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Your Sunscreen Might Be Killing the World's Coral Reefs

Researchers say the chemical oxybenzone damages the DNA of baby corals, disruptes their endocrine system, causes the corals to deform, and induces bleaching.
Photo by David Lees/Getty

Sunscreen is usually associated with summer, pool parties, and blissful days lying upon a tranquil beach. But, according to the findings of a recent study, it should also invoke concern about endangered coral reefs.

Researchers from the United States and Israel evaluated the effects of oxybenzone, which is commonly used in sunscreens, as well as hair-styling products, shampoos and conditioners, insect repellants, and soaps and found that it severely damaged baby corals and contributed to the decline in coral reefs around the world.

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Lead study author Craig Downs, who is the executive director of Virginia-based Haereticus Environmental Laboratory, said that the chemical damaged the DNA of corals, disrupted their endocrine system, caused them to deform, and induced bleaching — a phenomenon that makes corals expel the algae living in their tissue and turn completely white. While coral bleaching is typically associated with warmer ocean temperatures, oxybenzone exposure can make corals more susceptible to bleaching at lower temperatures.

"So if bleaching normally occurs at 31 degrees Celsius, we saw oxybenzone causing coral bleaching at 26 degrees Celsius," Downs said.

When a coral is bleached out, it is still alive, but with the main source of food gone, it becomes stressed and more prone to disease and death.

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The oxybenzone findings have come at a very critical time. According to the US National Oceanic and Atmospheric Administration, a major, global coral bleaching event is currently underway. It began in the North Pacific in 2014 and spread this year into the South Pacific and Indian Ocean. The agency says US coral reefs have been hit disproportionately hard — by the end of this year, almost 95 percent of US coral ecosystems will be exposed to ocean conditions that can cause bleaching.

While oxybenzone is far from the sole culprit behind coral bleaching and death, it helps to magnify the effects of ocean acidification and climate change on coral reefs. When the US government asked Downs and some of his fellow researchers to investigate the deterioration coral reefs in marine protected areas, sunscreen was not even on the list of suspected causes.

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"At one of the [marine protected areas] in the Virgin Islands, it was a local who told us that we needed to visit around 5pm after all the tourists leave and look at the oil slick on the water," Downs said.

The water, he said, had an oily sheen at the end, prompting the scientists to begin exploring the idea that pollution from sunscreens may actually have something to do with the coral deaths.

"When we started to look at the compounds that were found in the sunscreens, the chemical oxybenzone was the one that always drew our attention," Downs said. "It was always there, it was always there in high concentration."

Related: A Massive Amount of Death Is Plaguing the World's Oceans

The study, which first tested the effect of oxybenzone on baby corals in a laboratory and then measured the actual concentration of the chemical in certain parts of ocean, found that even very low concentration of the compound had a toxic effect on corals. According to the findings, the lowest concentration to have a damaging effect was 62 parts per trillion – equivalent to a drop of water in six Olympic-sized pools.

The water in Trunk Bay in the Virgin Islands National Park was found to have a concentration of 1.4 parts per million, and the average concentration for other coral reef locations in the national park was about 250 parts per billion. In Hawaii, it ranged between 800 parts per trillion and 19 parts per billion.

"The biggest finding of this study is that local pollution has an effect on coral reefs around the world," Downs said. "One of the easiest responses to this study is to not use products that have oxybenzone if you are going to be swimming near coral reefs. And companies can participate by phasing out oxybenzone and using chemicals that are more environmentally sustainable."

Follow Esha Dey on Twitter: @deyesha

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