Major uncertainty still exists on the safety of engineered nanomaterials (ENMs). This is primarily due to difficulties in studying such small-scale objects and especially tracing their fate and behaviour in laboratory experiments and, even more so, the environment. Labelling of ENMs can serve a very important role of tracer in the environment, and ultimately be used as a tool to create unique ENM identities and support the concept of “safer-by-design”. The proposed project will compare different labelling techniques, both conventional (fluorescent labels) and emerging (stable isotopic and chemical labelling) where the host and ER have complementary expertise, and investigate multiple labels. It will consider aspects of industrial synthesis and scaling up and carry out a field experiment involving labelled ENMs. The ER will be hosted by the team who pioneered stable isotope labelling of ENMs and benefit from placements with the JRC and Glantreo, whilst bringing to the project his own unique expertise on ENM synthesis and tracing.