On December 12, 2024, the U.S. Environmental Protection Agency (EPA) issued several final significant new use rules (SNUR) for certain chemical substances that were the subject of premanufacture notices (PMN) and are also subject to an Order issued by EPA pursuant to the Toxic Substances Control Act (TSCA). 89 Fed. Reg. 100361. Two of the SNURs are for substances identified generically as multi-walled carbon nanotubes (PMN P-21-216 and PMN P-21-217). The SNURs require persons who intend to manufacture (including import) or process any of these 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 required notification initiates EPA’s evaluation of the conditions of use for that chemical substance. In addition, the manufacture or processing for the significant new use may not commence until EPA has conducted a review of the required notification, made an appropriate determination regarding that notification, and taken such actions as required by that determination. The SNURs will be effective February 10, 2025.

According to the SNURs, the significant new uses for multi-walled carbon nanotubes (generic) (P-21-216 and P-21-217) are:

• Protection in the workplace: Requirements as specified in 40 C.F.R. Section 721.63(a)(1) and (3) through (5) and (c). EPA states that when determining which persons are reasonably likely to be exposed as required for Section 721.63(a)(1) and (4), engineering control measures or administrative control measures shall be considered and implemented to prevent exposure, where feasible. For purposes of Section 721.63(a)(5), respirators must provide a National Institute for Occupational Safety and Health (NIOSH) assigned protection factor (APF) of at least 1,000 if the capture and reduction rate is at least 99.5 percent but not 99.975 percent or greater, or at least 50 if the capture and reduction rate is at least 99.975 percent;
• Hazard communication: Requirements as specified in 40 C.F.R. Section 721.72(a) through (d), (f), and (g)(1), (3), and (5). According to EPA, for purposes of Section 721.72(g)(1), these substances may cause: eye irritation; skin irritation; respiratory sensitization; skin sensitization; genetic toxicity; reproductive toxicity; carcinogenicity; and specific target organ toxicity. For purposes of Section 721.72(g)(3), EPA states that these substances may be: toxic to aquatic life. Alternative hazard and warning statements that meet the criteria of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) and U.S. Occupational Safety and Health Administration (OSHA) Hazard Communication Standard (HCS) may be used;
• Industrial, commercial, and consumer activities: Requirements as specified in 40 C.F.R. Section 721.80(f). It is a significant new use to manufacture these substances to contain the confidential impurity listed in the Order at greater than one percent (by weight). It is a significant new use to process or use these substances other than for the confidential use allowed in the Order. It is a significant new use to process or use these substances other than in application methods that do not generate a vapor, mist, dust, or aerosol, unless such application method occurs in an enclosed process;
• Disposal: Requirements as specified in 40 C.F.R. Section 721.85 (a)(1) and (2), (b)(1) and (2), and (c)(1) and (2). It is a significant new use to release these substances directly, whether by point (stack) or non-point (fugitive) sources, to air; and
• Release to water: Requirements as specified in 40 C.F.R. Section 721.90(a)(1), (b)(1), and (c)(1).