EPA is developing TSCA section 5(a)(2) significant new use rules (SNURs) on conditions of use identified as not currently ongoing in the final scope documents for the High Priority Substances undergoing TSCA section 6 risk evaluations. EPA is authorized to designate a particular new use (or return of a phased-out use) of a chemical substance as a "significant new use" under TSCA section 5(a)(2) by rule after consideration of relevant factors. These rules would be used to require notice to EPA before chemical substances and mixtures are used in new ways that might create concerns. Persons subject to the SNUR who intend to manufacture (including import) or process the chemical substance for the significant new use must notify EPA at least 90 days prior to initiating activities via a significant new use notice (SNUN).