The mineral nature of asbestos

Our plain-English summary of The mineral nature of asbestos, by M. Ross, A.M. Langer, G.L. Nord, et al (Regulatory Toxicology and Pharmacology, 2008).

The study

• Authors: M. Ross, A.M. Langer, G.L. Nord, R.P. Nolan, R.J. Lee, D. Van Orden, J. Addison
• Journal: Regulatory Toxicology and Pharmacology
• Published: 2008;52(1 Suppl):S26-30
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Fibrous minerals are common in nature but asbestiform minerals are rare. The unique mineralogical characteristic common to all the asbestos minerals is their morphologic form (or habit of crystallization) as polyfilamentous fiber bundles. The individual fibrils within the bundles have a tendency to be very long with a narrow range of diameters and grow with their long fiber axis in parallel orientation to the bundle length. The asbestiform habit imparts to the asbestos minerals sufficient flexibility and tensile strength so that most can be woven into cloth. In the past application has focused on their ability to insulate against the transfer of heat. However, these minerals possess other properties which make them useful in many industrial applications.

In plain English

This article was a descriptive review of the mineralogy of asbestos. It did not study people or animals and reported no new health data. The authors explained that fibrous minerals are fairly common in nature but asbestiform minerals are rare. What all asbestos minerals share is their growth as polyfilamentous fiber bundles. They described six commercial minerals regulated as asbestos in the United States: chrysotile, a serpentine mineral, and five amphiboles (actinolite, amosite, anthophyllite, crocidolite and tremolite). The same amphibole minerals more commonly occur in non-asbestos forms that lack the industrial properties of asbestos. Citing earlier work, the authors reported that more than 95% of commercially developed asbestos ore deposits were chrysotile. Commercially viable deposits usually contain 2–4% asbestos, and world chrysotile production was 2 million metric tons in 2001. They described chrysotile fibrils as rolled-up sheets about 25 nm across. They stated that chrysotile has lower chemical durability than the amphibole asbestos minerals because its outer magnesium layer is readily leached.

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: Narrative review of asbestos mineralogy, history and commercial occurrence, drawing on published literature; no new data collected
• Who was studied: No human or animal population; the subject was the six minerals known collectively as asbestos and related fibrous minerals
• Exposure: Six commercial minerals regulated as asbestos in the United States: chrysotile (serpentine) and the amphiboles actinolite, amosite (grunerite asbestos), anthophyllite, crocidolite (riebeckite asbestos) and tremolite. Other asbestiform minerals such as palygorskite, winchite, richterite and fluoro-edenite were also mentioned.
• Main results:
  • Fibrous mineral crystals are fairly common in nature, but asbestiform minerals are rare
  • The non-asbestos forms of these minerals do not have the industrial properties of asbestos
  • Non-asbestos amphiboles are common and make up 5% of the earth's crust
  • More than 95% of commercially developed asbestos ore deposits were chrysotile; the remainder was mainly crocidolite and amosite
  • With a few exceptions, commercially viable asbestos deposits contain 2–4% asbestos in the ore body
  • Chrysotile was described as the only asbestos mineral of current commercial importance, with worldwide production of 2 million metric tons in 2001
  • Chrysotile fibrils, formed from rolled-up sheets, generally have a diameter around 25 nm
  • Chrysotile has lower chemical durability than the amphibole asbestos minerals because its outer magnesium layer is readily leached
• The authors' conclusion: The article has no separate conclusion section. Its abstract states the authors' view that the defining mineralogical feature shared by all asbestos minerals is their growth form as polyfilamentous fiber bundles.

Topics

Medical terms in this study, explained in our Lexicon: Asbestiform, Asbestos, Habit, polyfilamentous, Fibril, Flexibility, Tensile Strength.

Related studies

• Rapporteur's Report Session 2: characterization of fibrous minerals — A.M. Langer (2008)
• Rapporteur's Report Session 6: risk assessment of asbestos and other fibrous mineral particulates — R.P. Nolan, A.M. Langer (2008)
• The search for asbestos within the Peter Mitchell Taconite iron ore mine, near Babbitt, Minnesota — M. Ross, R.P. Nolan, et al. (2008)
• Some investigations into the nature and cause of massive fibrosis (MF) in the lungs of South African gold, coal, and asbestos mine workers — M.C. Leibowitz, B. Goldstein (1987)
• Pulmonary mineral fibers after occupational and environmental exposure to asbestos in the Russian chrysotile industry — A. Tossavainen, E. Kovalevsky, et al. (2000)
• Role of associated mineral fibres in chrysotile asbestos health effects: the case of balangeroite — F. Turci, M. Tomatis, et al. (2009)

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