WTO notification · TBT
United StatesUpdated: check whether it is now adopted or in force
Official title
Octamethylcyclotetra-Siloxane (D4); Draft Scope of the Risk Evaluation To Be Conducted Under the Toxic Substances Control Act; Notice of Availability and Request for Comments
The United States issued an addendum on 17 November 2025 to the earlier TBT notification G/TBT/N/USA/1775. Addenda often report that a measure was adopted, changed, postponed or withdrawn. The measure was first notified on 13 September 2021. The comment period closed on 2 December 2025.
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Octamethylcyclotetra-Siloxane (D4), risk evaluation
The comment period closed on 2 December 2025. You can still raise concerns about the measure with your country's WTO TBT enquiry point, quoting the document symbol G/TBT/N/USA/1775/Add.2; it can take them up with the United States.
Find your country's enquiry point on WTO ePing (opens in a new tab)Latest notice (G/TBT/N/USA/1775/Add.2, 17 November 2025)
The latest notice extends the comment period.
Octamethylcyclotetrasiloxane (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-)(D4); Draft Risk Evaluation Under the Toxic Substances Control Act (TSCA); Extension of the Comment Period
In the Federal Register of 17 September 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) (notified as G/TBT/N/USA/1775/Add.1). 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 17 November 2025, for 15 days. The comment period for the document published on 17 September 2025, at 90 FR 44821 (FRL-12964-01-OCSPP) is extended. Comments must be received on or before 2 December 2025; 15 days after 17 November 2025. 90 Federal Register (FR) 50944, 13 November 2025: This action and previous actions notified as under the symbol G/TBT/N/USA/1775 are identified by Docket Number…
Notice of Availability and Request for Comments - In accordance with implementing regulations for the Toxic Substances Control Act (TSCA), the Environmental Protection Agency (EPA) is announcing the availability of and soliciting public comment on the draft scope of the risk evaluation to be conducted for octamethylcyclotetra-siloxane (D4). D4 (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-; Chemical Abstracts Service Registry Number (CASRN) 556-67-2), is a chemical substance for which EPA received a manufacturer request for risk evaluation. The draft scope for this chemical substance includes the conditions of use, hazards, exposures, and the potentially exposed or susceptible subpopulations that EPA plans to consider in conducting the risk evaluation for this chemical substance. EPA is also opening a 45-calendar day comment period on the draft scope to allow for the public to provide additional data or information that could be useful to the Agency in finalizing the scope of the risk evaluation; comments may be submitted to this docket.
Every notice about this measure published here, newest first. Each one is the notifying member's own text.
AddendumG/TBT/N/USA/1775/Add.2
Comment deadline: Closed on 2 December 2025
Octamethylcyclotetrasiloxane (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-)(D4); Draft Risk Evaluation Under the Toxic Substances Control Act (TSCA); Extension of the Comment Period
In the Federal Register of 17 September 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) (notified as G/TBT/N/USA/1775/Add.1). 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 17 November 2025, for 15 days. The comment period for the document published on 17 September 2025, at 90 FR 44821 (FRL-12964-01-OCSPP) is extended. Comments must be received on or before 2 December 2025; 15 days after 17 November 2025. 90 Federal Register (FR) 50944, 13 November 2025: This action and previous actions notified as under the symbol G/TBT/N/USA/1775 are identified by Docket Number…
AddendumG/TBT/N/USA/1775/Add.1
Comment deadline: Closed on 17 November 2025
Octamethylcyclotetrasiloxane (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-) (D4); Draft Risk Evaluation Under the Toxic Substances Control Act (TSCA); Notice of Availability and Request for Comment
The Environmental Protection Agency (EPA or Agency) is announcing the availability of and seeking 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 human health and the environment driven primarily by certain conditions of use analyzed in the draft risk evaluation. Comments must be received on or before 17 November 2025. 90 Federal Register (FR) 44821, 17 September 2025: This notice and a previous notice notified as G/TBT/N/USA/1775 are identified by Docket Number EPA-HQ-OPPT-2018-0443. The Docket Folder is available on Regulations.gov at and provides access to primary and supporting documents as well as comments received. Documents are also accessible from Regulations.gov by searching the Docket Number. WTO Members and their stakeholders are asked to submit comments to the…
Regular notificationG/TBT/N/USA/1775
Comment deadline: Closed on 25 October 2021
Octamethylcyclotetra-Siloxane (D4); Draft Scope of the Risk Evaluation To Be Conducted Under the Toxic Substances Control Act; Notice of Availability and Request for Comments
Notice of Availability and Request for Comments - In accordance with implementing regulations for the Toxic Substances Control Act (TSCA), the Environmental Protection Agency (EPA) is announcing the availability of and soliciting public comment on the draft scope of the risk evaluation to be conducted for octamethylcyclotetra-siloxane (D4). D4 (Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-; Chemical Abstracts Service Registry Number (CASRN) 556-67-2), is a chemical substance for which EPA received a manufacturer request for risk evaluation. The draft scope for this chemical substance includes the conditions of use, hazards, exposures, and the potentially exposed or susceptible subpopulations that EPA plans to consider in conducting the risk evaluation for this chemical substance. EPA is also opening a 45-calendar day comment period on the draft scope to allow for the public to provide additional data or information that could be useful to the Agency in finalizing the scope of the risk evaluation; comments may be submitted to this docket.
Expodite writes its summary from the official record. The notification and the documents it notifies are on the WTO's own websites.
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