What: On November 13, 2025, the U.S. Environmental Protection Agency (EPA) announced it would delay the deadline for comments on the draft risk evaluation for Octamethylcyclotetrasiloxane (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8- octamethyl-) (D4) by 15 days.
Why: D4 is a colorless, volatile, oily liquid primarily used to make silicone chemicals. D4 commercial uses include adhesives and sealants, automotive care products, paints and coatings, and other plastic and rubber products. D4 is also used as an ingredient in consumer products such as cosmetics, medical devices, and food contact materials.
Under the Toxic Substances Control Act (TSCA), the purpose of a risk evaluation is to determine whether a chemical substance presents an unreasonable risk of injury to human health or the environment. For D4, EPA used the best available science to preliminarily determine, based on the weight of scientific evidence, that D4 poses unreasonable risk to human health and the environment driven primarily by certain conditions of use analyzed in the draft risk evaluation.
Action: Comments are now due December 2, 2025.
Additionally, the EPA will hold a virtual public meeting December 2-5, 2025, for the agency’s Science Advisory Committee on Chemicals (SACC) to discuss the draft risk evaluation and technical support documents for D4.
EPA has also announced the postponement of a virtual public preparatory meeting until December 1, 2025, for the SACC and the public to consider and ask questions regarding the scope and clarity of the draft charge questions. Registration instructions for the virtual preparatory and peer review meetings are available on the SACC website.
EXTENSION NOTICE:
POSTPONEMENT NOTICE:
Science Advisory Committee on Chemicals (SACC); Notice of Postponement of Public Meeting
RISK EVALUATION:
Trichloroethylene (TCE); Regulation Under the Toxic Substances Control Act
CONTACT: Nick Goldstein
EMAIL: nick.goldstein@sba.gov
TAG(S): EPA
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