Carbon nanotubes (CNTs) consist exclusively of carbon, an element present in all living beings and the air. This fact complicates the detection of the CNTs in the environment. There is currently no information on the actual existing amounts of carbon nanotubes in the environment and their distribution in the individual compartments (e.g. water, soil.

 

An important point for the assessment of potential hazards of nanomaterials for organisms is the determination of actually occurring or expected environmental concentrations. For example, if toxic effects occur only at very high concentrations, which will never occur in the environment, then adverse effects are unlikely, and hence there is no risk for the environment.

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Due to the lack of experimental data, researchers simulate the distribution of nanomaterials in the environment with the help of special computer programs in order to predict or to calculate expected environmental concentrations (PEC value). As a starting point for this calculation, the production volumes of carbon nanotubes are used. Since carbon nanotubes are mainly used as composites, only a very small portion passes directly into air or water. The majority is disposed either in landfills or incinerators. Comparing the calculated environmental concentrations with the dangerous levels obtained in laboratory toxicity tests, it appears at present that carbon nanotubes pose no risks to environmental organisms [1,2].

 

Carbon nanotubes are also used for applications such as batteries or textiles. Results of computer simulations for these case products have shown that the CNTs will be released with high probability not only during production, but also during use and disposal [3]. For example, in case of incomplete burning of discarded CNT-containing products low levels of the carbon nanotubes may enter in the environment. When comparing the potentially achievable environmental concentrations of carbon nanotubes with those of other carbon-based materials such as carbon black, then the quantities calculated for the CNTs are considered to be very low [4].

 

However, these calculated values need to be confirmed in the future by actual measurements or adapted to increasing production volumes. First methodological approaches for the direct detection of carbon nanotube in the environment have been developed [5].

 

Literature arrow down

  1. Gottschalk, F et al. (2009), Environ Sci Technol, 43(24): 9216-9222.
  2. Mueller, NC et al. (2008), Environ Sci Technol, 42(12): 4447-4453.
  3. Koehler, AR et al. (2008), J Cleaner Prod, 16(8-9): 927-937.
  4. Koelmans, AA et al. (2009), Environ Pollut, 157(4): 1110–1116.
  5. Sobek, A. (2009), Environ Pollut, 157(4): 1065-1071.

 

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