Is Cyclotetrasiloxane safe in cosmetics?
Cyclotetrasiloxane has a safety rating of "POOR" in our database. EU status: restricted. US status: permitted. 10 toxicological study endpoint(s) are available in our database.
Cyclotetrasiloxane
Also known as: Cyclotetrasiloxane, octamethyl-, D4, BRN 1787074, EINECS 209-136-7, Silicone SF 1173 (+6 more)
INCI: CYCLOTETRASILOXANE
Cyclotetrasiloxane (CAS 556-67-2) is a cosmetic cosmetic ingredient functioning as solvent, volatile carrier, conditioning agent. NOAEL 17.8 mg/kg bw/day (PDF-verified against ToxValDB ECHA IUCLID); EU Regulation 1223/2009 status: restricted, max ≥0.1% w/w prohibited in all consumer and professional products under EU Reg 2024/1328; enforcement June 6, 2026. 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 556-67-2 →
Auto-generated CPSR Part A draft with source citations
Cross-Vertical Regulatory Divergence
Cyclotetrasiloxane is classified GHS CMR hazard (H226, H361, H413) in the chemicals database but is restricted in EU cosmetics at max ≥0.1% w/w prohibited in all consumer and professional products under EU Reg 2024/1328; enforcement June 6, 2026.
Source: Cosmetics: ingredients.eu_status/eu_max; Chemicals: ghs_classifications.signal_word/hazard_statement_code
Function
solvent, volatile carrier, conditioning agent
Safety Rating
POOR
Regulatory Status
EU EU Status
restricted
EU Max Conc.
≥0.1% w/w prohibited in all consumer and professional products under EU Reg 2024/1328; enforcement June 6, 2026
US US Status
permitted
US Notes
No FDA restriction; CIR has not flagged for human toxicity; no cyclomethicone ban in US as of 2026
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Cyclotetrasiloxane.
Calculate MoS for your specific formulation with the MoS Calculator.
Toxicological Studies
10 study endpoints found for Cyclotetrasiloxane. 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 | =0.1 mg/kg bw/day | dermal | rat | dermal absorption | SCCS_vision_codex |
| NOAEL | =0.1 mg/kg bw/day | dermal | rat | dermal absorption | SCCS_vision_codex |
| NOAEL | =0.1 mg/kg bw/day | dermal | rat | dermal absorption | SCCS_vision_codex |
| NOAEL | =0.1 mg/kg bw/day | dermal | rat | dermal absorption | SCCS_vision_codex |
| NOAEL | =0.2 mg/kg bw/day | oral | rat | NOAEL study | SCCS_vision_codex |
| NOAEL | =0.2 mg/kg bw/day | oral | rat | NOAEL study | SCCS_vision_codex |
| NOAEL | =0.2 mg/kg bw/day | oral | rat | NOAEL study | SCCS_vision_codex |
| NOAEL | =0.2 mg/kg bw/day | oral | rat | NOAEL study | SCCS_vision_codex |
| NOAEL | =17.8 mg/kg bw/day | oral | rat | NOAEL study | SCCS_vision_codex |
| NOAEL | =17.8 mg/kg bw/day | oral | rat | NOAEL study | SCCS_vision_codex |
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 of its vapour, through the skin and by ingestion.
Pre-Calculated Safety Assessment
Pre-calculated NOAEL → SED → MoS audit trail for Cyclotetrasiloxane across SCCS product categories, with measured dermal absorption where available.
EPA ToxValDB — Toxicity Values
9 toxicity values from EPA ToxValDB (aggregated from CCTE, HPV, ToxRefDB, IRIS, and other regulatory dossiers).
| Endpoint | Value | Species | Route | Duration | Source |
|---|---|---|---|---|---|
| LC50 | =36 mg/L | Rat | inhalation | - | ChemIDplus |
| LD50 | =754.3 mg/kg | Rabbit | dermal | - | ChemIDplus |
| LD50 | =1540 mg/kg | Rat | oral | - | ChemIDplus |
| LD50 | =1770 mg/kg | Rat | dermal | - | ChemIDplus |
| LEL | =250 mg/kg-day | Rat | oral | short-term | Uterotrophic Hershberger DB |
| LEL | =250 mg/kg-day | Mouse | oral | short-term | Uterotrophic Hershberger DB |
| LEL | =1000 mg/kg-day | Mouse | oral | short-term | Uterotrophic Hershberger DB |
| LEL | =849.212 mg/m3 | Rat | inhalation | chronic (developmental) | EPA TSCA 8e |
| LEL | =8492.12 mg/m3 | Rat | inhalation | chronic (developmental) | EPA TSCA 8e |
EU CLP Annex VI Harmonized Classification
Legally binding harmonized classification per Regulation (EC) No 1272/2008 (CLP) Annex VI.
Signal Word
Warning
Pictograms
Health HazardEnvironmental Hazard
Hazard Class and Category
Repr. 2; Aquatic Chronic 1
Hazard Statements
- H361f ***
- H410 Very toxic to aquatic life with long lasting effects
Specific Concentration Limits / M-factors
M = 10
Inserted via ATP: ATP15
Endocrine Disruptor Evidence (Expanded)
Cross-referenced EDC classifications, mechanism data, and dose-response evidence from EDLists, SIN List, and cosmetic-specific detail sources.
Suspected
Evidence: Moderate
(2020)
Health effects: Yes
Affected pathways: Estrogenic
Source list: III
Cosmetic-Specific Mechanism
Category: other
Receptor targets: ERα
LOEC: 1×10⁻⁵ M (10 µM, in vitro GH3 cells)
EU status: restricted (max 0.1% in rinse-off products)
weak agonist
Dose-Response Data Points
| Endpoint | Target | Value | Direction |
|---|---|---|---|
| dermal_SC_cumulative | skin | 27.5 µg/cm²/24h | - |
| dermal_epidermis_cumulative | skin | 6.4 µg/cm²/24h | - |
| dermal_absorption_range | skin | 0.1–8.1% % | - |
| Competitive ER binding; prolactin release from GH3 | ER | EC50/IC50: EC50 binding ~10^-5 M; GH3 prolactin response >=10 uM; LOEC: 10 uM; NOEC: 1 uM mixed | agonist (weak) |
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
10,000 - 100,000 tonnes
Substance Type
SUBSTANCE
SVHC Candidate
Yes (since 27-Jun-2018)
Hazard classification: Restricted (Annex XVII)
SVHC reason: PBT (Article 57d)
Substance of Very High Concern (SVHC)
Included: 27-Jun-2018
PBT (Article 57d); vPvB (Article 57e)
EU CosIng Annex Listing
European Commission CosIng database Annex references per Regulation (EC) No 1223/2009.
Annex II — Prohibited
Ref: 1388
(EU) 2019/831
CMR: Reprotoxic Cat. 2()
Expanded Jurisdictional Detail
Additional regulatory detail beyond the 7-jurisdiction summary: Saudi SFDA, Korea MFDS, ASEAN ACD, Japan/Korea, Brazil/India, and cross-jurisdictional restriction entries.
SA Saudi SFDA (II - Prohibited)
BRIN Brazil/India Cosmetics
India: Prohibited (GNRAS)
Additional Jurisdictional Restrictions (4)
| Jurisdiction | Status | Max % | Product Type |
|---|---|---|---|
| AU | restricted | 8.7 | cosmetics |
| ID | banned | - | All cosmetic products prohibited |
| ID | banned | 0% | All cosmetic products |
| TH | banned | 0% | All cosmetic products |
Expanded Dermal Absorption Data
Cross-database dermal penetration: EPA Dryad physics-based, Roberts Mendeley permeation, and SCCS-aggregated measured values.
Aggregated DA Values (1 records across 5 sources)
| Type | DA % | Method | Skin Model | SCCS Ref |
|---|---|---|---|---|
| measured_sccs_opinion | 0.94% | - | - | SCCP/0893/05 |
Additional Ingredient Properties
1 property record from structured ingredient metadata.
hair_care
{"hair_function": "conditioning", "hair_type_suitability": "fine/medium", "curl_pattern_suitability": "all", "porosity_suitability": "low", "protein_sensitivity": "neutral", "moisture_protein_balance": "no", "cg_method_approved": "non-water-soluble", "silicone_type": "not-a-sulfate", "sulfate_type": "no", "drying_alcohol": "no", "fatty_alcohol": "yes", "heat_protectant": "yes", "color_safe": "neut…
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Defoamer
Processing aids not otherwise specified
Solvent
Surfactant (surface active agent)
Wetting agent (non-aqueous)
Regulatory List Membership (3)
EU Banned in Cosmetics
EU Restricted for Children (Cosmetics)
EU CosIng Cosmetics Ingredient Database
Expert Verdict
Expert safety assessment and concern-level summary for Cyclotetrasiloxane.
Regulatory Flags
svhc
pbt
vpvb
endocrine-disruptor
eu-restricted-2026
reach-reg-2024-1328
reproductive-toxicant
bioaccumulative
environmental-hazard
volatile-silicone
cyclic-siloxane
pops-candidate
avoid
eu_banned_cosmetics
eu_children_restricted
eu_cosing_listed
NOAEL Studies Summary
View details ->Public NOAEL study rows linked to Cyclotetrasiloxane by CAS number or substance name.
Studies
36
Lowest NOAEL
0.1
Highest NOAEL
1600
Units vary across source rows: mg/kg, mg/kg bw, mg/kg bw/day
SCCS_vision_codex
Dermal Absorption
View details ->| Absorption % | Method | Vehicle |
|---|---|---|
| 0.94% | SCCS PDF direct extraction | - |
Known Synonyms
Cyclotetrasiloxane, octamethyl-
D4
BRN 1787074
EINECS 209-136-7
Silicone SF 1173
Oktamethylcyklotetrasiloxan
UNII-CZ227117JE
2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane
2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetroxatetrasilocane
Oktamethylzyklotetrasiloxan
cyclic dimethylsiloxane tetramer
Chemical Function
Solvent
Regulatory Lists
children; Europe; Personal care
inert_ingredient; non_food_use; Pesticides
detected; Europe; Personal care - general moisturizing - hand/body lotion; Personal care - sunscreen
Europe; Toys and children's products
detected; Europe; Other direct contact consumer goods; Toys and children's products
detected; Europe; Other direct contact consumer goods; Toys and children's products
consumer_product; Europe
Europe; Raw materials
Europe; Other direct contact consumer goods
children
children
Europe
banned; Europe; Personal care
Europe
detected; Toys and children's products
Arts and crafts/Office supplies - children's art and toys; detected
detected; Personal care - child specific; Toys and children's products
detected; Personal care
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.
ChEMBL ID
CHEMBL1869229
Frequently Asked Questions
Is Cyclotetrasiloxane allowed in the EU?
Cyclotetrasiloxane EU regulatory status: restricted. Maximum allowed concentration: ≥0.1% w/w prohibited in all consumer and professional products under EU Reg 2024/1328; enforcement June 6, 2026. This is based on EU Regulation 1223/2009 and its amendments.
What does Cyclotetrasiloxane do in cosmetics?
Cyclotetrasiloxane functions as: solvent, volatile carrier, conditioning agent. It is classified as a cosmetic ingredient in our database. CAS number: 556-67-2.
What is the NOAEL for Cyclotetrasiloxane?
The NOAEL (No Observed Adverse Effect Level) for Cyclotetrasiloxane is =0.1 mg/kg bw/day based on a dermal absorption study via dermal route in rat. A total of 10 study endpoints are available. Source: SCCS_vision_codex.
Is Cyclotetrasiloxane used outside cosmetics?
Cyclotetrasiloxane 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 Cyclotetrasiloxane have different safety status in cosmetics vs industrial chemicals?
Cyclotetrasiloxane is classified GHS CMR hazard (H226, H361, H413) in the chemicals database but is restricted in EU cosmetics at max ≥0.1% w/w prohibited in all consumer and professional products under EU Reg 2024/1328; enforcement June 6, 2026.
Compliance Tools
Check Cyclotetrasiloxane 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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