Life cycle assessment and engineered nanomaterials: looking to the past to inform the future – considering nanoscale silver as an example

Engineered nanomaterials (ENM) present an enabling technology for society, in that they enable new products and processes in ways that are different from their bulk material counterparts. However, the benefits of nanotechnology to society across all three paradigms of sustainability must also be weighed against their costs. Life cycle assessment (LCA) facilitates quantifying and categorizing the environmental considerations over the lifetimes or a portion of the lifetimes of these products. The goal of this study is to explore how over the past two decades ENM LCA research has moved through multiple focus areas and scopes of analysis, including cradle to gate, cradle to grave, and then finally nano-specific end of life considerations. Each of these evolutions in focus of study have generated new insight into the benefits and costs of ENM. One of the next frontiers of LCA of ENM is considering their role in the circular economy. Nano-scale silver (nano-Ag) is utilized in this retrospective to illustrate the different areas of focus and what has been found.