The U.S. Environmental Protection Agency (EPA) published on February 3, 2010, a proposed significant new use rule (SNUR) under Section 5(a)(2) of the Toxic Substances Control Act (TSCA) for multi-walled carbon nanotubes. The proposed rule would require persons who intend to manufacture, import, or process the substance for an activity that is designated as a significant new use by the proposed rule to notify EPA at least 90 days before commencing that activity. EPA states that the required notification would provide EPA with the opportunity to evaluate the intended use and, if necessary, to prohibit or limit that activity before it occurs. Comments are due March 5, 2010.

The proposed rule provides the following basis for action:

The PMN states that the substance will be used as an additive/filler for polymer composites and support media for industrial catalysts. Based on test data on analogous respirable, poorly soluble particulates and on other carbon nanotubes (CNTs), EPA identified concerns for lung effects, immunotoxicity, and mutagenicity from exposure to the PMN substance. For the uses described in the PMN, worker inhalation and dermal exposures are minimal due to the use of adequate personal protective equipment. Therefore, EPA has not determined that the proposed manufacturing, processing, or use of the substance may present an unreasonable risk. EPA has determined, however, that use of the substance without the use of gloves and protective clothing, where there is a potential for dermal exposure; use of the substance without a National Institute for Occupational Safety and Health (NIOSH)-approved full-face respirator with an N100 cartridge, where there is a potential for inhalation exposure; or use other than as described in the PMN, may cause serious health effects. Based on this information, the PMN substance meets the concern criteria at 721.170(b)(3)(ii).

The proposed SNUR would apply only to the multi-walled carbon nanotubes described in premanufacture notice (PMN) P08-199. According to EPA, in the past, some stakeholders have asked whether these types of SNURs apply to all variants of carbon nanotubes. EPA states: “This is not the case.” The chemical name listed in the proposed SNUR is “multi-walled carbon nanotubes (generic),” and the CAS Number is “not available.” On November 6, 2009, EPA published a proposed SNUR for the multi-walled carbon nanotubes described in PMN P08-177.