A Comparison Of Fibre Dimensions In Chrysotile, Crocidolite And Amosite Particles From Samples Of Airborne Dust And From Post-Mortem Lung Tissue Specimens

Our plain-English summary of A Comparison Of Fibre Dimensions In Chrysotile, Crocidolite And Amosite Particles From Samples Of Airborne Dust And From Post-Mortem Lung Tissue Specimens, by F.D. Pooley, N.J. Clark (1980).

The study

• Authors: F.D. Pooley, N.J. Clark
• Published: Biological Effects Of Mineral Fibres (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 30, Pp. 79-86 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 004987. The article is still under copyright, so we describe it here rather than post it.

In plain English

This laboratory study, part of a continuing UK project, used an analytical transmission electron microscope to measure the length and diameter of chrysotile, crocidolite and amosite asbestos fibres. The fibres came from several hundred post-mortem lung tissue specimens from diseased and control cases. They were compared with airborne dust samples, including crocidolite and amosite dust from South African mining operations. In all samples, fibres shorter than 5 micrometres predominated. In lung tissue, 5%, 10.5% and 23% of chrysotile, crocidolite and amosite fibres were longer than 6 micrometres. Their mean diameters were 0.07, 0.14 and 0.28 micrometres. Crocidolite and amosite fibres got thicker as they got longer, amosite more quickly. Chrysotile was not compared with airborne dust. For crocidolite and amosite, fibres found in the lung appeared larger than airborne ones, which the authors said might indicate selective retention of longer fibres. Other researchers had linked long, thin fibres to mesothelioma. Here, 3.7% of chrysotile fibres from lung were longer than 8 micrometres and thinner than 0.25 micrometres, with similar figures for the other two minerals. The authors concluded the three minerals appear to represent a similar hazard when fibre size is considered.

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: Laboratory measurement study (part of a continuing study) of fibre size by analytical transmission electron microscopy, comparing fibres extracted from post-mortem lung tissue with fibres in airborne dust samples
• Who was studied: Several hundred post-mortem lung tissue specimens from diseased cases (mesothelioma and asbestosis) and control cases, collected by pathologists in the UK, plus airborne dust samples, including crocidolite dust from the Pomfret Mine and amosite dust from the Penge Mine in South Africa
• Exposure: Chrysotile, crocidolite and amosite asbestos fibres, characterized by length and diameter
• Main results:
  • In lung tissue, the percentages of fibres longer than 6 micrometres were 5% for chrysotile, 10.5% for crocidolite and 23% for amosite (the scan reads '237'; the amosite table rows add to 23.0)
  • In lung tissue, the mean diameter of crocidolite fibres was 0.14 micrometres, compared with 0.07 micrometres for chrysotile
  • In lung tissue, the mean diameter of amosite fibres was 0.28 micrometres
  • In lung tissue, 56.3% of crocidolite fibres longer than 10 micrometres had a projected diameter of less than 0.25 micrometres
  • In lung tissue, the corresponding figure for amosite fibres longer than 10 micrometres was 13.4%. The authors described amosite diameter as increasing with length more rapidly than crocidolite diameter, while chrysotile diameter changed very little with length
  • In airborne dust from South African mining operations, amosite fibres averaged 4.3 micrometres in length, compared with 2.6 micrometres for crocidolite
  • In the same airborne dust, mean diameter was 0.33 micrometres for amosite and 0.15 micrometres for crocidolite
  • Compared with lung tissue, each airborne dust sample had a smaller percentage of fibres of both amphiboles over 6 micrometres in length, and more fibres under 2 micrometres in length
  • The size distributions of amosite and crocidolite fibres were similar in airborne dust samples and in the lung
  • For both amphiboles, fibres found in the lung appeared larger than airborne fibres, which the authors said perhaps indicates selective retention of longer fibres
  • The percentage of lung fibres large enough to be optically visible was under 5% for chrysotile, under 6% for crocidolite and under 30% for amosite
  • In lung tissue, the percentage of fibres longer than 8 micrometres and less than 0.25 micrometres in diameter was 3.7% for chrysotile. The figures for crocidolite and amosite are printed in the scan as '3.367' and '3.77'. The authors examined this size range in light of a suggestion by other researchers (Stanton and Layard) about fibres most important for mesothelioma
  • In all samples, fibres shorter than 5 micrometres predominated, and fibres over 25 micrometres were seen very infrequently
• The authors' conclusion: The authors concluded that chrysotile, crocidolite and amosite fibres in lung tissue have distinct size characteristics. They also concluded that the three minerals appear to represent a similar hazard when the size of the fibres they form is considered.
• Limitations the authors state:
  • The authors recognized that extensive sample preparation may alter the physical and chemical properties of fibres, although repeatedly processed test specimens showed no major changes
  • For chrysotile, preparation can break up aggregates into extra-fine fibrils, which the authors said produces only very small statistical changes in the size distribution
  • The airborne samples were collected on open samplers, so they did not represent only respirable material
  • Chrysotile fibre sizes in lung were not compared with airborne chrysotile, because of extreme variability in particle morphology and dust clouds
  • The data were still being collected as further specimens were examined

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Crocidolite, Amosite, Mesothelioma.

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