Asbestos bodies or fibers and the diagnosis of asbestosis

Our plain-English summary of Asbestos bodies or fibers and the diagnosis of asbestosis, by M.L. Warnock, G. Wolery (Environmental Research, 1987).

The study

• Authors: M.L. Warnock, G. Wolery
• Journal: Environmental Research
• Published: 1987;44(1):29-44
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001005).

Abstract

A committee of the College of American Pathologists has proposed that the diagnosis of asbestosis requires fibrosis in respiratory bronchiolar walls and the presence of asbestos bodies (ABs) in tissue sections. To determine whether histologic ABs reliably reflect asbestos fiber concentrations in asbestosis, we compared the concentration of ABs in histologic sections to concentrations of ABs and fibers in tissue extracts of 14 asbestos workers with nonspecific interstitial fibrosis. ABs in histologic sections and extracts correlated well, r = 0.95. Counted and classified by electron microscopy, electron diffraction, and X-ray spectroscopy, commercial amphibole fibers (r = 0.94) also correlated well with ABs, but noncommercial amphiboles (r = -0.02) or chrysotile (r = 0.29) did not. In five subjects with a high percentage of noncommerical amphibole fibers, fewer than 0.5 histologic ABs/cm2 were present despite a total amphibole concentration that was similar to that in subjects with more histologic ABs. We conclude that ABs will be scarce or absent in histologic sections from some subjects with asbestosis, and that for such subjects, extracts of asbestos fibers should yield over 500,000 total amphibole fibers/g dry lung to signify that interstitial fibrosis may be caused by asbestos.

In plain English

This study, from the University of California, San Francisco, examined lungs from 14 men who had occupational asbestos exposure and interstitial lung fibrosis but no lung cancer. It asked whether asbestos bodies seen in tissue sections reliably reflect how much asbestos fiber is in the lung. The authors counted asbestos bodies in iron-stained sections and in lung extracts, and identified fibers by electron microscopy. Section and extract counts correlated closely (r = 0.95, cases 3 to 10). Extracted bodies correlated with amosite and crocidolite fibers (r = 0.94) but poorly with tremolite, anthophyllite, actinolite and glaucophane combined (r = -0.02) or with chrysotile (r = 0.29). Several men had very few bodies in sections even though their total amphibole fiber levels were similar to those of men with more bodies. The median total amphibole level was 1.31 million fibers per gram of dry lung in these men, against 0.141 million in 19 previously reported men without occupational exposure. The authors concluded that asbestos bodies may not be found in sections in some people with asbestosis. They proposed a tentative figure of over 500,000 total amphibole fibers per gram of dry lung as supporting an asbestos cause.

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 study of lungs obtained at autopsy, comparing asbestos body counts in tissue sections with asbestos body and fiber counts in lung tissue extracts; previously reported control values used for comparison
• Who was studied: 14 men with a history of occupational asbestos exposure, macroscopically visible interstitial lung fibrosis, and no lung cancer (6 from coroner's autopsies, 8 referred by private pathologists to confirm asbestosis), studied at the University of California, San Francisco; controls were previously reported values from 19 men with no history of asbestos exposure in their work. Dates of collection are not given.
• Exposure: Occupational asbestos exposure; lung burden measured as asbestos bodies and as uncoated fibers classed as chrysotile, commercial amphiboles (amosite and crocidolite, 'AC') and noncommercial amphiboles (tremolite, anthophyllite, actinolite and glaucophane, 'TAAG')
• Main results:
  • Asbestos bodies in tissue sections and in lung extracts correlated with r = 0.95 for cases 3 to 10. In cases 11 to 14 bodies in sections were too numerous to count, and in cases 1 and 2 none were found after examining an average of 6.1 square centimeters of lung.
  • In the 14 men, extracted asbestos bodies correlated with amosite plus crocidolite fibers (r = 0.94) and with total amphiboles (r = 0.80).
  • Extracted asbestos bodies correlated poorly with noncommercial amphibole (TAAG) fibers (r = -0.02) and with chrysotile fibers (r = 0.29).
  • Noncommercial TAAG fibers made up an average of 63% of amphibole fibers in subjects 1 to 9 (those with fewer asbestos bodies), compared with an average of 2% in subjects 10 to 14.
  • Subjects 1 to 9 had similar total amphibole concentrations (0.6 to 1.6 million per gram of dry lung), yet the authors judged that probably only subjects 1 to 5 failed a previously proposed criterion of more than one asbestos body per section. Table 2 shows fewer than 0.5 bodies per square centimeter in sections for cases 1 to 5.
  • In all 14 men, total amphibole fiber concentrations were over 500,000 per gram of dry lung.
  • The median total amphibole concentration was 1.31 million per gram of dry lung in the men with asbestosis versus 0.141 million per gram in the 19 controls (p less than 0.05). Median chrysotile concentrations were similar in the two groups.
  • The ratio of asbestos bodies to total amphibole fibers varied widely among the 14 men, from 1:6 to 1:38,000.
  • The assigned grade of visible (macroscopic) fibrosis was inversely related to asbestos body concentration (Spearman r = -0.61). Nine of the 14 men (64%) had pleural plaques.
• The authors' conclusion: The authors concluded that in some people with asbestosis confirmed by electron microscopy, asbestos bodies will not be found in tissue sections. They proposed that more than 0.5 asbestos bodies per square centimeter in sections, or more than 2000 extracted bodies per gram of dry lung, supports a diagnosis when there is no other cause of fibrosis and a history of asbestos exposure. Otherwise, total amphibole fibers should exceed 500,000 per gram of dry lung. They also suggested iron stains and a systematic search for asbestos bodies in all cases of possible idiopathic interstitial fibrosis.
• Limitations the authors state:
  • The authors called the 500,000 total amphibole fibers per gram figure tentative and said it may be revised downward when more cases are analyzed.
  • The authors acknowledged that subjects 1 to 9 might instead have had idiopathic pulmonary fibrosis, although they gave reasons against this.
  • The authors noted that the noncommercial amphibole fibers may only be a marker of earlier chrysotile exposure rather than the cause of the fibrosis.
  • The authors noted that bodies that look like typical asbestos bodies do not always have asbestos cores.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Fibrosis, Interstitial Fibrosis, Amphibole Group, Chrysotile.

Related studies

• Asbestos bodies and the diagnosis of asbestosis in chrysotile workers — J. Holden, A. Churg (1986)
• Relationships between ferruginous bodies and uncoated asbestos fibers in lung tissue — R.F. Dodson, M. O'Sullivan, et al. (1996)
• Pulmonary ferruginous bodies in city dwellers. A study of their central fiber — P. Gross, R.T. DeTreville, et al. (1969)
• Asbestos bodies and fibers in lung tissues — A. Fondimare, J. Desbordes (1974)
• Focused X-Ray Histological Analyses to Reveal Asbestos Fibers and Bodies in Lungs and Pleura of Asbestos-Exposed Subjects — L. Pascolo, A. Gianoncelli, et al. (2016)
• Asbestos fibers in laryngeal tissues. Findings in two patients with asbestosis associated with laryngeal tumors — A. Hirsch, J. Bignon, et al. (1979)

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