Is Mercuric Oxide safe in cosmetics?
Mercuric Oxide has a safety rating of "MODERATE" in our database. EU status: prohibited. US status: prohibited.
Mercuric Oxide
Also known as: Mercury(II) oxide, Mercury oxide (HgO), Caswell No. 544A, EPA Pesticide Chemical Code 052102, Gelbes quecksilberoxyd (+10 more)
INCI: MERCURIC OXIDE
Mercuric Oxide (CAS 21908-53-2) is a cosmetic cosmetic ingredient functioning as Historically used as an antimicrobial/preservative and in skin-lightening. EU Regulation 1223/2009 status: prohibited; 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 data.
View industrial chemical safety profile for CAS 21908-53-2 →
Auto-generated CPSR Part A draft with source citations
Cross-Vertical Regulatory Divergence
Mercuric Oxide is prohibited in EU cosmetics but has active industrial GHS classifications (H315, H317, H319, H335, H360, H370, H300, H311).
Source: Cosmetics: ingredients.eu_status; Chemicals: ghs_classifications.signal_word/hazard_statement_code
Function
Historically used as an antimicrobial/preservative and in skin-lightening formulations. No legitimate current cosmetic function.
Safety Rating
MODERATE
Chemistry & Identifiers
IUPAC Name
oxomercury
InChIKey
UKWHYYKOEPRTIC-UHFFFAOYSA-N
Regulatory Status
EU EU Status
prohibited
US US Status
prohibited
US Notes
PROHIBITED - 21 CFR 700.13 bans mercury compounds in cosmetics. An extremely narrow exception exists for mercury-based preservatives in eye-area cosmetics at <65 ppm mercury (calculated as metal), and only where no effective and safe alternative preservative is available - but this exception does not apply to mercuric oxide as a functional ingredient.
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Mercuric Oxide.
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
SkullToxicCancerHealth hazEnviroAqua
Hazard Statements
Fatal if swallowed Toxic in contact with skin May cause damage to kidneys May cause damage to nervous system and kidneys through prolonged or repeated exposure Very toxic to aquatic life with long lasting effects
Short-term Exposure Effects
The substance is mildly irritating to the eyes, skin and respiratory tract. The substance may cause effects on the kidneys. Medical observation is indicated.
Long-term Exposure Effects
The substance may have effects on the kidneys, central nervous system and peripheral nervous system. This may result in ataxia, sensory and memory disturbances, tremors, muscle weakness and kidney impairment.
Routes of Exposure
The substance can be absorbed into the body by inhalation of its aerosol, through the skin and by ingestion.
PubChem Annotations
Safety and regulatory annotations from PubChem (NCBI) aggregated sources.
Safety (3)
Carcinogen Classification
3, not classifiable as to its carcinogenicity to humans. (L135)
Source: Toxin and Toxin Target Database (T3DB)
Evidence for Carcinogenicity
A4: Not classifiable as a human carcinogen. /Mercury, elemental and inorganic forms, as Hg/
Source: Hazardous Substances Data Bank (HSDB)
ICSC Safety Card
0981
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Biocide
Expert Verdict
Expert safety assessment and concern-level summary for Mercuric Oxide.
Regulatory Flags
preservative
Known Synonyms
Mercury(II) oxide
Mercury oxide (HgO)
Caswell No. 544A
EPA Pesticide Chemical Code 052102
Gelbes quecksilberoxyd
Hydrargyrum oxid flav
Natural montroydite
Oxide mercurique jaune
Oxido amarillo de mercurio
Red oxide of mercury
Red Precipitate
Yellow oxide of mercury
Hydrargyrum oxydatum rubrum
Oxyde de mercure
Oxyde mercurique
Chemical Function
Biocide
Regulatory Lists
active_ingredient; Europe; Pesticides
Australian Status
AICIS status: listed
Frequently Asked Questions
Is Mercuric Oxide allowed in the EU?
Mercuric Oxide EU regulatory status: prohibited. This is based on EU Regulation 1223/2009 and its amendments.
What does Mercuric Oxide do in cosmetics?
Mercuric Oxide functions as: Historically used as an antimicrobial/preservative and in skin-lightening formulations. No legitimate current cosmetic function.. It is classified as a cosmetic ingredient in our database. CAS number: 21908-53-2.
Is Mercuric Oxide classified as hazardous under GHS?
Mercuric Oxide carries a GHS signal word of "DANGER". Hazard statements: Fatal if swallowed Toxic in contact with skin May cause damage to kidneys May cause damage to nervous system and kidneys through prolonged or repeated exposure Very toxic to aquatic life with long lasting effects. 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 Mercuric Oxide used outside cosmetics?
Mercuric Oxide also appears in industrial chemical safety data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Does Mercuric Oxide have different safety status in cosmetics vs industrial chemicals?
Mercuric Oxide is prohibited in EU cosmetics but has active industrial GHS classifications (H315, H317, H319, H335, H360, H370, H300, H311).
Compliance Tools
Check Mercuric Oxide compliance across multiple jurisdictions:
Ingredient Decoder
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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
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