UV-dependent freshwater effect factor of nanoscale titanium dioxide for future life cycle assessment application.

Abstract

Environmental impacts of nanoscale titanium dioxide (TiO2 ) should be assessed throughout the lifetime of nanoparticles (NPs) to improve the state of knowledge of the overall sustainability. Life cycle assessment (LCA) has been previously recognized as a promising approach to systematically evaluating environmental impacts of NPs. As a result of their unique nanospecific properties, characterization factors (CF) were previously used for compensating the release and potential impacts of TiO2 NPs. However, because TiO2 NPs are known to generate reactive oxygen species and elicit toxicity to freshwater organisms, the lack of adequate UV-dependent effect factors (EFs) remains a major shortcoming when addressing their life cycle impacts. To complement the LCA of TiO2 -NPs-enabled products under their specific applications, we recapitulated the freshwater toxicity of TiO2 NPs and then modeled in USEtox to determine trophic level EF ranges under UV and non-UV exposure conditions. Results indicate that EFs derived for non-UV exposure were 52 (42.9-65) potentially affected fraction (PAF) m3 /kg, and combined toxicity data derived EFs were 70.1 (55.6-90.5) PAF m3 /kg. When considering only the UV-induced exposure condition, the modeled EF increased to 500 (333-712) PAF m3 /kg. Our work highlights that case-dependent EFs should be considered and applied to reflect more realistic ecological impacts and illustrate comprehensive life cycle environmental impacts for nanoenabled products. Integr Environ Assess Manag 2023;19:578-585. © 2022 SETAC.