Life Cycle Aspects of Nanoproducts, Nanostructured Materials, and Nanomanufacturing: Problem Definitions, Data Gaps, and Research Needs
Chicago, Illinois: November 5-6, 2009
CEA and LCA: Two Complementary Approaches at US EPA
Jeff Morris
National Program Director for Nanotechnology Office of Research and Development
US Environmental Protection Agency
Comprehensive Environmental Assessment
While the basic paradigms of health and ecological risk assessment are still relevant for nanotechnology, EPA expands them in the comprehensive environmental assessment (CEA) approach to encompass the product life cycle of nanomaterials. By taking a broad view of the potential for releases of both primary and secondary materials to multiple environmental media, the evaluation of the environmental and health risks of nanomaterials is seen as an issue that cuts across EPA programmatic domains and is not simply categorized as solely an air, water, toxics, or solid waste issue. The CEA approach (Davis and Thomas, 2006; Davis, 2007) starts with a qualitative life cycle framework. It takes into consideration multiple environmental pathways, transport and transformation processes, cumulative and aggregate exposure by various routes, and ecological as well as human health effects. Depending on the availability of data, both quantitative and qualitative characterizations of risks may result. However, given the limited information currently available on nanomaterials, the CEA approach is being used to identify where key data gaps exist with respect to selected case studies of specific applications of nanomaterials.
Life Cycle Assessment: EPA’s Current Research Focus
A key science question for EPA is: Which manufactured nanomaterials have a high potential for release from a life-cycle perspective, and what decision-making methods and practices can be applied to minimize the risks of nanomaterials throughout their life cycle? To begin to address this question, EPA is conducting research to understand releases that can occur either during production, use, recycling, or disposal of nanomaterials.
In addition to human and ecological exposure, there is a need to better understand how the manufacture, use, and waste management of nanomaterials will contribute to other environmental problems, including climate changes due to global warming and stratospheric ozone depletion; land use leading to acidification, eutrophication, and photo-oxidation; odor, noise, waste heat, radiation, and casualties. To address these issues, researchers are implementing more comprehensive assessment tools, such as life-cycle assessment (LCA), that can establish comparative impacts of products and processes in terms of well-defined impact categories. Such an assessment can be applied across the entire life cycle [materials acquisition (cradle) to disposal (grave)] or along any desired part thereof (gate-to-gate). Hence within a single assessment, LCA for nanomaterials has the potential to address both the toxicological and environmental questions associated with these materials.
A number of LCAs have recently appeared in open literature, helping researchers to identify the key concerns that must be addressed if the goal of a full-scale LCA is to be realized. The proper life-cycle boundaries, particularly the “grave,” must be defined for a given material. This can be confusing when considering nanomaterials because they may have the potential to permeate much smaller regions, passing throughout the environment. Data gaps concerning the transport, persistence, and toxicity of nanomaterials must be filled. This is challenging, because the diverse properties of nanomaterials (i.e. surface charge, size, shape, chemical composition) that can be synthesized will strongly impact how these materials disperse and react within the body and the environment. Thus, either a large amount of research or the development of accurate predictive models is needed to acquire the missing data. Additionally, issues such as the treatment of nanomaterials incorporated into larger composite materials and the recycle of nanomaterials must be addressed.
The value of any assessment is not only the data it generates, but how the data are applied. Are there acceptable tradeoffs associated with nanomaterials? Is the large-scale production of an environmentally taxing material justified if it has medical applications or can reduce costs or enhance performance? Questions such as these illustrate the ultimate need for a valuation system with suitable metrics. To this end, research is needed to develop an easily applied, LCA-based framework that can be used with other pertinent factors such as cost and societal benefit to provide a comprehensive evaluation of nanomaterials throughout their life cycle.
EPA’s CEA and LCA research can be used to inform government, industry, and academia about potential proactive and greener approaches for manufacturing nanomaterials that are designed to prevent nanomaterial release into the environment. It could also be used as input for future thorough LCAs. The development of a robust assessment tool can support decisions in the development of appropriate nanotechnologies. Such a tool is highly needed and has yet to be fully developed. In addition, the necessity for specific data will help with the design of fate, transport, and toxicity studies that are necessary to better understand the use and release of nanomaterials. The goal is to develop a decision-support framework available to stakeholders that is easy to apply and can accommodate a wide variety of nanomaterials.