Role of associated mineral fibres in chrysotile asbestos health effects: the case of balangeroite

Our plain-English summary of Role of associated mineral fibres in chrysotile asbestos health effects: the case of balangeroite, by F. Turci, M. Tomatis, R. Compagnoni, et al (The Annals of Occupational Hygiene, 2009).

The study

• Authors: F. Turci, M. Tomatis, R. Compagnoni, B. Fubini
• Journal: The Annals of Occupational Hygiene
• Published: 2009;53(5):491-7
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: To evaluate the biodurability of balangeroite, present as contaminant of chrysotile asbestos in the Balangero mine, in order to have indication whether it might have been a confounding factor in the association of the mesothelioma cases reported among mine workers and employees.

Methods: The modifications taking place following incubation of the fibres in simulated phagolysosomal fluids have been measured on balangeroite, on one pure chrysotile sample (Val Malenco), on one chrysotile from Balangero with some associated balangeroite, and on two tremolite samples.

Results: The incubation modifies both chrysotile and balangeroite with substantial release in the medium of the metal ions which occupy the octahedral site in the mineral structure of the fibre while tremolite is virtually unaffected.

Conclusions: Considering the profound differences between the structure of balangeroite and amphiboles, previous results and observations on the poor ecopersistence of balangeroite, and the present data, we conclude that balangeroite traces may contribute to the overall toxicity of the airborne fibres in Balangero, but may not be compared to tremolite nor considered the sole responsible for the excess of mesothelioma found in Balangero.

In plain English

This was a laboratory study of balangeroite, a fibrous mineral found mixed with chrysotile asbestos at the now-disused Balangero mine in Italy. The authors tested how well it holds up in a fluid made to imitate the acidic conditions inside cells that engulf inhaled fibres. Their aim was to see whether balangeroite might have been a confounding factor in mesothelioma cases reported among the mine's workers. Five samples were tested: balangeroite, a commercial Balangero chrysotile containing some balangeroite, a pure chrysotile from Val Malenco, and two tremolite samples. Each was kept in the fluid at pH 4.5 for 30 days. Both tremolite samples were extremely stable and released only traces of silicon and magnesium. The chrysotile samples lost 16% (Balangero) and 10% (Val Malenco) of their magnesium and 4% of their silicon. Balangeroite released 4% of both elements in nearly equal amounts. Iron release could not be measured. The authors concluded that balangeroite may contribute to the overall toxicity of the airborne fibres at Balangero. In their view it cannot be compared to tremolite, nor considered solely responsible for the excess of mesothelioma there. They noted that test-tube data only predict a potential hazard.

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 (in vitro) dissolution experiment: mineral fibres incubated in a simulated phagolysosomal fluid (a fluid imitating conditions inside cells that engulf particles) at pH 4.5 for 30 days at 37 degrees C; all incubations were done twice
• Who was studied: No people were studied. Five mineral samples from the Italian Western and Central Alps were tested: a commercial chrysotile from the Balangero mine containing some balangeroite; a balangeroite field sample from Balangero; a tremolite from Jovenceaux-Oulx (Susa valley); an iron-rich tremolite from Lanzo Valley; and a pure chrysotile from Val Malenco
• Exposure: Chrysotile, balangeroite and tremolite fibres were each placed in the simulated fluid at 3 mg per ml and kept unstirred, in the dark, for 30 days at 37 degrees C. The magnesium and silicon dissolved into the fluid were then measured.
• Main results:
  • Both tremolite samples were extremely stable and released only traces of silicon and magnesium (less than 0.5% removed during incubation)
  • Both chrysotile samples lost a large share of their magnesium: 16% of the total magnesium in the commercial Balangero sample and 10% in the Val Malenco sample. Each also lost 4% of its silicon.
  • Balangeroite released substantial amounts of both magnesium and silicon (4% of the total) in nearly equal quantities
  • The authors stated that tremolite did not appear to be attacked by the fluid, while chrysotile and balangeroite were both appreciably modified. In their view this suggests that both have a much lower biopersistence (staying power in the body) than amphiboles.
• The authors' conclusion: The authors concluded that balangeroite traces may contribute to the overall toxicity of the airborne fibres at Balangero. They added that it may not be compared to tremolite, nor considered solely responsible for the excess of mesothelioma found at Balangero.
• Limitations the authors state:
  • The authors stated that in vitro data are only predictive of a potential hazard, and that in vivo tests would be needed to establish a fibre's toxicity
  • The authors stated that the present data may not add much to knowledge of the hazard of exposure to balangeroite
  • Iron release could not be measured, because any iron removed would precipitate out of the fluid. This applies even though balangeroite contains more iron than silicon.

Mines named here

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

• Balangero mine, Balangero, about 20 km north of Turin, Piedmont

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile, Tremolite.

Medical terms in this study, explained in our Lexicon: Chrysotile, Balangeroite, Balangero Mine, Confounding, Mesothelioma, Tremolite, Octahedral Site, Amphibole Group.

Related studies

• Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 1: Identification and characterization — C. Groppo, M. Tomatis, et al. (2005)
• Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 3: Depletion of antioxidant defenses — E. Gazzano, C. Riganti, et al. (2005)
• Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 2: Oxidant activity of the fibers — F. Turci, M. Tomatis, et al. (2005)
• Pulmonary mineral fibers after occupational and environmental exposure to asbestos in the Russian chrysotile industry — A. Tossavainen, E. Kovalevsky, et al. (2000)
• The effect of weathering on ecopersistence, reactivity, and potential toxicity of naturally occurring asbestos and asbestiform minerals — S. Enrico Favero-Longo, F. Turci, et al. (2009)
• Comparison of direct and indirect methods of measuring airborne chrysotile fibre concentration — C. Eypert-Blaison, S. Veissiere, et al. (2010)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.