Designing a More Environmentally Friendly Sunscreen

Scientists are sourcing new ultraviolet ray-blocking compounds from algae, seaweed, cyanobacteria and other marine creatures

sunscreen
Some chemical compounds used in sunscreens, such as oxybenzone and octinoxate, are facing scrutiny from legislators and environmental advocates. Scientists are looking to the ultraviolet light-blocking compounds produced by marine organisms as potential replacements. Kittiphan Teerawattanakul/EyeEm/Getty Images

In 2016, Craig Downs, an ecotoxicologist at Haereticus Environmental Laboratory, stepped in front of an audience at a scientific symposium in Honolulu, Hawai‘i, to present his and his colleagues’ finding: oxybenzone, a common ultraviolet (UV) ray–blocking ingredient in sunscreens, disrupts larval coral and makes reefs more susceptible to bleaching. The announcement caused what had been a ripple of concern around sunscreen safety to turn into a tidal wave.

“Dr. Downs’s study,” says Senator Mike Gabbard of Hawai‘i, “was basically a catalyst for an international movement to ban the sale of sunscreens that contain oxybenzone.” Gabbard joined grassroots efforts against sunscreen pollution, and introduced legislation banning oxybenzone and octinoxate in Hawai‘i. Jurisdictions worldwide, from Aruba to Taiwan, have since passed similar laws.

But legislators’ scrutiny of sunscreen chemistry didn’t stop there. In December 2021, Maui cracked down even further: the island will now only allow sunscreens that use UV ray filters that are included on the list of substances generally recognized as safe by the US Food and Drug Administration (FDA). The FDA is also tightening the reigns—the agency is proposing more rigorous criteria that could eventually see many current UV ray filters banned.

The attention has fueled the scientists searching for the next generation of sunscreens—ones that are more environmentally friendly and, potentially, more effective. The search has them looking below the glittering surface of the ocean to the animals that naturally filter harsh sunlight with their own potent UV-absorbing shields.

One of the most well-studied classes of compounds being considered by sunscreen manufacturers is mycosporine-like amino acids (MAAs). First discovered in the ocean 60 years ago, MAAs are ubiquitous: algae, fungi, and cyanobacteria all make the nitrogen-based compounds. These organisms use MAAs as sun protection, but ongoing research shows they also supply antioxidant, antibiotic, and anti-inflammatory properties.

Perhaps counterintuitively, many common sunscreen ingredients are not particularly stable in sunlight, especially chemical filters like avobenzone. MAAs, however, are far less prone to photodegradation. The amino acids also scavenge free radicals—molecules with unpaired electrons that can damage proteins and DNA. MAAs are also water-soluble and less sensitive to acidity than mineral-based filters, like titanium dioxide, which makes them easier to formulate into sunscreens.

But MAAs aren’t the only game in town. The ocean is teeming with sun care solutions. Many microalgae and cyanobacteria produce carotenoids that protect against UVA rays. Some cyanobacteria secrete free radical scavengers and physical barriers to UV light such as scytonemin. Then there are the anti-photoaging, UVB-absorbing polyphenols produced by sea cucumbers, algae, seagrasses, and mangroves.

In Europe, some sun care brands are already testing the waters with sunscreens based on these new compounds. Ingredient manufacturers Mibelle Biochemistry and Gelyma, for instance, have launched new sunscreen filters based on MAAs from red algae. Skincare company Aethic is using an MAA in a cream targeting sun damage. “We’re the only people to have it; we have a worldwide exclusive license from King’s College London,” says Aethic founder Allard Marx.

But in the United States and Canada, where sunscreens are treated as over-the-counter drugs, not cosmetics like in most European countries, a more stringent regulatory environment makes it harder for new sunscreens to be approved. Typically, the process takes up to six years and costs about US $5-million, according to Downs.

For Senator Gabbard, however, that lengthy process is vital. “The important lesson that we and the world have learned is that it’s critical to ensure that drugs are safe and effective for the public and environmental health before they’re allowed on the market,” he says.

Cláudia Mieiro, a marine biologist at the University of Aveiro in Portugal, agrees. She thinks that algae-based sunscreens are promising. But, she adds, “We don’t know their impact, so we must go deep in their effects before starting to advertise that they are safer.”

If sunscreens derived from compounds created by marine organisms successfully navigate safety regulations, obstacles remain to bringing them to market.

The MAA used by Aethic in its cream, for instance, is derived from seaweed, where it is found in very low concentrations, says Marx. “So their extraction cost is extortionately high.”

For marine economist Miguel Quiroga, at the Universidad de Concepción in Chile, there is a real concern that turning to these compounds could exact a heavy toll on the coastal environment and local communities. As an example, he points to the damage caused when the demand for seaweed cosmeceuticals surged in the early 2000s. The rush for seaweed denuded Chile’s coastline, which was only able to recover after a government program Quiroga is involved with started subsidizing fishermen to cultivate and restore the algae.

While positive about the potential boost to local living standards that a growing market for marine sunscreens could bring, Quiroga urges caution: “You have to equilibrate the use of these resources with the possibility of doing this in a sustainable way.”

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

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