On June 12, 2026, the U.S. Environmental Protection Agency (EPA) released the final report and meeting minutes of the Science Advisory Committee on Chemicals (SACC) regarding the draft risk evaluation of octamethylcyclotetrasiloxane (D4) conducted under the Toxic Substances Control Act (TSCA). The report summarizes the outcomes of the SACC's peer review of EPA’s draft risk evaluation and supporting technical documents during a virtual public meeting held from December 2–4, 2025. D4 is a chemical used in the manufacture of silicone polymers and is present in various consumer products, including cosmetics and hair care products. During its review, the SACC evaluated the scientific approaches, methodologies, and data used in EPA’s draft risk assessment and identified opportunities to improve the completeness of the evaluation. EPA stated that it will consider the committee’s recommendations, along with public comments, in developing the final TSCA risk evaluation for D4. The release of the final SACC report forms part of EPA’s scientific review process and supports the agency’s efforts to ensure that chemical risk evaluations are based on robust scientific evidence and meet TSCA requirements. The report and meeting materials have been made publicly available through the relevant regulatory docket.
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