Estimation of fibril lengths in chrysotile asbestos fibres

Our plain-English summary of Estimation of fibril lengths in chrysotile asbestos fibres, by A.W. Atkinson, R.B. Gettins, A.L. Rickards (Nature, 1970).

The study

• Authors: A.W. Atkinson, R.B. Gettins, A.L. Rickards
• Journal: Nature
• Published: 1970;226(5249):937-8
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This 1970 letter in Nature, by authors at Turner Brothers Asbestos Co. Ltd in Rochdale, Lancashire, was a laboratory study of how chrysotile asbestos is built, not a study of health or disease. The authors set out to estimate how long the individual fibrils inside chrysotile fibre bundles are. They gently stirred fibre bundles in a water-and-surfactant solution to separate mainly single fibrils. They then estimated length from electron micrographs with a statistical method comparing the number of fibrils to the number of fibril ends in a field of view, and checked it with a frictional drag reduction method. Samples came from Canada (Cassiar and Bells) and South Africa (Kaapsche Hoop). As far as the damaged scan of the table can be read, these two methods gave mean lengths of roughly 1.4 to 4.0 millimetres. Lengths calculated from viscosity measurements using Burgers equations disagreed with directly observable lengths of mechanically shortened chrysotile fibrils in suspension. The authors concluded that fibres several centimetres long were made of fibrils at least several millimetres long. They noted that separating the fibrils may have shortened some, so fibrils might be centimetres long.

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 of the physical properties of chrysotile fibrils (materials science short report; no human or animal subjects)
• Who was studied: Chrysotile asbestos samples: Canadian (Cassiar), Canadian (Bells) and South African (Kaapsche Hoop), plus a mechanically shortened fibril suspension used for calibration
• Exposure: Chrysotile fibre bundles dispersed by gentle stirring in aqueous surfactant solution into mainly single fibrils; lengths estimated by electron microscopy (statistical method), drag reduction in turbulent flow, and viscosity measurements
• Main results:
  • Electron micrograph length was estimated statistically from the ratio of fibrils to fibril ends in a field of view, because long fibrils exceeded the microscope's field of view
  • As the scanned table appears to show, mean estimated lengths by the statistical electron micrograph method and the drag reduction method were 1.8 and 1.7 mm (Canadian Cassiar), 1.4 and 1.7 mm (Canadian Bells) and 4.0 and 3.9 mm (South African Kaapsche Hoop). The column assignment is uncertain because the table layout is damaged.
  • The authors stated that the drag reduction (rheological) measurements confirmed the lengths estimated by electron microscopy
  • Lengths calculated from viscosity measurements (Burgers equations) disagreed with directly observable lengths of mechanically shortened fibrils in suspension; the authors suggested the curved, flexible nature of chrysotile fibrils was responsible
  • Fibrils were estimated to be at least several millimetres long, within one order of magnitude of the macro-fibre length, corresponding to an aspect ratio of approximately 10 to the power 5
• The authors' conclusion: The authors concluded that carefully dispersed chrysotile fibres several centimetres long are composed of fibrils at least several millimetres long, and that the fibrils may possibly be of the order of centimetres long, extending the whole length of the parent fibre bundles
• Limitations the authors state:
  • Even gentle separation of fibrils from their bundles may have shortened some fibrils
  • Drag-based lengths were calculated assuming an average fibril diameter of 400 angstroms
  • Only an outline is given; fuller accounts of the methods were to be published elsewhere

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Cassiar mine, British Columbia

All asbestos mines

Topics

Medical terms in this study, explained in our Lexicon: Fibril, Chrysotile.

Related studies

• Pulmonary effects in rats inhaling size-separated chrysotile asbestos fibres or p-aramid fibrils: differences in cellular proliferative responses — D.B. Warheit, M.A. Hartsky, et al. (1996)
• A study of the length and diameter of fibres, in lung and in broncho-alveolar lavage fluid, following exposure of rats to chrysotile asbestos — E. Kauffer, J.C. Vigneron, et al. (1987)
• Quantitative assessment of chrysotile fibrils in the bloodstream of rats which have ingested the mineral under different dietary conditions — M. Weinzweig, R.J. Richards (1983)
• Significance of fibre length in the clearance of asbestos fibres from the lung — A. Morgan, R.J. Talbot, et al. (1978)
• Asbestos-stimulated tumour necrosis factor release from alveolar macrophages depends on fibre length and opsonization — K. Donaldson, X.Y. Li, et al. (1992)
• Fibrogenesis by mineral fibres: an in-vitro study of the roles of the macrophage and fibre length — M. Aalto, A.G. Heppleston (1984)

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