Ingredient Dictionary

CYCLOPENTASILOXANE

Decamethylcyclopentasiloxane is an organosilicon compound.

How much products actually contain

No product states its amount yet.

Of the products containing it, 1,031 list it before the 1% line and 95 after it (usually 1% or less).

Products using this ingredient

12 of 1,088 confirmed · likeliest to carry enough first · See all 1,088

Definition

Decamethylcyclopentasiloxane is an organosilicon compound.

Source: PubChem

US FDA substance register · UNII 0THT5PCI0R · registered name CYCLOMETHICONE 5 · single chemical substance

Source: US FDA Unique Ingredient Identifier (UNII)

Cyclopentasiloxane is the cyclic dimethyl polysiloxane that conforms to the formula:

Cosmetic roles

Makes skin soft and smoothSKIN CONDITIONING - EMOLLIENTBase that dissolves other ingredientsSOLVENTKeeps skin in good condition (CosIng catch-all)SKIN CONDITIONINGSoftens hairHAIR CONDITIONING

Safety & regulatory references

Not classified under Korea’s toxic-substance GHS list · existing chemical substance · priority-management substance

Source: Korea toxic substances GHS register (NIER)

Restriction Restricted under COMMISSION REGULATION (EU) 2024/1328. 1. Shall not be placed on the market (a) as a substance on its own; (b) as a constituent of other substances; or (c) in mixtures; in a concentration equal to or greater than 0,1 % by weight of the respective substance after 6 June 2026. [...] 3. By way of derogation: (a) for D4 and D5 in wash-off cosmetic products, paragraph 1, point (c), shall apply after 31 January 2020. For the purposes of this point, “wash-off cosmetic products” means cosmetic products as defined in Article 2(1), point (a), of Regulation (EC) No 1223/2009 of the European Parliament and of the Council (*1) that, under normal conditions of use, are washed off with water after application; (b) for all cosmetic products other than the ones mentioned in paragraph 3(a), paragraph 1 shall apply after 6 June 2027. · SCCS opinion: Opinion on Cyclomethicone: D4 and D5; OPINION ON decamethylcyclopentasiloxane (cyclopentasiloxane, D5) in cosmetic products

Source: EU CosIng ingredient list

Reviewed by CIR: Safety assessment of Cyclomethicone, Cyclotetrasiloxane, Cyclopentasiloxane, Cyclohexasiloxane and Cycloheptasiloxane

Source: US Cosmetic Ingredient Review (CIR)

More data — names, identifiers, properties, test records, literature

Official labels & definitions

JCIA labelling name シクロペンタシロキサン: 本品は、環状ポリシロキサンで、次の化学式で表される。

Source: JCIA labelling names (Japan)

Names & identifiers

CYCLOPENTASILOXANEINCI사이클로펜타실록세인Korean label name (MFDS standard)Cyclopentasiloxane, 2,2,4,4,6,6,8,8,10,10-decamethyl-SynonymシクロペンタシロキサンJapanese labelling name

CAS No.chemical registry number: 541-02-6
EC No.EU chemical inventory number: 208-764-9
DTXSIDUS EPA chemical ID: DTXSID1027184
DTXCIDUS EPA compound ID: DTXCID907184

IUPAC: 2,2,4,4,6,6,8,8,10,10-Decamethyl-1,3,5,7,9,2,4,6,8,10-pentoxapentasilecane
Molecular formula: C10H30O5Si5
Molecular weight: 370.77 g/mol

Measured properties

Appearance: CBI, Liquid · Colorless volatile liquid, [Merck Index]
Boiling point: 210 °C
Melting point: -38 °C
Solubility: In water, 1.7X10-2 mg/L at 25 °C
Density: 0.9593 g/cu cm at 20 °C
Stability: Stable under recommended storage conditions.
Viscosity: 3.9 cSt at 25 °C
Melting/freezing point: -38 ℃
Initial boiling point and range: 210 ℃
Flash point: 77 ℃
Vapour pressure: 0.2 ㎜Hg
Water solubility: 0.24 ㎎/ℓ
Relative density: 0.9593
n-Octanol/water partition coefficient (Kow): 5.20
Molecular weight: 370.77

Values measured on the substance itself. The KOSHA data are a reference for writing and reviewing safety data sheets, not a specification for a commercial raw material.

Source: PubChem · KOSHA safety data sheets (Korea)

What products actually use it for

What the 256 products reported to the US EPA with this ingredient use it for. Products outside cosmetics are included, so the top few rows are its main uses.

Solvent115
Softener and conditioner92
Lubricating agent12
Emulsifier10
Surface modifier6
Intermediate3
Viscosity modifier3
Degradant/impurity (EPA)3

7 other uses

Diluent3
Film former3
Fragrance2
Anti-adhesive/cohesive1
Terminator/blocker1
Cleaning agent1
Processing aids not otherwise specified1

Source: US EPA CompTox dashboard

Irritation and sensitisation studies

5 skin studies and 2 eye studies are on record.

Classed as low4

The study conclusions largely agree (100%). These tests are on the raw material itself; irritation at the amount in a finished product is a different question.

See all 7 studies

Classification not possible
Skin Irritation · Screening
Not likely to be sensitizing
skin sensitisation: in vivo (LLNA) · Screening · equivalent or similar to OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Studies Indicate No Significant Irritation
skin irritation: in vivo · Screening · OECD Guideline 404 (Acute Dermal Irritation / Corrosion) equivalent or similar to
Classification not possible
Skin Sensitization · Screening
Studies Indicate No Significant Irritation
skin irritation: in vivo · Screening · other guideline: Federal Regulations Title 16, Section 1500.41 according to
Studies Indicate No Significant Irritation
eye irritation: in vivo · Screening · OECD Guideline 405 (Acute Eye Irritation / Corrosion) equivalent or similar to
Not classified
Eye Irritation · Screening