Comprehensive probabilistic modelling of environmental emissions of engineered nanomaterials

Concerns about the environmental risks of engineered nanomaterials (ENM) are growing, however, currently very little is known about their concentrations in the environment. Here, we calculate the concentrations of five ENM (nano-TiO2, nano-ZnO, nano-Ag, CNT and fullerenes) in environmental and technical compartments using probabilistic material-flow modelling. We apply the newest data on ENM production volumes, their allocation to and subsequent release from different product categories, and their flows into and within those compartments. Further, we compare newly predicted ENM concentrations to estimates from 2009 and to corresponding measured concentrations of their conventional materials, e.g. TiO2, Zn and Ag. We show that the production volume and the compounds' inertness are crucial factors determining final concentrations. ENM production estimates are generally higher than a few years ago. In most cases, the environmental concentrations of corresponding conventional materials are between one and seven orders of magnitude higher than those for ENM. Highlights: • Material flow modelling is used to predict flows and concentrations of nanomaterials. • Nano-TiO2 is highest due to high production and uses with significant release. • Predicted concentrations are for most materials higher than in 2009. • Concentrations of conventional materials are higher than those of nanomaterials. -- The mass flows of five engineered nanomaterials to technical and environmental compartments are modelled and compared to earlier estimates and to measured conventional materials