EPA is proposing significant new use rules (SNURs) under the Toxic Substances Control Act (TSCA) for 31 chemical substances, 30 of which were the subject of premanufacture notices (PMNs) and 1 (a microorganism) that was the subject of a Microbial Commercial Activity Notice (MCAN). 17 of these chemical substances are subject to Orders issued by EPA pursuant to the TSCA. This action would require persons who intend to manufacture (defined by statute to include import) or process any of these 31 chemical substances for an activity that is proposed 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 use, under the conditions of use for that chemical substance, within the applicable review period. Persons may not commence manufacture or processing for the significant new use until EPA has conducted a review of the notice, made an appropriate determination on the notice, and has taken such actions as are required by that determination.