On June 26, 2013, the U.S. Environmental Protection Agency (EPA) promulgated final significant new use rules (SNUR) for 17 chemical substances that were the subject of premanufacture notices (PMN), including for certain carbon nanotubes. The SNURs require persons who intend to manufacture or process any of these 17 chemical substances for an activity that is designated as a significant new use to notify EPA at least 90 days before commencing that activity. The final rule includes EPA’s response to comments. EPA encourages any manufacturers or processors who intend to conduct testing or submit a significant new use notification (SNUN) to contact EPA prior to commencing testing to avoid duplicative testing, to identify alternative testing, and to discuss protocols and testing strategies. A commenter suggested that EPA provide mandatory nano-specific ingredient and warning labeling requirements. In response, EPA states that the SNURs and consent orders that are the basis for the SNURs do not require nano-specific labeling or warnings because: “(1) the basis for the consent orders and SNURs is not that they are nanomaterials per se, but rather is based on their specific properties and potential risks, and (2) companies that manufacture, process, and use chemical substances that are carbon nanotubes and fullerenes already clearly identify those chemical substances as nanomaterials.” The proposed SNURs would allow the submission of data in support of a new chemical exposure limit (NCEL) under 40 C.F.R. Section 721.30. EPA notes that, because of the uncertainty surrounding the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) of 1 microgram per cubic meter (µg/m3), it “will not adopt the NIOSH REL as a NCEL at this time because EPA cannot determine that at the REL the potential exposures may not present an unreasonable risk.” EPA states that it will consider the final NIOSH REL, or other alternative exposure controls for carbon nanotubes, if a submission requesting such is made under 40 C.F.R. Section 721.30. EPA states that, despite uncertainties cited by a commenter, it “believes that its assessment and risk management of nanomaterials, although sometimes hampered by a lack of submitted data, is adequate to identify and prevent potential unreasonable risks to human health or the environment from manufacturing processing, and using nanomaterials including risks to workers.” The final rule will be effective on August 26, 2013.