What is a SNUR? TSCA significant new use rules and SNUNs

What is a SNUR under TSCA?

A SNUR (Significant New Use Rule) is a US EPA rule under the Toxic Substances Control Act (TSCA), section 5(a)(2) that designates a specific chemical use as a "significant new use". Unless exempt, anyone planning to manufacture, import or process the chemical for that use must file a Significant New Use Notice (SNUN) at least 90 days ahead and wait for EPA's determination and any required action.

SNURs are codified in 40 CFR Part 721.

Why EPA issues SNURs

EPA says SNURs "can be used to require notice to EPA before chemical substances and mixtures are used in new ways that might create concerns" (EPA). A 5(e) or 5(f) order after a premanufacture notice (PMN) binds only that submitter, so EPA generally issues a SNUR before others depart from those restrictions (EPA).

Existing chemicals get SNURs too. The 2020 rule on long-chain PFAS made importing certain of them in surface coatings on articles, or as part of carpets, a significant new use, and it removed the usual article exemption. The January 2024 rule on 329 inactive PFAS covers any manufacture or processing for any use (40 CFR 721.11777).

How 40 CFR Part 721 is built

Part 721 holds every EPA significant new use rule in five subparts. Subpart A covers who must notify, filing and exemptions. Subpart B (721.50 to 721.91) is a menu of standard significant new uses. Subpart C is recordkeeping. Subpart D is the expedited process for issuing, limiting or revoking a SNUR. Subpart E lists each substance or category covered by SNURs and the uses that count as new.

A Subpart E entry names the chemical and points to Subpart B, which applies only when called up (721.50): workplace protection (721.63), hazard communication (721.72), industrial, commercial or consumer activity (721.80), disposal (721.85) and release to water (721.90).

Who is covered

Under 721.5, a person who intends to manufacture or process for a significant new use must file, unless exempt. The principal importer files an import SNUN. A distributing manufacturer or processor must also file unless each recipient was notified in writing of the Subpart E section, already knows it, or cannot do the new use. If they learn a recipient is doing the use without a SNUN, they must stop supply or notify the recipient and EPA within 15 working days, then get a written assurance within 15 more working days and send EPA a copy. Noncompliance is a TSCA section 15 violation (721.35), with civil penalties currently up to $49,772 per violation per day (40 CFR 19.4).

The cut-off date catches people out. A use counts as new from the date the proposed rule is published, not the final rule's effective date (89 FR 1822). A use that stopped before the final rule doesn't count as ongoing.

721.45 exempts qualifying R&D, impurities, certain byproducts, manufacture or processing solely for export if the substance is labeled for export, and activity under a 5(e) order. Test marketing needs an EPA-granted exemption. Importing or processing as part of an article is normally exempt, but a specific SNUR can switch that off.

When a SNUN is due and how to file

File the SNUN at least 90 calendar days before you start (721.25). Processors still need their own SNUN until EPA amends the SNUR (EPA).

The 90 days is not an automatic clearance. You wait until EPA makes its determination and takes any required action. A December 2024 amendment, effective January 17, 2025, wrote that limit into the regulation. The statute already required it. The notice must also describe known categories of use, not just the one you intend. EPA can extend the 90-day review by up to 90 more days for good cause, and must publish the extension in the Federal Register (15 U.S.C. 2604).

EPA then makes one of three findings, without weighing costs, and including potentially exposed or susceptible subpopulations. Unreasonable risk requires action under section 5(f). Insufficient information, a use that may present an unreasonable risk, or substantial production with substantial exposure, requires action under section 5(e). If the use is not likely to present an unreasonable risk, you may proceed.

Filing goes through EPA's CDX on EPA Form 7710-25, built in the e-PMN software. You don't have to run new tests unless a section 4 rule or order applies. But you must submit the test data you hold and describe data that's known or reasonably ascertainable. EPA warns that a SNUN with no test data is more likely to end in a 5(e) or 5(f) action (FR, Oct 15, 2026).

40 CFR 700.45 lists a $37,000 fee, or $6,480 for a qualifying small business. Every joint submitter must qualify for the lower fee. Check EPA's current fee table before paying.

SNUNs are rare. EPA counted 10 in FY2025 and 23 in FY2023. (EPA statistics). Keep the SNUN file for five years (721.40).

Export and import duties

Exporting a substance listed in Subpart E, or covered by a proposed rule that would amend Subpart E, triggers TSCA 12(b) export notification (721.20). For a SNUR (final or proposed) it's one notice per exporter per country, the first export only. It's due within seven days of forming the intent to export or on the export date, whichever is earlier. For a proposed SNUR the duty starts 30 days after publication (707.65). Articles are generally exempt, and so are amounts below 1% (0.1% for known or potential human carcinogens) (707.60).

Importers sign the TSCA positive certification under 19 CFR 12.121, which covers SNURs. Check the intended use against the rule before you certify (EPA).

How to check whether a SNUR covers your chemical

Start with the TSCA Inventory FLAG field. "S" means a final SNUR, "SP" a proposed one, "5E" a 5(e) order. The Inventory is updated about every six months, so a new proposal can be missing. An S flag is only a pointer. It does not list the uses, and a SNUR does not mean the substance is on the Inventory.

Search ChemView by CAS, accession or PMN number. SNURs show up under EPA Actions. Then read the Subpart E paragraph: the uses, the Subpart B items it calls up and any carve-outs. For a rule too new for those tools, search the Federal Register for Part 721.

Some SNURs, like the inactive PFAS rule, define scope by structure. Match your substance to that definition. And if the identity is confidential, file a bona fide intent request under 721.11. EPA then says, within 30 days, whether it is covered, which Subpart E section applies and whether any uses are confidential. "It is always the obligation of the manufacturer or processor selling a chemical substance to notify the user of the SNUR status of that substance" (EPA). You can also get the seller's certification that your use is not a significant new use.

You can ask RegAffairs AI whether a SNUR covers your chemical, with citations back to the stored source documents.