Bottles promising to be reef safe or reef friendly have become a common sight on beach shop shelves. The claim sounds reassuring, but in the United States it is not defined or checked by any regulator, so it is worth knowing what lies behind it.
The ingredients in question
Most of the concern centres on two chemical UV filters, oxybenzone (benzophenone-3) and octinoxate (octyl methoxycinnamate). Laboratory studies have linked them to coral bleaching and to damage in young corals. In 2018 Hawaii became the first US state to pass a law banning the sale of sunscreens containing either ingredient without a prescription, and the ban took effect on 1 January 2021. The US Virgin Islands and the Pacific nation of Palau introduced similar restrictions, and Key West in Florida voted for one too, although a later state law stopped Florida cities from enforcing their own sunscreen bans.
Other filters such as octocrylene and homosalate are also being studied, along with preservatives and microplastics found in some formulas. Scientists point out that much of the evidence comes from laboratory tests at concentrations that may be higher than in open water, and that climate change and warmer seas remain the main threat to reefs. The research is still developing.
Is mineral always better?
Sunscreens based on zinc oxide or titanium dioxide are often sold as the reef-friendly choice. They are generally regarded as a gentler option for the ocean, but they can contain nanoparticles, which are smaller than 100 nanometres and help the cream rub in clear. Some researchers have raised questions about how nano-sized particles affect sea life, so some shoppers look for formulas marked non-nano.
How to choose
- Read the ingredient list rather than the front of the pack, because the reef-safe wording itself carries no legal meaning.
- If you plan to swim in the sea, a mineral formula without oxybenzone and octinoxate is the option most local rules point to.
- Cover up: a rash guard, a hat and shade reduce how much sunscreen you need in the first place.
- Apply sunscreen 15 to 30 minutes before going into the water so more of it stays on your skin.
Whatever you pick, dermatologists stress that sun protection itself is not optional. Skipping sunscreen to protect the reef trades one problem for another, while a well-chosen product and some clothing can protect both.
Sources: Hawaii Act 104 (2018) and its 2021 entry into force, US Food and Drug Administration guidance on sunscreen labelling, NOAA National Ocean Service, published laboratory studies on UV filters.