Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 1: Identification and characterization

Our plain-English summary of Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 1: Identification and characterization, by C. Groppo, M. Tomatis, F. Turci, et al (Journal of Toxicology and Environmental Health. Part a, 2005).

The study

• Authors: C. Groppo, M. Tomatis, F. Turci, E. Gazzano, D. Ghigo, R. Compagnoni, B. Fubini
• Journal: Journal of Toxicology and Environmental Health. Part a
• Published: 2005;68(1):1-19
• Cited by: 49 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In the Italian western Alps, asbestos mineralization (both chrysotile and tremolite amphibole) takes place from serpentinites, together with other less common asbestiform minerals not regulated by the current legislation. In the context of a study on the evaluation of the asbestos risk in this area, the possible role played by the associated asbestiform minerals in the overall toxicity of the airborne fraction has been examined. The first mineral investigated was balangeroite [(Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)36], an iron-rich asbestiform contaminant of chrysotile from the Balangero mine (Piedmont), which crystallizes as rigid and brittle fibers. In order to prepare a sample in a form appropriate for chemical and cellular tests, the fibers were separated from the rock and comminuted without damage to their crystalline structure and surface state (as confirmed by X-ray diffraction [XRD] and ultraviolet-visible [UV-Vis] spectroscopy). The first properties examined were durability in simulated body fluids (Gamble's solution) and toxicity to epithelial cells. When compared to UICC crocidolite (the amphibole blue asbestos, regarded as the most pathogenic form), balangeroite appears even more durable than crocidolite. Balangeroite and UICC crocidolite showed a similar in vitro cytotoxic effect on a human epithelial cell line, as evidenced by leakage of intracellular lactate dehydrogenase (LDH) activity, which, observed after a 24-h incubation, was dose dependent and maximal at 12 microg/cm2 for each fiber type. Data show that chemical composition, form, durability, and cell toxicity indicate balangeroite as a potentially harmful fibrous mineral that needs to be examined by further chemical and cellular tests.

In plain English

This laboratory study examined balangeroite, an iron-rich fibrous mineral found as a contaminant of chrysotile at the Balangero mine in Piedmont, Italy, and not regulated as asbestos. The authors separated balangeroite fibers from a rock sample, characterized them, and ground them for testing. The sample was mostly balangeroite with some chrysotile, and grinding did not appear to change its crystal structure. In a simulated body fluid (Gamble's solution), balangeroite released less silicon and iron than UICC crocidolite, a standard blue asbestos sample used for comparison. At 63 days, crocidolite had released about sevenfold more iron. The authors took this to mean balangeroite was more durable under these test conditions. In human lung epithelial cells (A549) exposed for 24 hours, both fibers caused similar cell damage, measured as leakage of the enzyme LDH. The damage rose with dose and peaked at 12 µg/cm2. The authors concluded that balangeroite is a good candidate for modulating, and likely enhancing, the toxicity of the associated chrysotile. They noted that the fluid test does not mimic processes in the body and that too little material existed for animal tests.

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 study: mineralogical characterization of natural fibers, a cell-free durability test in simulated body fluid, and an in vitro cytotoxicity test on cultured human cells (no animal or human data)
• Who was studied: Balangeroite fiber bundles taken from a rock sample from the northern part of the Balangero mine (Piedmont, Italy); human lung epithelial cells (A549 line) for the cell tests; UICC crocidolite as the comparison (positive control)
• Exposure: Ground balangeroite fibers (with minor chrysotile) compared with UICC crocidolite. Durability was tested at 1 mg/ml in Gamble's solution for 63 days. Cytotoxicity was tested over 24 hours at 0.24 to 24 µg/cm2.
• Main results:
  • In simulated body fluid, balangeroite released less silicon and iron than crocidolite, which the authors interpreted as higher durability in these experimental conditions
  • At 63 days, iron released from crocidolite was about sevenfold higher than from balangeroite
  • Silicon released from balangeroite levelled off at almost half the amount released by crocidolite
  • In A549 human lung epithelial cells, balangeroite and crocidolite caused similar cell damage (LDH leakage) after 24 hours. The damage was dose dependent and maximal at 12 µg/cm2 for each fiber type.
  • Balangeroite surface area was 16 m2/g, compared with 8 m2/g for UICC crocidolite and 27 m2/g for UICC chrysotile A
  • The tested sample was mainly balangeroite with some chrysotile present
• The authors' conclusion: The authors concluded that balangeroite is a good candidate for modulating, and likely enhancing, the toxicity of the chrysotile it accompanies
• Limitations the authors state:
  • The simulated body fluid test does not mimic processes occurring in the body
  • Biopersistence cannot be fully measured without animal testing
  • Too little material was available for animal tests, so toxicity estimates rely on in vitro data
  • Pure balangeroite could not be obtained; traces of chrysotile remain because the two minerals are intergrown

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.

Medical terms in this study, explained in our Lexicon: Asbestiform, Balangeroite, Chrysotile, Tremolite, Amphibole Group, Serpentinite, Balangero Mine, Crystalline.

Related studies

• 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)
• Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 3: Depletion of antioxidant defenses — E. Gazzano, C. Riganti, et al. (2005)
• 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)
• Role of associated mineral fibres in chrysotile asbestos health effects: the case of balangeroite — F. Turci, M. Tomatis, et al. (2009)
• The ability of mineral dusts and fibres to initiate lipid peroxidation. Part I: parameters which determine this ability — M. Gulumian (1999)
• Asbestiform minerals in ophiolitic rocks of Calabria (southern Italy) — A. Campopiano, A. Olori, et al. (2018)

Browse more research in Journal of Toxicology and Environmental Health. Part a, or return to medical research.