On 18 October 2011 the EU Commission adopted the Recommendation on the definition of a nanomaterial. According to this recommendation a “Nanomaterial” means:
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.
In specific cases and where warranted by concerns for the environment, health, safety or competitiveness the number size distribution threshold of 50 % may be replaced by a threshold between 1 and 50 %.
By derogation from the above, fullerenes, graphene flakes and single wall carbon nanotubes with one or more external dimensions below 1 nm should be considered as nanomaterials.
Europe is the first area to make a decision on this definition and guidance from the Scientific Committee (SCHENIR) included an argument, that in its opinion “a low mass concentration of nanoparticles in a product may still represent a high number of particles and a mass based distribution can be skewed by the presence of relatively few large and thus heavy particles“. Therefore it considered number size distribution as a more relevant metric for possible effects of nanoparticles than mass concentration.
This is a move away from other existing regulatory / industry specific metrics, which are based on mass and aerodynamic separation and sampling methods and it will be interesting to see how this decision impacts on these other measurement systems in the future. The dosage metric for inhaled delivery of drug products is one area which comes to mind, breathing / medical air definitions together with ambient environment and vehicle exhaust monitoring.
It is still very early days in ‘nano material’ safety. We continue to investigate the impact of micron sized particles on environmental health and there will be some years of discussion and development of standards and methods. I’m sure that discussion will follow on how we define the size measurement, based on method used, but whatever the method I suspect that it has got to be easier to measure dimensions rather than trying to capture particles in a specific size range < 100nm and then weigh them (and by the way this could be debated with micron sized particles too) ?