Sunscreen Ingredient Is Killing Off World’s Coral Reefs

Even tiny amounts of oxybenzone can begin disrupting coral growth, new study claims.

Ruth Schuster
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A plastic bag floating over a coral reef.Credit:
Ruth Schuster

An ingredient in the sunscreen we slather on our bodies to avert skin cancer is killing off coral reefs, an international team of scientists warns. It’s not great for you either, though the degree of hazard to humankind is still being elucidated.

The component is oxybenzone, a chemical that mimics the female hormone estrogen and is widely used in sunscreen, skin lotions and creams, and even hairspray. Even tiny amounts of sunscreen — the equivalent of a single drop in six Olympic-sized swimming pools — contains enough oxybenzone to begin disrupting coral growth, according to the study published in Archives of Environmental Contamination and Toxicology.

Oxybenzone’s effects on the human body are not absolutely clear, though there is , and a correlation has been found between the mother’s exposure during pregnancy and low birth weight in girls.

Otherwise, the evidence at this point is mixed, for humans. For corals, thanks to Tel Aviv University, oxybenzone is not mixed. It is bad news, hurting the wretched microanimals in multiple ways.

One: It damages the corals’ DNA, inhibiting their ability to reproduce.

Two: being a hormone mimic, oxybenzone disrupts the endocrine (hormone) system in young coral buds. The results of the endocrinal mayhem include gross deformities, say the scientists. These include gigantic mouths that grow to five times normal size. Yet the young corals still starve to death because they helplessly grow skeletons that encase them.

Finally, the oxybenzone makes the young corals more susceptible to bleaching at lower temperatures, rendering them less resilient to climate change. Coral bleaching happens when the one-celled, algae-like protozoa with which the coral has a symbiotic relationship are expelled, decamp or die. Under normal conditions, the protozoa live inside the coral tissues, quietly photosynthesizing and emitting oxygen. These protozoa give corals their colors. Once they’re gone, the naked coral is lighter or white. Bleaching is not necessarily fatal for the coral, but it is a sign that the coral is not a happy camper.

“Oxybenzone pollution predominantly occurs in swimming areas, but it also occurs on reefs five to 20 miles from the coast as a result of submarine freshwater seeps that can be contaminated with sewage,” said Omri Bronstein of TAU’s Department of Zoology. The sewage bears oxybenzone from sources such as cosmetics.

Bronstein conducted exposure experiments on coral embryos at the Inter-University Institute for Marine Science in Eilat, together with Craig Downs of Virginia’s Haereticus Environmental Laboratory.

The problem is not trivial. Testing off the Virgin Islands, the researchers found concentrations of oxybenzone 23 times above the minimum considered toxic to corals. The study was conducted by Prof. Yossi Loya and a team of marine scientists from TAU, working with scientists from Haereticus, Ben-Gurion University of the Negev, the U.S. National Aquarium, the National Oceanic and Atmospheric Administration and other U.S. institutions.

You have oxybenzone

Corals aren’t the only ones with sunscreen inside. A .

The Environmental Working Group, an American research and advocacy organization founded in 1993, says .

Wearing a different hat, the CDC says .”

Another study from 2008 shows a correlation (which is short of causality) between oxybenzone concentration in the body and low birth weights in girls whose mothers were exposed to the chemical during pregnancy ( and ).

In both heavy industry and the cosmetics industry, oxybenzone is used to absorb ultraviolet light.

Israel regulates its use, confirms the Health Ministry. “Use of oxybenzone in cosmetics (including cosmetics used to protect from the sun) is limited to up to 10 percent,” the ministry stated to Haaretz. “The substance is widely used around the world, mainly in sunscreen products. The Health Ministry in Israel keeps track of developments and changes in global regulation regarding cosmetics and updates [the rules, presumably] accordingly.”

What can you do about this oxybenzone plague? Use some other sunscreen (and lotions and lipstick) that doesn’t have it, or wear long sleeves to the beach.