Legal and practical challenges in classifying nanomaterials according to regulatory definitions

The European Union (EU) has adopted nano-specific provisions for cosmetics, food and biocides, among others, which include binding definitions of the term nanomaterial. Here we take an interdisciplinary approach to analyse the respective definitions from a legal and practical perspective. Our assessment reveals that the definitions contain several ill-defined terms such as insoluble or characteristic properties and/or are missing thresholds....