Significance of aspect ration in regulation of asbestos fiber exposure

Our plain-English summary of Significance of aspect ration in regulation of asbestos fiber exposure, by A.M. Langer (Annals of the New York Academy of Sciences, 1979).

The study

• Author: A.M. Langer
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:601-4
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy.

Summary of the article

This article introduced a workshop on the significance of aspect ratio in regulating asbestos fiber exposure and set out the participants' recommendations. The author recalled that a 1964 New York Academy of Sciences conference on the biological effects of asbestos had stressed an interdisciplinary approach. That conference had only peripherally addressed the physical-chemical nature of asbestos fibers, the properties that give them biological activity, and their relationship with fibrous rock-forming silicates that are not asbestos. The workshop was shaped with the Office of Environmental Assessment of the US Bureau of Mines. It had three sections: physical and biological properties of asbestos and acicular mineral fragments; the role of regulatory agencies; and aspect ratio and health hazards of asbestos fibers. Afterwards, T. Zoltai and the author drafted what they believed was a consensus of the participants. The recommendations were:
(1) use standard mineralogical terminology, such as US Bureau of Mines Information Circular No. 8751 (1977).
(2) use the term asbestos only when the source or megascopic characteristics are known; otherwise describe fibers as indistinguishable from asbestos or use general mineralogical terms.
(3) study the chemical, physical and crystallographic properties of asbestiform fibers, including fiber dimension (aspect ratio), alongside biological and medical studies.
(4) stop limiting "asbestos" to the 5 (or 6) commercial minerals, study fibrous rock-forming silicates, and control them like asbestos until safety is demonstrated.
(5) collect more data on inorganic fibers in human tissues.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This 1979 article was the author's introduction to a workshop on aspect ratio and asbestos fiber exposure, not a study, and reported no new data. It described the topics and the recommendations, which T. Zoltai and the author wrote as what they believed was the participants' consensus. One organizer gave the aim as communication among groups concerned with elongated mineral particles from mining and milling nonasbestos ores such as taconite, talc and crushed stone. The recommendations called for standard mineralogical terms and said "asbestos" may be used only when the mineral's physical characteristics, such as habit, tensile strength and flexibility, are known at a megascopic level. For submicroscopic fibers, the term may also be used if the source is known and not mixed with other nonasbestiform fibrous minerals. They proposed not limiting "asbestos" to the 5 (or 6) commercial minerals, and considering all minerals with an asbestiform habit in relevant studies, though known hazards of commercial asbestos may or may not apply to untested asbestiform fibers. Fibrous rock-forming silicates were to be studied and controlled the same as asbestos until "safety" is demonstrated.

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: Introduction to a scientific workshop, with the participants' recommendations; not a research study
• Who was studied: No people or animals were studied. The workshop brought together investigators from several disciplines. R. E. Corcoran and colleagues in the Office of Environmental Assessment of the United States Bureau of Mines helped shape the workshop.
• Exposure: Asbestos fibers and elongated mineral particles produced in the mining and milling of nonasbestos ores, e.g. taconite, talc and crushed stone. This includes fibrous rock-forming silicates and nonasbestiform amphiboles.
• Main results:
  • Recommendation: all agencies and individuals dealing with asbestos health hazards should adopt standard mineralogical terminology, such as the definitions in U.S. Bureau of Mines Information Circular No. 8751 (1977)
  • Recommendation: in electron microscope studies, calling particles "fibers" should not be taken as conclusive identification of an asbestiform habit
  • Recommendation: the term asbestos may be used only when the mineral species' physical characteristics are known on a megascopic level. These are the mineral habit (fiber), tensile strength and flexibility, which distinguish asbestiform minerals from their rock-forming analogues.
  • Recommendation: the term asbestos may also be applied to submicroscopic fibers if the source materials are known and are not admixed with other nonasbestiform fibrous minerals
  • Recommendation: when the source is unknown but the fibers match known asbestos minerals, investigators should say the fibers are indistinguishable from asbestos and add caveats
  • Recommendation: future research should study the chemical, physical and crystallographic properties of asbestiform fibers, including fiber dimension (aspect ratio). These efforts should be correlated with biological, medical and public health studies.
  • Recommendation: stop limiting "asbestos" to the 5 (or 6) minerals in commercial deposits, and consider all minerals crystallized in the asbestiform habit in relevant studies
  • Recommendation: fibrous rock-forming silicates, especially nonasbestiform amphiboles with asbestiform analogues, should be studied immediately. They should be controlled the same as asbestos until "safety" is demonstrated.
  • Recommendation: more data should urgently be collected on the varieties and characteristics of inorganic fibers in human tissues
• The authors' conclusion: The recommendations were what T. Zoltai and the author believed to be a consensus of the workshop participants. T. Zoltai wrote the first and major draft.
• Limitations the authors state:
  • The informal discussions at the workshop were not recorded
  • The known health hazards of commercial asbestos fibers may or may not apply to untested asbestiform fibers of other minerals

Topics

Medical terms in this study, explained in our Lexicon: Aspect Ratio (Length-to-diameter ratio), Silicate, Acicular, Asbestiform, Fiber Dimensions.

Related studies

• Fiber dimensions and aspect ratio of crocidolite, chrysotile and amosite particles detected in lung tissue specimens — F.D. Pooley, N. Clark (1979)
• High aspect ratio materials: role of surface chemistry vs. length in the historical "long and short amosite asbestos fibers" — M. Tomatis, F. Turci, et al. (2010)
• Solubility of asbestos and man-made mineral fibers in vitro and in vivo: its significance in lung disease — A. Morgan, A. Holmes (1986)
• Asbestos and other ferruginous bodies: their formation and clinical significance — A.M. Churg, M.L. Warnock (1981)
• Review of the significance of fibre size in fibre-related lung disease: a centrifuge cell for preparing accurate microscope-evaluation specimens from slurries used in inoculation studies — V. Timbrell (1989)
• Malignant mesothelioma caused by childhood exposure to long-fiber low aspect ratio tremolite — F. Magee, J.L. Wright, et al. (1986)

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