Flavor ingredient regulatory record
2-Naphthalenethiol
2-Naphthalenethiol is a thiol in the sulfur family, FEMA GRAS under FEMA number 3314 (CAS 91-60-1). Its odor is pungent, sulfurous, earthy, musty.
- FEMA
- 3314
- CAS
- 91-60-1
- JECFA
- 531
- EU FL
- 12.033
- Formula
- C10H8S
GRAS status: FEMA GRAS, publication 5. Recorded by FDA in the Substances Added to Food inventory under CAS 91-60-1.
Structure
Identity
Also known as: RPA 2, 2-Mercaptonaphthalene, β-Naphthyl mercaptan, 2-Naphthyl mercaptan, β-Thionaphthol, β-Mercaptonaphthalene, β-Naphthalenethiol, 2-Thionaphthol, Vulcamel TBN, Renacit 1, NSC 4749, naphthalene-2-thiol.
Can 2-Naphthalenethiol be labeled natural?
Since 2-Naphthalenethiol is found in nature, US labeling follows how it was obtained: natural flavor from a natural source and a natural process, artificial when 2-Naphthalenethiol is synthesized. The EU and UK grant the natural claim only to that natural route; Mercosur and Mexico call synthetic material identical-to-natural.
- United States
- Natural or artificial, by process
- European Union and UK
- Natural only from natural material
- Mercosur and Mexico
- Natural or identical-to-natural
How each market defines the classes: natural vs artificial flavor under 21 CFR 101.22.
Regulatory status, with citations
United States
2-Naphthalenethiol is FEMA GRAS under FEMA number 3314. It is cited in the Code of Federal Regulations at 21 CFR 172.515.
European Union and United Kingdom
Listed on the Union List of flavouring substances as FL 12.033, Annex I Part A under Regulation (EC) 1334/2008, evaluation status approved (JECFA). The UK retains the same list.
JECFA (WHO / FAO)
JECFA number 531, evaluated at the 53rd meeting in 1999. no safety concern at current levels of intake.
Other US flags
Not on the California Proposition 65 list. Listed on the EPA TSCA inventory.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. 2-Naphthalenethiol appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 91-60-1, where EPA names it 2-Naphthalenethiol.
Active in US commerce
EPA designates this substance active, so no Notice of Activity Form B is required before manufacturing. What active and inactive mean.
EPA publishes no regulatory flags on this listing. What the flags mean.
From the EPA non-confidential TSCA Inventory, July 2026 release. EPA also maintains a confidential portion it does not publish. Search the Inventory by CAS number.
Odor and taste
Odor: Pungent, sulfurous, earthy, musty.
Where it is used
2-Naphthalenethiol is used in savory dishes, seasoning, sauces and snacks, typically as a sulfur note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to 2-Naphthalenethiol by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| 6-Methylquinoline | 2744 | 77% | In nature |
| beta-Naphthyl methyl ether | 4704 | 76% | Not determined |
| Methyl beta-naphthyl ketone | 2723 | 74% | Not determined |
| 1-Methylnaphthalene | 3193 | 73% | In nature |
| Benzyl mercaptan | 2147 | 73% | In nature |
More thiols in this index
Hydrogen sulfide · Furfuryl isopropyl sulfide · 4-(Methylthio)-4-methyl-2-pentanone · Ammonium hydrogen sulphide · Dimethyl trisulfide · 3-(Methylthio)propylamine
2-Naphthalenethiol FAQ
Is 2-Naphthalenethiol on the FEMA GRAS list?
It is. FEMA number 3314 covers 2-Naphthalenethiol. It is also codified at 21 CFR 172.515.
What is the FEMA number for 2-Naphthalenethiol?
The FEMA number for 2-Naphthalenethiol is 3314 and its CAS registry number is 91-60-1. FEMA files it in the sulfur flavor category.
Is 2-Naphthalenethiol natural or artificial?
2-Naphthalenethiol occurs in nature, so the label depends on the route: 2-Naphthalenethiol won from a natural source by a physical, enzymatic or microbiological process is natural flavor in the United States, and synthesized 2-Naphthalenethiol is artificial. In the EU and UK the natural claim likewise needs the natural route, while Mercosur and Mexico keep a third class, identical-to-natural, for the synthetic material.
Is 2-Naphthalenethiol approved in the EU?
2-Naphthalenethiol is on the EU Union List of flavouring substances as FL 12.033 (Annex I Part A) under Regulation 1334/2008.
Has JECFA evaluated 2-Naphthalenethiol?
Yes. JECFA number 531, evaluated at the 53rd meeting in 1999. Conclusion: no safety concern at current levels of intake.
What is 2-Naphthalenethiol used for?
2-Naphthalenethiol is described as pungent, sulfurous, earthy, musty. It shows up in savory dishes, seasoning, sauces and snacks.
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Sources and attribution. The identity and regulatory facts on this page are taken from the FDA Substances Added to Food inventory, a US government record, which lists this substance as 2-NAPHTHALENTHIOL under CAS 91-60-1 and carries its FEMA number, its JECFA flavor number. The inventory is searchable at FDA. FDA records its technical effect as flavor enhancer, flavoring agent or adjuvant.
A FEMA GRAS conclusion is reached by the Expert Panel of the Flavor and Extract Manufacturers Association of the United States, and the FEMA number names that conclusion. FEMA publishes its own entry for this substance in the FEMA Flavor Library, which is the authoritative record of what the Panel decided and is worth reading alongside this page.
Ambrose Compliance is not affiliated with, endorsed by, or sponsored by FEMA. FEMA and FEMA GRAS are used here as identifiers for a published regulatory determination, not as marks of any relationship between FEMA and Ambrose.
About this page. Facts come from the FDA Substances Added to Food inventory, the Code of Federal Regulations, the EPA TSCA Inventory, the EU Union List, JECFA and the Ambrose database, with FEMA's published determination cited where it applies; parts of the text are written by Ambrose AI, which can make mistakes. Check the cited source before relying on anything here. This is not regulatory or legal advice.