SCIENCE
10/21/2015 05:39 am ET

Sunscreen Could Be Killing The World's Coral Reefs, Study Says

Just one drop of the stuff can damage delicate corals.

Credit: Georgette Douwma/Getty Images
A new study says sunscreen may be damaging the planet's coral reefs.

Just two weeks ago, the National Oceanic and Atmospheric Administration (NOAA) raised the alarm about the terrible plight facing the Earth’s coral reefs. For the third time in history, the world is in the midst of a global coral bleaching event, the agency said.

"We are losing huge areas of coral across the U.S., as well as internationally," said Mark Eakin, NOAA’s Coral Reef Watch coordinator, citing climate change and events like the current El Niño as primary reasons for the mass die-off.

A new study published this week is bringing even more bad news about the world’s dying corals. According to researchers, there may be another, oft-overlooked threat to reefs worldwide: sunscreen.

Scientists who conducted their research in Hawaii and the U.S. Virgin Islands found that the chemical oxybenzone -- used in more than 3,500 sunscreen products worldwide, including those by popular brands such as Coppertone, L’Oreal and Banana Boat -- was extremely harmful to fragile coral reefs.

"The chemical not only kills the coral, it causes DNA damage in adults and deforms the DNA in coral in the larval stage, making it unlikely they can develop properly," a news release reported. 

The researchers said even a tiny amount of oxybenzone-containing sunscreen can damage corals. As The Washington Post noted, "the equivalent of a drop of water in a half-dozen Olympic-sized swimming pools" was sufficient to cause harm.

Every year, approximately 14,000 tons of sunscreen ends up in coral reefs worldwide.  

"The use of oxybenzone-containing products needs to be seriously deliberated in islands and areas where coral reef conservation is a critical issue," said lead researcher Craig Downs. "We have lost at least 80 percent of the coral reefs in the Caribbean. Any small effort to reduce oxybenzone pollution could mean that a coral reef survives a long, hot summer, or that a degraded area recovers."

But keeping sunscreen away from reef systems will be no easy feat.

The product, which can protect wearers from the ill effects of sun exposure, including skin cancer and burns, is used widely, and researchers say that the contamination of reefs isn’t just caused by beach-goers who swim in waters near corals but by everyone who wears sunscreen in their day-to-day lives.

"The most direct evidence [of damage] we have is from beaches with a large amount of people in the water," John Fauth, one of the study's co-authors and an associate professor of biology at the University of Central Florida, told the Post. "But another way is through the wastewater streams. People come inside and step into the shower. People forget it goes somewhere."

However, steps can be taken to prevent the contamination of reefs with sunscreen products.

The U.S. National Park Service recommends using "reef-friendly" sunscreen made with titanium oxide or zinc oxide, instead of oxybenzone. (The Environmental Working Group lists some examples on its website.)

When frolicking on the beach, rash guards, scuba suits and hats are other environmentally-friendly ways to protect oneself from the sun. 

Some tourist destinations have even instituted no sunscreen rules to protect their reefs, NPR reported. In Akumal, Mexico, for instance, an area known for its sea turtles and corals, visitors are urged to apply eco-friendly sunscreen (or none at all) so as to not disturb the marine life. 

Credit: Getty Images
Bleached branching coral in the Maldives. According to the NOAA, the world is currently in the midst of a global coral bleaching event.

Coral reefs aren't just underwater eye candy. They are "some of the most diverse and valuable ecosystems on Earth," NOAA said. Reefs are crucial to the well-being of other marine life, and they protect miles and miles of coastline from storm surge. 

The biodiversity of reefs is also "considered key to finding new medicines for the 21st century," NOAA said. "Many drugs are now being developed from coral reef animals and plants as possible cures for cancer, arthritis, human bacterial infections, viruses and other diseases."

In addition, coral reefs provide economic and environmental services to millions of people through industries like fishing and tourism. The commercial value of U.S. fisheries from reefs is reportedly over $100 million.

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