Guidelines for mineral fibre analyses in biological samples: report of the ERS Working Group. European Respiratory Society

Our plain-English summary of Guidelines for mineral fibre analyses in biological samples: report of the ERS Working Group. European Respiratory Society, by P. De Vuyst, A. Karjalainen, P. Dumortier, et al (The European Respiratory Journal, 1998).

The study

• Authors: P. De Vuyst, A. Karjalainen, P. Dumortier, J.C. Pairon, E. Monsó, P. Brochard, H. Teschler, A. Tossavainen, A. Gibbs
• Journal: The European Respiratory Journal
• Published: 1998;11(6):1416-26
• Cited by: 132 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Microscopic techniques for analysing asbestos fibres in lung tissue and bronchoalveolar lavage have provided major information in the understanding of asbestos-related diseases. These analyses are increasingly applied for clinical work and medicolegal problems. Differences in sampling, preparation and counting techniques, definitions of reference populations and expression of results have caused major difficulties in comparing results from different laboratories. Therefore it appeared necessary to set a goal to harmonize these analyses between the European laboratories active in this field. This article summarizes the work of a European Respiratory Society working group with participation from nine European laboratories. The five main issues touched upon are: 1) definitions of control populations and reference levels; 2) sampling, preparation and analytical techniques; 3) asbestos fibres in lung tissues in different pathologies; 4) asbestos bodies in lung tissue, bronchoalveolar lavage and sputum; and 5) basis for the interpretation of fibres and asbestos bodies in biological samples. These guidelines indicate the crucial importance of several factors for the interpretation of the results; namely, adequate sampling, comparable analytical procedures and expression of the results, the use of well-defined reference populations, and a comprehensive understanding of the factors affecting the fibre retention and the dose-responses associated with the different asbestos-related diseases.

In plain English

This article was a guidelines report, not a new study. A European Respiratory Society working group drawn from nine European laboratories met in Brussels (December 1994) and Barcelona (September 1995). Its aim was to harmonize how asbestos fibres and asbestos bodies (coated fibres) are measured in lung tissue, bronchoalveolar lavage (lung washing) fluid and sputum. The group reviewed published studies and set out recommendations on reference populations, sampling, preparation, counting and reporting. The report stated that lung fibre levels differ by disease: highest in asbestosis, lower in mesothelioma and lowest in pleural plaques. It listed values that several laboratories treat as indicating nontrivial exposure. These were 1 asbestos body per mL of lavage fluid, 1000 asbestos bodies per gram of dry lung, and 1 million amphibole fibres longer than 1 µm, or 0.1 million longer than 5 µm, per gram of dry lung. It called these relative and arbitrary limits. Sputum testing was described as very insensitive. The authors concluded that a high fibre burden indicates exposure but is not proof of disease. They added that a negative result is not proof of absence of significant exposure, especially for chrysotile.

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: Consensus guidelines report (ERS Task Force report) summarizing the work of a European Respiratory Society working group, including a review of published studies
• Who was studied: No study population of its own. The working group came from nine European laboratories (Germany, UK, Belgium, Spain, France, Finland, Italy) and held meetings in Brussels in December 1994 and Barcelona in September 1995.
• Exposure: Methods for measuring asbestos fibres (chrysotile, crocidolite, amosite, anthophyllite, tremolite, actinolite) and asbestos bodies in lung tissue, bronchoalveolar lavage fluid and sputum, by light and electron microscopy
• Main results:
  • Reference values used by participating laboratories as the upper limit for urban individuals without occupational exposure were roughly 1–2 × 10^6 fibres per gram of dry lung for total amphibole fibres, and 0.1 × 10^6 per gram for amphibole fibres longer than 5 µm.
  • The ideal lung tissue sample was described as three pooled pieces from different parts of the lung. With such samples, average variability in results was around 50%, with a maximum of three-fold.
  • Lung tissue asbestos body counts by light microscopy agreed closely between three European laboratories (r2 of 0.965 for Lab 2 versus Lab 1, and 0.855 for Lab 3 versus Lab 1).
  • In a comparison of transmission electron microscopy fibre counts by five European laboratories, there were obvious differences between laboratories. However, low-count samples were consistently reported as low and high-count samples as high.
  • The report stated that lung fibre levels follow a gradient across diseases: highest median levels in asbestosis, lower levels in mesothelioma and the lowest in pleural plaques.
  • Several European and American laboratories regard these levels as indicative of nontrivial asbestos exposure: 1 asbestos body per mL of lavage fluid, 1000 asbestos bodies per gram of dry lung tissue, 1 × 10^6 amphibole fibres (longer than 1 µm) per gram, and 0.1 × 10^6 amphibole fibres (longer than 5 µm) per gram of dry lung tissue. The report described these as relative and arbitrary limits.
  • Asbestos bodies in sputum were described as highly specific for past exposure but a very insensitive measure of lung fibre burden.
• The authors' conclusion: The authors concluded that standardized methods, adequate reference populations, and an understanding of fibre retention and disease dose-responses are crucial for interpreting these analyses. A high fibre burden indicates exposure but is not proof of disease. A negative result does not prove absence of significant exposure, especially for chrysotile. Invasive procedures should not be used only to collect samples.
• Limitations the authors state:
  • Mineral fibre analysis measures only the fibres present at the time of sampling and gives no information on fibres already cleared. This matters for chrysotile, which is less biopersistent than amphiboles.
  • Electron microscopy results vary more between laboratories than light-microscopy asbestos body counts, which makes comparisons between laboratories harder.
  • The exposure thresholds are relative and arbitrary, and fibre or asbestos body counts overlap widely between people classified as exposed and unexposed.

Topics

Medical terms in this study, explained in our Lexicon: Bronchoalveolar Lavage (BAL), Asbestos Bodies, Sputum, Dose-response relationship.

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