Choosing the Right Sunscreen at the Beach to Protect the Oceans

A swim, a few strokes, and part of what protects the skin already finds its way into the sea. Yet some UV filters are now watched for their effects on marine life. So, can we really choose sunscreen without pitting skin protection against the health of the oceans?

What leaves the skin during swimming doesn’t really vanish into the sea

As soon as you enter the water, the protective film applied to the skin doesn’t stay completely in place. Indeed, some ultraviolet filters join the marine environment directly while swimming. Moreover, others pass through wastewater after showers, extending their spread. Thus, the U.S. Environmental Protection Agency (EPA) classifies them among emerging contaminants to monitor in aquatic ecosystems.

Among the most studied substances are notably oxybenzone, octinoxate and octocrylene. In addition, studies cited by NOAA indicate that these compounds can affect certain marine organisms at varying concentrations. However, researchers emphasize one essential point: the effects depend heavily on doses and exposure conditions, which complicates definitive conclusions.

In a coral reef, a few molecules reach an ecosystem already under pressure

A coral reef is not simply a decorative underwater backdrop. On the contrary, corals live in symbiosis with microorganisms essential to their survival. In the laboratory, some UV filters trigger reproductive disruptions, cellular stress, and sometimes bleaching. However, scientists are still trying to understand these effects under natural conditions.

This uncertainty does not diminish the importance of the topic. Indeed, reefs cover a small portion of the oceans, but they harbor about 25 % of marine biodiversity, according to NOAA. In other words, fish, crustaceans and mollusks depend on them directly. They use these zones as refuges, feeding grounds and reproduction sites, which makes them essential to the balance of marine life.

Sunscreen products thus add to an already fragile context. On one hand, the warming of the oceans, pollution and human activities strongly weaken corals. On the other hand, UV filters are only one factor among others. It is precisely this accumulation of pressures that explains why several authorities are now adopting a precautionary approach to limit cumulative risks.

Hawaii and Palau have turned a laboratory debate into a real policy choice

In Hawaii, the scientific debate ultimately led to legislative action. Since January 1, 2021, the state bans the sale of creams containing oxybenzone or octinoxate without a prescription. Practically, this measure aims to reduce pressure on coral reefs already heavily exposed to tourism and human activities.

Palau, for its part, has adopted an even stricter approach. The archipelago has indeed banned several ingredients deemed potentially toxic to reefs. Thus, this decision sends a strong international signal. In a territory where tourism and biodiversity coexist closely, the choice of a sunscreen becomes a concrete environmental act, not merely trivial.

The best choice for the ocean may start even before you open the tube

Should we, however, give up on sunscreen? Absolutely not. The American Academy of Dermatology instead recommends a minimum SPF 30 protection, broad-spectrum and water-resistant. In addition, it advises combining this protection with covering clothing and seeking shade. Moreover, reapplication should occur after swimming or sweating to stay effective.

To limit the impact on marine environments, the most effective approach is to reduce direct exposure. For example, a UV-protective T-shirt, a hat, or a shaded area makes a real difference. Furthermore, product choice also matters. However, labels like reef-safe do not guarantee complete innocuity, which invites vigilance regarding marketing labels.

Mineral filters, such as zinc oxide or titanium dioxide, often present themselves as a promising alternative. Nevertheless, NOAA notes that particle size influences their potential impact, especially for nanoparticle forms. Thus, between protecting skin and protecting oceans, the solution will likely depend on better-studied formulations, but also on more informed choices, well before the next trip to the beach.