Guidance UpdateLiveGuidance Update
EPA Publishes Default Values for New Chemicals Risk Assessments
Toxic Substances Control Act (TSCA) - New Chemicals ProgramU.S. Environmental Protection Agency (EPA)US
Announced
Nov 24, 2025
Effective
Nov 24, 2025
Description
EPA published the key default values (assumptions) used in its risk assessments of new chemicals under TSCA. These default values are assumptions used by EPA in environmental release and occupational exposure assessments. The agency made these assumptions available in the New Chemicals Division Reference Library to increase transparency and efficiency in the TSCA New Chemicals Program.
Sources
Key Findings
EPA Publishes Default Values for New Chemicals Risk Assessments
sing Common Assumptions Used in Assessing New Chemicals ### **Released Nov. 24, 2025** Today, U.S. Environmental Protection Agency (EPA) is publishing the key “default values” used in its risk assessments of new chemicals under the Toxic Substances Control Act (TSCA). Default values are assumptions used by EPA in environmental release and occupational exposure assessments. The agency is making these assumptions avail