Quantitative X-ray diffraction analysis of crocidolite and amosite in bulk or settled dust samples

Our plain-English summary of Quantitative X-ray diffraction analysis of crocidolite and amosite in bulk or settled dust samples, by J.V. Crable, M.J. Knott (American Industrial Hygiene Association Journal, 1966).

The study

• Authors: J.V. Crable, M.J. Knott
• Journal: American Industrial Hygiene Association Journal
• Published: 1966;27(5):449-53
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy.

In plain English

This 1966 laboratory methods paper from the U.S. Public Health Service described a way to measure how much crocidolite or amosite asbestos is in bulk process materials or settled dust, using X-ray diffraction with quartz added as an internal standard. Samples were ground so the fibers were less than 3.5 microns long and then scanned. To check accuracy, the authors analyzed prepared mixtures of known amounts of ground crocidolite or amosite with calcined diatomaceous earth: 11 crocidolite mixtures and 12 amosite mixtures. The mean recovery was 99.62% for crocidolite and 96.88% for amosite. Crocidolite recoveries were reasonably uniform from 5 to 100% crocidolite. No amosite was detected in a sample that contained 1.57% amosite. The authors concluded that samples should contain at least 5% of the asbestos fiber for reliable results. They noted that several things can interfere: other minerals whose peaks overlap the asbestos peaks, the nonfibrous forms riebeckite and grunerite, and quartz already present in the dust. The paper measured materials, not people or health effects.

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 analytical method development and accuracy testing (X-ray diffraction with an internal standard); no human or animal subjects
• Who was studied: Prepared known samples: 11 mixtures of ground crocidolite and 12 mixtures of ground amosite with calcined diatomaceous earth, at the Division of Occupational Health laboratory in Cincinnati, Ohio
• Exposure: Crocidolite and amosite in bulk or settled dust samples, ground to less than 3.5 microns and measured by X-ray diffraction with quartz as the internal standard
• Main results:
  • Crocidolite test mixtures: mean recovery 99.62% (standard deviation 0.94%)
  • Crocidolite recoveries were reasonably uniform over the range of 5 to 100% crocidolite; the lower end of the working range was approximately 5% crocidolite
  • Amosite test mixtures: mean recovery 96.88% (standard deviation 1.23%)
  • No amosite was detected in sample 1, which contained 1.57% amosite
  • For amosite, the authors found the procedure applicable when the sample contains more than 4% amosite, with individual deviations of less than 5% of the amosite content throughout the 15 to 100% range
• The authors' conclusion: The authors concluded that the method applies to approximately 1-gram portions of material and that samples should contain at least 5% of the asbestos fiber for reliable results
• Limitations the authors state:
  • Other crystalline substances in the dust can overlap the main diffraction peak of the asbestos mineral. The authors stated this is circumvented by using the secondary diffraction line.
  • The nonfibrous (massive) forms, riebeckite for crocidolite and grunerite for amosite, give nearly identical patterns and will interfere if present in significant quantity. The authors considered this not serious in practice because commercial milling separates the fibers.
  • Quartz already present in industrial dust can interfere with the quartz internal standard, which requires a correction

Topics

Medical terms in this study, explained in our Lexicon: X-Ray Diffraction (XRD), Crocidolite, Amosite, Settled Dust.

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