The utility of electron microscopy in detecting asbestos fibers and particles in BALF in diffuse lung diseases

Our plain-English summary of The utility of electron microscopy in detecting asbestos fibers and particles in BALF in diffuse lung diseases, by T. Kido, Y. Morimoto, K. Yatera, et al (BMC Pulmonary Medicine, 2017).

The study

• Authors: T. Kido, Y. Morimoto, K. Yatera, H. Ishimoto, T. Ogoshi, K. Oda, K. Yamasaki, T. Kawanami, S. Shimajiri, H. Mukae
• Journal: BMC Pulmonary Medicine
• Published: 2017;17(1):71
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: In patients with diffuse lung diseases, differentiating occupational lung diseases from other diseases is clinically important. However, the value of assessing asbestos and particles in bronchoalveolar lavage fluid (BALF) in diffuse lung diseases by electron microscopy (EM) remains unclear. We evaluated the utility of EM in detecting asbestos fibers and particles in patients with diffuse lung diseases.

Methods: The BALF specimens of 107 patients with diffuse lung diseases were evaluated. First, detection of asbestos by EM and light microscopy (LM) were compared. Second, the detection of asbestos using surgically obtained lung tissues of 8 of 107 patients were compared with the results of EM and LM in BALF. Third, we compared the results of mineralogical components of particles in patients with (n = 48) and without (n = 59) a history of occupational exposure to inorganic dust.

Results: BALF asbestos were detected in 11 of 48 patients with a history of occupational exposure by EM; whereas asbestos as asbestos bodies (ABs) were detected in BALF in 4 of these 11 patients by LM. Eight of 107 patients in whom lung tissue samples were surgically obtained, EM detected BALF asbestos at a level of >1,000 fibers/ml in all three patients who had ABs in lung tissue samples by LM at a level of >1,000 fibers/g. The BALF asbestos concentration by EM and in lung tissue by LM were positively correlated. The particle fractions of iron and phosphorus were increased in patients with a history of occupational exposure and both correlated with a history of occupational exposure by a multiple regression analysis.

Conclusions: EM using BALF seemed to be superior to LM using BALF and displayed a similar sensitivity to LM using surgically-obtained lung tissue samples in the detection of asbestos. Our results also suggest that detection of elements, such as iron and phosphorus in particles, is useful for evaluating occupational exposure. We conclude that the detection of asbestos and iron and phosphorus in particles in BALF by EM is very useful for the evaluation of occupational exposure.

In plain English

This study, from the University of Occupational and Environmental Health in Japan, examined lung-wash fluid (bronchoalveolar lavage fluid) from 107 patients with diffuse lung diseases enrolled between January 2012 and December 2014. Of these, 48 had a history of work exposure to inorganic dust. The authors compared electron microscopy with light microscopy for finding asbestos. Electron microscopy found asbestos (uncoated fibers or asbestos bodies) in 11 of the 48 dust-exposed patients. It found none in the 59 patients without a history of occupational dust exposure. Light microscopy found asbestos bodies in only 4 of those 11. Eight patients also had lung tissue examined. The three of them with more than 1,000 asbestos bodies per gram of dry lung tissue all had more than 1,000 fibers per ml of lavage fluid by electron microscopy. Particles containing iron and phosphorus made up larger fractions in dust-exposed patients. The authors concluded that electron microscopy of lavage fluid seemed better than light microscopy of lavage fluid, and about as sensitive as light microscopy of lung tissue. They listed mixed diseases, few tissue samples and a single institution as limitations.

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: Clinical study at a single institution comparing methods for detecting asbestos and other particles in bronchoalveolar lavage fluid (electron microscopy versus light microscopy), with lung tissue comparison in a subset
• Who was studied: 107 patients who underwent bronchoalveolar lavage for diagnosis of diffuse lung diseases at the University of Occupational and Environmental Health, Japan, January 2012 to December 2014. 48 had and 59 did not have a history of occupational exposure to inorganic dust. Eight also had lung tissue analyzed: six from surgery for lung cancer, one from a diagnostic biopsy and one from autopsy.
• Exposure: History of occupational exposure to inorganic dust. Jobs listed included building construction, electrical construction, foundry molding, mining, a ship's hold, an asbestos factory, automobile, cement and train factories, and piping and water supply construction. Asbestos was measured as 'AFs' (uncoated asbestos fibers plus asbestos bodies) in lavage fluid. Fiber types were not reported for the group as a whole; one illustrative asbestos body was described as actinolite.
• Main results:
  • Electron microscopy detected asbestos fibers or bodies in lavage fluid of 11 of 48 exposure-positive patients (22.9%). It detected them in 0 of 59 exposure-negative patients, meaning those without a history of occupational dust exposure (p less than 0.001). The 11 included all 6 patients with asbestosis, 4 of 16 exposure-positive patients with idiopathic pulmonary fibrosis, and 1 of 7 with chronic hypersensitivity pneumonia.
  • Among the 11 patients in whom electron microscopy found asbestos, light microscopy detected asbestos bodies in 4 (36.3%) and electron microscopy detected asbestos bodies in 5 (45.5%). Light microscopy detected no asbestos bodies in any other patient.
  • Based on the measured concentrations, the authors suggested that electron microscopy had about a 1,000-fold greater ability to detect asbestos fibers, and a 500-fold greater ability to detect asbestos bodies, than light microscopy had for asbestos bodies in lavage fluid.
  • Of the 8 patients with lung tissue analyzed, 3 had more than 1,000 asbestos bodies per gram of dry lung tissue by light microscopy (2 with asbestosis, 1 with idiopathic pulmonary fibrosis). All 3 had more than 1,000 asbestos fibers per ml of lavage fluid by electron microscopy.
  • In the 8 tissue patients, the lung tissue asbestos body concentration (light microscopy) was correlated with lavage asbestos fiber concentration by electron microscopy (Spearman rS = 0.913, p less than 0.01). It was also correlated with lavage asbestos bodies by electron microscopy (rS = 0.791, p less than 0.05, per Table 4). It was not significantly correlated with lavage asbestos bodies by light microscopy (rS = 0.514).
  • The mean fraction of particles containing iron was 16.2% (SD 18.3) in exposure-positive patients with asbestos detected, 9.0% (SD 16.8) in exposure-positive patients without asbestos detected, and 1.0% (SD 2.8) in exposure-negative patients. The authors reported both exposure-positive subgroups as significantly higher than the exposure-negative group.
  • The mean fraction of particles containing phosphorus was 15.5% (SD 14.6), 11.4% (SD 17.7) and 3.3% (SD 9.1) in the same three groups.
  • In multiple regression, occupational exposure history (standardized beta 0.337, p less than 0.001) and age (beta minus 0.181, p = 0.045) were associated with the iron fraction. Detection of asbestos by electron microscopy was not significant (beta 0.184, p = 0.055). Occupational exposure history was associated with the phosphorus fraction (beta 0.325, p = 0.001).
• The authors' conclusion: The authors concluded that electron microscopy of lavage fluid was superior to light microscopy of lavage fluid, and that its sensitivity for asbestos was similar to light microscopy of surgically obtained lung tissue. They added that detecting iron and phosphorus in particles may be useful for assessing occupational exposure.
• Limitations the authors state:
  • The patients' lung diseases were heterogeneous.
  • Lung tissue was analyzed in only eight patients.
  • Lavage fluid was analyzed at only one institution; the authors said results should be confirmed in a multicenter trial.
  • Iron concentrations increase under various conditions, so the authors suggested a study with more variables and more patients.

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Lung Disease, Bronchoalveolar Lavage (BAL), Occupational Exposure, Asbestos Bodies.

Related studies

• Alveolar fiber load in asbestos workers and in subjects with no occupational asbestos exposure: an electron microscopy study — G. Chiappino, K.H. Friedrichs, et al. (1988)
• Study of inorganic particles, fibers, and asbestos bodies by variable pressure scanning electron microscopy with annexed energy dispersive spectroscopy and micro-Raman spectroscopy in thin sections of lung and pleural plaque — C. Rinaudo, A. Croce, et al. (2010)
• The sensitivity of lavage analysis by light and analytical electron microscopy in correlating the types of asbestos from a known exposure setting — R.F. Dodson, M. O'Sullivan, et al. (2003)
• On the utility of dark-field electron microscopy in the determination of the degree of deformation in chrysotile asbestos: an environmental research application — K. Seshan (1978)
• Erionite bodies and fibres in bronchoalveolar lavage fluid (BALF) of residents from Tuzköy, Cappadocia, Turkey — P. Dumortier, L. Coplü, et al. (2001)
• An electron microscopy study of the effect of asbestos dust on the lung — J.M. Davis (1963)

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