On September 2, 2014, the U.S. Environmental Protection Agency (EPA) promulgated final significant new use rules (SNUR) under Section 5(a)(2) of the Toxic Substances Control Act (TSCA) for 36 chemical substances that were the subject of premanufacture notices (PMN). The substances include multi-walled carbon nanotube (generic) (P-08-0392), multi-wall carbon nanotubes (generic) (P-09-257), multi-walled carbon nanofibers (generic) (PMNs P-10-115, P-10-116, P-10-117, P-10-118, P-10-119, P-10-120, P-10-121, P-10-122, P-10-123, P-10-124, P-10-125, and P-10-126), and carbide derived nanocarbon (generic) (PMN P-11-290). Persons who intend to manufacture or process any of these 36 chemical substances for an activity that is designated as a significant new use must notify EPA at least 90 days before commencing that activity. The final SNURs take effect November 3, 2014.

The September 2, 2014, notice includes EPA’s response to comments. Two commenters suggested that EPA adopt the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) of one microgram per cubic meter (µg/m3) for carbon nanotubes as a new chemical exposure limit (NCEL) for SNURs for carbon nanotubes. EPA responded that it “will not adopt the NIOSH REL as a NCEL at this time because EPA cannot determine that potential exposures at the REL 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.