As part of an ongoing effort to identify research needs and data gaps in assessing the broad environmental implications of nanomaterials, this case study focuses on a specific nanomaterial in a particular application: multiwalled carbon nanotubes (MWCNTs) in flame-retardant coatings applied to upholstery textiles. The selection of this specific nanomaterial and particular application was made with input from representatives across the U.S. Environmental Protection Agency (EPA) and was based in part on its relevance to EPA programmatic interests and the similarity in the potential for release and exposure over the product life cycle compared to conventional flame-retardant materials that are being phased out of use. Like previous case studies of nanoscale titanium dioxide and nanoscale silver, this case study is built on the comprehensive environmental assessment (CEA) approach, which is both a framework and a process. The CEA framework (Figure 1-1) starts with the inception of a material and encompasses environmental fate, exposure-dose, and impacts associated with that material. The framework also considers differences in environmental media and the physical, chemical, biological, and social conditions in which the material occurs. Here, the framework is used to organize information about MWCNTs in the case study systematically. This information does not represent a completed or even preliminary risk assessment; rather, it is intended to inform research planning. The External Review Draft of the document provided a basis for identifying and prioritizing data gaps and research needs for MWCNTs and other nanomaterial assessments as part of the CEA process (Figure 1-2). Specifically, a group of expert stakeholders representing diverse technical (e.g., human health effects, ecological effects, material characterization) and sector (e.g., industry, academia, government) perspectives engaged in a structured, collective judgment workshop process such that each individual had equal input in identifying research. 1870611