Life-cycle assessment of engineered nanomaterials: a literature review of assessment status

The potential environmental impacts of engineered nanomaterials (ENMs), and their engineered nanoparticles (ENPs), have, in recent years, been a cause of concern. Life-cycle assessment (LCA) is a highly qualified tool to assess products and systems and has an increasing extent been applied to ENMs. However, still only 29 case studies on LCA of ENMs have been published in journals and this article investigates these studies. Generally, data on production of ENMs as well as the coverage of the life cycle are limited. In particular, within use and disposal stages data are scarce due to many unknowns regarding the potential release and fate of ENMs/ENPs to and in the environment. This study investigates the sensitivity of case studies with respect to ecotoxicity impacts through a quantification of the potential ecotoxicity impacts to algae, daphnia and fish as a result of direct release of Ag and TiO2 ENPs (mainly <200 nm in nominal diameter size) from various ENM products to the freshwater compartment. It was found that Ag and TiO2 release, from 1 g Ag or TiO2 ENM product, poses up to ca. 3.5 orders of magnitude higher ecotoxicity impact than the production of 1 g polymer (PP, PE and PET average) or 1 Wh of grid mix electricity from Scandinavia. ENMs from Ag had higher ecotoxic impact than those from TiO2 and there was a linear regression between Ag ENM content in the considered products and the potential ecotoxicity impacts to the freshwater species, according to release of total Ag during use (mainly washing).