Is Potassium Metabisulfite safe in cosmetics?
Potassium Metabisulfite has a safety rating of "MODERATE" in our database. EU status: restricted. US status: permitted.
Potassium Metabisulfite
Also known as: Sulfite, potassium metabi-, Potassium disulfite (K2S2O5), Potassium metabisulfite (K2S2O5), Potassium pyrosulfite (K2S2O5), EINECS 240-795-3 (+1 more)
INCI: POTASSIUM METABISULFITE
Potassium Metabisulfite (CAS 16731-55-8) is a cosmetic cosmetic ingredient functioning as Reducing agent; Antioxidant; Preservative (hair waving/straightening systems). EU Regulation 1223/2009 status: restricted; GHS signal word DANGER. Industrial safety data is also available in the chemical safety database. Same-CAS public records also appear in industrial chemical safety and pharmaceutical data.
View industrial chemical safety profile for CAS 16731-55-8 →
Cross-Vertical Regulatory Divergence
Potassium Metabisulfite is classified GHS Danger (H315, H318, H335, H302) in the chemicals database but is restricted in EU cosmetics.
Source: Cosmetics: ingredients.eu status; Chemicals: ghs classifications.signal word/hazard statement code
Function
Reducing agent; Antioxidant; Preservative (hair waving/straightening systems)
Editorial assessment
MODERATE
Preliminary editorial note — not a computed safety verdict.
Chemistry & Identifiers
InChIKey
RWPGFSMJFRPDDP-UHFFFAOYSA-L
Regulatory Status
EU EU Status
restricted
US US Status
permitted
US Notes
Recognized in 21 CFR; CIR concluded safe as used in cosmetics. Also FDA-listed for food use
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Potassium Metabisulfite.
Calculate MoS for your specific formulation with the MoS Calculator.
GHS Hazard Classification
Globally Harmonized System classification per ECHA C&L inventory and ILO/WHO International Chemical Safety Cards.
Signal Word
DANGER
Pictograms
Corr
Hazard Statements
Causes serious eye damage
Short-term Exposure Effects
The substance is corrosive to the eyes. The substance is irritating to the skin, respiratory tract and gastrointestinal tract. Exposure could cause asthma-like reactions or urticaria in sensitive persons.
Long-term Exposure Effects
Repeated or prolonged inhalation may cause asthma-like symptoms. The substance may have effects on the skin.
Routes of Exposure
The substance can be absorbed into the body by inhalation and by ingestion.
Sensitization Profile
Contact sensitization data for Potassium Metabisulfite based on clinical patch test studies and IFRA standards.
Sensitization Rate
low
Allergen Class
preservative
EU Allergen Listed
no
Patch Test Positive Rate
0.2%
Cross-reactivity Group
none
Reaction Type
contact-dermatitis
Source: SCCS Opinion
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
1,000 - 10,000 tonnes
Substance Type
SUBSTANCE
SVHC Candidate
No
PubChem Annotations
Safety and regulatory annotations from PubChem (NCBI) aggregated sources.
Safety (2)
Evidence for Carcinogenicity
Evaluation: There is inadequate evidence for the carcinogenicity in humans of sulfur dioxide, sulfites, bisulfites and metabisulfites. There is limited evidence for the carcinogenicity in experimental animals of sulfur dioxide. There is inadequate evidence for the carcinogenicity in experimental animals of sulfites, bisulfites and metabisulfites. Overall evaluation: Sulfur dioxide, sulfites,…
Source: Hazardous Substances Data Bank (HSDB)
ICSC Safety Card
1175
Source: WHO/JECFA
Regulatory (2)
JECFA Evaluation
POTASSIUM METABISULFITE | 1998 | 0-0.7 mg/kg bw | Group ADI, expressed as sulfur dioxide, for calcium hydrogen sulfite, calcium metabisulfite, calcium sulfite, potassium hydrogen sulfite, potassium metabisulfite, potassium sulfite, sodium hydrogen sulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, and sulfur dioxide | TRS 891-JECFA 51/30 | FAS 42-JECFA 51/95
Source: WHO/JECFA
EU Food Improvement
Food additives
Source: EU Food Improvement Agents
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Antioxidant
Biocide
Dye
Filler
Food preservative
Fragrance
Hair waving or straightening
Oxidizing agent
Preservative
Reducing agent
Regulatory List Membership (2)
IFRA Fragrance Transparency List
FDA Substances Added to Food (EAFUS)
Editorial summary
Preliminary editorial summary for Potassium Metabisulfite — not a computed safety verdict. See the sourced toxicological data above.
Regulatory Flags
potential-allergen
preservative
ifra_fragrance
fda_food_additive
Known Synonyms
Sulfite, potassium metabi-
Potassium disulfite (K2S2O5)
Potassium metabisulfite (K2S2O5)
Potassium pyrosulfite (K2S2O5)
EINECS 240-795-3
UNII-65OE787Q7W
Chemical Function
Preservative
Reducing agent
Hair waving or straightening
Fragrance
Biocide
Antioxidant
Dye
Regulatory Lists
active_ingredient; Europe; Pesticides
IFRA Transparency
food_additive; Substances Added to Food (formerly EAFUS) (2/2019)
Australian Status
AICIS status: listed
Cross-Vertical Safety Context
Same-CAS public records found in pharmaceutical data.
SOURCE
ChEMBL / DrugCentral / FAERS
DB_PHARMA CAS match
Pharmaceutical Data
Same-CAS rows from the pharmaceutical spoke database.
Compound
POTASSIUM METABISULFITE
ChEMBL ID
CHEMBL2106901
Max Phase
-1
Frequently Asked Questions
Is Potassium Metabisulfite allowed in the EU?
Potassium Metabisulfite EU regulatory status: restricted. This is based on EU Regulation 1223/2009 and its amendments.
What does Potassium Metabisulfite do in cosmetics?
Potassium Metabisulfite functions as: Reducing agent; Antioxidant; Preservative (hair waving/straightening systems). It is classified as a cosmetic ingredient in our database. CAS number: 16731-55-8.
Is Potassium Metabisulfite classified as hazardous under GHS?
Potassium Metabisulfite carries a GHS signal word of "DANGER". Hazard statements: Causes serious eye damage. This classification is based on the ILO/WHO International Chemical Safety Card and ECHA C&L inventory data. Note: GHS classification applies to the pure substance — at cosmetic use concentrations, hazard thresholds may not be met.
Is Potassium Metabisulfite used outside cosmetics?
Potassium Metabisulfite also appears in industrial chemical safety and pharmaceutical data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Does Potassium Metabisulfite have different safety status in cosmetics vs industrial chemicals?
Potassium Metabisulfite is classified GHS Danger (H315, H318, H335, H302) in the chemicals database but is restricted in EU cosmetics.
Compliance Tools
Check Potassium Metabisulfite compliance across multiple jurisdictions:
Ingredient Decoder
Paste a full ingredient list for instant analysis
82 Allergen Checker
Check for EU declarable fragrance allergens
Substance Compliance
Check compliance across multiple jurisdictions
MoS Calculator
Calculate Margin of Safety using SCCS methodology
Heavy Metal Limits
Compare limits across jurisdictions
Related Ingredients
Dipotassium EDTA
EXCELLENT
Same category
Chelating agent; preservative booster
Glyceryl Caprylate/Caprate
EXCELLENT
Same category
Emulsifier; Humectant; Softener and c...
Hexanediol (1,2-Hexanediol)
EXCELLENT
Same category
Solvent, humectant, emollient, preser...
Phenethyl Alcohol
EXCELLENT
Same category
Fragrance ingredient; preservative (a...
Polyepsilon-Lysine
EXCELLENT
Same category
Preservative (antimicrobial); hair co...
Sodium Lauriminodipropionate Tocopheryl Phosphate
EXCELLENT
Same category
Antistatic, cleansing, foaming, hair ...
(20S)-Protopanaxadiol
MODERATE
Similar safety
(Cnidium Officinale/Coptis Chinensis/Glycyrrhiza Uralensis) Root Extract
MODERATE
Similar safety
Skin conditioning
(Cryptomeria Japonica/Chamaecyparis Obtusa) Stem Ferment Extract
MODERATE
Similar safety
Antimicrobial, antioxidant, humectant
(Eclipta Prostrata/Houttuynia Cordata) Leaf Extract
MODERATE
Similar safety
Skin conditioning
(Lepidium Meyenii/Sarcodon Aspratus) Root Water
MODERATE
Similar safety
Skin conditioning
(Licorice/Reynoutria Japonica) Root/Stem Extract
MODERATE
Similar safety
Skin conditioning, antioxidant
POTASSIUM COCOYL (ARGININE/GLUTAMIC ACID/ISOLEUCINE/LEUCINE/LYSINE/PHENYLALANINE/PROLINE/THREONINE/VALINE)
GOOD
Browse nearby
Cleansing, Surfactant - Cleansing, Su...
POTASSIUM LAUROYL/OLIVOYL (ALANINE/ARGININE/ASPARAGINE/ASPARTIC ACID/GLUTAMIC ACID/LYCINE/ISOLEUCINE/LEUCINE/LYSINE/METHIONINE/PHENYLALANINE/PROLINE/SERINE/THREONINE/TRYPTOPHAN/TYROSINE/VALINE)
GOOD
Browse nearby
Cleansing, Skin Conditioning - Emolli...
POTASSIUM OLIVOYL (ALANINE/ARGININE/ASPARAGINE/ASPARTIC ACID/GLUTAMIC ACID/ GLYCINE/ISOLEUCINE/LEUCINE/LYSINE/METHIONINE/PHENYLALANINE/PROLINE/SERINE/THREONINE/TRYPTOPHAN/TYROSINE/VALINE)
GOOD
Browse nearby
Cleansing, Surfactant - Cleansing, Su...
Is Potassium Metabisulfite in Your Products?
Scan any product label with Piro — our free ingredient scanner. Point your camera at the ingredients list and get instant safety scores for every ingredient.
Try Piro Free →Analyze Your Full Ingredient List
Paste any INCI list into the Decoder for instant safety analysis, or calculate the Margin of Safety for Potassium Metabisulfite in your formulation.