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The draft document is intended to be used as part of a process to identify what is known and, more importantly, what is not yet known that could be of value in assessing the broad implications of specific nanomaterials. Like previous case studies (see History/ Chronology below), this draft case study on multiwalled carbon nanotubes (MWCNTs) is based on the comprehensive environmental assessment (CEA) approach, which consists of both a framework and a process. Unlike previous case studies this case study incorporates information about a traditional (i.e., “non-nano-enabled”) product, against which the MWCNT flame-retardant coating applied to upholstery textiles (i.e., the “nano-enabled” product) can be compared. The comparative element serves dual-purposes: 1) to provide a more robust database that facilitates identification of data gaps related to the nano-enabled product and 2) to provide a context for identifying key factors and data gaps for future efforts to evaluate risk-related trade-offs between a nano-enabled and non-nano-enabled product.

This draft case study does not represent a completed or even a preliminary assessment of MWCNTs; rather, it uses the CEA framework to structure information from available literature and other resources (e.g., government reports) on the product life cycle, fate and transport processes in various environmental media, exposure-dose characterization, and impacts in human, ecological, and environmental receptors. Importantly, information on other direct and indirect ramifications of both primary and secondary substances or stressors associated with the nanomaterial is also included when available. The draft case study provides a basis for the next step of the CEA process, whereby collective judgment is used to identify and prioritize research gaps to support future assessment efforts that inform near-term risk management goals.

Engineered nanoscale materials (nanomaterials) are generally described as having at least one dimension between 1 and 100 nanometers (nm). They often have novel or unique properties that arise from their small size. Like all technological developments, nanomaterials offer the potential for both benefits and risks. The assessment of such risks and benefits requires information, but given the nascent state of nanotechnology, much remains to be learned about the characteristics and effects of nanomaterials. The draft case study document provided a starting point for a workshop process that engaged experts with diverse technical (e.g., toxicology, polymer science, environmental fate and transport) and sector (e.g., industry, academia, government) backgrounds. Experts used the draft case study document to identify and prioritize research gaps that could support future assessment and risk management efforts for multiwalled carbon nanotubes (MWCNTs). This prioritization took place through a structured decision process that allowed each expert to have equal input on the outcome. RTI International, an EPA contractor, independently conducted this structured workshop process through the use of web-based tools and a face-to-face workshop.

Some research gaps identified through this workshop process may be specific to the use of MWCNT in flame-retardant coatings applied to upholstery textiles; others may relate more broadly to MWCNT irrespective of its application, while still others may apply more widely to nanomaterials in general. In each instance, the identified research gap will inform the development of the final case study document, which is intended to support research planning throughout the scientific community.

This document seeks to identify what is known and unknown related to assessing the health and environmental implications of a nanomaterial; in this case multiwalled carbon nanotubes (MWCNTs) used in flame-retardant coatings applied to textiles.

We are actively working on revising the draft case study document to highlight the priority research areas identified through the RTI workshop process, as well as incorporate valuable feedback from public commenters and experts participating in the RTI workshop process. The revised document will undergo a formal external letter peer review in Spring 2013, after which additional revisions will be carried out in response to reviewer comments. The final case study is expected to be available in Fall 2013.

U.S. EPA. Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotube and Decabromodiphenyl Ether Flame-Retardant Coatings Applied to Upholstery Textiles (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-12/043A, 2012.

Comments on the assessment may be submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select Environmental Protection Agency and the key word EPA-HQ-ORD-2012-0512 (for the docket ID).

More information on the EPA Public Information Exchange meeting can be found in the Federal Register Notice.