Access

Review

Nature Nanotechnology 4, 634–641 (1 October 2009) | doi:10.1038/nnano.2009.242

Towards a definition of inorganic nanoparticles from an environmental, health and safety perspective

M|[eacute]|lanie Auffan , J|[eacute]|r|[ocirc]|me Rose , Jean-Yves Bottero , Gregory V. Lowry , Jean-Pierre Jolivet & Mark R. Wiesner

The regulation of engineered nanoparticles requires a widely agreed definition of such particles. Nanoparticles are routinely defined as particles with sizes between about 1 and 100 nm that show properties that are not found in bulk samples of the same material. Here we argue that evidence for novel size-dependent properties alone, rather than particle size, should be the primary criterion in any definition of nanoparticles when making decisions about their regulation for environmental, health and safety reasons. We review the size-dependent properties of a variety of inorganic nanoparticles and find that particles larger than about 30 nm do not in general show properties that would require regulatory scrutiny beyond that required for their bulk counterparts.