Since the discovery of carbon nanotubes (CNTs) in 1991, this group of carbon molecules has been considered as a wonder material due to some interesting properties. They are stronger than steel but very light in weight. Depending on the production method, the nanotubes can be conducting in nature, semi-conducting or even isolating, which makes this material very interesting for the electronic industry. But up to now production volumes of carbon nanotubes are still very low.

How can I come into contact with this material?

Since carbon nanotubes are produced in very low amounts and since their application is limited, the chance of direct contact of humans with these nanotubes is low. Carbon nanotubes are used in some composite materials or electronic components. Since there is no release of nanotubes from these products under normal circumstances there exists only a small chance of getting into contact with once the products are disposed of at the end of the products' life cycle.

Is there any risk from this material to humans and the environment?

Due to their long and fibre-like structure carbon nanotubes may elicit fibre-like (adverse) biological effects in the lung which is why they have been thoroughly investigated from the beginning. A general principle is that fibre-like materials can cause lung problems if the fibres are longer than 15-20 micrometres (one fourth to one third of a diameter of a human hair). Fibres with such length are well-known to cause adverse effects in the lung inducing lung inflammation and lung tumours (asbestosis-like disease). This principle also applies to carbon nanotubes with a similar length and rigidity. The clearance mechanisms of the lung can't cope with such long and stiff materials causing a permanent inflammation of the affected tissue(s) which may then lead to tumour formation after a prolonged period of time (20 to 30 years).

Conclusion

Due to the low production volume of carbon nanotubes there is unlikely to be significant negative influences for humans and the environment. The situation may change however if the worldwide production volumes increase significantly due to new applications and new products containing carbon nanotubes.

By the way...

• In 2013 the Bayer Group closed its production site for carbon nanotubes due to economic reasons.