Octinoxate: Safety, absorption, free radical damage

Octinoxate (ethylhexyl methoxycinnamate or octyl methoxycinnamate) is a chemical commonly used in sunscreen, it’s one of the oldest sunscreen filters and it’s used to block UVB rays.

Oxtinoxate’s texture is like a transparent liquid making it perfectly suitable for “light-weight” sunscreens formula.

Octinoxate spectrum range and stability

Octinoxate can absorb UVB rays, it’s spectrum also cover a very little part of UVA rays, but that’s not sufficient and it needs to be combined together with other filters.

It is not photostable, so it degrades fastly at sunlight presence.

When octinoxate and avobenzone are combined in the same sunscreen they become more unstable (study) and they produce more free radical damage that it can persist even after the product exposure has stopped.

Octinoxate allergies and absorption

It’s well known that octinoxate is dangerous to some species of animals and it can definitely damage coral reefs, but what does science says about its effects on human?

Octinoxate can penetrate stratum corneum, several studies conclude that it persist in the body even after 24h of exposure. When it’s used during a week it has been reported that can be found in urine and inside human plasma. These studies also mention that octinoxate can also be found in human milk.

Fortunately, octinoxate poses a low risk of allergies and only a few photoallergic cases have been reported.

Octinoxate endocrine disruption

Octinoxate belongs to a chemical group called “cinnamates” which have been reported by several studies that they can alter our endocrine system in a negative way.

It can disrupt human estrogen receptors in vivo and in vitro and also showed anti-androgenic activity being able to decrease dihydrotestosterone activity.

Octinoxate can also disrupt thyroid hormone receptors posing a risk for neurological and reproductive development (that has been proven in rats).

Octinoxate and free radical damage

Even though octinoxate can prevent some sun induced DNA damage, when is exposed to sun it can produce carbon-centred and oxygen-centred free radical damage (study).