Octinoxate (6.8%)
Ethylhexyl Methoxycinnamate (also known as Octinoxate or Octyl Methoxycinnamate) is the ester of 2-ethylhexyl alcohol and methoxycinnamic acid (CAS #5466-77-3). It is a clear, oil-soluble liquid and the most commonly used chemical sunscreen ingredient worldwide. It absorbs UVB radiation in the 280–320 nm range with peak protection at 310 nm, but provides no UVA protection. It is permitted up to 10% in the EU and up to 7.5% in the US; the formula being evaluated here is used at 6.8%.
Effectively absorbs UVB radiation (280–320 nm), helping to protect skin from UVB-induced damage. It is cosmetically elegant and widely available, making it a practical UVB filter in many formulations. It is considered "safe as used" by regulatory bodies when formulated within permitted concentrations.
Provides UVB protection only — must be combined with UVA filters for broad-spectrum coverage. It is photounstable and can lose approximately 10% of its SPF efficacy within 35 minutes of sun exposure; pairing with stabilizers such as Tinosorb S is recommended. In vitro and animal studies have indicated potential estrogen-like (hormonal) activity; while not confirmed under real-life human conditions, pregnant individuals and children under 2 years old are advised to opt for physical sunscreens (zinc oxide/titanium dioxide) or newer-generation filters as a precaution.
