Octinoxate
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 not highly photostable on its own, losing approximately 10% of its SPF protection ability within 35 minutes of sun exposure.
Provides effective UVB protection (280–320 nm), making it a widely used and cosmetically elegant sunscreen agent. It is permitted up to 10% in the EU and 7.5% in the US, and is considered "safe as used" by regulatory bodies. Photostability and broad-spectrum coverage can be improved when combined with other sunscreen agents such as Tinosorb S.
In vitro and animal studies suggest potential hormonal (estrogen-like / estrogenic) effects; while these were not conducted under real-life human conditions, caution is advised for pregnant individuals and children under 2 years old, who may prefer physical sunscreens (zinc oxide/titanium dioxide) or Tinosorb-based alternatives. Not photostable on its own — should be combined with other sunscreen agents for stable, broad-spectrum protection. Does not protect against UVA rays.
