Crystal structure determination of a lifelong biopersistent asbestos fibre using single-crystal synchrotron X-ray micro-diffraction

Our plain-English summary of Crystal structure determination of a lifelong biopersistent asbestos fibre using single-crystal synchrotron X-ray micro-diffraction, by C. Giacobbe, D. Di Giuseppe, A. Zoboli, et al (IUCrJ, 2021).

The study

• Authors: C. Giacobbe, D. Di Giuseppe, A. Zoboli, M. Lassinantti Gualtieri, P. Bonasoni, A. Moliterni, N. Corriero, A. Altomare, J. Wright, A.F. Gualtieri
• Journal: IUCrJ
• Published: 2021;8(Pt 1):76-86
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The six natural silicates known as asbestos may induce fatal lung diseases via inhalation, with a latency period of decades. The five amphibole asbestos species are assumed to be biopersistent in the lungs, and for this reason they are considered much more toxic than serpentine asbestos (chrysotile). Here, we refined the atomic structure of an amosite amphibole asbestos fibre that had remained in a human lung for ∼40 years, in order to verify the stability in vivo. The subject was originally exposed to a blend of chrysotile, amosite and crocidolite, which remained in his parietal pleura for ∼40 years. We found a few relicts of chrysotile fibres that were amorphous and magnesium depleted. Amphibole fibres that were recovered were undamaged and suitable for synchrotron X-ray micro-diffraction experiments. Our crystal structure refinement from a recovered amosite fibre demonstrates that the original atomic distribution in the crystal is intact and, consequently, that the atomic structure of amphibole asbestos fibres remains stable in the lungs for a lifetime; during which time they can cause chronic inflammation and other adverse effects that are responsible for carcinogenesis. The amosite fibres are not iron depleted proving that the iron pool for the formation of the asbestos bodies is biological (haemoglobin/plasma derived) and that it does not come from the asbestos fibres themselves.

© Giacobbe et al. 2021.

In plain English

The authors analysed asbestos fibres taken at autopsy from the lung of one man who died in 2017 with malignant mesothelioma of the parietal pleura of the left lung. From 1970 to 1980 he worked at a factory in Northern Italy making asbestos-containing products, where he was exposed to chrysotile, crocidolite and amosite. The authors estimated the fibres had been in his lung for 37 to 47 years. Fibres from tumour-free lung tissue were examined by electron microscopy and synchrotron X-ray micro-diffraction. About 97% of the fibres found were crocidolite and amosite. The other 3% were silica-rich fibres, which the authors identified as the dissolution product of chrysotile. No crystalline chrysotile was seen. The atomic structure of one 30-micrometre amosite fibre, measured at its tip and at its centre, was nearly the same in both places. The authors concluded that the atomic structure of amphibole asbestos fibres stays stable in the lungs for a lifetime, and that the iron in asbestos bodies does not come from the fibres. They noted that the fibre's iron content was likely overestimated.

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 mineralogical analysis (electron microscopy and single-crystal synchrotron X-ray micro-diffraction) of fibres recovered at autopsy from one person's lung tissue
• Who was studied: One man who worked for ten years (1970 to 1980) in a factory producing asbestos-containing products in Northern Italy, diagnosed with malignant mesothelioma, died in 2017
• Exposure: Occupational exposure to chrysotile, crocidolite and amosite at a factory making asbestos-cement products
• Main results:
  • The subject's malignant mesothelioma was located in the parietal pleura of the left lung
  • From the subject's history, the authors hypothesized that the fibres had stayed in the lung for 37 to 47 years
  • Of the fibres detected in material from the subject's lung tissue, 97 (2)% were crocidolite and amosite
  • The remaining 3(1)% of fibres were silica-rich fibres, which the authors described as the product of chrysotile dissolving through loss of magnesium
  • No crystalline chrysotile fibres were found
  • Free amphibole fibres ranged from 8.69 to 51.0 micrometres long. More than 75% were longer than 19.1 micrometres and 50% were longer than 22.3 micrometres.
  • Chemical mapping of an uncoated amosite fibre showed no enrichment or depletion of elements at the edges or core
  • The structure models from the top edge and the centre of the analysed amosite fibre strongly overlapped (r.m.s. deviation 0.016)
  • The only difference was a small fluorine content at the top of the fibre (site partition 0.96 (3) for O and 0.04 (3) for F). The authors attributed this to the crystal's original zonation.
  • The authors reported that atoms did not diffuse along the fibre, and that the elements forming the asbestos bodies did not come from within the fibre
• The authors' conclusion: The authors concluded that the atomic structure of amphibole asbestos fibres remains stable in the lungs for a lifetime, while chrysotile dissolves. They also concluded that the iron for asbestos-body formation is biological rather than coming from the fibres.
• Limitations the authors state:
  • Mössbauer spectroscopy could not be applied to a single fibre, so the iron distribution relied only on the structure refinement
  • All iron was assumed to be in the Fe2+ form, so the iron content was overestimated

Topics

Medical terms in this study, explained in our Lexicon: Crystal Structure, Silicate, Latency, Amphibole Asbestos, Serpentine Group, Chrysotile, Amosite, Crocidolite.

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