The European Commission defines what a "nanomaterial" is

On 18 October, the European Commission recommended a definition that is to be used for all regulatory purposes.

The wording describes a nanomaterial as "a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm – 100 nm."

- We have come up with a solid definition based on scientific input and a broad consultation. Industry needs a clear coherent regulatory framework in this important economic sector, and consumers deserve accurate information about these substances. It is an important step towards addressing any possible risks for the environment and human health, while ensuring that this new technology can live up to its potential, says European Environment Commissioner Janez Potočnik.

The definition is based on scientific advice from the Scientific Committee on Emerging and Newly Identified Health Risks and the Joint Research Centre (JRC).

Commission recommendation on the definition of nanomaterial