Surface characteristics of asbestos fibers released from asbestos- cement products

Our plain-English summary of Surface characteristics of asbestos fibers released from asbestos- cement products, by J.A. Helsen, P. van de Velde, A. Kuczumow, et al (American Industrial Hygiene Association Journal, 1989).

The study

• Authors: J.A. Helsen, P. van de Velde, A. Kuczumow, A. Deruyttere
• Journal: American Industrial Hygiene Association Journal
• Published: 1989;50(12):655-63
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004442).

In plain English

This laboratory study examined asbestos fibers from an asbestos-cement corrugated roof sheet weathered for 51 years in rural central Belgium. The authors collected fibers by spraying the sheet with distilled water for 150 hours and by scraping its surface. They analyzed the fibers' composition by electron microscopy, comparing it with virgin chrysotile, amosite and crocidolite, and compared their benzo[a]pyrene adsorption with virgin and ashing-treated chrysotile. Of 32 randomly chosen fibers, 30% met all of the authors' respirability criteria, and about 80% met the aspect-ratio criterion alone. The recovered fibers were chrysotile or a modified form of it, and none of the analyzed particles was identified as an amphibole. The fibers were depleted of magnesium and contained calcium, with magnesium falling as calcium rose. The adsorption tests showed a less clear difference between weathered and virgin fibers. The authors concluded that the fibers can no longer be called chrysotile in the strict mineralogical sense, and that the biological consequences of this change remain unknown. They could not compare the fibers with the asbestos originally used to make the sheet.

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 analysis of fibers recovered from one naturally weathered asbestos-cement corrugated sheet, compared with virgin reference asbestos fibers
• Who was studied: One asbestos-cement corrugated sheet from the roof of an isolated building in a rural area of central Belgium, weathered for 51 years. 32 fibers were randomly chosen for dimensional analysis.
• Exposure: Fibers released from the sheet were collected in two ways: by spraying with distilled water in a weathering box for 150 hours, or by scraping with a scalpel. The composition reference fibers were Canadian chrysotile (grade 4), Cassiar chrysotile, Russian chrysotile (grade 6), and amosite and crocidolite from Central Asbestos. The benzo[a]pyrene adsorption comparisons used virgin chrysotile and chrysotile treated by low temperature ashing.
• Main results:
  • Of the 32 randomly chosen sprayed-off fibers, only 30% met the length, diameter and aspect-ratio criteria for respirability together.
  • Using aspect ratio alone, about 80% of the inspected fibers fell in the respirable class.
  • All recovered fibers were chrysotile or a modified form of it.
  • None of the analyzed particles could be identified as an amphibole.
  • The fibers were magnesium depleted and contained calcium in a position not yet defined.
  • In both sprayed and scraped fibers, the magnesium-to-silicon ratio decreased as the calcium-to-silicon ratio increased. At a given calcium ratio, magnesium was always lower in the sprayed fibers.
  • Benzo[a]pyrene adsorption showed a less clear distinction between pure and weathered asbestos.
  • Benzo[a]pyrene adsorption increased in this order: scraped fibers, ashing-treated chrysotile, virgin chrysotile, then sprayed fibers, which adsorbed slightly more.
  • The authors reported that low temperature ashing treatment influenced both the specific surface and the adsorption of chrysotile.
• The authors' conclusion: The authors concluded that the weathered fibers can no longer be qualified as chrysotile in the strict mineralogical sense, and that the true biological consequences of this modification remain unknown.
• Limitations the authors state:
  • The collected fibers could not be compared with the asbestos originally used by the manufacturer.
  • Remaining cement could not be separated from the fibers without risking changes to their surface properties, which affected the adsorption tests.
  • No absolute measurements of silicon content were possible.
  • The adsorption experiments need further work and should be extended to compounds of different polarity.

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

Related studies

• Simulation tests to assess occupational exposure to airborne asbestos from asphalt-based roofing products — F. Mowat, R. Weidling, et al. (2007)
• Potential health hazards associated with exposures to asbestos-containing drywall accessory products: A state-of-the-science assessment — A.D. Phelka, B.L. Finley (2012)
• Simulation tests to assess occupational exposure to airborne asbestos from artificially weathered asphalt-based roofing products — P. Sheehan, F. Mowat, et al. (2010)
• More on the dynamics of dust generation: the effects of mixing and sanding chrysotile, calcium carbonate, and other components on the characteristics of joint-compound dusts — D.W. Berman, G.P. Brorby, et al. (2012)
• Colorectal cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• Evaluation of take-home exposure to asbestos from handling asbestos-contaminated worker clothing following the abrasive sawing of cement pipe — A. Abelmann, J.R. Maskrey, et al. (2017)

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