Nanocarriers are transport and encapsulation systems that primarily serve to protect and improve the dispersibility of predominantly hydrophobic active ingredients but also enable their targeted delivery and controlled release at the site of action. Nanocarriers are mainly made of either organic or inorganic materials, but various combinations of materials in complex structures are also under development. Most nanocarriers represent entities that are rationally designed to meet the functional requirements of a specific application. They can therefore be understood as Advanced Materials. Nanocarrier systems are already being used in medicine, cosmetics, agriculture, food, and household products. They are therefore used in a variety of products, ideally designed to be safe and sustainable, and may need to be registered before they can be placed on the market. Inspired by medical research, nanocarriers are also increasingly being used for precision farming (nano-agrochemicals) or products, such as air fresheners or lithium-ion batteries, and could thus be released into the environment in large quantities. To enable the identification of critical nanocarriers in subsequent investigations, a comprehensive literature review of the broad and heterogeneous research field of nanocarriers is provided, as well as an approach for categorization based on the origin and chemical composition of their constituent materials. A definition of nanocarriers based on size (1–1000 nm) and function is also proposed for their risk assessment.

The emissions of tyre wear particles (TWPs) into the environment are increasing and have negative impacts on the environment and human health. The aim of this study was therefore to establish a mass balance for vehicle tyres und TWP emissions in Austria using static material flow analysis, which enabled a quantification of mass flows of rubber including carbon black as the most mass-relevant tyre filler. Vehicle-specific and mileage-dependent emission factors were used to calculate the TWP emissions. The results for the year 2018 indicate that 80% of the tyre rubber remained in use, while 14% was re-treaded, recycled, incinerated or exported as end-of-life tyres and 6% was emitted as TWPs to air, soil or surface water. Of these 21,200 t/y released and dissipative lost TWPs, 6% were microscale, with a possible size between 0.1 and 10 μm, and 0.3% were nanoscale below 0.1 μm. The mass balance on the substance level shows that the TWPs contained 5,500 t/y of carbon black emitted in the form of airborne TWPs (6%) or entering in the soil or surface waters (47% each). Regarding air pollution from road vehicles, about 3,600 t/y were non-exhaust emissions, including tyre, brake and road-surface wear, which contributed to 9% of total dust emissions across Austria. Scenario analysis for 2050 with regard to e-mobility and the European Green Deal reveals that non-exhaust emissions can only be significantly reduced by a general reduction of the mileage or an environmentally friendly tyre design. This modelling approach provides a solid basis for decision makers in traffic planning as well as for chemical risk assessment. However, dynamic models with higher temporal and spatial resolution are needed to predict future mass flows of TWPs and their environmental fate, including their degradation products and possible accumulation effects.