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EPA Announces Public Comment Period for Manufacturer Requested Risk Evaluation for D4

For Release: June 12, 2020

EPA is opening a public comment period for a manufacturer requested risk evaluation of octamethylcyclotetra-siloxane (D4), a chemical used to make other silicone chemicals and as an ingredient in some personal care products. The manufacturer requested risk evaluation of D4 is the third evaluation of this kind to be requested under the Toxic Substances Control Act (TSCA).

Under the Lautenberg Act amendments to TSCA, chemical manufacturers can now request that EPA conduct a risk evaluation on a specific chemical. By giving manufacturers the opportunity to prioritize, identify, and request the evaluation of chemicals and conditions of use of interest to them, EPA is encouraging sensible and timely assessment of chemicals in the marketplace.

Upon publication of the Federal Register notice, EPA will accept public comments on the request for 45 days in docket EPA-HQ-OPPT-2018-0443 on

EPA welcomes all public comments on this request, particularly on the following:

  • any information not included in the manufacturer request that the commenters believe EPA would need to conduct a risk evaluation;
  • additional conditions of use the agency is proposing to include in the risk evaluation; and
  • information on conditions of use not included in the manufacturer request or in the additional conditions of use EPA is proposing to include in the risk evaluation.

After the comment period closes, the agency will review the comments and either grant or deny the request to conduct a risk evaluation within 60 days. If this request is granted, the manufacturers would be responsible for half the cost of the risk evaluation.

Learn more about the manufacturer requested risk evaluation for D4.

Read more about manufacturer requested risk evaluations on EPA’s website.


On March 19, 2020, EPA received a manufacturer request to conduct a risk evaluation of D4 from Dow Silicones Corporation, Elkem Silicones USA Corporation, Evonik Corporation, Momentive Performance Materials, Shin-Etsu Silicones of America, Inc., and Wacker Chemical Corporation through the American Chemistry Council’s Silicones Environmental, Health, and Safety Center.

On April 8, 2020, EPA found this request to be facially complete. Under 40 CFR 702.37(e)(1), no later than 60 business days after receiving a request that EPA has determined to be facially complete, EPA is required to (1) submit for publication in the Federal Register the receipt of the request, (2) open a public docket for the request, and (3) provide no less than 45 calendar days for public comment.

EPA currently has 33 chemicals in various stages of the TSCA risk evaluation process - the first 10 chemicals selected in 2016, 20 high-priority chemicals that completed the TSCA prioritization process in December 2019, and three chemicals that are the subject of manufacturer requested risk evaluations.