Peer Review of the Draft Risk Evaluation for Octamethylcyclotetrasiloxane (D4)
Octamethylcyclotetrasiloxane (D4) is undergoing risk evaluation under the Toxic Substances Control Act.
D4 is a colorless, oily liquid with an annual total U.S. production volume between 750 million and 1 billion pounds. The primary uses for D4 are to make other silicone chemicals with commercial uses including, but not limited to, adhesives and sealants, automotive care products, paints and coatings, and other plastic and rubber products.
Meeting Information
The Science Advisory Committee on Chemicals (SACC) held a peer review meeting on December 2-4, 2025 to discuss the draft risk evaluation for D4. The Committee will publish the meeting minutes and final report within 60 days from the conclusion of the meeting. A preparatory meeting was also held on December 1, 2025 to discuss the scope and clarity of the charge questions. To view the meetings on YouTube, follow the links under Meeting Viewing Information.
SACC Peer Review Meeting Materials
Peer Reviewers
On September 10, 2025, EPA requested nominations of scientific and technical experts to be considered as ad hoc reviewers assisting the SACC with this peer review. On October 9, 2025, EPA requested comments on qualified and available candidates under consideration to serve as ad hoc reviewers assisting the SACC with this peer review. Biographies of the interested and available candidates are posted in the docket EPA-HQ-OPPT-2025-1610 on www.regulations.gov. On October 29, 2025, EPA posted in the docket the biographies of the ad hoc reviewers who have been selected for this peer review based on the scientific expertise needed to address the SACC peer review charge and to obtain a breadth and balance of different scientific viewpoints across the SACC and ad hoc peer reviewers.
For additional information, contact the Designated Federal Official, Dr. Alaa Kamel at kamel.alaa@epa.gov.