Sunscreen is essential in protecting humans from UV rays that can lead to skin cancer and other issues. But while it's proven to save people, in many cases, it's also killing coral reefs. Now, new research shows just how deadly sunscreen can be to marine life. It's been known for years that sunscreens containing oxybenzone are the likely culprit of the damages suffered by coral reefs. The chemical is highly effective at blocking UV rays from human skin, but once it's in the ocean, it's no longer harmless to other forms of life, a fact that has led to the banning of certain sunscreen formulas in reef-heavy areas, such as Hawai'i, the U.S. Virgin Islands, Palau and Bonaire. But what wasn't known was just how that chemical ended up being so toxic to the marine environment, and without that information, there's no guarantee that sunscreen alternatives are any safer. That's the information gap a new study, published in the journal Science on Thursday, sought to close. They placed 21 anemones in seawater under a lightbulb that emits a full spectrum of sunlight, with five of the animals being covered with a box that blocks the UV light that usually interacts with oxybenzone. The animals were then exposed to 2 mg of oxybenzone per liter of seawater. "Anemones, like corals, have a translucent surface, so if oxybenzone were acting as a phototoxin, the UV rays hitting the light group would trigger a chemical reaction and kill the animals – while the dark group would survive," researchers said in an article they wrote explaining their findings. And that's exactly what happened. All it took was six days for the first anemone that had been exposed to oxybenzone and left in UV light to die. Ten days later, all of the light-covered anemones were dead, while all of the anemones that weren't hit by the UV rays were alive. The researchers discovered that the anemones' bodies automatically treated oxybenzone as a foreign substance, kickstarting metabolic processes that altered the chemical makeup of the oxybenzone. This is a common process that plants and animals do to make foreign substances less toxic, but in the case of this particular chemical, it just made the foreign substance deadly. "It holds on to the energy it absorbs from UV light and kicks off a series of rapid chemical reactions that damage cells. Rather than turning the sunscreen into a harmless, easy-to-excrete molecule, the anemones . . . read the full article here.