Pseudoasbestos bodies and fibers in bronchoalveolar lavage of refractory ceramic fiber users

Our plain-English summary of Pseudoasbestos bodies and fibers in bronchoalveolar lavage of refractory ceramic fiber users, by P. Dumortier, I. Broucke, P. De Vuyst (American Journal of Respiratory and Critical Care Medicine, 2001).

The study

• Authors: P. Dumortier, I. Broucke, P. De Vuyst
• Journal: American Journal of Respiratory and Critical Care Medicine
• Published: 2001;164(3):499-503
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Refractory ceramic fibers (RCF) are widely used to replace asbestos in applications requiring high heat resistance. Ferruginous bodies mimicking asbestos bodies (ABs) have been detected in the lungs of RCF production workers. This raises the question about their presence in other occupational groups and whether "typical ABs" still reflect past asbestos exposures in all settings. An AB counting by phase-contrast light microscopy and a screening test by analytical electron microscopy were systematically performed on all bronchoalveolar lavage fluids (BALF) submitted to our laboratory in 1992 through 1997 (n = 1,800). When RCF were detected in electron microscopy, the structures considered as "typical ABs" were marked under light microscopy and prepared for further chemical and structural analysis. Pseudo-ABs on RCF were detected in samples from nine subjects (0.5%). All of them had worked either as foundry workers, steel workers, or welders. In these subjects, alumino-silicate fibers compatible with RCF accounted for 42% of the core fibers analyzed, other nonasbestos fibers for 28%, and asbestos fibers for 30%. ABs thus remain a valid marker of asbestos retention but attention must be paid to a possible occurrence of pseudo-asbestos bodies on RCF and other nonasbestos fibers in end-users of refractory fibers.

In plain English

This laboratory study, from a chest department in Brussels, Belgium, examined bronchoalveolar lavage fluid (fluid washed out of the lungs) from 1,800 patients referred for fiber or particle analysis between 1992 and 1997. Asbestos bodies (coated fibers) in every sample were counted under a light microscope, and every sample was also screened by electron microscopy. Fibers compatible with refractory ceramic fibers (RCF), man-made fibers used to replace asbestos in high-temperature insulation, were found in nine patients (0.5%). All nine had worked in foundries or steelworks, or as welders. RCF exposure had never been reported in their work histories. In these nine patients, alumino-silicate fibers made up 42% of the analyzed body cores, other nonasbestos fibers 28%, and asbestos 30%. Routine light microscopy could not tell these 'pseudo-asbestos bodies' apart from true asbestos bodies. The authors concluded that asbestos body counting remains in most cases a valid marker of asbestos exposure, but that coated nonasbestos fibers may occur in RCF end-users. They noted that the screening test is less sensitive, so some cases may have been missed.

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 case series drawn from routine mineralogical analysis of bronchoalveolar lavage fluid: light microscopy asbestos body counts plus an electron microscopy screening test on every sample
• Who was studied: Bronchoalveolar lavage fluid samples from 1,800 patients (clinical or medicolegal cases referred for fiber or particle analysis) at a laboratory at Hôpital Erasme, Brussels, Belgium, from January 1992 to December 1997; nine of them had fibers compatible with RCF
• Exposure: Refractory ceramic fibers (man-made vitreous fibers used to replace asbestos in high-temperature insulation) and other refractory fibers, encountered by end-users in foundries, steelworks and welding; asbestos and other fibers were also present
• Main results:
  • Alumino-silicate fibers compatible with RCF, as pseudo-asbestos body cores or uncovered fibers, were found in 9 of 1,800 patients (0.5%)
  • All nine patients had worked in foundries or steelworks, or as welders
  • Exposure to RCF was never reported in the occupational history given by the referring physician
  • In the nine patients, amorphous alumino-silicate fibers made up 42% of the body cores analyzed, other nonasbestos fibers 28%, and asbestos 30%
  • Nonasbestos core fibers made up 50% or more of the analyzed cores in five of the nine patients
  • Routine phase-contrast light microscopy could not distinguish between the different core fibers
  • Geometric mean diameter was 0.27 micrometres (95% CI 0.23 to 0.32) for the 125 pseudo-asbestos body core fibers, compared with 0.14 micrometres (0.13 to 0.15) for the 1,081 true asbestos body core fibers in the laboratory's database
  • Geometric mean length was 35.4 micrometres (95% CI 32.2 to 39.0) for pseudo-asbestos body core fibers, compared with 31.8 micrometres (30.8 to 32.9) for true asbestos body core fibers
  • Geometric mean aspect ratio (length to width) was 136 (95% CI 113 to 163) for pseudo-asbestos body core fibers, compared with 219 (207 to 232) for true asbestos body core fibers
  • Two further patients, a grinder and a trimmer in two different foundries, had pseudo-asbestos bodies on crystalline silica and crystalline iron oxide fibers but no RCF
  • The two patients with typical pleural plaques (Patients 7 and 9) had mostly asbestos fibers as body cores
  • No ferruginous bodies on glass wool, rock wool or slagwool were detected in the 1,800 electron microscopy screening tests
• The authors' conclusion: The authors concluded that asbestos body counting in lavage fluid or lung tissue remains in most cases a valid marker of asbestos exposure, but that attention must be paid to possible ferruginous bodies on nonasbestos fibers in end-users of RCF
• Limitations the authors state:
  • The electron microscopy screening test is much less sensitive than light microscopy, so additional cases may have been missed and the percentages may be underestimated
  • There were no data for patients examined before the end of 1991, so no conclusion could be drawn on time trends
  • Interpretable electron diffraction patterns could not be obtained for the silicon-, aluminum- and iron-rich fibers

Topics

Medical terms in this study, explained in our Lexicon: Bronchoalveolar Lavage (BAL), Ferruginous body, Asbestos Bodies, Asbestos Exposure, Silicate.

Related studies

• Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers — H. Greim, M.J. Utell, et al. (2014)
• Refractory ceramic fibers: Fiber characteristics, potential health effects and clinical observations — M.J. Utell, L.D. Maxim (2018)
• Potential significance of airborne fiber dimensions measured in the U.S. refractory ceramic fiber manufacturing industry — T.J. Lentz, C.H. Rice, et al. (1999)
• Refractory ceramic fiber exposure and pleural plaques — J. Lockey, G. Lemasters, et al. (1996)
• Mechanism of refractory ceramic fiber- and rock wool-induced cytotoxicity in alveolar macrophages — K.A. Kim, W.K. Lee, et al. (2001)
• Refractory ceramic fiber (RCF) toxicity and epidemiology: a review — M.J. Utell, L.D. Maxim (2010)

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