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.
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
Editorial assessment
POOR
Preliminary editorial note — not a computed safety verdict.
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)
Editorial summary
Preliminary editorial summary for Thorium Dioxide — not a computed safety verdict. See the sourced toxicological data above.
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
Related Ingredients
Acrylates/Vinyl Neodecanoate Crosspolymer
EXCELLENT
Same category
Emulsion stabilising, film forming
Adipic Acid
EXCELLENT
Same category
Buffering
Aluminum Magnesium Oxide
EXCELLENT
Same category
Absorbent, bulking agent, opacifying ...
Ammonium VA/Acrylates Copolymer
EXCELLENT
Same category
Antistatic, binding, film forming, ha...
Ammonium VA/Crotonic Acid Copolymer
EXCELLENT
Same category
Antistatic, film forming, hair fixing...
Aphanothece Sacrum Polysaccharide
EXCELLENT
Same category
Absorbent, emulsion stabilising, film...
1,2,4-Benzenetriacetate
POOR
Similar safety
Hair dye precursor (triacetyl ester o...
1,2,4-Trihydroxybenzene
POOR
Similar safety
Hair colorant (auto-oxidative dye)
1,4-Butanediol
POOR
Similar safety
Solvent, humectant, viscosity control...
1-Nitropropane
POOR
Similar safety
None in cosmetics - industrial solven...
2,3-Epoxypropyl Cocodimonium Chloride
POOR
Similar safety
Antistatic / hair conditioning agent ...
2,3-Epoxypropyl Lauryldimonium Chloride
POOR
Similar safety
Antistatic / hair conditioning agent ...
CI 77947 (Zinc Oxide)
GOOD
Chemical family
Colorant; UV Filter; Skin Protectant....
Nano Zinc Oxide
GOOD
Chemical family
UV Filter
Phosphorus Pentoxide
MODERATE
Chemical family
Catalyst; Chelating agent; Flame reta...
Is Thorium Dioxide 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 Thorium Dioxide in your formulation.