Examples of existing definitions

The document outlines nanomaterial definitions from the ISO, OECD, EU, and various US and Canadian agencies, noting that most center on a size range of 1nm to 100nm. It highlights that the European Union uses a specific particle number distribution threshold (50% or more) and a surface area by volume ratio proxy. The briefing concludes that divergent definitions lead to legal uncertainty, where a substance may be regulated as a nanomaterial in one jurisdiction or product category but treated as a bulk substance in another.

• The International Organization for Standardization (ISO) provides a foundational definition of nanomaterial as having external dimensions, internal structure, or surface structure in the nanoscale, which it defines as ranging from approximately 1nm to 100 nm.
• The OECD defines a nanomaterial as a chemical that is either a nano-object (confined in one, two, or three dimensions at the nanoscale) or nano-structured (having internal or surface structure at the nano scale), with the nano-scale typically between 1nm and 100 nm.
• The United States lacks a single regulatory definition; instead, the EPA uses a working definition from the National Nanotechnology Initiative, and the FDA identifies nanomaterials as those with at least one dimension between approximately 1nm and 100nm or those exhibiting related dimension-dependent properties.
• Health Canada's working definition includes materials with at least one external dimension, or internal/surface structure, within the 1 to 100 nanometer range, as well as materials outside this range that exhibit nanoscale properties or phenomena.
• The European Commission's 2011 recommendation defines nanomaterials based on a number size distribution where 50% or more of particles have one or more external dimensions between 1nm and 100nm, though it allows for lower thresholds based on safety or competitiveness concerns.
• The European Union's definition specifically includes fullerenes, graphene flakes, and single wall carbon nanotubes with dimensions below 1 nm, and allows a specific surface area by volume ratio of 60m2/cm3 to be used as a proxy to establish a material as a nanomaterial.
• Inconsistent definitions across jurisdictions create legal uncertainty and regulatory gaps, potentially resulting in a substance being regulated as a nanomaterial in the EU but as a bulk material in the US, or being treated differently depending on whether it is used in biocides versus cosmetics.

APA

Center for International Environmental Law (n.d.). Examples of existing definitions. https://www.ciel.org/wp-content/uploads/2015/07/Nano_definition_Nov2014.pdf

Chicago

Center for International Environmental Law. Examples of existing definitions. n.d. https://www.ciel.org/wp-content/uploads/2015/07/Nano_definition_Nov2014.pdf.

Wikipedia

{{cite report |author=Center for International Environmental Law |title=Examples of existing definitions |url=https://www.ciel.org/wp-content/uploads/2015/07/Nano_definition_Nov2014.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{centerforinternationalenvironmentallawndexamples, author = {{Center for International Environmental Law}}, title = {{Examples of existing definitions}}, institution = {Center for International Environmental Law}, url = {https://www.ciel.org/wp-content/uploads/2015/07/Nano_definition_Nov2014.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }