Carbon nanotubes (CNTs) have been shown to be carcinogenic. They induce lung cancer by penetrating the lung cells which induces inflammation. They are also persistent and there is evidence of them being toxic to reproduction.
Function and use
There are different types of CNTs depending on the number of side-walls and the atomic structure in these side-walls. The simplest CNTs are single-walled (SW), double-walled (DW) and multi-walled (MW) CNT. Due to technical challenges, commercial CNTs are rarely fully purified and therefore consist of a high abundance of carbon and some inorganic catalyst impurities. The actual purity of the CNTs depends on the manufacturing procedure and type of potential refinement of the products.
Often CNTs are produced or refined to possess specific properties such as high electrical conductivity, optical transmission, or extremely high tensile strength.
Areas of application
The properties of CNTs open up for a wide range of potential applications, including sporting goods, batteries and accumulators; electronics, sensors, optics, metal articles, laboratory chemicals; polymer composites, chemical process intermediates; rubber products and fine chemical manufacturing.
There are no restrictions of CNTs, but exposure limit values for workers have been proposed in different parts of the world.
One example where safety concerns have led to the development of a non-nanotube alternative is for the superblack color system Vantablack, where the new generations VBx1 and 2 are made without carbon nanotubes.
Alternatives to CNTs have been proposed for specific applications, the main reason being to save costs. Examples are nanocarbon and polymer nanotubes. The safety of these alternatives remain to be investigated.