What does the restriction note for POTASSIUM METABISULFITE mean?

The restriction field for POTASSIUM METABISULFITE reads: III/99 V/9. This is the restriction note from the CosIng inventory. For authoritative conditions and limits, always refer to the linked annex entries.

How do I check if my formula contains POTASSIUM METABISULFITE?

Use the INCI Checker to screen a full ingredient list across selected markets, or use the substance market comparison to review this identity across all supported market datasets.

InventoryRef 3699411/08/2020

POTASSIUM METABISULFITE

Dipotassium disulphite

POTASSIUM METABISULFITE is linked to 2 EU annex records on this page. Inventory note: III/99 V/9.

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Regulatory evidence by market

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Market	Evidence status	Records	Source language
European Union	Evidence linked Restricted entry found Open this evidence	2	English and EU languages
Great Britain	Source mapped Official source mapped; ingredient rule not imported	0	English
Canada	Source mapped Official source mapped; ingredient rule not imported	0	English and French
New Zealand	Evidence linked Permitted list with conditions Open this evidence	1	English
ASEAN	Source mapped Official source mapped; ingredient rule not imported	0	English and national languages
China	Source mapped Official source mapped; ingredient rule not imported	0	Chinese with selected English material
Japan	Source mapped Official source mapped; ingredient rule not imported	0	Japanese; official English translation available
South Korea	Source mapped Official source mapped; ingredient rule not imported	0	Korean with some English names
United States	Source mapped Official source mapped; ingredient rule not imported	0	English
Australia	Source mapped Official source mapped; ingredient rule not imported	0	English
Brazil	Source mapped Official source mapped; ingredient rule not imported	0	Portuguese with INCI crosswalks
India	Source mapped Official source mapped; ingredient rule not imported	0	English and Hindi
Saudi Arabia	Source mapped Official source mapped; ingredient rule not imported	0	Arabic and English

Chemical identity and properties

PubChem 2D chemical structure for CAS 16731-55-8

CAS 16731-55-8PubChem CID 28019

Potassium Metabisulfite

Potassium metabisulfite appears as a white granular or powdery solid with a sharp odor of sulfur dioxide. Decomposes at 150 to 190 °C. Density 2.3 g / cm3. Contact severely irritates skin, eyes, and mucous membranes. Low toxicity. Used as a food preservative and an antioxidant. — CAMEO Chemicals

Molecular formula: K2O5S2
Molecular weight: 222.33 g/mol
Exact mass: 221.8461284 Da
Topological polar surface area: 125.0 Å²
Hydrogen-bond donors: 0
Hydrogen-bond acceptors: 6
Covalent units: 3
Defined stereocentres: 0

Also known as

Potassium disulfiteDipotassium pyrosulfiteDipotassium disulfiteSobisuDipotassium metabisulfitepotassium metabisulphitePotassium disulfite (K2S2O5)Potassium pentaoxodisulfate

16 more reported names

Pyrosulfurous acid, dipotassium saltIns-224Potassium metabisulfite (e 224)65OE787Q7WE-224RefChem:867887240-795-3Potassium pyrosulfitePotassium metabisulfite [NF]Potassium metabisulfite (NF)Dipotassium disulphiteCCRIS 1427HSDB 5062EINECS 240-795-3KaliumpyrosulfitUNII-65OE787Q7W

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External database identifiers

ChEMBL:CHEMBL2106901
EPA DTXSID:DTXSID1021293

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

PubChem 2D chemical structure for CAS 4429-42-9

CAS 4429-42-9PubChem CID 23663620

Potassium Bisulfite

Potassium bisulfite solution is a colorless aqueous with a slight sulfur dioxide odor. Used as a reducing agent and chemical preservative. — CAMEO Chemicals

IUPAC name: potassium hydrogen sulfite

Molecular formula: HKO3S
Molecular weight: 120.17 g/mol
Exact mass: 119.92834655 Da
Topological polar surface area: 79.6 Å²
Hydrogen-bond donors: 1
Hydrogen-bond acceptors: 4
Covalent units: 2
Defined stereocentres: 0

Also known as

7773-03-7Monopotassium sulfiteQJK5LO891PSulfurous acid, potassium salt (1:1)POTASSIUM BISULPHITEUNII-QJK5LO891PPotassium sulfite, hydrogenINS NO.228

16 more reported names

POTASSIUM BISULFITE [II]HSDB 1263INS-228POTASSIUM BISULFITE [HSDB]Sulfurous acid, monopotassium saltPOTASSIUM BISULFITE [MART.]EINECS 231-870-1E-228POTASSIUM BISULFITE (II)POTASSIUM BISULFITE (MART.)RefChem:175431POTASSIUM BISULFITE SOLUTIONPOTASSIUM BISULPHITE SOLUTIONUN2693231-870-1potassium;hydrogen sulfite

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External database identifiers

EPA DTXSID:DTXSID6064795

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Inventory details for POTASSIUM METABISULFITE

INCI name

POTASSIUM METABISULFITE

INN name

potassium metabisulfite

Description

Dipotassium disulphite

Record provenance

Inventory reference: 36994
Imported identity: POTASSIUM METABISULFITE
Source update: 11/08/2020

European Commission CosIng source notes

Annex records for POTASSIUM METABISULFITE

Annex III Restriction reference

Entry 99

Inorganic sulfites and bisulfites (12)

Annex V Restriction reference

Entry 9

SODIUM SULFITE / AMMONIUM BISULFITE / AMMONIUM SULFITE / POTASSIUM SULFITE / POTASSIUM hydrogen SUL…

CAS: 7757-83-7 / 10192-30-0 / 10196-04-0 / 10117-38-1 / 7773-03-7 / 7631-90-5 / 7681-57-4 / 16731-55-8

EC: 231-821-4 / 233-469-7 / 233-484-9 / 233-321-1 / 231-870-1 /231-548-0 / 231-673-0 / 240-795-3

Key data

CAS

16731-55-8 / 4429-42-9

240-795-3 / -

Restriction

III/99 V/9

Function

HAIR WAVING OR STRAIGHTENING: Modifying the chemical structure of the hair, allowing it to be set in the style required (permanent waves or hair straightening).
PRESERVATIVE: Exclusively or mainly intended to inhibit the development of micro-organisms in the cosmetic product. All authorised preservatives are substances in the positive list of Annex V to the Cosmetics Regulation 1223/2009.
REDUCING: Changing the chemical nature of another ingredient by adding hydrogen (or removing oxygen).

Official EU ingredient-name evidence

The ingredient name exactly matches the official 2025 EU glossary of common ingredient names.

#22696 · POTASSIUM METABISULFITE

The 2 markets that hold a rule for this substance do not classify it the same way.

restricted: European Union
permitted on a positive list: New Zealand

See every substance the markets disagree about

Ingredients with overlapping formulation functions

OCTAPEPTIDE-15ANTIOXIDANT, REDUCING, SKIN PROTECTING

OLIGOPEPTIDE-30ANTIOXIDANT, CHELATING, HAIR CONDITIONING, REDUCING, SKIN PROTECTING

P-HYDROXYANISOLEANTIOXIDANT, REDUCING

PHALAENOPSIS APHRODITE CALLUS EXTRACTANTIOXIDANT, REDUCING, SKIN PROTECTING

POTASSIUM SULFITEANTIOXIDANT, HAIR WAVING OR STRAIGHTENING, PRESERVATIVE, REDUCING

POTASSIUM TETRATHIONATEREDUCING

RH-POLYPEPTIDE-28REDUCING, SKIN CONDITIONING

RH-POLYPEPTIDE-60REDUCING, SKIN CONDITIONING

Additional official and scientific sources

11 external databases to check this identity in

Each link searches that source for this identity. What each source is, and its legal weight

ECHA CHEM / Information on chemicals PubChem PUG REST EU Safety Gate cosmetic product alerts ECHA CHEM US EPA CompTox Cosmetic Ingredient Review safety assessments FDA Global Substance Registration System ILO/WHO International Chemical Safety Cards Japan NITE-CHRIP NIOSH Pocket Guide to Chemical Hazards OECD eChemPortal

How POTASSIUM METABISULFITE appears in the CosIng inventory

The CosIng inventory lists POTASSIUM METABISULFITE as a cosmetic ingredient and this page links it to 2 annex records. The inventory entry captures names and identifiers, while the annex records show where the substance is prohibited, restricted or positively listed in EU cosmetics law.

POTASSIUM METABISULFITE is also tagged with 3 cosmetic functions in the official data. Function labels describe intended use, but they do not replace regulatory review of linked annex records before formulation or labelling work.

Frequently asked questions

POTASSIUM METABISULFITE appears in the EU CosIng inventory and has linked annex records. Check the annex records above for applicable restrictions, concentration limits and conditions of use. Annex II listing means prohibited; Annex III means restricted; Annexes IV, V and VI mean permitted under specified conditions.

The restriction field for POTASSIUM METABISULFITE reads: "III/99 V/9". This is the restriction note recorded in the CosIng inventory for this ingredient. For authoritative conditions and limits, always refer to the linked annex entries above.

According to the EU CosIng inventory, POTASSIUM METABISULFITE carries the following function designation(s):

CAS 16731-55-8 / 4429-42-9 may appear across multiple EU annex records. Viewing the CAS lookup page shows all Annex II–VI entries sharing this identifier, which is useful for identifying cross-annex regulatory status of the same chemical substance.

Use the INCI Checker to screen a full ingredient list across selected markets, or compare this substance across all supported market datasets.

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Source note for POTASSIUM METABISULFITE

This page combines the CosIng inventory entry for POTASSIUM METABISULFITE with 2 linked Annex II–VI records from the local dataset built from public European Commission cosmetic ingredient materials.

Use this inventory page to research POTASSIUM METABISULFITE and compare linked records, but verify restrictions and legal status against the current official source text and law before making regulatory decisions.

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