Flavor ingredient regulatory record
Sulfur Dioxide
Sulfur Dioxide is a flavoring substance, FEMA GRAS under FEMA number 3039 (CAS 7446-09-5). Its odor is ... Characteristic, irritating, pungent odor .
- FEMA
- 3039
- CAS
- 7446-09-5
- Formula
- O2S
- EC
- 231-195-2
GRAS status: FEMA GRAS, publication 3. Recorded by FDA in the Substances Added to Food inventory under CAS 7446-09-5.
Structure
Identity
Also known as: Sulfur superoxide, Sulfurous acid anhydride, Sulfurous anhydride, Sulfurous oxide, Sulfur oxide (SO2), Fermenticide liquid, Sulfur dioxide (SO2), Sulfur oxide, Sulphur dioxide, E 220, MeSH ID: D013458, sulphur dioxide.
Can Sulfur Dioxide be labeled natural?
The process decides for Sulfur Dioxide. It occurs in nature, so a natural-source, natural-process material is natural flavor in the US and synthetic Sulfur Dioxide is artificial. 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
Sulfur Dioxide is FEMA GRAS under FEMA number 3039. It is cited in the Code of Federal Regulations at 21 CFR 182.3862.
European Union and United Kingdom
No EU FL number is on file for Sulfur Dioxide. That is not a finding either way. The Union List covers defined flavouring substances, so natural complex materials are handled as flavouring preparations under Parts B to F and never receive a number, and substances used as additives sit under Regulation 1333/2008 instead. Confirm the position before EU or UK use.
JECFA (WHO / FAO)
Sulfur Dioxide has not been evaluated by JECFA as a flavouring agent, or no evaluation is on file.
Other US flags
Listed under California Proposition 65 for developmental toxicity since July 29, 2011; a warning may be required in California depending on exposure.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. Sulfur Dioxide appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 7446-09-5, where EPA names it Sulfur dioxide.
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: ... Characteristic, irritating, pungent odor .
Taste: Acid taste.
Where it is used
Typical applications for Sulfur Dioxide are not on file yet.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to Sulfur Dioxide by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| Formic acid | 2487 | 55% | In nature |
| Hydrogen sulfide | 3779 | 54% | In nature |
| Nitrous Oxide | 2779 | 51% | In nature |
| Ammonia | 4494 | 49% | In nature |
| Phosphoric Acid | 2900 | 44% | In nature |
Sulfur Dioxide FAQ
Is Sulfur Dioxide FEMA GRAS?
Yes. The FEMA Expert Panel lists Sulfur Dioxide as GRAS under FEMA number 3039. The Code of Federal Regulations lists it at 21 CFR 182.3862.
What are the FEMA and CAS numbers for Sulfur Dioxide?
Sulfur Dioxide is FEMA 3039, CAS 7446-09-5.
How is Sulfur Dioxide described, and where does it show up?
Flavorists describe Sulfur Dioxide as ... Characteristic, irritating, pungent odor . On the palate it is acid taste.
Does Sulfur Dioxide count as natural in the US and the EU?
Nature makes Sulfur Dioxide, which is why the US label turns on process. A natural route gives natural flavor; synthesis gives artificial Sulfur Dioxide, same molecule. 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.
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Guides: What Is FEMA GRAS? · Natural vs artificial · Filing a GRAS notification
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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 SULFUR DIOXIDE under CAS 7446-09-5 and carries its FEMA number and its 21 CFR citations. The inventory is searchable at FDA. FDA records its technical effect as antimicrobial agent, antioxidant, color or coloring adjunct, 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.