophyllite are named), in subjects with occupational, environmental, unclear or no known asbestos exposure
• Main results:
  • Asbestos fibers, mainly short ones, were found in all ten abdominal organs covered by the review
  • The highest concentration was in colorectal tissue of exposed (or possibly exposed) workers, up to 152.32 million fibers per gram of dry tissue (Ehrlich et al., STEM with EDS); this was also the highest chrysotile value
  • In the kidney, the highest count (86.9 million fibers per gram of dry tissue) was found in the unexposed group
  • Fiber content of the organs overlapped between exposed, possibly exposed and unexposed subjects
  • In one included study (Uibu et al.), among the 10 subjects with lung asbestos content of at least 1 million fibers per gram of dry tissue, mean concentrations were 0.85 in para-aortic and 0.55 in mesenteric lymph nodes
  • The authors said they did not know why colon counts were highest. They speculated that the colon may receive both inhaled fibers carried by blood or lymph and fibers swallowed with drinking water and food.
• The authors' conclusion: The authors concluded that they could not identify a distribution pattern of asbestos fibers in any organ. They considered the information not enough for firm conclusions, but a starting point.
• Limitations the authors state:
  • Significant variability among the included articles
  • The included studies were performed on convenience samples
  • Biopsies may not provide enough tissue compared with autopsies, so data from the two are hard to compare

Topics

Medical terms in this study, explained in our Lexicon: Translocation, Biomarker, Cumulative Dose, Fibers Per Gram, STEM.

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