EPA is withdrawing two significant new use rules (SNURs) promulgated under section 5(a)(2) of the Toxic Substances Control Act (TSCA) for chemical substances which were the subject of premanufacture notices (PMNs), i.e., multi-walled carbon nanotubes (PMN P-08-177) and single-walled carbon nanotubes (PMN P-08- 328). These chemical substances are subject to TSCA section 5(e) consent orders issued by EPA. EPA published the SNURs using direct final rulemaking procedures. EPA received a notice of intent to submit adverse comments on these rules. Therefore, the Agency is withdrawing these SNURs, as required under the expedited SNUR rulemaking process. EPA also intends to publish in the Federal Register, under separate notice and comment rulemaking procedures, proposed SNURS for these two chemical substances.