On January 26, 2023, EPA proposed a significant new use rule (SNUR) for PFAS substances that are currently classified as “inactive” on the TSCA Inventory. A substance is considered inactive on the TSCA Inventory when it has not been manufactured, imported, or processed in the U.S. since 2006. When the rule is finalized, anyone who wants to begin any manufacturing, importing, or processing activity involving any of these PFAS substances would be subject to the SNUR and would be required to obtain permission from EPA via a Significant New Use Notification (SNUN) at least 90 days before commencing the said activity. EPA would then review and make an affirmative determination as to whether the activity detailed in the SNUN presents an unreasonable risk to human health or the environment. EPA proposes some exceptions from the SNUR requirement, including when one of these PFAS are present as an impurity or byproduct and when the substances are imported or processed as part of an article. Comments on the proposed rule are being accepted until March 27, 2023.