An estimated 14,000 tonnes of sunscreen end up in the ocean every year. While protecting our skin from UV radiation is essential, certain sunscreen ingredients are causing serious harm to coral reefs — ecosystems that support 25% of all marine life.
The Problem Chemicals
Two ingredients have drawn particular scientific attention: oxybenzone (BP-3) and octinoxate (ethylhexyl methoxycinnamate). Research published in the journal Archives of Environmental Contamination and Toxicology showed that oxybenzone can cause coral bleaching at concentrations as low as 62 parts per trillion.
These chemicals don't just bleach coral — they damage coral DNA, deform larvae, and disrupt reproduction. Young coral is particularly vulnerable, with studies showing that oxybenzone can induce coral larvae to prematurely encase themselves in their own skeleton, effectively killing them.
Scale of the Issue
Popular tourist beaches can see sunscreen concentrations thousands of times above the threshold for coral damage. In Hawaii's Hanauma Bay, an estimated 190 kg of sunscreen enters the water daily during peak season.
The problem extends beyond beaches. Sunscreen washes off in showers and enters wastewater systems, eventually reaching coastal waters through treatment plant discharge.
Reef-Safe Alternatives
Mineral sunscreens using zinc oxide or titanium dioxide sit on top of the skin rather than being absorbed, and are generally considered safer for marine life. Look for "reef-safe" or "reef-friendly" labels, though be aware these terms aren't yet regulated in most countries.
Physical sun protection — hats, rash guards, shade — remains the most marine-friendly option.
Legislative Action
Hawaii became the first US state to ban oxybenzone and octinoxate sunscreens in 2021. Palau, the US Virgin Islands, and Key West have followed. The EU is reviewing the safety of several UV filters under its chemicals strategy.
Beyond Sunscreen
While sunscreen is a visible issue, it's important to remember it's just one of many chemical threats to coral reefs. Climate change, ocean acidification, agricultural runoff, and overfishing all play larger roles. Addressing the full picture is what the CONTRAST project is all about.
This article is part of the CONTRAST project, funded by the European Union under Horizon Europe. Views expressed are those of the author(s) only.