Chemical Substances Undergoing Prioritization
As required under section 6(b) of the Toxic Substances Control Act (TSCA), EPA must conduct a prioritization process to determine if chemical substances are a high- or low-priority for risk evaluation.
2023-2024 Prioritization Process
In December 2023, EPA initiated the process of prioritizing five chemicals as candidates for high-priority designation and subsequent risk evaluation:
- Vinyl Chloride (CASRN 75-01-4),
- Acetaldehyde (CASRN 75-07-0),
- Acrylonitrile (CASRN 107-13-1),
- Benzenamine (CASRN 62-53-3), and
- 4,4’-Methylene bis(2-chloroaniline) (MBOCA) (CASRN 101-14-4).
All five chemicals were selected from the 2014 TSCA Work Plan, which is a list of chemicals identified by EPA for further assessment based on their hazards and potential for exposure.
In selecting these five chemicals, EPA considered numerous factors including how they are used, their known hazards and exposures, and the availability of information on each chemical to allow for fulsome risk evaluations to be completed. Between September and November 2023, EPA met with federal partners, industry, environmental organizations, labor organizations, state and local governments, and Tribes to discuss the prioritization process and presented a list of 15 chemical substances that EPA was considering for prioritization. EPA took feedback from these discussions into consideration when selecting this set of five chemicals for prioritization.
Upon publication of the Federal Register Notice, EPA will accept comments and request further information on all of these factors, as well as any other information relevant to the potential risks of these chemicals that will inform the Agency’s review of these chemicals. EPA is particularly interested in information regarding the chemicals’ uses and encourages companies that make and use them to submit comment.
In March 2024, EPA extended the comment period for MBOCA for 30 days. Comments on MBOCA can be submitted to docket EPA-HQ-OPPT-2018-0464 on www.regulations.gov until April 17, 2024. Comments on the other four chemicals can be submitted until March 18, 2024. For more information, please see the federal register notice at EPA-HQ-OPPT-2023-0601.
Read the federal register notice.
Previous Prioritization Under TSCA
On March 20, 2019, EPA initiated the prioritization process by issuing a list of 40 chemical substances and began the effort to designate 20 substances as “high priority” for subsequent risk evaluation and to designate 20 substances as “low-priority,” meaning that risk evaluation is not warranted at this time. On December 20, 2019, EPA finalized the designation of the 20 high-priority chemicals. On February 20, 2020, EPA finalized the designation of the 20 low-priority chemicals.
- Learn more about the 20 high-priority chemical substances.
- Read the December 2019 Federal Register notice finalizing the high-priority designations.
- Learn more about the 20 low-priority chemical substances.
- Read the February 2020 Federal Register notice finalizing the low-priority designations.
- Read the March 2019 press release announcing the candidates for prioritization.
- Read the March 2019 Federal Register notice initiating the prioritization process.