Evaluation of the genotoxic and transformation potential induced by asbestos compared to cleavage fragments

Our plain-English summary of Evaluation of the genotoxic and transformation potential induced by asbestos compared to cleavage fragments, by S. La Maestra, G.M. Militello, S. Alberti, et al (Scientific Reports, 2025).

The study

• Authors: S. La Maestra, G.M. Militello, S. Alberti, M. Benvenuti, L. Gaggero
• Journal: Scientific Reports
• Published: 2025;15(1):3613
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The World Health Organization has confirmed that asbestos fibres are carcinogenic, claiming that asbestos-related diseases should be eradicated worldwide. Actinolite, amosite, anthophyllite, chrysotile, crocidolite, and tremolite are regulated asbestiform mineral phases. However, in nature, asbestos minerals occur either in a fibrous and asbestiform (original morphology characterized by high length-to-width ratio and provided of high tensile strength and flexibility) or fibrous but not asbestiform appearance. This study used human epithelial cancer cells (A549) and a mouse fibroblast cell line (Balb/c 3T3) to compare the genotoxic and carcinogenic effects of a sample of amphibole asbestos with samples of fibrous not asbestiform named cleavage fragments (CV) obtained by grinding non-asbestiform amphiboles. The results showed that exposure of alveolar lung cells to asbestos and elongated mineral particles, in the habit of cleavage fragments (CF) derived from the grinding of non-asbestiform amphiboles and serpentines, causes cytotoxic effects, oxidative stress and genotoxic damage. Moreover, CF obtained from an actinolite schist induces a transformation effect in the Balb/c 3T3 model. Together, these findings highlight the importance of considering CF as a potential threat to human health since it can cause genotoxic damage by triggering cellular transformation processes that overlap with the mechanisms involved in the carcinogenesis processes of asbestos.

© 2025. The Author(s).

In plain English

This was a laboratory study on cells grown in dishes. The authors compared an amphibole asbestos sample (F3) with cleavage fragments, which are elongated particles made by grinding non-asbestiform minerals from Italian rocks: two actinolite schists (A1, A5), an amphibole vein in serpentinite (A4), and a serpentinised peridotite with a lizardite vein (A3). They exposed human lung cancer cells (A549) and mouse cells (Balb/c 3T3) to these dusts. The concentration that halved colony formation in the mouse cells was 1.90 micrograms per square centimetre for both F3 and A3. It was higher for A1, A4 and A5, at 22.73 to 60.38. All samples raised oxidative stress. DNA damage rose significantly only with A3, A5 and F3, and F3 caused more damage than A5. In a cell transformation test, which looks for early cancer-like changes in lab cells, F3 and A5 produced transformed foci and A3 did not. The authors concluded that ground non-asbestiform amphiboles increased genotoxic damage and transformation potential through mechanisms typical of asbestos. They called for studies in living organisms and a possible reassessment of legislation.

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: In vitro laboratory study (cell culture experiments)
• Who was studied: Human epithelial lung cancer cell line A549 and mouse fibroblast cell line Balb/c 3T3, obtained from a cell bank in Genoa, Italy; no human subjects or animals
• Exposure: One sample recognised as asbestos under current legislation (F3, asbestiform amphibole from an amphibole vein in serpentinite, Ligurian Apennines) compared with cleavage fragments from non-asbestiform amphiboles of the tremolite-actinolite series (A1 and A5, actinolite schists from the Ligurian Alps; A4, amphibole vein in serpentinite from the Ligurian Apennines) and a fibrous lizardite sample (A3, serpentinised peridotite from Piedmont). The samples were ground by hand and micronised. Concentrations in the colony test ranged from 1.90 to 45.70 micrograms per square centimetre.
• Main results:
  • In Balb/c 3T3 cells, the IC50 (the concentration reducing colony formation by 50%) was 1.90 micrograms per square centimetre for both F3 (asbestos) and A3. It was 46.88 for A1, 60.38 for A4 and 22.73 for A5. No-effects doses were 0.40 (F3), 14.20 (A1), 0.40 (A3), 6.61 (A4) and 1.90 (A5).
  • In A549 cells, reactive oxygen species (oxidative stress) increased for all tested samples at 6 hours (P less than 0.01). A549 cells exposed to A5 were more susceptible to redox alterations than cells exposed to the other samples.
  • For the asbestos sample F3, reactive oxygen species kept rising at 24 hours (P less than 0.001).
  • In the Comet test on A549 cells, DNA damage increased significantly only with A3, A5 and F3. A3 caused damage only at its IC50 (P less than 0.001). A5 caused damage at both its no-effects dose (P less than 0.01) and its IC50 (P less than 0.001).
  • The asbestos sample F3 followed the same DNA damage pattern as A5 but at higher damage levels (F3 vs A5, P less than 0.01).
  • Only F3, A3 and A5 were tested in the Balb/c 3T3 transformation assay. F3 produced a transforming effect at 1.9 micrograms per square centimetre (P less than 0.001) and at 3.8 (P less than 0.01).
  • Sample A5 produced a transforming effect at 3.8 micrograms per square centimetre (P less than 0.05), peaking at 7.6 (P less than 0.01).
  • Sample A3 produced no transforming effect at any dose used.
  • All samples had negative zeta-potentials (surface charge). The asbestos sample F3 had the most negative value (minus 30.25 mV) and A4 the least negative (minus 20.37 mV).
• The authors' conclusion: The authors concluded that elongated mineral particles, like asbestos, can trigger cytotoxicity and redox imbalance. They also concluded that particles obtained by grinding prismatic amphiboles significantly increase genotoxic damage and transformation potential, reflecting typical asbestos carcinogenesis mechanisms. They called for in vivo studies and said a reassessment of current legislation would eventually be necessary.
• Limitations the authors state:
  • The study was in vitro only. The authors state that further in vivo studies are needed to better understand the actions of these particles.

Topics

Medical terms in this study, explained in our Lexicon: Cleavage Fragment, Carcinogenic, Actinolite, Amosite, Anthophyllite, Chrysotile, Crocidolite, Tremolite.

Related studies

• An evaluation of the risks of lung cancer and mesothelioma from exposure to amphibole cleavage fragments — J.F. Gamble, G.W. Gibbs (2008)
• The carcinogenicity of WHO fibers of silicon carbide: SiC whiskers compared to cleavage fragments of granular SiC — K. Rödelsperger, B. Brückel (2006)
• Dimensions of elongated mineral particles: a study of more than 570 fibers from more than 90 cases with implications for pathogenicity and classification as asbestiform vs. cleavage fragments — V.L. Roggli, C.L. Green (2019)
• An inter-laboratory study to determine the effectiveness of procedures for discriminating amphibole asbestos fibers from amphibole cleavage fragments in fiber counting by phase-contrast microscopy — M. Harper, E.G. Lee, et al. (2012)
• Comments on "Dimensions of elongated mineral particles with implications for pathogenicity and classification as asbestiform versus cleavage fragments" — M.M. Finkelstein (2019)
• Neoplastic-like transformation effect of single-walled and multi-walled carbon nanotubes compared to asbestos on human lung small airway epithelial cells — L. Wang, T.A. Stueckle, et al. (2014)

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