On October 30, 2019, EPA announced that in response to an April 2019 court decision on the Toxic Substances Control Act (TSCA) Inventory Notification (Active-Inactive) Requirements Final Rule, EPA will publish a supplemental notice of proposed rulemaking that includes two additional questions about “reverse engineering” that manufacturers and processors would be required to answer when making confidential business information (CBI) claims. According to EPA, these questions would help provide additional information on CBI claims for specific chemical identities and would ensure that chemical companies are fully supporting their CBI claims. EPA is also proposing a process for manufacturers and processors to use to amend and update certain previously submitted claims to include responses to these additional questions, as required to be addressed by federal circuit court decision. EPA notes that the supplemental notice is limited in scope and that “it impacts only the universe of CBI claims made for specific chemical identities for chemicals reported as ‘active’ in response to the Active-Inactive Rule.” Publication of the supplemental notice in the Federal Register will begin a 30-day comment period.