Is Thorium Dioxide safe in cosmetics?
Thorium Dioxide has a safety rating of "POOR" in our database. EU status: prohibited. US status: prohibited.
Poor
Cosmetic Ingredient
Thorium Dioxide
Also known as: EINECS 215-225-1, Thorianite, Thorium anhydride, Thortrast, Thorium-232 dioxide (+3 more)
INCI: THORIUM DIOXIDE — NO COSMETIC INCI (RADIOACTIVE SUBSTANCE)
Thorium Dioxide (CAS 1314-20-1) is a cosmetic cosmetic ingredient functioning as Historically used as X-ray contrast agent (Thorotrast); no legitimate cosmetic. EU Regulation 1223/2009 status: prohibited. 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 1314-20-1 →
Auto-generated CPSR Part A draft with source citations
Cross-Vertical Regulatory Divergence
Thorium Dioxide is prohibited in EU cosmetics but has active industrial GHS classifications (H301, H311, H331, H350, H373).
Source: Cosmetics: ingredients.eu_status; Chemicals: ghs_classifications.signal_word/hazard_statement_code
Function
Historically used as X-ray contrast agent (Thorotrast); no legitimate cosmetic function
Safety Rating
POOR
Chemistry & Identifiers
IUPAC Name
dioxothorium
InChIKey
ZCUFMDLYAMJYST-UHFFFAOYSA-N
Regulatory Status
EU EU Status
prohibited
US US Status
prohibited
US Notes
Prohibited — radioactive material; regulated under NRC. FDA withdrew Thorotrast from medical use decades ago
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Thorium Dioxide.
Calculate MoS for your specific formulation with the MoS Calculator.
PubChem Annotations
Safety and regulatory annotations from PubChem (NCBI) aggregated sources.
Safety (1)
Evidence for Carcinogenicity
Thorium Dioxide: known to be a human carcinogen. /Ionizing Radiation: Thorium Dioxide/
Source: Hazardous Substances Data Bank (HSDB)
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Binder
Softener and conditioner
Regulatory List Membership (1)
California Proposition 65 (OEHHA)
Expert Verdict
Expert safety assessment and concern-level summary for Thorium Dioxide.
Regulatory Flags
prop65
Known Synonyms
EINECS 215-225-1
Thorianite
Thorium anhydride
Thortrast
Thorium-232 dioxide
UNII-9XA7X17UQC
ThO2
thoria
Chemical Function
Softener and conditioner
Binder
Regulatory Lists
OEHHA Proposition 65 (3/2019)
OEHHA Proposition 65 (1/2023)
Australian Status
AICIS status: listed
Frequently Asked Questions
Is Thorium Dioxide allowed in the EU?
Thorium Dioxide EU regulatory status: prohibited. This is based on EU Regulation 1223/2009 and its amendments.
What does Thorium Dioxide do in cosmetics?
Thorium Dioxide functions as: Historically used as X-ray contrast agent (Thorotrast); no legitimate cosmetic function. It is classified as a cosmetic ingredient in our database. CAS number: 1314-20-1.
Is Thorium Dioxide used outside cosmetics?
Thorium Dioxide also appears in industrial chemical safety data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Does Thorium Dioxide have different safety status in cosmetics vs industrial chemicals?
Thorium Dioxide is prohibited in EU cosmetics but has active industrial GHS classifications (H301, H311, H331, H350, H373).
Compliance Tools
Check Thorium Dioxide 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
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