EPA Designates the Next Five High Priority Chemicals for Risk Evaluation under the TSCA

What: On December 18, 2024, the U.S. Environmental Protection Agency (EPA) announced that it will formally designate five chemicals as High-Priority Substances that will undergo a risk evaluation under the Toxic Substances Control Act (TSCA). The five chemicals are:

  • Vinyl Chloride;
  • Acetaldehyde;
  • Acrylonitrile;
  • Benzenamine; and
  • 4,4’-Methylenebis(2-chloroaniline), or MBOCA.

Why: EPA began the prioritization process for these chemicals in December 2023, formally proposing designation in July 2024, by opening a 90-day comment period. These five chemicals will now begin the process of risk evaluation to determine whether they present an unreasonable risk of injury to health or the environment. If at the end of the process, EPA determines that the chemical presents an unreasonable risk of injury or health to the environment, the agency will immediately start the risk management process to address unreasonable risk. The agency will next release for public comment preliminary lists of manufacturers subject to fees for the five chemicals designated.

Consistent with the agency’s announcement in December 2023 of its intent to initiate the prioritization of five chemicals every year, the agency also initiated the prioritization of five additional chemical substances. This will begin the 9–12-month prioritization process before the agency formally designates them as high-priority substances. Those chemicals are:

  • Benzene;
  • Ethylbenzene;
  • Naphthalene;
  • Styrene; and
  • 4-tert­-Octylphenol.

EPA is opening a 90-day public comment period and is requesting further information on how these chemicals are used, their potential hazards and exposures, and the availability of information on each.

Action: Comments are due March 18, 2025.

Learn more about chemicals undergoing prioritization.

Register for the January 14, 2025, webinar for information on fee-payers.

Comment on the initiation of the prioritization process.

Advocacy Contact: Send an email to Emily Jones at Emily.Jones@sba.gov.