Nanomaterials or non-nanomaterials?
The European Commission Joint Research Centre (JRC) has contributed to the development of a low cost and highly efficient screening strategy to implement the European Commission's Recommendation for a definition of nanomaterials.
A variety of EU regulations (Cosmetic Products, Novel Foods, Biocidal Products and the proposal for Medical Devices) require information on nanomaterials and an assessment of their safety. Essentially, according to the Commission's recommendation, a nanomaterial is a material containing particles and where more than half of the particles have at least one external dimension in the size range 1 nm – 100 nm.
To find out whether a material actually is a nanomaterial, and whether specific regulatory provisions apply, it is important to measure the size of particles from 1 nm up to several hundred nanometres. This can be costly and time-consuming since it often involves Transmission Electron Microscopy (TEM) and elaborate sample preparation.
It is also possible to identify nanomaterials by determining their volume specific surface area (VSSA). This involves the adsorption of a monolayer of an inert gas on the surface of the particles and can be done by a well-known, low cost and standardised method to be applied to dry powders without further sample preparation.
However, there were many doubts whether the two methods TEM and VSSA always lead to the same classification. Therefore the EU FP7 project NanoDefine, in which the JRC leads the development of a decision-making framework for classification of nanomaterials as well as validation and standardisation activities, evaluated the extent of agreement between the classifications obtained by using EM and VSSA on a large set of diverse particulate substances.
Based on the results obtained on highly characterised benchmark materials, the researchers derived an efficient strategy for distinguishing between nano- and non-nano materials, which has been published in the Journal of Nanoparticle Research. The strategy recommended by the NanoDefine consortium, which relies on the use of VSSA as screening method, is highly resource-efficient and cost-saving, and has been recommended by the JRC for inclusion in a technical guidance for implementation of the nanomaterial definition.
Reference: Wohlleben, W et al. "Reliable nanomaterial classification of powders using the volume-specific surface area method", J. Nanopart. Res. 19 (2017) 61, doi:10.1007/s11051-017-3741-x
Source: EC JRC