Asbestos in talc

Our plain-English summary of Asbestos in talc, by A.N. Rohl (Environmental Health Perspectives, 1974).

The study

• Author: A.N. Rohl
• Journal: Environmental Health Perspectives
• Published: 1974;9:129-32
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001284).

Abstract

Talc deposits include asbestos minerals such as chrysotile and amphiboles that may be carried over into consumer products. Optical microscopy and x-ray diffraction analyses may not reveal their presence. Examples are given of electron microscopy procedures that permit detection and measurement.

In plain English

This short laboratory methods paper, by one author at the Mount Sinai School of Medicine, examined how well standard techniques detect asbestos minerals in talc. The author explained that talc deposits can contain chrysotile, tremolite and anthophyllite, which may carry over into consumer products. The author mixed a talc screened as free of asbestos with known amounts of pure chrysotile, tremolite or anthophyllite and analyzed the mixtures by x-ray diffraction. With the more sensitive step-scanning mode, the lowest detectable concentrations were 0.25% for chrysotile, 0.10% for tremolite and 2.0% for anthophyllite. With ordinary continuous scanning they were 1.0%, 2.0% and 4.0%. Electron microscope counts of chrysotile fibers showed fairly good correlation with chrysotile concentration. From these counts the author calculated about 40 x 10^8 fibers per milligram at 1% chrysotile, and about 10^9 fibers per milligram at 0.25%, the x-ray detection limit. The author concluded that very large numbers of asbestos fibers may go undetected in talc products if only optical microscopy and x-ray diffraction are used, and that electron microscopy can be very sensitive.

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 methods study comparing detection limits of x-ray diffraction (step scanning versus continuous scanning) and electron microscope fiber counting for asbestos minerals deliberately mixed into talc
• Who was studied: No people were studied. Laboratory samples were used: a talc selected as free of asbestos (small amounts of chlorite and phlogopite mica tolerated), mixed with screened pure samples of anthophyllite, tremolite and chrysotile
• Exposure: Known dilutions of chrysotile, tremolite and anthophyllite in talc, prepared at varying concentrations
• Main results:
  • Step-scanning x-ray diffraction: chrysotile was not detected at dilution levels below 0.25%
  • Step-scanning x-ray diffraction: tremolite was detected down to about 0.1% (0.10% in Table 1)
  • Table 1 detection limits for chrysotile: 0.25% by step scanning and 1.0% by continuous scanning
  • Table 1 detection limits for tremolite: 0.10% by step scanning and 2.0% by continuous scanning
  • Table 1 detection limits for anthophyllite: 2.0% by step scanning and 4.0% by continuous scanning
  • Electron microscope counts of chrysotile fibrils showed fairly good correlation with chrysotile dilution levels
  • Calculated from fiber counts: about 40 x 10^8 chrysotile fibers per milligram at a 1% dilution level
  • Calculated: about 10^9 chrysotile fibers per milligram at 0.25%, the lowest level detectable by x-ray diffraction
  • The author estimated that a cosmetic talcum powder in which step scanning found no chrysotile might contain billions of fibers released during dusting with a half-gram dose
• The authors' conclusion: The author concluded that very large numbers of asbestos fibers may be present in talc end products yet remain undetected if only optical microscopy and x-ray diffraction are used, while electron microscopy can be a very sensitive method for detecting minute amounts of asbestos in talc

Topics

The National Library of Medicine indexes this study under subjects our site covers: Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Talc, Asbestos, Chrysotile, Amphibole Group, X-Ray Diffraction (XRD).

Related studies

• Identification and quantitation of asbestos in talc — A.N. Rohl, A.M. Langer (1974)
• Mineralogical features associated with cytotoxic and proliferative effects of fibrous talc and asbestos on rodent tracheal epithelial and pleural mesothelial cells — A.G. Wylie, H.C. Skinner, et al. (1997)
• Characterization of talc and associated minerals — D.H. Hamer, F.R. Rolle, et al. (1976)
• Evaluation by electron microscopy techniques of asbestos contamination in industrial, cosmetic, and pharmaceutical talcs — L. Paoletti, S. Caiazza, et al. (1984)
• Asbestos in commercial indian talc — S. Fitzgerald, E. Harty, et al. (2019)
• Talc dust pneumoconiosis — A. Berner, B. Gylseth, et al. (1981)

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