Is Aluminum Hydroxide safe in cosmetics?
Aluminum Hydroxide has a safety rating of "GOOD" in our database. EU status: permitted. US status: permitted. 2 toxicological study endpoint(s) are available in our database.
Aluminum Hydroxide
Also known as: Al(OH)3, Alum, Aluminum hydroxide (Al(OH)3), Aluminum(III) hydroxide, British aluminum AF 260 (+6 more)
INCI: ALUMINUM HYDROXIDE
Aluminum Hydroxide (CAS 21645-51-2) is a cosmetic cosmetic ingredient functioning as Opacifying, Skin Protecting, Viscosity Controlling, Buffering, Pigment Coating. Reported NOAEL =92 mg/kg bw/day in Mouse (ToxValDB_ECHA_IUCLID); EU Regulation 1223/2009 status: permitted, max Category-specific elemental aluminum limits per SCCS/1662/23. 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 21645-51-2 →
Auto-generated CPSR Part A draft with source citations
Function
Opacifying, Skin Protecting, Viscosity Controlling, Buffering, Pigment Coating
Safety Rating
GOOD
Chemistry & Identifiers
IUPAC Name
aluminum trihydroxide
InChIKey
WNROFYMDJYEPJX-UHFFFAOYSA-K
Regulatory Status
EU EU Status
permitted
EU Max Conc.
Category-specific elemental aluminum limits per SCCS/1662/23
US US Status
permitted
US Notes
CIR concluded safe (2014). GRAS as direct food additive. OTC skin protectant at 0.15-5%. Approved substrate for aluminum lake colorants.
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Aluminum Hydroxide.
Calculate MoS for your specific formulation with the MoS Calculator.
Toxicological Studies
2 study endpoints found for Aluminum Hydroxide. NOAEL (No Observed Adverse Effect Level) values are used to calculate the Margin of Safety per SCCS methodology.
| Endpoint | Value | Route | Species | Study Type | Source |
|---|---|---|---|---|---|
| NOAEL | =92 mg/kg bw/day | oral | Mouse | reproduction developmental | ToxValDB_ECHA_IUCLID |
| NOAEL | =266 mg/kg bw/day | oral | Rat | reproduction developmental | ToxValDB_ECHA_IUCLID |
GHS Hazard Classification
Globally Harmonized System classification per ECHA C&L inventory and ILO/WHO International Chemical Safety Cards.
Routes of Exposure
The substance can be absorbed into the body by inhalation.
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
1,000,000 - 10,000,000 tonnes
Substance Type
SUBSTANCE
SVHC Candidate
No
Additional Ingredient Properties
2 property records from structured ingredient metadata.
acne
{"cas_number": "21645-51-2", "anti_acne_mechanism": "anti_inflammatory", "comedogenicity_rating_0_to_5": "0", "acne_type_efficacy": "inflammatory/non_inflammatory", "sebum_reduction_pct_clinical": "5-15", "prescription_required_usa": "No", "otc_drug_monograph_category": "No", "max_otc_concentration_pct": "No limit", "japan_quasi_drug_anti_acne": "No", "korea_functional_cosmetic_acne": "No", "eu_co…
mineral_clay
{"cas_number": "21645-51-2", "ingredient_class": "other", "chemical_formula": "Al(OH)3", "mineral_origin": "synthetic", "particle_size_range_um": "0.5-10", "surface_area_m2_per_g": "5-20", "crystal_structure": "hexagonal", "color_appearance": "white", "opacity": "opaque", "refractive_index": "1.57", "oil_absorption_g_per_100g": "40-80", "water_absorption_capacity": "80-150%", "surface_charge_at_pH…
PubChem Annotations
Safety and regulatory annotations from PubChem (NCBI) aggregated sources.
Safety (4)
Carcinogen Classification
Not listed by IARC. IARC classified aluminum production as carcinogenic to humans (Group 1), but did not implicate aluminum itself as a human carcinogen. (L135) A link between use of aluminum-containing antiperspirants and increased risk of breast cancer has been proposed (A235), but studies have not been able to establish a clear link (A15468).
Source: Toxin and Toxin Target Database (T3DB)
Evidence for Carcinogenicity
A4: Not classifiable as a human carcinogen. /Aluminum metal and insouble compound/
Source: Hazardous Substances Data Bank (HSDB)
ICSC Safety Card
0373
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Skin Eye Respiratory Irritation
Irritation of the eyes has been noted in patients who have been exposed /to aluminum alkyls/. /Aluminum alkyls/ | Irritation skin, respiratory system.
Source: Hazardous Substances Data Bank (HSDB)
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Adhesion/cohesion promoter
Binder
Catalyst
Conductive agent
Degradant/impurity
Dye
Filler
Flame retardant
Humectant
No specific technical function
Regulatory List Membership (2)
EU Regulated in Personal Care
FDA Substances Added to Food (EAFUS)
Expert Verdict
Expert safety assessment and concern-level summary for Aluminum Hydroxide.
Regulatory Flags
fda_food_additive
NOAEL Studies Summary
View details ->Public NOAEL study rows linked to Aluminum Hydroxide by CAS number or substance name.
Studies
2
Lowest NOAEL
92 mg/kg bw/day
Highest NOAEL
266 mg/kg bw/day
ToxValDB_ECHA_IUCLID
Known Synonyms
Al(OH)3
Alum
Aluminum hydroxide (Al(OH)3)
Aluminum(III) hydroxide
British aluminum AF 260
EINECS 244-492-7
Martinal
Trihydrated alumina
Alugelibye
UNII-5QB0T2IUN0
Aluminum hydroxide, dried
Chemical Function
Humectant
Softener and conditioner
Viscosity modifier
Opacifer
Regulatory Lists
drinking_water; Europe; manufacturing; plastic_additive
active_ingredient; animal_products; Europe; pharmaceutical; residue
Europe; plastic_additive
Arts and crafts/Office supplies - general arts and crafts supplies - arts and crafts paint; Europe
inert_ingredient; Pesticides
Europe; Personal care
Europe; Personal care
food_additive; Substances Added to Food (formerly EAFUS) (2/2019)
Canada; pharmaceutical
Canada; pharmaceutical
inert_ingredient; non_food_use; Pesticides
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
ALUMINUM HYDROXIDE
ChEMBL ID
CHEMBL1200706
Max Phase
4
Adverse Event Associations
888
Frequently Asked Questions
Is Aluminum Hydroxide allowed in the EU?
Aluminum Hydroxide EU regulatory status: permitted. Maximum allowed concentration: Category-specific elemental aluminum limits per SCCS/1662/23. This is based on EU Regulation 1223/2009 and its amendments.
What does Aluminum Hydroxide do in cosmetics?
Aluminum Hydroxide functions as: Opacifying, Skin Protecting, Viscosity Controlling, Buffering, Pigment Coating. It is classified as a cosmetic ingredient in our database. CAS number: 21645-51-2.
What is the NOAEL for Aluminum Hydroxide?
The NOAEL (No Observed Adverse Effect Level) for Aluminum Hydroxide is =92 mg/kg bw/day based on a reproduction developmental study via oral route in Mouse. A total of 2 study endpoints are available. Source: ToxValDB_ECHA_IUCLID.
Is Aluminum Hydroxide used outside cosmetics?
Aluminum Hydroxide 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.
Compliance Tools
Check Aluminum Hydroxide 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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