EPA Requests Nominations of Peer Reviewers for TSCA Risk Evaluation of D4

Released September 10, 2025

The U.S. Environmental Protection Agency (EPA) is seeking nominations of scientific and technical experts to be considered as ad hoc reviewers assisting the Science Advisory Committee on Chemicals (SACC) with the peer review of the draft risk evaluation of octamethylcyclotetrasiloxane (D4) under the Toxic Substances Control Act (TSCA).

Nominations for ad hoc reviewers should include the candidate’s name, affiliation, contact information, and must be submitted by September 25, 2025, to the OCSPP Peer Review mailbox at OCSPP-PeerReview@epa.gov. These nominations will help the agency select approximately seven to eight ad hoc reviewers to assist the SACC with their review.  

Nominees should be scientists with sufficient professional qualifications, including training and experience, to provide expert comments on the scientific issues for this review. Individuals nominated for this peer review meeting should have expertise in one or more of the following areas: 

• Identification of hazards relevant to human health risk assessment.  
• Evaluation and use of the D4 physiologically based pharmacokinetic (PBPK) model. 
• Handling of uncertainties associated with exposure and release assessments. 
• Characterization of bioaccumulation, bioconcentration, biomagnification, and potential trophic transfer. 
• Human fish consumption for the general population and potentially exposed or susceptible subpopulations. 
• Identification of hazards relevant to ecological risk assessment. 

Prospective candidates will be asked to submit confidential financial information. This confidential financial information must fully disclose, among other financial interests, the candidate's employment, stocks and bonds, and where applicable, sources of research support. EPA evaluates the candidates' financial disclosure forms to assess whether there are financial conflicts of interest, appearance of a loss of impartiality, or any prior involvement with the development of the documents under consideration (including previous scientific peer review) before the candidates are considered further.    

The final selection of the ad hoc peer reviewers will depend upon the scientific expertise needed to address the SACC peer review charge and obtaining a breadth and balance of different scientific viewpoints across the SACC and ad hoc peer reviewers. The peer review will take place at a virtual public meeting in December 2025. EPA will announce the dates for this meeting in the coming weeks.    

For more information on the SACC peer review, contact the Designated Federal Official, Dr. Alaa Kamel kamel.alaa@epa.gov.