Mesothelioma: Do asbestos and carbon nanotubes pose the same health risk?

Our plain-English summary of Mesothelioma: Do asbestos and carbon nanotubes pose the same health risk?, by M.C. Jaurand, A. Renier, J. Daubriac (Particle and Fibre Toxicology, 2009).

The study

• Authors: M.C. Jaurand, A. Renier, J. Daubriac
• Journal: Particle and Fibre Toxicology
• Published: 2009;6:16
• Cited by: 76 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Carbon nanotubes (CNTs), the product of new technology, may be used in a wide range of applications. Because they present similarities to asbestos fibres in terms of their shape and size, it is legitimate to raise the question of their safety for human health. Recent animal and cellular studies suggest that CNTs elicit tissue and cell responses similar to those observed with asbestos fibres, which increases concern about the adverse biological effects of CNTs. While asbestos fibres' mechanisms of action are not fully understood, sufficient results are available to develop hypotheses about the significant factors underlying their damaging effects. This review will summarize the current state of knowledge about the biological effects of CNTs and will discuss to what extent they present similarities to those of asbestos fibres. Finally, the characteristics of asbestos known to be associated with toxicity will be analyzed to address the possible impact of CNTs.

In plain English

This article was a review, not a new study. The authors summarized published animal and cell experiments on carbon nanotubes (CNTs), both single-walled and multi-walled. They compared these with what is known about how asbestos fibres act on mesothelial cells, the cells from which mesothelioma arises. In one reviewed mouse study, only long multi-walled CNTs and long amosite caused inflammation and granulomas after injection into the abdominal cavity. Another reported mesotheliomas in cancer-prone mice, carrying one altered copy of the p53 gene, that were injected with multi-walled CNTs or with crocidolite. That study was criticized for its choice of mice, its dose and its methods. A third study injected CNTs into the scrotum, a method the authors said is not usually used to test fibres. It found mesothelioma in 86% of 7 rats given multi-walled CNTs, and none in rats given only the injection liquid or crocidolite. The authors noted that data on mesothelial cells were limited, that CNT uptake by these cells was unproven, and that CNTs vary widely. They concluded that CNTs may elicit responses similar to those caused by asbestos fibres.

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: Review of published animal and cell studies on carbon nanotubes, compared with knowledge of asbestos fibres' mechanisms of action
• Who was studied: No new subjects. The review covered published experiments in rodents (mice and rats) and in various cultured cell types, including human and rat mesothelial cells.
• Exposure: Single-walled and multi-walled carbon nanotubes of various sources and sizes, compared with asbestos fibres (amosite, crocidolite, chrysotile) as described in the reviewed studies
• Main results:
  • Reviewed study (Poland et al.): C57Bl/6 mice were given intraperitoneal injections of 50 μg of MWCNTs per mouse. Only the long MWCNT samples and the long amosite sample produced inflammation and granulomas.
  • Reviewed study (Takagi et al.): mesotheliomas were found in cancer-prone p53+/- mice after intraperitoneal MWCNTs and after crocidolite, which was used as positive control. The study was criticized over the type of mice, the exposure method, the high dose and other points.
  • Reviewed study (Sakamoto et al.): after a single intrascrotal injection of MWCNTs in 7 Fischer 344 rats observed for 52 weeks, mesothelioma incidence was 86% in MWCNT-treated rats. No mesothelioma was found in the 5 vehicle-treated controls or the 7 crocidolite-treated rats.
  • Reviewed cell study: DNA breakage and DNA repair were found in normal and malignant human mesothelial cells exposed to SWCNTs.
  • The authors reported that uptake of CNTs into cells is controversial in the literature.
  • Some reviewed studies indicated that, unlike asbestos, CNTs quench reactive oxygen species in an acellular system.
• The authors' conclusion: The authors concluded that, based on the literature and on knowledge of how asbestos fibres act, CNTs may elicit responses similar to those caused by asbestos fibres.
• Limitations the authors state:
  • For brevity the review treated CNTs as a single entity, although the CNT family is highly heterogeneous.
  • Data on the effects of CNTs on mesothelial cells remain limited.
  • There is no definitive data on whether mesothelial cells take up CNTs.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma.

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