Electron microscope characteristics of inhaled chrysotile asbestos fibre

Our plain-English summary of Electron microscope characteristics of inhaled chrysotile asbestos fibre, by F.D. Pooley (British Journal of Industrial Medicine, 1972).

The study

• Author: F.D. Pooley
• Journal: British Journal of Industrial Medicine
• Published: 1972;29(2):146-53
• Cited by: 54 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Pooley, F. D. (1972).Brit. J. industr. Med.,29, 146-153. Electron microscope characteristics of inhaled chrysotile asbestos fibre. Specimens from 300 lungs have been examined under the electron microscope to determine the morphology and diffraction characteristics of any chrysotile asbestos they contained. In 120 cases, material was prepared by alkali digestion and the residual dust was examined. In all cases standard 6-micron histological slides were partially ashed before the residue was transferred to the electron microscope grids. Of the 300 specimens examined, 20 came from men with prolonged industrial exposure to chrysotile, 87 from cases of mesothelioma, and the remainder from control groups drawn from rural and industrial populations. Chrysotile fibres were readily identified by the characteristic polycrystalline diffraction pattern. The hollow appearance of the single fibres and their shape and arrangement also help in the identification. Specimens from men without industrial exposure contained either single short fibres or aggregates scattered throughout the lungs. In specimens from industrially exposed men, fibres were very numerous and found as strands of single fibres mainly grouped together in discrete locations. Ferruginous bodies were found rarely and only on straight fibre bundles of over several micrometers in length.

In plain English

This study described how chrysotile asbestos looks under the electron microscope in human lung tissue. The author examined specimens from about 300 lungs: general population groups, people with pleural and peritoneal mesothelioma and their controls, and 20 men with prolonged industrial exposure to chrysotile. Partly burned (ashed) tissue sections were examined in every case, and about 120 cases also had tissue dissolved in alkali. Chrysotile was readily identified by its electron diffraction pattern. Lungs of the occupationally exposed men held a great deal more asbestos, mostly as strands of fibres. In the control groups, chrysotile fibres were always very sparse, a number of preparations had none, and the fibre appeared mainly as aggregates and short fibres. Asbestos bodies with chrysotile cores were very rare and were found only in heavily exposed lungs, where uncoated fibres outnumbered coated ones by several thousand to one. The author concluded that most asbestos bodies seen under the optical microscope may be formed on amphibole fibres. The paper did not report how often chrysotile was found in each group.

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: Descriptive electron microscope study of lung specimens (fibre appearance and diffraction). It did not report how often chrysotile was found.
• Who was studied: About 300 lung specimens. The table lists general population groups from Dorchester (48), Liverpool (40) and London (45, retrospective) in England, and from Malmo, Sweden (32 controls). It lists mesothelioma cases from Malmo (33, pleural and peritoneal), Canada (16), Holland (28) and Great Britain (18), plus 13 Holland mesothelioma controls. It also lists 20 cases in an industrial exposure group from Great Britain and South Africa.
• Exposure: Chrysotile asbestos. The industrial exposure group were men with prolonged industrial exposure to chrysotile, described as people previously employed in the production and processing of chrysotile asbestos. The other groups were not occupationally exposed (rural, urban and industrial area populations).
• Main results:
  • Across the specimens, chrysotile fibres were readily identified by their characteristic polycrystalline electron diffraction pattern.
  • Lungs of occupationally exposed men contained a great deal more asbestos than the control groups.
  • In the occupationally exposed group, chrysotile was generally found as strands of single fibres, mainly grouped together in discrete locations in the lung.
  • In the control groups, chrysotile fibres were always very sparse, and a number of preparations were free of chrysotile. When present, the fibre occurred mainly as large aggregates and as dispersed, very short fibres or small bundles.
  • Classical asbestos bodies with a chrysotile core were very rare and were found only in lungs with heavy exposure to chrysotile. In those lungs, uncoated chrysotile fibres outnumbered coated fibres by several thousand to one.
  • In the non-occupationally exposed group, no asbestos bodies with chrysotile cores were found, although bodies on amphibole fibres were detected.
  • All chrysotile particles subjected to diffraction analysis gave the characteristic chrysotile pattern. Based on earlier work, the author stated that the fibres could have lost up to about 50% of their magnesium content, but no more.
• The authors' conclusion: The author concluded that chrysotile in lungs takes very varied forms but can be positively identified by its diffraction pattern. The character of the particles differs between occupationally and non-occupationally exposed people. Asbestos bodies form very rarely on chrysotile, and only on straight fibre bundles over several microns long. The majority of asbestos bodies seen under the optical microscope may be said to be formed on amphibole asbestos fibres.
• Limitations the authors state:
  • Heating makes chrysotile brittle, and agitation of heated samples may break particles apart. The author therefore interpreted the 20 heat-treated digested residues with care.
  • The paper did not report how often chrysotile was found in the cases; this was to be published separately.
  • No rigid dimensions could be applied to the chrysotile particles detected.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Mesothelioma, Polycrystalline, Ferruginous Bodies.

Related studies

• Distribution and characteristics of amphibole asbestos fibres, measured with the light microscope, in the left lung of an insulation worker — A. Morgan, A. Holmes (1983)
• The effects of chrysotile asbestos dust on lung macrophages maintained in organ culture. An electron-microscope study — J.M. Davis (1967)
• Quantitative assessment of inorganic fibrous particulates in dust samples with an analytical transmission electron microscope — F.D. Pooley, N.J. Clark (1979)
• Chemical characterization of uncoated asbestos fibers from the lungs of asbestos workers by electron microprobe analysis — A.M. Langer, I.B. Rubin, et al. (1972)
• The identification of asbestos dust with an electron microscope microprobe analyser — F.D. Pooley (1975)
• On the utility of dark-field electron microscopy in the determination of the degree of deformation in chrysotile asbestos: an environmental research application — K. Seshan (1978)

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