Procedure for the detection and identification of asbestos and other fibres in fibrous inorganic materials

Our plain-English summary of Procedure for the detection and identification of asbestos and other fibres in fibrous inorganic materials, by L.J. Monkman (The Annals of Occupational Hygiene, 1979).

The study

• Author: L.J. Monkman
• Journal: The Annals of Occupational Hygiene
• Published: 1979;22(2):127-39
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A systematic procedure for the detection and identification of asbestos and other fibres in insulation and other fibrous materials is described. The need for adequate sampling and acid pre-treatment to remove the bulk of the non-fibrous matrix of such samples is stressed. The method requires an initial low-power stereo-microscopic examination followed by petrological polarization microscopic identification of the fibres. The optical characteristics required for the unambiguous identification of the common asbestos minerals are given.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This article from the Turner & Newall Ltd Asbestos Fibre Laboratory in Manchester described its procedure for identifying asbestos and other fibres in insulation and other fibrous materials. This was a methods paper, not a study of people or disease. The procedure required a representative sample, separated into layers under a low-power stereo microscope. Each layer was treated with dilute hydrochloric acid to remove non-fibrous material. The fibres were then identified by polarization microscopy, mainly from refractive index, birefringence and other optical properties. Step-by-step tables covered chrysotile, amosite, crocidolite, anthophyllite, tremolite and actinolite, as well as glass, mineral wool and organic fibres. The method was tested on prepared chrysotile mixtures containing a minor amount of amosite, examining at least 20 fields of view in two separate preparations at x180 magnification. In these tests a 0.01% detection limit could be reached only with special care and sometimes luck, while 0.1% was readily achievable by a competent laboratory. The author concluded that 0.1% appears to be a reasonable working lower limit for the method. The author warned that prolonged acid treatment can dissolve very fine chrysotile fibres.

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: Description of a laboratory method (optical microscopy procedure for identifying fibres in bulk materials), with a small detection-limit test on prepared fibre mixtures
• Who was studied: No people were studied. The method applies to samples of boiler, pipework and other insulation and fibrous inorganic materials. The detection limit was tested on 5 mg samples randomly chosen from prepared mixtures of chrysotile (major phase) and amosite (minor phase), at the Turner & Newall Asbestos Fibre Laboratory, Manchester, UK.
• Exposure: Fibre types the method identifies: the asbestos minerals chrysotile, amosite, crocidolite, anthophyllite, tremolite and actinolite, plus glass, slag and mineral wool fibres and natural and man-made organic fibres
• Main results:
  • In the prepared chrysotile and amosite mixtures, a detection limit of 0.01% for the minor fibre could be achieved when at least 20 fields of view in two separate preparations were examined at x180, but only with special care and in some instances some luck
  • At the 0.1% level, detection of the minor fibre was significantly easier and readily achievable by a competent laboratory
  • At the 0.1% level, examining at least 20 fields of view in two preparations at a magnification of x180 should show a total of 10 to 20 minor-phase fibres longer than 100 micrometres
  • For real samples with a fibre content of 10 to 60% of the total sample, the author estimated that the detection limit for amosite or crocidolite in the presence of major amounts of chrysotile should be between 0.01 and 0.06% of the total sample
  • The author judged dispersion staining to be a useful aid for measuring refractive index, but less reliable than polarization microscopy for detecting asbestos at trace or minor levels, because matrix particles can hide fine, short fibres
• The authors' conclusion: The author concluded that polarization microscopy provides both the required detection sensitivity and enough diagnostic features for unambiguous identification of the common asbestos fibres, and that a 0.1% detection level appears to be a reasonable working lower limit for the method as described
• Limitations the authors state:
  • Prolonging the acid treatment can dissolve very fine chrysotile fibres and some mineral wool fibres
  • Some tremolite and actinolite asbestos may show almost parallel extinction and be confused with anthophyllite; X-ray diffraction or infrared spectroscopy may then be needed
  • Sampling is usually outside the laboratory's control, so results depend on a representative sample being supplied
  • Extreme variability in fibre bundle size in insulation samples directly affects the reliability of quantitative estimates

Topics

Medical terms in this study, explained in our Lexicon: Asbestos.

Related studies

• Environmental exposure to asbestos and other inorganic fibres using animal lung model — E. Fornero, E. Belluso, et al. (2009)
• The analysis of lagging materials for asbestos: CEGB procedures — D.L. Ward (1979)
• In situ identification of asbestos fibres collected on membrane filters for counting — N.P. Vaughan, S.J. Rooker, et al. (1981)
• Inorganic materials and living organisms: surface modifications and fungal responses to various asbestos forms — S. Daghino, E. Martino, et al. (2005)
• "Rinse and trickle": a protocol for TEM preparation and investigation of inorganic fibers from biological material — R. Vigliaturo, S. Capella, et al. (2016)
• The effect of cigarette smoking on the detection of small radiographic opacities in inorganic dust diseases — P.D. Blanc, G. Gamsu (1988)

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