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 This website is no longer updated and links to external websites and some internal pages may not work.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

Unsubstituted Phenylenediamines; Final Test Rule

EPA is issuing a final rule, under section 4 of the Toxic Substances Control Act (TSCA), requiring manufacturers and processors of ortho-phenylenediamine (o-pda; CAS No. 95-54—5), meta-phenylenediamine (m-pda: CAS No. 108-45-2), para-phenylenediamine (p-pda; CAS No. 100—50—3) and the sulfate salts of m-pda (m-pda.H3, SO4; CAS No.54—17-08) and p-pda (p-pda.H3, SO4; CAS No. 1624—57—75) to perform testing for neurotoxic effects, chemical fate, and aquatic toxicity.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.