Coordinating modeling and experimental research of engineered nanomaterials to improve life cycle assessment studies

Life cycle assessment (LCA) - a comprehensive modeling framework used to identify environmental and human health impacts associated with products, processes, and technologies - is increasingly recommended for emerging nanotechnologies. LCA applied prospectively can guide design decisions and enable reduction of future impacts. A growing literature describes the potential for LCA to inform development of safer nanotechnologies, for example by identifying the manufacturing inputs or processes with the greatest potential for improvement. However, few published studies to date include all life cycle stages in part because of uncertainty regarding engineered nanomaterial (ENM) releases and impacts, which precludes comprehensive environmental assessment of nano-enabled products. Life cycle impact assessment (LCIA) converts emissions into environmental damages through linked fate-exposure-effect models that require robust experimental data and a mechanistic understanding for each of these components. In the case of ENMs, there are pertinent knowledge gaps, high uncertainties in experimental data, and disagreement regarding the suitability of existing fate, exposure, and effect models. This frontier review summarizes recent advances in human and aquatic ecotoxicity LCIA for ENMs and calls for greater coordination between LCA modelers and experimentalists, including those that study fate and transport, environmental transformations, occupational exposure, and toxicology, to inform responsible development of nanotechnology, enabling ENMs to reach their full potential.