Q.01

What is a SNUR?

A SNUR (Significant New Use Rule) is a US EPA rule under the Toxic Substances Control Act (TSCA). It names a use of a chemical substance as a "significant new use." Anyone who plans to manufacture (including import) or process that substance for that use must then send EPA a Significant New Use Notice (SNUN) at least 90 days before starting [1]. SNURs are codified in 40 CFR part 721 [2].

Legal basis

  • TSCA section 5(a)(2) lets EPA decide that a use of a chemical is a "significant new use." EPA must do this by rule, after considering all relevant factors, including those listed in that section [2].
  • TSCA section 5(a)(1)(B) is what triggers the 90-day notice [2].
  • The general provisions are in 40 CFR part 721, subpart A. They cover who is subject, recordkeeping, exemptions, and how the rule applies to uses that started before it took effect. 40 CFR 721.5 sets out who must submit a SNUN [1].

How it works

  • Why EPA issues them: many SNURs follow a premanufacture notice (PMN) review for a new chemical, where EPA found that one or more of the concern criteria in 40 CFR 721.170 were met [1]. EPA has also issued them for existing chemicals, for example benzidine-based dyes and DnPP. Its stated aim is to get advance notice of new uses that could change human and environmental exposure [3].
  • What counts as a "new use": this is specific to each rule. Examples from the rules:
    • Use without gloves, a NIOSH-approved full-face respirator (APF of at least 50) and hazard communication [1].
    • Going over a 1 ppb surface-water concentration, or an annual volume limit [1].
    • "Any use" at all [3].
  • The notice itself: SNUN submitters follow the same notice requirements and EPA procedures as PMN submitters (40 CFR 721.1(c), 40 CFR part 720) [1].
    • You must submit test data you hold, and describe data that is known to you or reasonably ascertainable. New testing is required only where a TSCA section 4 test rule or a section 5(b)(4) listing applies [4].
  • What EPA can do after a SNUN: EPA may take action under TSCA sections 5(e), 5(f), 6 or 7. If it takes no action, it must publish its reasons in the Federal Register under section 5(g) [1].
  • Cut-off date: a use counts as "new" from the date the proposed rule is published, not from the final rule's effective date. So anyone who starts the use in between must stop when the rule takes effect and file a SNUN, unless they meet the advance-compliance terms in 40 CFR 721.45(h) [4].
  • Articles: 40 CFR 721.45(f) normally exempts importing or processing a substance as part of an article. EPA can switch that exemption off for a specific SNUR, as it did for benzidine-based dyes [4].

Import and export obligations

  • Export: a substance in a proposed or final SNUR triggers TSCA section 12(b) export notification (40 CFR part 707, subpart D). This is a one-time notice for the first export, or intended export, to each country [4].
  • Import: a substance in a final SNUR triggers TSCA section 13 import certification (19 CFR 12.118 through 12.127 and 127.28). The importer certifies that the shipment complies with TSCA, including any SNUR requirements [1].

Approach: I read EPA's SNUR rulemakings published in the Federal Register (40 CFR part 721). The sections cited above are taken from the standard explanations in those rules, not from the current eCFR text of part 721.

I can look up the SNURs that cover a particular substance or CAS number if that would help.

Q.02

When do I need to file a SNUN?

You have to file a SNUN at least 90 days before you start to manufacture (which includes import) or process a substance covered by a SNUR, for any activity that the SNUR names as a significant new use [5][6]. Filing on time doesn't let you start once the 90 days run out. You can't begin that use until EPA has reviewed the notice, made a determination on it, and taken whatever action that determination requires [5][7].

What triggers the obligation

  • Your intent to do something the SNUR covers. The duty applies to any person, large or small, who "intends to engage in any activity described in the final rule as a 'significant new use'". That person must notify EPA before starting [8].
  • What the rule names. For substances that went through a PMN and are under a TSCA section 5(e) Order, the significant new uses are any manufacture, processing, use, distribution or disposal that doesn't follow the Order's restrictions [8]. Other SNURs can cover "any" manufacture or processing. The 2024 SNUR for 329 inactive PFAS is an example [7].
  • Substance-specific carve-outs. Each SNUR's regulatory text can switch off its requirements once the substance has been incorporated into an article, has reacted or cured, or has been reacted onto a semiconductor wafer [9][10][11]. You need to read the paragraph for your own substance.

The cut-off date for uses already under way

  • A use only counts as a significant new use if it was not ongoing. EPA tests this as of the date the proposed rule was published, not the final rule's effective date [6]. In the November 2025 rule, for example, the cut-off was 4 April 2025 [12].
  • If a use was ongoing at proposal but stops before the final rule is issued, it no longer counts as ongoing [12].
  • If you start a designated use after the proposal but before the final rule takes effect, you must stop on the effective date. You can resume only after you file a SNUN and all TSCA prerequisites are met [12].

How you file and what goes in it

  • Form and procedure: use EPA Form 7710-25, generated with the e-PMN software, following 40 CFR 720.40 and 721.25 [12]. EPA's cost estimate assumes registration with its Central Data Exchange (CDX) [6].
  • Data: you don't have to generate new test data, unless a TSCA section 4 rule, order or consent agreement applies. You must submit information in your possession or control, and describe other information that is known to you or reasonably ascertainable (40 CFR 720.50) [12].
    • EPA warns that a SNUN with no test data is more likely to lead to action under section 5(e) or 5(f).
    • It advises contacting it early enough to run tests before you file [12].
  • Fee: $37,000, or $6,480 for small businesses as defined at 13 CFR 121.201 (40 CFR 700.45) [6].
  • Effort: EPA estimates 30 to 170 hours per submission [8]. It puts the total cost at about $45,000 for a large business and $14,500 for a small one [6].

Planning the timeline In practice, start about 90 days before your planned start date, plus EPA's review and any action it takes, plus time to run tests if you decide to submit data. EPA says it receives few SNUNs: 7 in fiscal year 2020, 9 in each of 2021 and 2022, 23 in 2023 and 7 in 2024 [8].

Separate from the SNUN, a substance under a SNUR also brings TSCA section 13 import certification and section 12(b) export notification (40 CFR part 707, subpart D) [6].

Approach: I read the standard explanatory sections of recent EPA SNUR rulemakings in the Federal Register (2024 and 2025). I didn't check the current eCFR text of 40 CFR 721.5, 721.25 or 721.45, which hold the general provisions on who must report and the exemptions.

If you give me a substance name, CAS number or PMN number, I can find the SNUR that covers it and set out exactly which activities would trigger a SNUN.

Q.03

How do I check if a SNUR covers my chemical?

You check SNUR coverage in two steps. First, look your substance up on the TSCA Chemical Substance Inventory and see whether its entry carries a SNUR flag. Then read the SNUR itself in 40 CFR part 721 to see whether your intended activity is one of the significant new uses it lists. If your substance's identity, or the use itself, is confidential, you have to ask EPA through a bona fide procedure.

1. Pin down the exact identity

  • For a public substance, use the CAS Registry Number.
  • For a confidential-identity substance, use the EPA accession number, PMN number and generic name. Confidential Inventory entries carry these identifiers in place of a CAS number [13].
  • EPA's applicability section says the rule "applies to you if you manufacture, process, or use the chemical substances identified in this document." It also gives NAICS codes 325 and 324110 as a guide only; the list isn't meant to be exhaustive [6].

2. Check the TSCA Inventory flags

  • Each Inventory entry lists regulatory flags. In the current Inventory, substances named in SNURs carry the flag "S". For example, CAS 160535-46-6 shows "PMN; S" [14] and is named in a 2014 SNUR [15]. CAS 1410795-87-7 shows "PMN; S; 5E" [16] and is also in a 2014 SNUR [17].
  • Some confidential entries carry "SP" instead [13]. I couldn't open EPA's flag key page to confirm what "S" and "SP" officially mean, so the reading above comes from matching Inventory entries against the rules.
  • The two lists are separate. EPA states that a SNUR on a substance "does not signify that the chemical substance is listed on the TSCA Chemical Substance Inventory" [18]. Check both.

3. Read the SNUR's regulatory text

  • Find the rule that names your substance, by CAS number, PMN number or docket. Then read its paragraph in 40 CFR part 721.
  • Whether you are covered depends on the use, not only on the substance. For PMN substances under a TSCA section 5(e) Order, the significant new use is any manufacture, processing, use, distribution or disposal that doesn't conform to the Order's restrictions [6].
  • Some SNURs define their scope by chemical structure instead of naming each substance. The 2024 SNUR for inactive PFAS is one. EPA says persons are expected to identify covered substances from the structural definition "regardless of whether there is a universally known unique identifier" [19].
  • Check whether your use was ongoing on the date the proposed rule was published. A use that was ongoing then, and didn't stop before the final rule, is not designated as a significant new use [18].

4. If the identity or the use is confidential (CBI)

  • Confidential use (40 CFR 721.11): you can ask EPA to identify a significant new use that is claimed as CBI. You must show a bona fide intent to manufacture or process the substance. Where the chemical identity is also CBI, you can combine both requests into one step [18].
  • Confidential identity: you can file a Bona Fide Intent to Manufacture or Import Notice. If EPA accepts that your intent is genuine, it searches the full Inventory master file and gives you a written determination of the substance's Inventory status, "including SNUR status" [19].
  • Questions: the TSCA Hotline is at TSCA-Hotline@epa.gov, (800) 471-7127 or (202) 554-1404 [6].

If you import or export

  • Import: the TSCA section 13 import certification covers compliance with all TSCA section 5 rules, so it covers SNURs. It applies to substances in bulk, in mixtures, and in articles where a rule requires it [6].
  • Export: exporting a substance named in a SNUR triggers section 12(b) export notification under 40 CFR 721.20 [6].

Approach: I used EPA's TSCA Chemical Substance Inventory and EPA's SNUR rulemakings in the Federal Register. I couldn't open EPA's own TSCA Inventory web pages this time, so the meaning of the flags comes from the Inventory entries and the rules, not from EPA's flag key.

If you send me a CAS number, PMN number or accession number, I can check the Inventory flags and find the SNUR that covers it.

Q.04