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

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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.

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Figure 1: Below what size do nanoparticles show properties not seen in larger particles with the same chemical composition?
Figure 2: Size dependence of various physical properties of nanoparticles.
Figure 3: Size dependence of the mechanisms of arsenic adsorption at the surface of iron oxide particles.
Figure 4: Toxicity of silver nanoparticles.
Figure 5: A number of physicochemical mechanisms can occur at the surface of an inorganic nanoparticle.


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This material is based on work supported by the US National Science Foundation (NSF) and Environmental Protection Agency (EPA) under an NSF Cooperative Agreement (EF-0830093, Center for Environmental Implications of NanoTechnology). The French Atomic Energy Commission (CEA) and National Center for Scientific Research (CNRS) are acknowledged for their support and funding of the international Consortium for the Environmental Implications of Nanotechnology. This work has also been funded by the French National Program ANR and ACI-FNS ECCO supported by the French National Institute for Earth Sciences and Astronomy.

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Correspondence to Mark R. Wiesner.

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Auffan, M., Rose, J., Bottero, J. et al. Towards a definition of inorganic nanoparticles from an environmental, health and safety perspective. Nature Nanotech 4, 634–641 (2009) doi:10.1038/nnano.2009.242

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