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How nanoparticles are counted in global regulatory nanomaterial definitions

The legal definition of a nanomaterial differs around the world, meaning that the same material may be classified as a nanomaterial, or not, depending on the country where it is classified. The first steps towards converging on an international definition are to recognize the differences between existing nanomaterial definitions and to agree on particle counting methods. Meanwhile, we propose a naming convention that indicates the key criteria of a specific definition of a nanomaterial.

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Fig. 1: Common ways of counting aggregates, agglomerates and their constituent particles.

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Acknowledgements

We thank V. Kestens (JRC Geel) for comments on an earlier version of the paper. The content expressed in this paper is solely the opinion of the authors and does not necessarily reflect the opinion of the European Commission.

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Correspondence to Kirsten Rasmussen.

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Rasmussen, K., Riego Sintes, J. & Rauscher, H. How nanoparticles are counted in global regulatory nanomaterial definitions. Nat. Nanotechnol. 19, 132–138 (2024). https://doi.org/10.1038/s41565-023-01578-x

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