Performance of asbestos fibre counting laboratories by transmission electron microscopy

Our plain-English summary of Performance of asbestos fibre counting laboratories by transmission electron microscopy, by B. Préat (The Annals of Occupational Hygiene, 2001).

The study

• Author: B. Préat
• Journal: The Annals of Occupational Hygiene
• Published: 2001;45(6):500-1
• Type of article: Comment, Letter
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This item was a letter to the editor, not a research study. The author commented on a paper by Kauffer et al. (2001) about a proficiency testing scheme for laboratories that count asbestos fibres by transmission electron microscopy (TEM). The author questioned whether the reference samples were representative, because each contained pure asbestos of only one type, with no other fibres and no matrix. The author asked why laboratories were given around one and a half months to return results. The author also suggested that the laboratories' improvement over three years might reflect extra quality control applied to the reference samples, and that sending each laboratory 8 filters from the same batch might encourage laboratories to share information. Citing Table 3 of the Kauffer paper, the author noted that 96% of standardized ratios from proficient laboratories in 1998 lay between 0.4 and 2.5. Measured against the French action limits of 5 f/L and 25 f/L, the author argued that a single result between 10 and 12.5 f/L would be indecisive. The author concluded that indirect-transfer TEM is one of the most unreliable methods used in occupational and environmental hygiene.

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 commenting on a published proficiency-testing study (Kauffer et al., 2001); no original data
• Who was studied: No study population of its own. The letter discusses the laboratories in the Kauffer et al. TEM proficiency scheme, each of which was sent 8 filters at 8 fibre density levels; the number of laboratories is not given in the letter.
• Exposure: Asbestos fibre counting by indirect-transfer TEM on reference samples of pure asbestos of a single type per sample. The fibre types are not named in the letter.
• Main results:
  • The author questioned how representative the reference samples were.
  • The author questioned the roughly one-and-a-half-month period laboratories were given to return results.
  • The author suggested that the laboratories' improved performance over the three-year period might be due to enhanced quality control applied to the reference samples.
  • The author suggested that sending each laboratory 8 filters from the same batch might encourage laboratories to exchange information.
  • Citing Table 3 of the Kauffer et al. paper (not the author's own data): 96% of standardized ratios from the proficient laboratories in 1998 were between 0.4 and 2.5.
  • The French action limits in use since 1996, as described by the author: below 5 f/L no action is needed; between 5 and 25 f/L a follow-up strategy is needed; above 25 f/L urgent action is needed.
  • On that spread of results, the author argued that a single laboratory result of 2 to 2.5 f/L could represent the lower action level, and a result above 10 f/L could mean the upper limit was exceeded.
  • The author argued that a single laboratory result between 10 and 12.5 f/L would be indecisive.
• The authors' conclusion: The author concluded that indirect-transfer TEM is one of the most unreliable methods used in occupational and environmental hygiene, and that this could even prevent full implementation of the French asbestos regulation.

Topics

Medical terms in this study, explained in our Lexicon: Transmission Electron Microscopy (TEM).

Related studies

• Confusion about the precision of asbestos fibres counting by electron microscopy — B. Préat (2000)
• The use of a new static device based on the collection of the thoracic fraction for the assessment of the airborne concentration of asbestos fibres by transmission electron microscopy — E. Kauffer, J.C. Vigneron, et al. (1996)
• Determination of mineral fibre in human lung tissue by light microscopy and transmission electron microscopy — A.J. Rogers (1984)
• Size distributions of occupational airborne asbestos textile fibres as determined by transmission electron microscopy — A.P. Rood, R.R. Streeter (1984)
• A comparison of light microscopy and transmission electron microscopy results in the evaluation of the occupational exposure to airborne chrysotile fibres — A. Marconi, E. Menichini, et al. (1984)
• A procedure for the estimation of asbestos collected on membrane filters using transmission electron microscopy (TEM) — A.P. Middleton, E.A. Jackson (1982)

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