Physical and Chemical Characteristics of Reference Samples

Our plain-English summary of Physical and Chemical Characteristics of Reference Samples, by R.E.G. Rendall (1980).

The study

• Author: R.E.G. Rendall
• Published: BIOLOGICAL EFFECTS OF MINERAL FIBRES (J.C. WAGNER, EDITOR), LYON: IARC SCIENTIFIC PUBLICATIONS, VOLUME 30., PP 87-96 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This paper, by an author at the National Centre for Occupational Health in Johannesburg, South Africa, updated the data on the physical and chemical characteristics of the UICC standard reference asbestos samples: crocidolite, amosite, anthophyllite, and Canadian and Rhodesian chrysotile. Much of it gathered results from other researchers, which the author said were quoted without checking. Among these, fibre lengths measured by scanning electron microscopy agreed well with earlier light-microscope measurements. Microprobe analysis of single fibres agreed well with chemical analysis of bulk material, but the author cautioned that the composition of fibres recovered from lung tissue can be changed by their time in the lung. Magnetic properties of the samples were also listed. The author's centre measured fibre diameters by transmission electron microscopy. It also made a series of amosite samples of different sizes by repeated air classification, and finer samples by settling in water. The author considered fibre length and diameter distributions probably the characteristics that matter most for health effects. The author raised the possibility of preparing samples with graded characteristics and proposed a new edition of the data sheets.

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: Review and compilation of data, largely from other studies, on the physical and chemical characteristics of the UICC reference asbestos samples, with some new laboratory data from the author's centre in Johannesburg
• Who was studied: The UICC standard reference asbestos samples (crocidolite, amosite, anthophyllite, Canadian chrysotile, Rhodesian chrysotile). Most earlier characterization work was done at the MRC Pneumoconiosis Unit, Cardiff, and the National Research Institute for Occupational Diseases, Johannesburg, before 1972.
• Exposure: No human or animal exposure was studied. The subject was the reference fibre samples themselves: crocidolite, amosite, anthophyllite and chrysotile (Canadian and Rhodesian).
• Main results:
  • Fibre length distributions determined by scanning electron microscopy (work by Beckett, 1973) agreed well with the original light-microscope determinations.
  • At the author's centre, a series of amosite samples with different size distributions was prepared by repeated air classification of the original UICC amosite sample.
  • In other researchers' work on chrysotile (Choi and Smith, 1973), surface area calculated by treating the fibres as solid rods agreed more closely with measured surface area than treating them as hollow tubes.
  • Dissolution studies by Allen (1973) found that nickel dissolved from UICC chrysotile at one-third the rate of magnesium.
  • Microprobe analysis of single fibres (Pooley, 1975) agreed well with chemical analysis of bulk material. The author cautioned that fibres recovered from tissue should be treated carefully, because their composition is affected by residence time in the lung.
  • The author stated that for amphibole fibres, settling in water over 48 hours produces suitable graded samples. Chrysotile needs settling followed by sieving, and air classification is not practical for chrysotile.
• The authors' conclusion: The author considered fibre length and diameter distributions probably the characteristics that matter most for health effects. The author raised the possibility of preparing samples with graded characteristics and proposed a new edition of the data sheets.
• Limitations the authors state:
  • Values determined at other institutes were quoted without being checked.
  • Not all new data could be included.
  • Preliminary investigations of how fibre composition relates to fibre diameter were inconclusive.

Topics

Medical terms in this study, explained in our Lexicon: UICC, Crocidolite, Amosite, Anthophyllite, Chrysotile, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM).

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