Human health characterization factors of nano-TiO2 for indoor and outdoor environments

The increasing use of engineered nanomaterials (ENMs) in industrial applications and consumer products is leading to an inevitable release of these materials into the environment. This makes it necessary to assess the potential risks that these new materials pose to human health and the environment. Life cycle assessment (LCA) methodology has been recognized as a key tool for assessing the environmental performance of nanoproducts. Until now, the impacts of ENMs could not be included in LCA studies due to a lack of characterization factors (CFs). This paper provides a methodological framework for identifying human health CFs for ENMs. The USEtox (TM) model was used to identify CFs for assessing the potential carcinogenic and non-carcinogenic effects on human health caused by ENM emissions in both indoor (occupational settings) and outdoor environments. Nano-titanium dioxide (nano-TiO2) was selected for defining the CFs in this study, as it is one of the most commonly used ENMs. For the carcinogenic effect assessment, a conservative approach was adopted; indeed, a critical dose estimate for pulmonary inflammation was assumed. We propose CFs for nano-TiO2 from 5.5E-09 to 1.43E-02 cases/kg(emitted) for both indoor and outdoor environments and for carcinogenic and non-carcinogenic effects. These human health CFs for nano-TiO2 are an important step toward the comprehensive application of LCA methodology in the field of nanomaterial technology.