Evaluation by electron microscopy techniques of asbestos contamination in industrial, cosmetic, and pharmaceutical talcs

Our plain-English summary of Evaluation by electron microscopy techniques of asbestos contamination in industrial, cosmetic, and pharmaceutical talcs, by L. Paoletti, S. Caiazza, G. Donelli, et al (Regulatory Toxicology and Pharmacology, 1984).

The study

• Authors: L. Paoletti, S. Caiazza, G. Donelli, F. Pocchiari
• Journal: Regulatory Toxicology and Pharmacology
• Published: 1984;4(3):222-35
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002563).

Abstract

Talc powders from national and international markets were analyzed in order to assess their fiber contents and the proportion of asbestos in the fibrous material. Samples of talc powders used as excipients in pharmaceutical and cosmetic preparations demonstrated fiber contents up to 30% of total particles. About a half of the talc powders revealed the presence of asbestos: in five samples chrysotile (a serpentine asbestos) was present, in the other ones tremolite and anthophyllite (an amphibole asbestos). The amounts of asbestos vary up to 90% in the different samples of the fibrous fraction. About 75% of observed asbestos fibers were thinner than 0.4 micron, i.e., below the resolving power of light microscopy which until now was the most utilized technique for evaluating the environmental pollution due to asbestos.

In plain English

Researchers at Italy's Istituto Superiore di Sanità examined 29 talc powders for industrial, cosmetic and pharmaceutical use. Fifteen came from the Italian market and 14 were supplied by the European Pharmacopoeia. They identified fibers and asbestos with electron microscopy, electron diffraction and X-ray microanalysis. Fibrous particles made up 2 to 30% of particles in the powders. Asbestos fibers were found in 8 of the 15 Italian talcs (tremolite in 7, chrysotile in 1). They were also found in 6 of the 14 European Pharmacopoeia talcs (chrysotile in 3, tremolite and anthophyllite in 2, tremolite and chrysotile in 1). In the two tremolite-and-anthophyllite samples, these fibers reached about 20% of all particles. About three-quarters of the asbestos fibers were thinner than about 0.4 micrometres, below the resolving power of phase-contrast light microscopy. The authors noted that failing to detect asbestos in a sample does not show the talc is asbestos free. They concluded that some samples showed very high asbestos contamination, possibly related to risk for people in contact with talc powders. They also concluded that better knowledge and suitable regulations were needed, should the results be confirmed on a vast scale.

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 analysis of talc powder samples by transmission electron microscopy with selected-area electron diffraction and X-ray microanalysis
• Who was studied: 29 talc powder samples for industrial, cosmetic and pharmaceutical uses: 15 from the Italian market and 14 provided by the European Pharmacopoeia from the international market and various geographic areas; analysed at the Istituto Superiore di Sanità, Rome (sampling dates not given)
• Exposure: Asbestos contamination of talc: the fibrous amphiboles tremolite and anthophyllite and the fibrous serpentine chrysotile. Particles counted as fibers if length-to-width ratio was 3 or more and width less than 3 micrometres; fibers longer than 5 micrometres were counted separately
• Main results:
  • Fibrous particles made up from 2 to 30% of particles in all the talc powders analysed
  • Italian market talcs: asbestos fibers found in 8 of 15 samples, tremolite in 7 and chrysotile in 1
  • European Pharmacopoeia talcs: asbestos fibers found in 6 of 14 samples. Three had chrysotile, 2 had tremolite and anthophyllite, and 1 had tremolite and chrysotile
  • In the 2 European Pharmacopoeia samples with amphibole asbestos, tremolite and anthophyllite reached about 20% of all particles in each. In Table 10 these samples are listed at 87 plus or minus 1.2 and 92 plus or minus 1.3 percent asbestos among their fibers
  • About three-fourths of the asbestos fibers in each sample had a diameter smaller than about 0.4 micrometres, below the resolving power of phase-contrast microscopy
  • Fibrous talc particles that looked very similar to amphibole fibers were frequently seen in all powders. They were distinguished from amphibole fibers by their electron diffraction patterns
• The authors' conclusion: The authors concluded that some samples showed a very high level of asbestos contamination, possibly related to risk for people in contact with talc powders. In their view this underlines the need for deeper knowledge of talc in use and for suitable regulations, should the results be confirmed on a vast scale.
• Limitations the authors state:
  • Where no asbestos fibers were detected, only an upper limit could be set; the sample cannot be inferred to be asbestos free
  • The method could not give a good estimate of the percentage by weight of other minerals in the talcs
  • Particle clusters and particles smaller than 0.2 micrometres were excluded from counts after early counts proved less reliable
  • The authors framed their call for regulation as conditional on confirmation of the results on a larger scale

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, Chrysotile, Serpentine Group, Tremolite, Anthophyllite, Amphibole Asbestos.

Related studies

• Identification of chlorite and serpentine in cosmetic or pharmaceutical talc — A.M. Blount, A.H. Vassiliou (1983)
• Amphibole content of cosmetic and pharmaceutical talcs — A.M. Blount (1991)
• Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology — B.L. Finley, S.M. Benson, et al. (2017)
• High-resolution imaging of organic pharmaceutical crystals by transmission electron microscopy and scanning moiré fringes — M. S'ari, N. Koniuch, et al. (2020)
• Evaluation of the presence of asbestos in cosmetic talcum products — J.S. Pierce, A.S. Riordan, et al. (2017)
• Cosmetic talc and ovarian cancer — D.L. Longo, R.C. Young (1979)

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