This version serves as the EPA's regular update of the inventory that occurs approximately every 6 months. For the first time, this version includes a field designating which chemical substances were "active" in U.S. commerce based on the following: reporting from the 2012 and 2016 Chemical Data Reporting cycles; Notices of Commencement received by the agency since 21 June 2006; and Notice of Activity Form A's received by the agency through the 7 February 2018 deadline, per the TSCA Inventory Notification (Active-Inactive) rule.