Environmental scanning electron microscopy technique to identify asbestos phases inside ferruginous bodies

Our plain-English summary of Environmental scanning electron microscopy technique to identify asbestos phases inside ferruginous bodies, by A. Croce, M. Musa, M. Allegrina, et al (Microscopy and Microanalysis, 2013).

The study

• Authors: A. Croce, M. Musa, M. Allegrina, P. Trivero, C. Rinaudo
• Journal: Microscopy and Microanalysis
• Published: 2013;19(2):420-4
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Ferruginous bodies observed in lungs of patients affected by mesothelioma, asbestosis, and pulmonary carcinoma are important to relate the illness to exposure, environmental or occupational, to asbestos. Identification of the inorganic phase constituting the core of the ferruginous bodies, formed around asbestos but also around phases different from asbestos, is essential for legal purposes. Environmental scanning electron microscopy/energy dispersive spectroscopy was used to identify the fibrous mineral phase in the core of ferruginous bodies observed directly in thin sections of tissue, without digestion of the biological matrix. Spectra were taken with sequential analyses along a line crossing the core of the ferruginous bodies. By comparing the spectra taken near to and far from the core, the chemical elements that make up the core could be identified.

In plain English

This laboratory methods study tested whether environmental scanning electron microscopy with energy dispersive spectroscopy (ESEM/EDS) could identify the mineral fiber inside ferruginous bodies directly in thin lung tissue sections, without digesting the tissue. Ferruginous bodies are the iron-protein-coated bodies the lung forms around inhaled asbestos and also around other materials. Using lung samples from two patients affected by mesothelioma, the authors took chemical readings at points along a line across one ferruginous body and compared its silicon-rich center with its outer coating. Calcium, phosphorus, sulfur and aluminium changed little and were assigned to the coating. Silicon, magnesium and part of the iron were assigned to the core fiber. Because the core held more magnesium than iron, the fiber was identified as anthophyllite. The authors noted that amosite could not be ruled out at first, and that both are legally defined asbestos. They described the results as only semiquantitative. The authors concluded that, for the purpose of this work, the presence of asbestos mineral in the body had been proven. They reported examining several other ferruginous bodies and identifying the core mineral in all of them.

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: Laboratory methods study (technique development) applying ESEM/EDS to ferruginous bodies in histological lung sections, with one ferruginous body described in detail
• Who was studied: Lung samples from two patients affected by mesothelioma. The analysis was reported in detail for one ferruginous body. Patient characteristics, location and dates are not given. Thin sections were prepared with help from a pathology service in Torino, Italy.
• Exposure: No exposure history is reported. The study analyzed the fiber inside a ferruginous body found in lung tissue, which was identified as anthophyllite (an amphibole asbestos). Amosite was considered as an alternative.
• Main results:
  • Along the analysis line across the ferruginous body, calcium, phosphorus, sulfur and aluminium did not change significantly and were attributed to the coating. Silicon, magnesium and part of the iron were attributed to the incorporated fiber.
  • In Table 1 (atomic %), the mean values at the core points compared with the coating points were:
• silicon: 0.19 versus 0.06
• magnesium: 0.10 versus 0.05
• iron: 0.76 versus 0.73

The authors stated that the core-minus-coating difference indicates the elements of the incorporated fiber.

• Amosite could not be excluded at first, because the coating is iron-rich and the data were semiquantitative. However, more magnesium than iron was found in the inner fiber, so it was identified as anthophyllite.
• Calcium content did not differ between the central and peripheral regions. It was therefore attributed to the coating or the tissue, not the fiber. This ruled out a tremolite-actinolite reading that might have resulted from analyzing only the center.
• Several ferruginous bodies (number not stated) were examined with the method, and the mineral inside was identified in all cases.
• The authors' conclusion: The authors concluded that, since both anthophyllite and amosite are legally defined asbestos, the presence of asbestos mineral in the ferruginous body had been proven for the purpose of this work. They also stated that the method more easily identifies iron-free minerals such as chrysotile.
• Limitations the authors state:
  • Because the sections were not polished or carbon-coated, the chemical results are only semiquantitative.
  • A phosphate phase in the coating could not be excluded with ESEM/EDS. The authors considered that only transmission electron microscopy could prove it.

Topics

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

Medical terms in this study, explained in our Lexicon: Scanning Electron Microscopy (SEM), Ferruginous Bodies, Mesothelioma, Carcinoma, energy dispersive X-ray spectroscopy (EDS).

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