Prioritization Actions Under TSCA
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. A high-priority substance may present unreasonable risk of injury to health or the environment because of a potential hazard and a potential route of exposure, and a low-priority substance is one for which a risk evaluation is not warranted at the time. During prioritization, as specified under TSCA section 6(b)(1)(A), EPA considers hazard and exposure potential of a chemical substance, its persistence and bioaccumulation, potentially exposed or susceptible subpopulations, storage near significant sources of drinking water, the conditions of use or significant changes in the conditions of use of the chemical substance, and the production volume or significant changes in production volume of the chemical substance manufactured or processed. At the end of the prioritization process, if a chemical is designated as a High-Priority Substance, EPA will initiate a risk evaluation for that chemical substance. EPA will then publish a draft scope of the risk evaluation followed by a 45-day public comment period. EPA will then publish a final scope document within 6 months of initiating the risk evaluation. EPA provides the status for all ongoing and completed risk evaluations under TSCA.
Chemicals Undergoing Prioritization
This table provides a current list of the chemicals undergoing the process for prioritization for risk evaluation under TSCA, as well as proposed and final designation status. See the Prioritization of Existing Chemicals for Risk Evaluation under TSCA page for an overview of the prioritization process. Thus far, Chemical substances being prioritized for risk evaluation 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.
|
Chemical Name |
CASRN number |
Date Initiated |
Docket ID Number |
Prioritization Status |
Priority Designation |
|
4-tert-Octylphenol (4-(1,1,3,3-Tetramethylbutyl)-phenol) |
140-66-9 |
12/2024 |
Initiated |
Pending proposed designation |
|
|
Benzene |
71-43-2 |
12/2024 |
Initiated |
Pending proposed designation |
|
|
Ethylbenzene |
100-41-4 |
12/2024 |
Initiated |
Pending proposed designation |
|
|
Napthalene |
91-20-3 |
12/2024 |
Initiated |
Pending proposed designation |
|
|
Styrene |
100-42-5 |
12/2024 |
Initiated |
Pending proposed designation |
Previous Prioritization Actions Under TSCA
2023-2024 Chemicals Receiving Final Designations
On December 18, 2024, EPA finalized the designations of these chemical substances as High-Priority Substances for risk evaluation.
- Acetaldehyde (CASRN 75-07-0);
- Acrylonitrile (CASRN 107-13-1);
- Benzenamine (CASRN 62-53-3);
- Vinyl Chloride (CASRN 75-01-4), 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 the combination of hazard, exposure (including uses), and persistence and bioaccumulation characteristics.
2019-2020 Chemicals Receiving Final Designations
On March 20, 2019, EPA initiated the prioritization process by issuing a list of 40 chemical substances and began the effort to designate 20 High-Priority Substances for subsequent risk evaluation and to designate 20 Low-Priority Substances, 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.
- Learn more about the 20 low-priority chemical substances.