Triethoxycaprylylsilane
Also known as Triethoxy(octyl)silane, Octyltriethoxysilane, n-Octyltriethoxysilane
“CIR Expert Panel says: safe as used in cosmetics.”
Triethoxycaprylylsilane is primarily used as a surface modifier/coating agent for inorganic UV filters (TiO2, ZnO). The CIR Expert Panel reviewed the alkoxyl alkyl silane class in 2016 and concluded safe as cosmetic ingredients at current use concentrations (up to 2.6% in suntan products). A 2015 PLoS One study (PMID 25966284) examined pulmonary effects of triethoxycaprylylsilane-coated ZnO nanoparticles vs. uncoated ZnO in mice; the coating did not substantially attenuate acute pulmonary inflammatory responses at high instilled doses. Inhalation exposure data from the CIR report showed no deaths in rats exposed to saturated vapor at 248 mg/m³ for 4 hours. Dermal studies showed moderate-to-severe skin irritation at 100% concentration in rabbits, though cosmetic use concentrations are far lower. Genotoxicity assays (Ames, chromosome aberration) were negative.
Effective surface modifier and coating agent for inorganic UV filters (TiO2, ZnO), improving dispersibility and reducing photocatalytic activity
Functions as binder, skin-conditioning emollient, and surface modifier in cosmetics
Clear colorless liquid with low dermal penetration potential; expected to not penetrate significantly through intact skin
Genotoxicity assays (Ames test, chromosome aberration, mouse micronucleus) uniformly negative up to high test concentrations
- · Moderate-to-severe dermal irritation at 100% concentration in rabbit studies (PII 3.041, PDII 5.1); not relevant to cosmetic use concentrations
- · Inhalation of triethoxycaprylylsilane-coated ZnO nanoparticles induced local pulmonary inflammation in rats at high experimental doses; a NOAEC could not be established
- · Hydrolysis to ethanol (3 moles per mole) and octylsilanetriol expected in biological environments; cosmetic-level exposure considered negligible
- · Minor impurities: ethanol (0.2%), octane (<1.5%), siloxanes (<2%), branched octyltriethoxysilanes (<2%)
CIR Safety Assessment of Alkoxyl Alkyl Silanes as Used in Cosmetics (Tentative Report June 2016) — Triethoxycaprylylsilane: Finding=S; Pa…
“The Panel concluded that Bis-Stearoxydimethylsilane, Stearoxytrimethylsilane, Triethoxycaprylylsilane and Trimethoxycaprylylsilane are safe as cosmetic ingredients in the practices of use and concentration described in this safety assessment.”— alalsi062016Tent.pdf, p. 2