Asbestos fibers in bronchoalveolar lavage and lung tissue of former asbestos workers

Our plain-English summary of Asbestos fibers in bronchoalveolar lavage and lung tissue of former asbestos workers, by H. Teschler, K.H. Friedrichs, G.B. Hoheisel, et al (American Journal of Respiratory and Critical Care Medicine, 1994).

The study

• Authors: H. Teschler, K.H. Friedrichs, G.B. Hoheisel, G. Wick, U. Soltner, A.B. Thompson, N. Konietzko, U. Costabel
• Journal: American Journal of Respiratory and Critical Care Medicine
• Published: 1994;149(3 Pt 1):641-5
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Bronchoalveolar lavage (BAL) provides a simple method of sampling inhaled particles deposited in the lower respiratory tract. We hypothesized that BAL could be used to measure the quantity and quality of lung asbestos burden. This would be true if BAL fluid asbestos fiber content reflected the total content as well as the size distribution of both uncoated and coated asbestos fibers in lung parenchyma. Therefore, we analyzed the asbestos fiber counts of 23 individual sample pairs in both BAL fluid and lung tissue samples obtained from 20 patients with occupational asbestos exposure using transmission electron microscopy (TEM). In addition, fiber type, fiber size, and aspect ratio were compared. Coated asbestos fibers were found in 10 of 23 BAL samples and 16 of 23 biopsies. The mean concentrations of coated asbestos fibers (i.e., asbestos bodies) in BAL and lung parenchyma showed a positive correlation (r = 0.75, p < 0.001). Likewise, the mean amphibole fiber concentrations correlated positively (r = 0.55, p < 0.01). However, there was no relationship between the mean chrysotile fiber counts in BAL and lung parenchyma (r = 0.18, p = 0.40). Asbestos fibers in lung tissue were significantly longer (8.2 +/- 0.5 versus 4.8 +/- 0.6 microns; p < 0.001) but had the same width (0.12 +/- 0.27 versus 0.11 +/- 0.15 microns; p = 0.24) when compared with those retrieved by BAL from the airspace compartment. The aspect ratio (dividing fiber length by width) was much higher in lung tissue than in BAL fluid (66.4 +/- 0.4 versus 42.9 +/- 0.5; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

In plain English

This study, from Essen, Germany, compared asbestos fibers in fluid washed from the lungs (bronchoalveolar lavage, BAL) with fibers in surgically removed lung tissue. The subjects were 20 former asbestos workers (19 men, 1 woman), with 23 paired samples. Exposure was mainly to mixed chrysotile and amphiboles, and crocidolite was the main amphibole found. Fibers were counted and measured by transmission electron microscopy. Amphibole counts in BAL and tissue were correlated (r = 0.55), as were coated fibers, or asbestos bodies (r = 0.75). Chrysotile counts were not significantly correlated (r = 0.18, P = 0.40). Asbestos bodies were found in 16 of 23 tissue samples. For BAL, the Results give 13 of 23 but the article's abstract gives 10 of 23. Three people with bodies in tissue had none in BAL. Tissue fibers were longer than BAL fibers (8.2 versus 4.8 micrometers) but about as wide. The authors concluded that BAL can help estimate amphibole but not chrysotile lung burden, and that a negative BAL cannot rule out significant exposure. They said the results apply only to former workers with moderate or high mixed exposure.

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: Comparison study of paired bronchoalveolar lavage fluid and lung tissue samples from the same patients, analysed by transmission electron microscopy
• Who was studied: 20 former asbestos workers (1 female, 19 male), mean age 57 ± 8 years, referred to the Ruhrlandklinik, Essen, Germany, for evaluation of suspected asbestos-induced disease. Lung tissue came from open lung biopsy (n = 11) or resection for carcinoma (n = 9). The 13 highly exposed patients all had asbestosis, and six of them also had asbestos-related malignancies (one mesothelioma, five bronchogenic carcinomas). There were 23 BAL and tissue sample pairs.
• Exposure: Occupational exposure, predominantly to a mixture of chrysotile and amphibole asbestos, for at least 3.0 years (mean 13 ± 8 years). Mean time since last exposure was 9 ± 6 years. Thirteen patients had high exposure (asbestos textile workers n = 3, insulators n = 6, welders n = 4). Seven had moderate exposure (welders n = 4, mechanical-repairers n = 2, sheet-metal worker n = 1). Crocidolite predominated among the amphiboles in all subjects, and amosite was also found.
• Main results:
  • Chrysotile fibers were found in 19 BAL samples and 14 tissue specimens out of the 23 pairs. Mean counts were 4.9 ± 6.1 x 10^3 per ml of BAL fluid and 3.1 ± 5.4 x 10^6 per gram of dry lung. BAL and tissue chrysotile concentrations showed no significant correlation (r = 0.18, P = 0.40).
  • Amphibole fibers: mean counts were 2.9 ± 3.5 x 10^3 per ml of BAL fluid and 96.0 ± 78.8 x 10^6 per gram of dry lung tissue. Paired BAL and tissue values were positively correlated (r = 0.55, P < 0.01). Eight patients had no uncoated amphibole fibers in BAL, and three of these also had none detectable in tissue.
  • Coated asbestos fibers (asbestos bodies) were found in 16 of 23 tissue specimens. The Results section reports them in 13 of 23 BAL samples, while the article's abstract reports 10 of 23 BAL samples. Three of the 16 subjects with coated fibers in tissue had none in BAL. Mean counts were 3.5 ± 4.9 x 10^3 per ml of BAL fluid and 15.2 ± 16.5 x 10^6 per gram of dry lung. The paired values were positively correlated (r = 0.75, P < 0.001).
  • Asbestos bodies were positively correlated with uncoated amphibole fibers, more strongly in lung tissue (r = 0.81) than in BAL (r = 0.54). Chrysotile fiber concentration was not significantly correlated with asbestos body counts in either BAL or lung tissue.
  • Fibers in lung tissue were longer than those in BAL. Geometric mean length was 8.2 ± 0.5 micrometers in tissue versus 4.8 ± 0.6 micrometers in BAL (p less than 0.001). Width did not differ significantly (0.12 ± 0.27 versus 0.11 ± 0.15 micrometers). Aspect ratio was higher in tissue (66.4 ± 0.4 versus 42.9 ± 0.5; p less than 0.001).
• The authors' conclusion: The authors concluded that BAL content of asbestos bodies and amphibole fibers is related to lung tissue burden, so BAL is a useful noninvasive way to predict retained amphibole. They said BAL is not recommended for predicting chrysotile burden. They added that occasional false-negative BAL findings mean BAL cannot rule out significant exposure, and that BAL predicts mean fiber width but underestimates mean fiber length in tissue.
• Limitations the authors state:
  • The results apply only to former asbestos workers exposed to moderate or high concentrations of mixed chrysotile and amphiboles.
  • Thin, fragmented chrysotile fibers may have been lost through the filter pores after digestion, which could have biased the chrysotile results. The authors noted that no clear systematic bias was discernible.
  • The wide scatter of the data may partly reflect sampling error and regional variation in fiber content within the lung. Some BAL samples came from a different lobe than the tissue sample.
  • The study design does not allow definitive conclusions about where in the lung (airspace versus interstitium) the fibers are located.

Topics

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

Medical terms in this study, explained in our Lexicon: Bronchoalveolar Lavage (BAL), Parenchyma, Asbestos Exposure, Transmission Electron Microscopy (TEM), Aspect Ratio (Length-to-diameter ratio), Asbestos Bodies, Amphibole Group, Chrysotile.

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