An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Assessing and Managing Chemicals under TSCA

Chemical Substances Undergoing Prioritization: High-Priority

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. 

There are no chemical substances currently undergoing prioritization.

TSCA requires that upon completion of a risk evaluation (other than those requested by a manufacturer), EPA must designate at least one additional High-Priority chemical to take its place, thus ensuring that the EPA’s risk evaluation queue always remains full. Learn more about the prioritization process for chemical substances under TSCA.

Recent Prioritization Activities

On December 20, 2019, EPA finalized the designation of 20 chemical substances as a high-priority for risk evaluation under TSCA. This was the final step of the prioritization process initiated on March 20, 2019. These chemicals will move through the process required by TSCA to evaluate any unreasonable risks they may present to human health or the environment.

In April 2020, EPA announced the availability of the draft scope documents for risk evaluations to be conducted for 20 high-priority chemicals.

On other pages:

Learn more about the December 2019 designation of 20 Low-Priority chemical substances