AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice; extension of comment period.

SUMMARY:

In the Federal Register of September 17, 2025, Environmental Protection Agency (EPA) announced the availability of and sought public comment on a draft risk evaluation under the Toxic Substances Control Act (TSCA) for Octamethylcyclotetrasiloxane (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-) (D4) (CASRN 556-67-2). The purpose of risk evaluations under TSCA is to determine whether a chemical substance presents an unreasonable risk of injury to health or the environment under the conditions of use (COUs), including unreasonable risk to potentially exposed or susceptible subpopulations identified as relevant to the risk evaluation by EPA, and without consideration of costs or non-risk factors. EPA used the best available science to prepare this draft risk evaluation and to preliminarily determine, based on the weight of scientific evidence, that D4 poses unreasonable risk to health and the environment driven primarily by COUs analyzed in the draft risk evaluation. This document extends the comment period, which was scheduled to end on November 17, 2025, for 15 days.

DATES:

The comment period for the document published on September 17, 2025, at 90 FR 44821 (FRL-12964-01-OCSPP) is extended. Comments must be received on or before December 2, 2025; 15 days after November 17, 2025.

ADDRESSES:

Submit your comments, identified by docket identification (ID) number EPA-HQ-OPPT-2018-0443, online at https://www.regulations.gov. Follow the online instructions for submitting comments. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Additional instructions on commenting and visiting the docket, along with more information about dockets generally, is available at https://www.epa.gov/​dockets.

FOR FURTHER INFORMATION CONTACT:

For technical information: Scott Drewes, Existing Chemical Risk Management Division (7404M), Office of Pollution Prevention and Toxics, Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460-0001; telephone number: (202) 564-8833; email address: drewes.scott@epa.gov.

For general information on TSCA: The TSCA Assistance Information Service Hotline, Goodwill Vision Enterprises, 422 South Clinton Ave., Rochester, NY 14620; telephone number: (800) 471-7127 or (202) 554-1404; email address: TSCA-Hotline@epa.gov.