Fiber analysis vignettes: Electron microscopy to the rescue!

Our plain-English summary of Fiber analysis vignettes: Electron microscopy to the rescue!, by V.L. Roggli (Ultrastructural Pathology, 2016).

The study

• Author: V.L. Roggli
• Journal: Ultrastructural Pathology
• Published: 2016;40(3):126-33
• Type of article: Review
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

There has been considerable interest in the exposure doses that contribute to the various asbestos-associated diseases. Epidemiological studies have shown important differences in the contributions of the various fiber types to asbestos-related diseases, with the amphiboles showing a greater degree of potency as compared to chrysotile. However, epidemiological studies have occasionally provided misleading results. Over the past several decades, there have been several examples where fiber analysis using electron microscopy produced unexpected results which were important to our understanding of disease-exposure relationships. It is the purpose of this article to summarize these fiber analysis vignettes.

In plain English

This article was a narrative review by one pathologist, though the journal labeled it a case report. It described unexpected results from electron microscopy of fibers in lung tissue. It summarized studies of Quebec chrysotile miners and millers, textile workers, insulators, railroad workers, a jewelry worker and auto mechanics. It added the author's own laboratory counts by scanning electron microscopy. In 92 insulators, the median was 300,000 fibers 5 µm or longer per gram of wet lung, versus below 600 in 20 controls; the vast majority were amosite. In 33 railroad workers, the median was 7670 fibers 5 µm or longer per gram of wet lung, and amosite was often increased. In 33 people with automotive work as their only known exposure, the median was 1040 fibers 5 µm or longer per gram of wet lung. Five household contacts of auto mechanics had levels within the reference range. The author concluded this did not support claims that insulators and railroad workers were exposed only to chrysotile. The author also concluded that fiber analysis did not support friction-product asbestos as a cause of mesothelioma.

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: Narrative review of published fiber-analysis studies, combined with summary counts from the author's own laboratory (partly unpublished). The journal labels it a case report.
• Who was studied: Reviewed groups: Quebec chrysotile miners and millers, asbestos textile workers, insulators, railroad workers, a jewelry worker and auto mechanics. The author's own lung tissue series: 92 insulators, 33 railroad workers, 33 people whose only known exposure was in the automotive industry, and 5 household contacts of auto mechanics, compared with 20 controls.
• Exposure: Occupational asbestos exposure in mining, textile, insulation, railroad, jewelry and automotive work. Fiber types were chrysotile, tremolite, amosite and crocidolite, measured in lung tissue by electron microscopy.
• Main results:
  • Insulators (author's series): the median asbestos body count in 89 cases was 26,600 per gram of wet lung tissue. The normal range is 0 to 20 per gram.
  • Insulators (author's series): the median fiber count by scanning electron microscopy was 300,000 fibers 5 µm or longer per gram of wet lung. The median for 20 controls was less than 600 fibers per gram.
  • Insulators (author's series): the vast majority of fibers analyzed were amosite.
  • Railroad workers (author's series of 33): the median fiber count by scanning electron microscopy was 7670 fibers 5 µm or longer per gram of wet lung.
  • Railroad workers (author's series): amosite was found at increased levels in many workers' lungs. In two mesothelioma cases, crocidolite was the only commercial amphibole found.
  • Railroad workers (author's series): the author stated that these findings did not support claims of exclusive chrysotile exposure.
  • Automotive-only exposure (author's series of 33): the median fiber count by scanning electron microscopy for the whole group was 1040 fibers 5 µm or longer per gram of wet lung.
  • Five household contacts of auto mechanics all had lung asbestos contents within the range of the reference population.
• The authors' conclusion: The author concluded that the insulator findings did not support claims of light and intermittent exposure to chrysotile alone. The author also concluded that fiber analysis did not support a role for asbestos from friction products (brakes and clutches) in causing mesothelioma.
• Limitations the authors state:
  • Two automotive-exposed cases with interstitial lung disease had elevated tremolite and/or chrysotile. The author called this of questionable significance, because people with interstitial lung disease clear fibers from the lung less well.

Topics

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

Medical terms in this study, explained in our Lexicon: Amphibole Group, Chrysotile.

Related studies

• 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)
• Elemental analysis of asbestos fibers by means of electron probe techniques — I.A. Rubin, C.J. Maggiore (1974)
• Electron microscopy analysis of mineral fibers in human lung tissue — K.H. Friedrichs, M. Brockmann, et al. (1992)
• Beryllium detection in human lung tissue using electron probe X-ray microanalysis — K.J. Butnor, T.A. Sporn, et al. (2003)
• Chemical characterization of asbestos body cores by electron microprobe analysis — A.M. Langer, I.B. Rubin, et al. (1972)
• Oxygen incineration and electron microscope x-ray microanalysis of mineral particles in biological tissues — W.J. Henderson, C. Melville-Jones, et al. (1978)

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