Why doesn't Typology use Ethylhexyl Methoxycinnamate?

The octinoxate is an organic ultraviolet filter commonly used in sun protection products. Its primary function is to absorb UVB rays (between 280 and 320 nm), which are responsible for sunburn and implicated in DNA alterations that lead to skin ageing and certain skin cancers. Thanks to its chemical structure derived from cinnamic acid, ethylhexyl methoxycinnamate works by capturing the energy of UV photons and dissipating it as harmless heat for the skin, thus reducing skin damage induced by sun exposure. This filter is liposoluble and therefore easily incorporated into the oily phases of cosmetic emulsions.

Octyl methoxycinnamate goes by several names but can be identified in sun care products by its INCI name "Ethylhexyl Methoxycinnamate".

From a regulatory standpoint, octinoxate is permitted as a UV filter in cosmetic products within the European Union, with a maximum concentration set at 10%. However, in the United States, it cannot be used at a concentration higher than 7.5%. Lastly, octinoxate is banned in certain parts of the world, such as Hawaii, due to its detrimental effects on marine wildlife and flora, particularly corals.

At Typology, we have made the decision not to use octinoxate in our sun care products because, in addition to posing environmental risks, there are several controversies surrounding its safety for human health.

Can ethylhexyl methoxycinnamate penetrate the skin barrier?

The ability of ethylhexyl methoxycinnamate to cross the skin barrier has been studied both in vitro and in vivo. A study conducted according to OECD standards on human skin ex vivo showed that this compound can cross the upper layers of the epidermis, but in a relatively limited way. In this experiment, a cosmetic formulation containing 10% radiolabelled octinoxate was applied at a dose of 2mg/cm² for 24 hours on healthy human skin taken during abdominal surgeries. After rinsing, the amount of filter that had penetrated the skin was estimated at 0.45% of the applied dose on average. This indicates a low but real percutaneous penetration capacity.

In vivo studies confirm that octyl methoxycinnamate can penetrate the skin barrier and reach the bloodstream. In a study conducted on 32 volunteers, including 15 men and 17 women, a sun formulation containing 10% ethylhexyl methoxycinnamate was applied to the entire body, four days a week for two weeks. The plasma concentrations of the molecule were measured between 3 and 4 hours after application, reaching up to 20 ng/mL in men and 10 ng/mL in women. Furthermore, octinoxate was found in the urine, at levels of 5 ng/mL in women and 8 ng/mL in men, attesting to a systemic absorption and urinary elimination of the compound.

It appears that octinoxate is not solely confined to the superficial layers of the epidermis after application, and its bioavailability is concerning, especially with regular use or in sensitive populations, such as the children.

Octinoxate, a potential endocrine disruptor?

Ethylhexyl methoxycinnamate is among the UV filters suspected of interfering with the endocrine system, due to converging observations obtained both in vitro and in vivo. Several studies, including one conducted on rats by the National Toxicology Program, have examined the impact of continuous exposure to octinoxate at different concentrations in the diet (1,000, 3,000, and 6,000 ppm). At the highest dose, a slight but significant increase in uterine weight, as well as a delay in balano-preputial separation and a decrease in ventral prostate weight were observed in second-generation males. However, no effect was noted on the anogenital distance or male reproductive performance, suggesting a partial and non-systematic action on the androgenic pathways.

Additional data from the Danish Environmental Protection Agency reinforces these conclusions. Studies on rats have revealed alterations to the reproductive system, such as reductions in sperm count in offspring exposed during gestation and the postnatal period. At higher doses, octinoxate also induced changes in uterine histology and an overexpression of uterine genes sensitive to oestrogens. Effects on thyroid function were also observed, with a decrease in the level of thyroxine, a thyroid hormone, in male rats fed for five days at 100 mg/kg/day.

As of now, the Scientific Committee on Consumer Safety (SCCS) regards octinoxate as an active endocrine substance due to its oestrogenic activity and low anti-androgenic activity in vitro and in vivo.

Does octyl methoxycinnamate pose risks to the environment?

Octinoxate, along with other organic sun filters such as avobenzone or octocrylene, is regularly detected in fresh and marine waters worldwide. These substances, which are not easily biodegradable, tend to accumulate in aquatic ecosystems, particularly in summer and in tourist areas with high population density. Moreover, several studies conducted in Hawaii have shown the frequent presence of chemical filters, including octinoxate, in corals. This contamination is associated with coral reef bleaching phenomena. In the long run, this compromises the resilience of corals to climate change and hinders their regeneration capacity.

Octinoxate has also been found repeatedly in various marine species, including fish (perch, cod, trout, etc) and molluscs. Organic UV filters can accumulate in tissues, particularly in the liver, as observed in a study conducted by Schneider in 2019, where octocrylene was dominant, followed by oxybenzone and then ethylhexyl methoxycinnamate. This can lead to disruptions in reproductive functions, abnormal development of the liver and brain in fish, and behavioural alterations in certain aquatic invertebrates.

In response to the ecological impact of octinoxate, some regions of the world, such as Hawaii, the US Virgin Islands, and the city of Key West in Florida, have decided to ban the use of sun protection products containing this filter within their territories.

• OLASZ HARKEN E. & al. Update About the Effects of the Sunscreen Ingredients Oxybenzone and Octinoxate on Humans and the Environment. Plastic Surgical Nursing (2018).

• NETCHIPOROUK E. & al. Hawaii and Other Jurisdictions Ban Oxybenzone or Octinoxate Sunscreens Based on the Confirmed Adverse Environmental Effects of Sunscreen Ingredients on Aquatic Environments. Journal of Cutaneous Medicine and Surgery (2019).

• ADLER B. L. & al. Sunscreen Safety: a Review of Recent Studies on Humans and the Environment. Current Dermatology Reports (2020).

• LIM H. W. & al. Sunscreen: FDA regulation, and environmental and health impact. Photochemical & Photobiological Sciences (2020).

• Scientific Committee on Consumer Safety (SCCS). Opinion on Ethylhexyl Methoxycinnamate (2024).