Determination of mineral fibre in human lung tissue by light microscopy and transmission electron microscopy

Our plain-English summary of Determination of mineral fibre in human lung tissue by light microscopy and transmission electron microscopy, by A.J. Rogers (The Annals of Occupational Hygiene, 1984).

The study

• Author: A.J. Rogers
• Journal: The Annals of Occupational Hygiene
• Published: 1984;28(1):1-12
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mineral fibre residues found in the lung provide an indication of past exposure and an important pointer as to whether disease is asbestos-related. A method is presented based on chemical digestion of the lung tissue, deposition of the mineral fraction of the digest on membrane filters followed by suitable preparation of the filters for either light microscopy or transmission electron microscopy examination. Results on the variability of fibre concentration with deposition site in the lung are included together with information on the precision of the method of estimation. This information provides the basis of interpretation for individual cases and for observations of trends in population studies. Results from a survey of fibre concentration in lungs from mesothelioma cases are compared with those obtained from a sample of the Australian male population.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This 1984 paper described a laboratory method, developed for the Australian Mesothelioma Surveillance Programme, for counting mineral fibres in human lung tissue. Tissue was dissolved with sodium hypochlorite, and the residue was examined by light microscopy (uncoated fibres and ferruginous bodies) and by transmission electron microscopy (chrysotile, amosite and crocidolite). The author reported that repeat tests on the lung of one heavily exposed asbestos worker showed the method was reproducible. Electron microscopy blanks contained short crocidolite and chrysotile fibres, which were traced to the filters themselves. In 128 Australian urban men aged 40-75 examined at necropsy, 95% had fewer than 250 000 uncoated fibres and fewer than 150 000 ferruginous bodies per gram of dry lung tissue. Among 27 mesothelioma cases, light microscopy found 12 within the normal range, 7 slightly elevated and 8 above three times the 95th percentile of the normal population. Compared with occupational histories, there was one false positive and five false negatives. The author concluded that lung fibre content provides a reasonable index of cumulative asbestos exposure, but cautioned about interpreting individual cases and extrapolating from so few cases.

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 method-development study (precision, sensitivity and detection-limit testing), applied to a necropsy series of urban men and a series of mesothelioma cases
• Who was studied: Method testing used lung tissue from one asbestos worker. The survey covered 128 deceased Australian male urban dwellers aged 40-75, selected from 429 consecutive necropsies; 30 of them were also examined by electron microscopy. The comparison group was the first 27 completed confirmed mesothelioma cases from the Australian Mesothelioma Surveillance Programme.
• Exposure: Asbestos fibre burden in lung tissue: uncoated fibres and ferruginous bodies counted by light microscopy; chrysotile, amosite, crocidolite and unidentified fibres counted by transmission electron microscopy. For the mesothelioma cases, past asbestos exposure was judged from occupational and environmental histories.
• Main results:
  • Detection limit by light microscopy: four fibres counted, equal to 60 000 fibres per g of dry tissue
  • Detection limit by electron microscopy, for fibres longer than 2 micrometres: 800 000 fibres per g of dry tissue
  • All electron microscopy blanks contained short (under 2 micrometre) crocidolite and chrysotile fibres. The contamination came from the Nuclepore filters themselves.
  • In the worker's lung, samples from 20 anatomical areas varied more than adjacent samples. The author judged that sampling a site other than a basal segment should not seriously change the order of magnitude of the result.
  • Urban male necropsy group (light microscopy): 95% had fewer than 250 000 uncoated fibres and fewer than 150 000 ferruginous bodies per g of dry tissue
  • Mesothelioma cases (light microscopy): 44% (12/27) within the normal population range; 26% (7/27) slightly elevated (1-2 times the 95th percentile); 30% (8/27) greater than 3 times the 95th percentile
  • Mesothelioma cases, lung fibre count compared with exposure history: one false positive and five false negatives
  • Seven mesothelioma cases (26%) had neither occupational-history evidence of asbestos exposure nor elevated lung asbestos levels
  • Mesothelioma cases (electron microscopy): elevated counts were mainly due to amosite and crocidolite, but 78% of cases had amosite and crocidolite levels below the 95th percentile of the urban population
  • No anthophyllite or tremolite was found in any of the mesothelioma samples
• The authors' conclusion: The author concluded that the mineral fibre content of human lung tissue provides a reasonable index of cumulative exposure to asbestos
• Limitations the authors state:
  • The case numbers are small, and the trends should be extrapolated to larger groups from other regions only with caution
  • The overall accuracy of the method at these trace levels could not be tested
  • Because of the false positive and false negatives, caution is needed in interpreting the cause of disease in individual cases
  • Counts between the blank level and the detection limit give only a qualitative estimate
  • The light microscopy counting rules used are known to have a small degree of bias
  • Uncoated fibres were undercounted at higher filter loadings, because other particles shielded them

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite, Chrysotile, Crocidolite.

Medical terms in this study, explained in our Lexicon: Transmission Electron Microscopy (TEM), Deposition, Mesothelioma.

Related studies

• Comparison of the results of asbestos fibre dust counts in lung tissue obtained by analytical electron microscopy and light microscopy — F.D. Pooley, D.L. Ranson (1986)
• A comparison of light microscopy and transmission electron microscopy results in the evaluation of the occupational exposure to airborne chrysotile fibres — A. Marconi, E. Menichini, et al. (1984)
• Electron microscopy analysis of mineral fibers in human lung tissue — K.H. Friedrichs, M. Brockmann, et al. (1992)
• A technical comparison of evaluating asbestos concentration by phase-contrast microscopy (PCM), scanning electron microscopy (SEM), and analytical transmission electron microscopy (ATEM) as illustrated from data generated from a case report — R.F. Dodson, S.P. Hammar, et al. (2008)
• Size distributions of occupational airborne asbestos textile fibres as determined by transmission electron microscopy — A.P. Rood, R.R. Streeter (1984)
• The use of a new static device based on the collection of the thoracic fraction for the assessment of the airborne concentration of asbestos fibres by transmission electron microscopy — E. Kauffer, J.C. Vigneron, et al. (1996)

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