You’re at the beach, slathering on sunscreen to protect from sunburn. As you swim out to the colorful coral reef, you admire the beautiful marine life. Little do you know that your sunscreen could be poisoning their homes.

A 2022 study published in Science reveals how oxybenzone, a chemical found in commonly-used sunscreens, has a damaging effect on aquatic homes. A team at Stanford University performed three experiments on sea glass anemones, close relatives of coral, in tanks that replicated ocean water conditions.

In one tank, the anemones were exposed to simulated sunlight and no oxybenzone. In a second tank, the anemones were exposed to oxybenzone, but no sunlight. In both conditions, the anemones survived for the entire 21 days of the experiment.

 In the third experiment, the anemones were not as lucky. The team put these anemones in tanks with both oxybenzone and simulated sunlight. By day 17, there were no survivors.

So why did the anemones die in the third experiment? In all experiments, the anemones chemically attached a sugar to oyxbenzone. In the dark, this has no effect. However, this sugar-attachment means that with sunlight, instead of blocking UV rays, the sunscreen’s active ingredient produces free radicals that kill anenomes and coral.

Unfortunately, as water temperature rises due to climate change, coral expels its algae, its main source of food and energy– a process known as coral bleaching. When exposed to oxybenzone, bleached sea anemones died five times faster than healthy ones.

Oxybenzone has been proven to harm aquatic homes, but other potentially harmful chemicals of similar nature have yet to be tested. Until we have more research, using reef-safe sunscreens that contain minerals zinc oxide and titanium dioxide is the best option for protecting both coral reefs and our skin.

According to the National Oceanic and Atmospheric Administration, an estimated one billion people benefit from the vital role that coral reefs play in our ecosystem. To appreciate the beauty of coral reefs and conserve their essential functions, we need to properly protect them from harm. If you ever happen to find yourself taking a trip to the beach, be conscious about your choice of sunscreen to protect the marine life around you.