Review on the adverse health effects of asbestiform antigorite, a non-regulated asbestiform serpentine mineral

Our plain-English summary of Review on the adverse health effects of asbestiform antigorite, a non-regulated asbestiform serpentine mineral, by X. Baur (American Journal of Industrial Medicine, 2018).

The study

• Author: X. Baur
• Journal: American Journal of Industrial Medicine
• Published: 2018;61(7):625-630
• Type of article: Review
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Although antigorite is generally described as platy, its fibrous (asbestiform) variant is present widespread in serpentinite rocks. In addition to its primarily fibrous occurrence, asbestiform antigorite may also be formed from serpentinite with massive appearance during tunneling and mining. It is not of commercial interest, but exposure may occur in the certain environments.

Methods And Results: Detailed studies of the structural features of this antigorite type revealed characteristics closely related to those of chrysotile. Therefore, it is plausible that this serpentine mineral may present a similar health risk for exposed subjects. This is in agreement with results from clinical and animal studies, as well as in vitro experiments showing the cytotoxic, fibrogenic, and carcinogenic potential of antigorite, similar to that of chrysotile and amphibole asbestos.

Conclusions: Current evidence supports a need for an update to existing regulations to include unregulated asbestiform antigorite, similar to regulatory measures taken for asbestos.

© 2018 Wiley Periodicals, Inc.

In plain English

This article is a single-author review of research on the health effects of asbestiform (fibrous) antigorite, a serpentine mineral not regulated as asbestos. The author searched PubMed and Embase, found 16 relevant articles, and added literature from the author's own collection, covering human, animal and laboratory studies. The review notes that fibrous antigorite has the same ideal chemical formula as chrysotile and cannot be definitively told apart from it by standard scanning electron microscopy with energy- or wavelength-dispersive spectroscopy. The studies it summarizes include a report from New Caledonia linking roads paved with antigoritic serpentinite to lung cancer and mesothelioma risk. They also include a Polish report of asbestosis in 25 workers processing nickel ore contaminated with fibrous antigorite, and rat experiments in which antigorite was injected into the abdominal cavity: 80% of the animals developed tumours and 77% developed mesothelioma. The author noted that information on antigorite's health effects is limited. In Turkish and Greek studies of mixed dusts, the role of each dust component was unclear. The author concluded that asbestiform antigorite should be regulated like commercial asbestos.

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: Systematic literature review with a qualitative summary of published human, animal and in vitro studies (published as a brief report)
• Who was studied: Published literature: PubMed and Embase searches returned 17 and 19 articles, of which 16 in total were judged relevant. These were supplemented by the author's own literature collection, agency databases and reference checking. The search was limited to English-language articles or English abstracts.
• Exposure: Asbestiform (fibrous) antigorite, a serpentine mineral with the same ideal chemical formula as chrysotile. It is found in serpentinite rocks and can also be formed from massive serpentinite during tunneling and mining.
• Main results:
  • The review reports that fibrous antigorite cannot be definitively distinguished from chrysotile using standard scanning electron microscopy with energy- or wavelength-dispersive spectroscopy.
  • In an Austrian tunnel (Kirchdorf, S35), asbestiform fibers in the tunnel air were first interpreted as chrysotile. Further studies cited by the review showed that asbestiform antigorite, produced by mechanical breakdown of massive antigoritic rock during tunneling, was the main source of the fibers.
  • A New Caledonia report (Baumann) cited by the review found that antigoritic serpentinite used for road construction resulted in high environmental exposure and health risk near such roads. The figures given are OR 495 (95% CI 46.2-4,679.7) and multivariate IRR 13 (95% CI 10.2-16.6). The review does not state the exact outcome or comparison group for these figures.
  • A Polish report (Wozniak et al) cited by the review diagnosed asbestosis in 25 workers of a company processing nickel ore contaminated with fibrous antigorite. The total number of workers examined is not given.
  • In rat studies cited by the review, antigorite extracted from nickel ore was injected intraperitoneally. 80% of the animals developed tumours, and mesothelioma developed in 77%. Crocidolite gave comparable results, while chrysotile produced tumours considerably less often.
  • By contrast, a cited study found that non-fibrous antigorite injected intraperitoneally in rats did not cause peritoneal mesothelioma.
  • In a cited cell study (Cardile et al), mesothelial and macrophage cell lines were exposed to fibrous antigorite at 5-100 μg/mL for 72 hours. This produced dose-dependent cell toxicity and the production of reactive oxygen species.
• The authors' conclusion: The author concluded that asbestiform antigorite should be subject to the same regulations and preventive measures as commercial asbestos types.
• Limitations the authors state:
  • The author states that information on the health effects of asbestiform antigorite is limited so far.
  • In the Turkish and Greek studies, antigorite occurred together with tremolite and chrysotile or lizardite, so the causal role of each dust component is not clear.
  • The literature search was limited to English-language articles and English abstracts of articles in other languages.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Chrysotile, Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Asbestiform, Antigorite, Serpentine Group, Serpentinite, Chrysotile, Fibrogenic, Carcinogenic, Amphibole Asbestos.

Related studies

• Role of associated mineral fibres in chrysotile asbestos health effects: the case of balangeroite — F. Turci, M. Tomatis, et al. (2009)
• Adverse health effects of asbestos: solving mysteries regarding asbestos carcinogenicity based on follow-up survey of a Chinese factory — E. Yano (2018)
• Reaction mechanism for the aqueous-phase mineral carbonation of heat-activated serpentine at low temperatures and pressures in flue gas conditions — L.C. Pasquier, G. Mercier, et al. (2014)
• Airborne concentrations of chrysotile asbestos in serpentine quarries and stone processing facilities in Valmalenco, Italy — A. Cattaneo, A. Somigliana, et al. (2012)
• Mortality patterns among hard rock gold miners exposed to an asbestiform mineral — J.D. Gillam, J.M. Dement, et al. (1976)
• Exposure to asbestiform minerals and radiographic chest abnormalities in a talc mining region of upstate New York — E.F. Fitzgerald, A.D. Stark, et al. (1991)

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