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Priority Setting

Appendix I: Examples of Classification Schemes in Literature

Classification of nanomaterials by their containing matrix

The US Army is developing a classification scheme to take into account the behaviour of the nanomaterial in products. They have suggested the following classes: freely dispersed particles, particles in viscous media, particles in diffuse coatings, durable coatings and composites, and nanostructured products. This classification scheme is meant to provide data to regulators on army-specific products along with providing improved criteria to determine potential EHS risks associated with nanomaterials. The reader is invited to contact Jeffery Steevens ( for more information on this project. 

The US National Institute of Occupation Safety and Handling (NIOSH) has suggested grouping of nanomaterials by physical state to improve safe handling and reduce worker exposure[1].  The suggested classes are: (a) bound of fixed nanostructures (polymer matrix); (b) liquid suspension, liquid dispersion; (c) dry dispersible nanomaterials and agglomerates; and (d) nanoaerosols and gas phase synthesis (on substrate).

Similar to the NIOSH approach, Hallock and colleagues[2] have suggested classifying nanomaterials by product matrix: pure nanomaterials, items contaminated with nanomaterials, liquid suspensions, and solid matrices to ensure safe disposal. In the work by Foss Hansen and colleagues[3], the team suggests a classification approach based on the location of the nanomaterial on the product, i.e., as part of a bulk substance (e.g., nanoelectronics), on the surface (e.g., films), or as particles (e.g., liquid suspensions) thereby allowing one to distinguish which nanoparticles are expected to cause exposure, which may cause exposure, and are not expected to cause exposure to the consumer.


[1] US NIOSH “General Safe Practices for Working with Engineered Nanomaterials in Research Laboratories” DHHS (NIOSH) Publication No. 2012-147. Available at

[2] Hallock, M.; Greenley, M.; DiBerardinis.; Kalin, D.Jo. Chem. Health & Safety, 2009, 16, 16-23.

[3] Hansen, S. F.; Michelson, E.; Kamper, A.; Borling, P.; Stuer-Lauridsen, F.; Baun, A. Ecotoxicology, 2008, 17, 438-447.

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