Octocrylene: Popular sunscreen ingredient found not as harmful on marine life as previously thought

11 Jul 2023 --- The paradoxical nature of sunscreen is well-documented, as the UV protection properties of certain ingredients can sometimes be overshadowed by potential health risks. In some cases, these compounds present a toxicity risk to marine life when dispersed into open water.

But new research reveals that environmental contamination by one particular ingredient, octocrylene – an organic UV filter featured widely in formulations – may be less detrimental to wildlife than previously thought.

Studying “chemical cocktails”
A study by Aaron Boyd, a PhD candidate at the University of Alberta in Edmonton, Canada, demonstrates how exposure to sunscreen is actually a low-risk for small aquatic animals, compared to some of the suncream’s individual chemicals.

Sunscreens contain ultraviolet filters (UVFs) which have been found to be toxic to marine life such as corals, leading to the ban of some UVFs in Hawaii and Palau. If sunscreen is applied to the skin before swimming in lakes and rivers, these UVFs and other chemicals will leach into surrounding waters.

Sunscreens contain ultraviolet filters (UVFs) which have been found to be toxic to marine life such as corals, leading to the ban of some UVFs in Hawaii and Palau.Boyd’s research investigates how the “chemical cocktail” in sunscreen interacts to affect marine life, instead of just focusing on the UVFs and other chemicals on their own.

“Researchers overwhelmingly perform studies testing the toxicity of UVFs in isolation by exposing test organisms to one chemical at a time,” says Boyd. “In fact, less than 3% of aquatic toxicology studies published to date have investigated whole sunscreen mixtures, leaving a massive knowledge gap to be addressed.”

Testing five different sunscreen mixtures
Boyd’s research compared the long-term toxicity of five different sunscreen mixtures, as well as their individual UVFs, on Daphnia water fleas. Daphnia are invertebrates that are commonly found in freshwater lakes throughout the world and are a good indicator of how pollution affects aquatic life.

“We were very surprised to find that sunscreen mixtures are much less toxic to water fleas than what would be expected based on the quantity of each UV filter present within the mixtures,” says Boyd.

“In fact, we found that Daphnia could survive long-term exposure to sunscreens containing octocrylene at concentrations >50 times higher than what would be completely lethal to all water fleas had they been exposed to the UVF alone.”

The rate at which new chemicals are developed and released into the environment is much faster than the rate at which scientists can properly study the consequences of contamination. “As a result,it’s important that we utilize our limited research resources effectively by identifying which contaminants are likely to cause harm to the environment, and which contaminants are lower risk,” says Boyd.

“We found that the other components of the sunscreen mixtures reduced the toxicity to such a large extent that perhaps these chemicals are not a contamination concern in most environments, allowing for us to reallocate our limited research resources towards identifying other contaminants that could be much more concerning,” says Boyd.

“This potentially indicates that the vast majority of studies investigating the toxicity of individual UV filters could be overestimating the toxicity of these chemicals in aquatic environments.”

Boyd still strongly recommends the use of sunscreen when spending time outdoors “regardless of any potential environmental toxicity of sunscreens.”

Developing safer alternative UV filters
Organic UV filters – avobenzone, octinoxate and oxybenzone – have been known to generate harmful by-products as they undergo photoreactive degradation in light, which ultimately poses a great threat to not only marine life but also the consumers using sunscreen products. 

Inorganic UV filters such as titanium dioxide and zinc oxide – although considered safer options – are not without threat, considering their photocatalytic nature and ability to generate reactive oxygen species, according to researchers writing in the journal Cosmetics.

Organic UV filters – avobenzone, octinoxate and oxybenzone – have been known to generate harmful by-products, but inorganic alternatives are not without threat.In a recent investigation of alternative UV filters, scientists tested how different metals affect the way certain materials absorb and use light. They looked at the functionality of layered double hydroxides, which are a class of materials with a layered crystal structure.

The researchers compared the light-absorbing properties of these materials to titanium dioxide and zinc oxide, which are commonly used in sunscreens. Among the three layered double hydroxides, zinc-titanium and zinc-aluminum were found to offer the properties that made them safer to use in cosmetics. 

Overall, the three three materials were found to absorb less light and had lower reactivity compared to zinc oxide and titanium dioxide.

The researchers also tested the sun protection effectiveness of the materials’ concentrations: one containing 2% Zinc-Titanium layered double hydroxides (LDH) the other with 2% zinc-aluminum LDH. 

The results “showed promise,” with both samples providing broad-spectrum protection and UVA protection. “This means they could potentially be used in sunscreens to protect the skin from harmful UV rays,” conclude the researchers.

Safe and functional sun care developments
In recent product launches targeting safer sun care, Australian manufacturer of natural sunscreen actives, Advance ZincTek, released EcoZinc. The non-nano zinc oxide powder is designed for reef-safe SPF-rated cosmetics and sunscreens. 

Korean original design manufacturer Cosmax also introduced Capsule Sun, an emulsifier-free sunscreen formula that avoids leaving a white cast. The solution evenly disperses large particle oil ingredients into an aqueous phase without emulsifiers. The product takes on a visible capsule form containing sunscreen ingredients “to ensure transparency.”

Meanwhile, Reef Relief, introduced a product that “goes further” than other sunscreens to not only protect coral reefs, but also feed and enrich them.

By Benjamin Ferrer