Variation of properties of chrysotile asbestos subjected to milling

Our plain-English summary of Variation of properties of chrysotile asbestos subjected to milling, by A.M. Langer, M.S. Wolff, A.N. Rohl, et al (Journal of Toxicology and Environmental Health, 1978).

The study

• Authors: A.M. Langer, M.S. Wolff, A.N. Rohl, I.J. Selikoff
• Journal: Journal of Toxicology and Environmental Health
• Published: 1978;4(1):173-88
• Cited by: 45 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mechanical milling is commonly used to produce short chrysotile asbestos for experimental purposes. Such manipulation also decreases fiber crystallinity, alters Si-O and Mg-O interlayer bonding, induces coordination changes in the brucite layer, diminishes the ability of fiber to reduce specific free radicals and physisorb organic molecules, and decreases hemolytic potency and antagonist sorption capabilities. The degree of alteration is related to the time of milling. Results of biological experimentation with these materials must be interpreted with caution. Interaction mechanisms in the biological setting are suggested for chrysotile fiber.

In plain English

This was a laboratory study, not a study of people or animals. The authors milled 50 mg portions of a short-fiber chrysotile asbestos (Calidria RG-144, from the New Idria, California, deposit) for 60 to 3600 seconds and examined how the material changed. Milling shortened fibers and fibrils. Fibers fell from 21% of particles counted in untreated material to 13% after 3600 seconds, and clumps rose from 0.5% to almost 10%. X-ray, infrared and electron spin resonance tests indicated reduced crystallinity and altered bonding, especially in the surface brucite layer, without significant loss of hydroxyl groups. In a test using sheep red blood cells, untreated chrysotile at 1 mg/ml destroyed 80 ± 5% of the cells (hemolysis), compared with 12% for chrysotile milled for 3600 seconds. The milled material needed 7.5 mg/ml rather than 0.4 mg/ml to reach 50% hemolysis. The fibers' uptake of the chemical DPPH rose after 60 seconds of milling but was lowest after 3600 seconds. The authors concluded that comparisons of the biological effects of fibers of different lengths should account for changes caused by preparing the size fractions.

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 experiment: physical and chemical analysis of milled chrysotile, plus in vitro tests (red blood cell hemolysis, free-radical adsorption)
• Who was studied: Calidria RG-144 chrysotile asbestos from the New Idria, California, deposit, supplied by Union Carbide Corp. Mature sheep red blood cells were used for the hemolysis test.
• Exposure: Chrysotile (50 mg portions) impact-milled in a Wig-L-bug amalgamator for 60 to 3600 seconds, compared with unmilled chrysotile
• Main results:
  • Fibers made up 21% of the particles counted in untreated chrysotile and 13% in chrysotile milled for 3600 seconds
  • In untreated chrysotile, 77% of fibrils were shorter than 0.5 micrometers. After 3600 seconds of milling, virtually all fibrils were shorter than 0.5 micrometers.
  • Clumps rose from 0.5% of objects counted in untreated material to almost 10% in material milled for 3600 seconds
  • X-ray counts under the (002) and (004) reflections fell with milling. Peak areas went from 8.36 to 3.50 square inches for (002) and from 6.99 to 5.69 square inches for (004), untreated versus 3600-second milling.
  • Infrared spectra indicated that milling altered some bonding, especially in the surface brucite layers, without significant dehydroxylation
  • Electron spin resonance showed a loss of hyperfine structure with progressive milling
  • Hemolysis at 1 mg/ml was 80 ± 5% for untreated chrysotile and 12% after 3600 seconds of milling. The concentration giving 50% hemolysis rose from 0.4 mg/ml (untreated) to 7.5 mg/ml (3600 seconds).
  • The ability of the polymers CMC and PVPNO to block hemolysis decreased with milling and was almost eliminated in the 3600-second milled material
  • DPPH chemisorption was 4.3 ± 1.5 micromol per gram untreated, 6.6 ± 0.8 after 60 seconds of milling, and 3.4 ± 0.7 after 3600 seconds
• The authors' conclusion: The authors concluded that comparisons of the biological potential of fibers of different lengths should take into account changes to the fibers caused by preparing the size fractions
• Limitations the authors state:
  • The infrared band assignments are tentative
  • The loss of ESR hyperfine splitting may partly reflect reduced particle size rather than crystal change
  • Whether the measured properties relate to fibrosis or cancer is speculative

Mines named here

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

• Santa Rita mine, Joaquin Ridge near Coalinga, California

All asbestos mines

Topics

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

Related studies

• How are the physical and chemical properties of chrysotile asbestos altered by a 10-year residence in water and up to 5 days in simulated stomach acid? — K. Seshan (1983)
• Characterization of talc and associated minerals — D.H. Hamer, F.R. Rolle, et al. (1976)
• Asbestos hemolysis — R.J. Schnitzer, F.L. Pundsack (1970)
• Mesotheliomas in rats following inoculation with acid-leached chrysotile asbestos and other mineral fibres — G. Monchaux, J. Bignon, et al. (1981)
• A possible mechanism of chrysotile asbestos toxicity — G.L. Fisher, B.T. Mossman, et al. (1987)
• The locus of pathogenicity of asbestos dust: a theory — P. Gross, R.A. Harley (1973)

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