The Secret Harm in Sunscreen

Skin-protecting sunscreens are devastating coral reefs around the globe.

Published November 10, 2015

Coral reefs cover less than one percent of the ocean floor but support an astonishing array of life—nearly 25 percent of all marine animals. In a new study, researchers found that oxybenzone, a common ingredient in sunscreens, is harming these delicate ecosystems.

Coral Infographic

The study was conducted in the U.S. Virgin Islands and Hawaii with some lab experiments held right here at the National Aquarium by former aquarist Kelli Cadenas. Scientists found that oxybenzone is highly toxic to corals, even in very small concentrations.

Composition of a Coral

Coral is not a single organism. In fact, it is comprised of thousands of tiny, soft-bodied animals, called polyps. Stony coral polyps create hard skeletons using calcium carbonate, forming the familiar wavy, branched and other intricately shaped colonies.

Healthy Coral DiagramBleached Coral Diagram

Symbiotic algae, called zooxanthellae, live within the polyps. They help give corals their vivid colors. Through photosynthesis the algae also provide corals with food energy.

The Crux of the Matter

Between 4,000 and 6,000 metric tons of sunscreen enter reef areas annually, subjecting corals to oxybenzone.

Scientists found that exposure to the UV-filtering chemical has three major effects:



A coral’s heart disease—it’s number one killer worldwide. Oxybenzone increases a coral’s susceptibility to bleaching, in which they reject their life-sustaining symbiotic algae. When the algae disappear, the coral turns a ghostly white. Bleaching frequently leads to the death of the coral colony.


Endocrine Disrupting

Essentially, oxybenzone deforms coral in its larval stage. The chemical causes young corals to become trapped in their own skeletons, eventually resulting in death.


DNA Altering

Oxybenzone also damages the DNA of adult corals, impacting their ability to reproduce. In the case that they are still able to reproduce, the offspring is often unhealthy, resulting in deformities.

Sunscreen Bottle

What Happens Next

With the continued presence of oxybenzone in marine environments, damaged coral reefs have little chance of recovery. So, how can we mitigate the problem, while keeping our own health in mind?

The simplest answer is to know what’s in your products. Choose a sunscreen that doesn’t list oxybenzone as an ingredient—this goes for swimmers and non-swimmers alike.

Sunscreen, when washed down the drain, can still make its way to the ocean. Products made from natural minerals (like zinc oxide) are a good place to start.

Taking advantage of swimwear and clothing that covers the body can also help protect coral reefs from harmful chemical exposure.

Stay tuned for more updates!

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