Alignment of respirable asbestos fibres by magnetic fields

Our plain-English summary of Alignment of respirable asbestos fibres by magnetic fields, by V. Timbrell (The Annals of Occupational Hygiene, 1975).

The study

• Author: V. Timbrell
• Journal: The Annals of Occupational Hygiene
• Published: 1975;18(4):299-311
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This article by V. Timbrell, of the Medical Research Council Pneumoconiosis Unit, described laboratory methods for lining up respirable asbestos fibres with magnetic fields. It was a methods paper, not a study of disease in people. The author reported that of a large number of samples examined, none failed to align. Fibres of natural asbestos aligned either parallel to the field (P-fibres) or at right angles to it (N-fibres). Some synthetic fluoramphiboles aligned differently. Aligned specimens made counting and measuring fibres under microscopes easier. Under a laser beam, the light patterns differed by sample: UICC anthophyllite (Finland) and Uganda tremolite showed P-fibres, India amosite and Zululand tremolite showed N-fibres, and UICC amosite (Transvaal) showed both. Added silica particles raised the trace without changing peak sizes. Dust from one asbestos worker's lung, with a history of moderate Transvaal amosite exposure, showed a relatively larger N-peak than the reference sample. The author linked this to the thinner N-fibres penetrating the lungs more efficiently. Two light-based fibre-size indices were described, and the author noted that each is affected by both fibre diameter and length.

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 methods paper describing magnetic alignment, microscopy and laser light-scattering techniques for asbestos fibres
• Who was studied: Asbestos samples from various mining areas, including UICC amosite (Transvaal), UICC crocidolite (Cape Province), UICC Canadian chrysotile, UICC anthophyllite (Finland), India amosite, Uganda tremolite, Zululand tremolite and a synthetic fluoramphibole. Also particles recovered from one asbestos worker's lung. The number of samples is not stated beyond 'a large number'.
• Exposure: Respirable asbestos fibres placed in magnetic fields (for thin films, a strong field of 5-10 kG was described as desirable), in air or liquid suspension
• Main results:
  • Of a large number of samples examined, including all the important commercial types, none failed to align in a magnetic field
  • Natural asbestos fibres showed only two alignment modes: parallel to the field (P-fibres) or normal to it (N-fibres). Some synthetic fluoramphiboles showed a different mode.
  • Light-scattering patterns showed UICC amosite (Transvaal) contained both P-fibres and N-fibres
  • India amosite showed N-fibres
  • Uganda tremolite showed P-fibres, while Zululand tremolite showed N-fibres
  • Heating UICC amosite to 600°C converted its N-fibres to P-fibres
  • Small N-peaks in UICC crocidolite traces illustrated the system's sensitivity to minute quantities of fibre
  • Non-aligning particles (silica added to an anthophyllite specimen) raised the trace without altering peak sizes
  • Particles from the lung of one worker with moderate Transvaal amosite exposure gave a relatively larger N-peak than the reference sample. The author attributed this to the thinner N-fibres penetrating more efficiently into the lungs.
  • In centrifuged UICC anthophyllite suspensions, one size index decreased and the other increased with decreasing fibre size
• The authors' conclusion: The author concluded that magnetic alignment of respirable asbestos fibres has many advantages in investigations of the biological effects of asbestos
• Limitations the authors state:
  • The two fibre-size indices are each affected by both fibre diameter and length, so they cannot give separate evidence on each

Related studies

• Interactions between magnetic nanowires and living cells: uptake, toxicity, and degradation — M. Safi, M. Yan, et al. (2011)
• Magnetic lung measurements of relation to occupational exposure in asbestos miners and millers of Quebec — D. Cohen, T.S. Crowther, et al. (1981)
• A procedure for the isolation of asbestos bodies from lung tissue by exploiting their magnetic properties: a new approach to asbestos body study — V. Borelli, C. Brochetta, et al. (2007)
• Lung cancer in relation to employment in the electrical utility industry and exposure to magnetic fields — D.A. Savitz, V. Dufort, et al. (1997)
• Ferromagnetic contamination in the lungs and other organs of the human body — D. Cohen (1973)
• Magnetometric evaluation for the effect of chrysotile on alveolar macrophages — T. Keira, M. Okada, et al. (1998)

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