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 This website is no longer updated and links to external websites and some internal pages may not work.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 »

Choosing the chemical name to list on the List of Hazardous Substances

How does EPA choose the chemical name(s) to list for each substance on the List of Hazardous Substances at Table 302.4 of 40 CFR 302.4?

A single chemical may often be known by several different names. To avoid confusion, the Agency has limited the chemical names listed in 40 CFR 302.4, Table 302.4 to the name(s) used to identify each substance under the environmental statutes and implementing regulations incorporated in the definition of hazardous substance. If a substance has more than one chemical name listed under these other statutes or regulations, each chemical name will appear as a separate entry (with the same CAS Registry Number) in Table 302.4.