Nanotoxicology: the asbestos analogy revisited

Our plain-English summary of Nanotoxicology: the asbestos analogy revisited, by A.B. Kane, R.H. Hurt (Nature Nanotechnology, 2008).

The study

• Authors: A.B. Kane, R.H. Hurt
• Journal: Nature Nanotechnology
• Published: 2008;3(7):378-9
• Cited by: 53 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this News & Views commentary, the authors discussed two recent mouse studies on whether carbon nanotubes might behave like asbestos and cause mesothelioma. In the first, by Donaldson and co-workers, long multiwalled carbon nanotubes (MWNTs) injected into the abdominal cavity of mice induced inflammation, granulomas and early fibrosis of the mesothelial lining. These lesions resembled those caused by long amosite fibres. Shorter nanotubes and carbon black had much less effect, and the seven-day exposure did not induce mesothelioma. In the second, by Kanno and colleagues, MWNTs injected into the abdominal cavity of p53+/– mice produced tumours in 88% of treated mice after 25 weeks, compared with 79% for crocidolite. C60 fullerene produced no mesotheliomas. The authors described the proposed mechanism: fibres longer than 10–20 μm cannot be fully engulfed by macrophages, which leads to frustrated phagocytosis, free radical release, persistent inflammation and DNA damage. They concluded that the studies provided evidence for an asbestos-like response in certain cases. However, they judged it premature to declare nanotubes a major mesothelioma risk factor in humans. Their reasons were uncertainty about whether inhaled nanotubes reach the mesothelium, the influence of aggregation state, the need to confirm the tumour diagnoses in the genetically engineered mice, limited biopersistence data, and difficulty extrapolating to other nanotube types. They suggested that identifying toxic features such as fibre length could guide safer nanotube design.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This article was a short commentary (a News & Views piece) by two authors at Brown University. It was not an original study. It discussed whether carbon nanotubes might act like asbestos in the body and described two recent mouse studies by other researchers. In one, by Donaldson and co-workers, long multiwalled carbon nanotubes injected into the abdominal cavity of mice caused inflammation, granulomas and early scarring of the mesothelial lining, similar to lesions from long amosite fibres. A seven-day exposure did not cause mesothelioma. In the other, by Kanno and colleagues, tumours were found in 88% of nanotube-treated genetically engineered mice after 25 weeks, compared with 79% of mice injected with crocidolite. The authors wrote that these studies gave evidence of an asbestos-like response to nanotubes, at least in certain cases. They also wrote that it would be premature to call carbon nanotubes a major risk factor for mesothelioma in humans. Their reasons included uncertainty about whether inhaled nanotubes reach the mesothelial lining, the need to confirm that the mouse tumours were mesotheliomas, and too little data on long-term biopersistence.

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: Commentary (News & Views) discussing two recently published animal studies by other research groups; not original research
• Who was studied: No population of its own. The two studies discussed used mice: ordinary mice in the Donaldson study, and p53+/– heterozygous genetically engineered mice in the Kanno study
• Exposure: In the studies discussed, multiwalled carbon nanotubes (long and shorter) were injected into the abdominal cavity of mice. Comparison materials were carbon black nanoparticles, amosite (Donaldson study), crocidolite and C60 fullerene (Kanno study)
• Main results:
  • Donaldson study (as described by the authors): in mice, long multiwalled carbon nanotubes caused inflammation, granulomas and early fibrosis of the mesothelial lining. Shorter nanotubes and carbon black had much less effect
  • Donaldson study: a seven-day exposure did not cause mesothelioma, but the early lesions were similar to those caused by long amosite fibres
  • Kanno study (as described by the authors): tumours in 88% of nanotube-treated mice after 25 weeks, compared with 79% of crocidolite-injected mice
  • Kanno study: the same mass dose of non-fibrous C60 fullerene produced minimal mesothelial reactions and no mesotheliomas
• The authors' conclusion: The authors concluded that the two studies give scientific evidence for an asbestos-like pathologic response to carbon nanotubes, at least in certain cases. They also concluded that it would be premature to declare carbon nanotubes a major risk factor for mesothelioma in humans
• Limitations the authors state:
  • It is unclear whether inhaled nanotubes would reach the mesothelial lining in sufficient numbers; data on nanotubes are scarce
  • The physical form of nanotubes that reaches internal tissues in real human exposure is unknown
  • The genetically engineered mice in the Kanno study are susceptible to foreign-body tumours, so the mesothelioma diagnosis needs confirmation
  • There are insufficient data to establish nanotube biopersistence over long time periods
  • The findings apply to long, unfunctionalized multiwalled nanotubes and are difficult to extrapolate to other nanotube types

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Inflammation, Granuloma, Fibrosis, Amosite, Crocidolite, Macrophage, Frustrated Phagocytosis.

Related studies

• Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study — C.A. Poland, R. Duffin, et al. (2008)
• The asbestos-carbon nanotube analogy: An update — A.B. Kane, R.H. Hurt, et al. (2018)
• Cell entry of one-dimensional nanomaterials occurs by tip recognition and rotation — X. Shi, A. von dem Bussche, et al. (2011)
• Induction of mesothelioma in p53+/- mouse by intraperitoneal application of multi-wall carbon nanotube — A. Takagi, A. Hirose, et al. (2008)
• Asbestos-like pathogenicity of long carbon nanotubes alleviated by chemical functionalization — H. Ali-Boucetta, A. Nunes, et al. (2013)
• Factoring-in agglomeration of carbon nanotubes and nanofibers for better prediction of their toxicity versus asbestos — A.R. Murray, E.R. Kisin, et al. (2012)

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