Are carbon nanotubes the `new asbestos`?


Source: European Commission, Environment DG

The demand for carbon nanotubes is increasing because they have unusual properties, such as unique electrical properties. However, their needle-like shape is similar to asbestos, raising questions about their safety. A recent study conducted on mice indicates that a specific type of carbon nanotube does have asbestos-like effects, but further research is needed to assess whether this is also the case for humans. Carbon nanotubes (CNT) are cylindrical carbon molecules, typically a few nanometres in diameter (1 nanometre = 1 millionth of a millimetre). They are very strong, conduct heat efficiently and have unique electrical properties that make them potentially useful in many fields such as optics, electronics and architecture. The demand for CNT is therefore expected to grow. However, there are concerns about their potential health hazards due to their superficial resemblance to asbestos. Exposure to asbestos causes a specific type of cancer called mesothelioma and there are concerns that CNT may also cause this cancer.

The research exposed mice to different types of asbestos, carbon nanoparticles and multi-walled carbon nanotubes (MWNT). MWNT consist of many nanotubes stacked inside each other. The mice were exposed to the substances in the lining of their abdominal cavity which is similar to the lining of the human chest cavity which is affected by asbestos and where mesothelioma normally arises. Indicators of the harmful effects usually caused by asbestos were monitored, such as inflammation and the production of scar-like structures or lesions.

The results revealed that only long multi-walled carbon nanotubes show asbestos-like behaviour. However, the authors point out that their test was specific for fibres and that nanocarbon in the form of particles could be harmful in ways that are not addressed in this study. This flags up the importance of choosing the correct method of evaluating toxicity.

The authors also point out some limitations in their study. Although the results do suggest a link between long CNT and the cancer caused by asbestos, it remains unknown whether there will be sufficient exposure in the environment or workplace to actually cause it. This indicates that there needs to be more in-depth research into exposure levels of long CNT before their use becomes more widespread.

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