Your Sunscreen Might Be Killing Coral Reefs in Hawai‘i

A chemical in sunscreen causes “zombie reefs.”
Bleached Elkhorn Coral.
Photo: Courtesy of NOAA 


Waiting 20 minutes for the sunscreen to soak in is a source of impatience for squirmy kids whose parents have to hold them down to rub—or spray—the cold, slippery protection from sunburns. Little do most parents know, a chemical in many sunscreens has been linked to what experts call “zombie” reefs, or reefs incapable of regenerating themselves.


“Oxybenzone kills reefs,” says Craig Downs, executive director of the nonprofit Haereticus Environmental Laboratory in Virginia. “It turns them into zombies—it sterilizes them.”


Downs and his associate, Mirella von Lindenfels, stressed the alarming ramifications of continued use of all personal care products that contain oxybenzone in a town hall during this week’s International Coral Reef Symposium at the Hawaiʻi Convention Center.


Coral reefs typically have the ability to regenerate themselves, but oxybenzone, found in many sunscreens, make it much more difficult to recover from damage, disease and bleaching caused by ship anchors, ocean acidification and climate change.


“You can’t have Hawaiʻi without coral reefs,” says Downs. “Where are you going to get your poke?”


How bad is it?

“Many ingredients in sunscreen products pose an existential threat to marine creatures,” says Downs, citing more zombie reefs in areas with significant human activity such as Hanauma Bay.


Experts think oxybenzone causes toxicity at 62 parts per trillion—the equivalent of one drop of water in 6.5 Olympic-size swimming pools. An estimated 8,000 to 16,000 tons of sunscreen enter coral reef areas each year.


Oxybenzone damages coral DNA and causes deformities. It acts as an endocrine disruptor, which makes the coral sterile. The chemical causes coral to grow more skeleton than is necessary, making it impossible to reproduce itself.


While oxybenzone doesn’t immediately kill reef, “it’s robbing coral reefs of their resilience and ability to recover.”


What if I let the sunscreen soak in first?  

Von Lindenfels displayed pictures of tour boats with snorkelers in the water and pointed to the sheen of sunscreen and tanning oils drifting from the crowd. Oxybenzone is most directly introduced into the ocean through direct contact from people who have applied the chemical.


But it’s not just those who apply it and immediately go swimming without letting it soak in. Oxybenzone is an extremely persistent chemical. When sunscreen is applied via aerosol cans, the chemical soaks into the sand, waiting for high tide to pull it into the ocean. “If you’re a mom, you get maybe four sprays,” says Downs. “If you’re a college girl, you use the whole thing at once.”


Traces of oxybenzone can also be found in urine 20 minutes after it is applied. The chemical survives through filters in the waste system and is eventually dumped into the ocean.


What’s being done?

Downs first revealed his data in 2012 during an International Programme on the State of the Ocean workshop. Since then, the MarineSafe campaign has initiated action.


“I think there’s a real appetite to do the right thing,” says von Lindenfels. “Communication is a challenge. People simply don’t know.”


Within the next three months, the MarineSafe Campaign will establish certification programs for personal care products. MarineSafe is also involved on the state level with the Department of Land and Natural Resources and the University of Hawaiʻi on social campaigns aimed at spreading awareness. On a federal level, NOAA has taken an active interest in promoting policy changes aimed at banning a list of chemicals that will be revised every three to four years.


“We know reefs around the world are in really bad shape,” says Downs.


What can I do?

Until the MarineSafe certification program kicks off, check the ingredients of sunscreens and other personal care products such as shampoos to ensure oxybenzone is not in them. While sunscreens that use aluminum oxide or zinc oxide to block UV rays tend to be a little on the thicker side, mineral-based sun protection is much more reef friendly. You can also limit sunscreen use by using large-brim hats and long-sleeve shirts as protection. Above all though, avoid using spray dispensers and aerosol cans.


“It’s depressing, to be honest, to discuss coral reefs because there’s so little we can do,” says Von Lindenfels. “But this is something we can do.”