Common Name(s): Nonyl nonoxynol-49,ethoxylated nonylphenol,eu-restricted legacy nonionic

CAS Number: N/a

DESCRIPTION

What It Does: Nonyl nonoxynol-49 emulsifies oils in water and solubilises lipophilic materials through nonionic micelle formation, with the 49-eo chain providing hydrophilicity balanced by the nonylphenyl hydrophobe for o/w emulsification tendency and excellent wetting on low-energy surfaces.

Why It's Used: Formulators historically chose nonyl nonoxynol ethoxylates for their excellent wetting performance on industrial substrates and robust emulsification. in modern cosmetic formulation, however, they must be avoided in rinse-off consumer products (eu regulation 2003/53/ec restricts npe >0.1% in rinse-off formulations) due to the estrogenic activity of nonylphenol — the primary environmental biodegradation metabolite. sustainable alternatives include alkyl polyglucosides (cosmos-approved), linear c12–15 alcohol ethoxylates, or eo/po block copolymers that provide equivalent emulsification without the environmental endocrine-disruption concern.

How It Works: Nonyl nonoxynol-49 functions as a nonionic surfactant through the branched nonylphenyl hydrophobe anchoring into oil droplets while the 49-unit polyethylene oxide chain extends into the water phase — the classic nonionic micelle structure. the restriction arises not from the npe molecule itself but from its biodegradation: environmental esterases cleave the eo chain progressively, generating shorter-chain npes and ultimately nonylphenol (np), which is highly lipophilic (logp 4.5), bioaccumulates, and activates estrogen receptor α (ec50 ~0.2 μm) causing reproductive disruption in aquatic organisms. the intact npe has low estrogenicity; its metabolite np drives the regulatory concern.

Typically Found In: Legacy industrial applications (check eu regulations for consumer use)

TECHNICAL DETAILS

Primary Category: Active ingredient – cosmetic active

Secondary Functions: Skin conditioning

Application Areas:

Typical Concentration Range: Up to 0.1% eu rinse-off

SOURCING & ETHICS

Vegan Status: Conditional - supplier confirmation required

Halal Status: Unverified - supplier confirmation required

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier. [audit 2026-07-29 rev2: the record's own source_notes does not assert a non-animal origin, or instructs the reader to verify with the supplier; "yes" asserts knowledge the record does not hold. determination requires shariah-panel sign-off.]

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Np endocrine mechanism: nonylphenol docks into the ligand-binding domain of erα through hydrophobic interactions of its 4-hydroxyphenyl group in the estrogen-binding pocket (k_d ~0.2 μm vs estradiol k_d ~0.1 nm — np is ~2000× weaker but environmentally persistent and bioaccumulating). at environmental concentrations of ppb in river water, chronic low-level erα activation causes intersex fish (vitellogenin production in male fish), measurably impacting aquatic reproductive biology downstream of industrial discharge.

Last Verified: 2026-03-12

Primary Sources: Cosing database,eu regulation 2003/53/ec nonylphenol restriction,np endocrine review