What is a significant lung asbestos fibre result?

Our plain-English summary of What is a significant lung asbestos fibre result?, by S.K. Suvarna, C. Layton (Histopathology, 2006).

The study

• Authors: S.K. Suvarna, C. Layton
• Journal: Histopathology
• Published: 2006;48(2):203-4
• Type of article: Letter
• Read it: PubMed · Publisher

In plain English

In this letter to the editor, two pathologists in Sheffield, UK, described a 10-year review of their laboratory's lung asbestos fibre counts made by light microscopy, asking what fibre level is significant. Of 432 cases assayed, 161 were malignant mesotheliomas, 105 were lung cancers and 68 were pulmonary fibrosis with a history of asbestos exposure. Another 86 cases lacked adequate data and were eliminated. Six 'controls', with no history of asbestos exposure or related disease, had 0 to 216 000 fibres per gram of dry lung tissue (mean 88 535). One mesothelioma had no detectable fibres. The rest ranged from 17 847 to 16 120 456 (mean 1026 754, median 307 584). In six cases also examined by electron microscopy, light microscopy gave roughly one tenth of the electron microscopy result. An asbestos worker who died of prostate cancer without lung pathology had over 30 million fibres per gram. The authors suggested a possible significance line near 80 000 fibres per gram. They noted that it was similar to the control mean and might be arbitrary. They concluded that a fibre count cannot establish medicolegal causation of mesothelioma without occupational history and health records.

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: Letter to the editor reporting a 10-year review of the authors' laboratory lung fibre counts by light microscopy
• Who was studied: 432 lung samples assayed at the Department of Histopathology, Northern General Hospital, Sheffield, UK: 161 malignant mesotheliomas (11 female, 150 male, mean age 72), 105 lung cancers, 68 pulmonary fibrosis cases with asbestos exposure history, and 6 'controls'. Dates are not given.
• Exposure: Asbestos fibre load in digested lung tissue, counted by light microscopy (coated and uncoated fibres) and expressed as fibres per gram of dry lung tissue. Fibre types are not identified.
• Main results:
  • The six 'controls' (no asbestos exposure history or related disease) had 0 to 216 000 fibres per gram of dry lung tissue (mean 88 535).
  • Among the 161 mesotheliomas, one case had no detectable fibres. The remainder ranged from 17 847 to 16 120 456 fibres per gram of dry lung tissue (mean 1026 754; median 307 584).
  • In six cases also analysed by electron microscopy, light microscopy and electron microscopy results were in an approximate 1 to 10 ratio.
  • An asbestos worker who died of prostate cancer without lung pathology had levels in excess of 30 million (30 × 10 to the 6th) fibres per gram of dry lung tissue.
  • Assuming 80–85% of mesotheliomas are attributable to asbestos, the authors said a significance line could be drawn at approximately 80 000 fibres per gram of dry lung tissue, which was similar to their control mean.
• The authors' conclusion: The authors concluded that the significance level for an individual case is open to interpretation. They stated that fibre assay cannot establish medicolegal causation for malignant mesothelioma without a balanced view of occupational history and health records. They had similar doubts about significance levels for other asbestos-related diseases.
• Limitations the authors state:
  • The control group was small (six cases).
  • 86 cases were eliminated for lacking adequate occupational or pathological data.
  • Results vary within and between laboratories, even with electron microscopy.
  • Fibres degrade over time in the lungs and probably during assay procedures.
  • Defining a normal or background fibre level is problematic, and historical background values may not apply to current cases.
  • The proposed significance value might be unfair or arbitrary.

Related studies

• One fibre or many; what causes mesothelioma? — A. Seaton (2002)
• A comparison of fibre counting across three European national proficiency testing schemes — A.D. Jones, M.C. Arroyo, et al. (2005)
• A comparison of the results from intra-pleural and intra-peritoneal studies with those from inhalation and intratracheal tests for the assessment of pulmonary responses to inhalable dusts and fibres — G. Drummond, R. Bevan, et al. (2016)
• Asbestos lung fibre analysis in the United Kingdom, 1976-96 — G. Berry (2002)
• Response of mouse lung to crocidolite asbestos. 2. Pulmonary fibrosis after long fibres — I.Y. Adamson, D.H. Bowden (1987)
• Response of mouse lung to crocidolite asbestos. 1. Minimal fibrotic reaction to short fibres — I.Y. Adamson, D.H. Bowden (1987)

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