Corals turn sunscreen into toxins

A new study found that when corals and sea anemones absorb oxybenzone, their cells turn it into phototoxins, molecules that are harmless in the dark but become toxic under sunlight.

• The biologists studied sea anemones as a model for corals.
• The study aims to uncover how sunscreen harms reefs so that we could better understand which components in sunscreens are really “coral-safe.”
• It is extremely difficult to perform experiments with corals under lab conditions, so anemones are typically much better for lab-based studies
• The study revealed that when corals and sea anemones absorb oxybenzone, their cells turn it into phototoxins, molecules that are harmless in the dark but become toxic under sunlight.

Sunscreen:

• Sunlight is made of many different wavelengths of light.
• Longer wavelengths like visible light are typically harmless.
• But light at shorter wavelengths like ultraviolet light can pass through the surface of skin and damage DNA and cells.
• Sunscreens, including oxybenzone, work by absorbing most of the UV light and converting it into heat.
• Oxybenzone is a common ingredient in many sunscreens.

Oxybenzone:

• Anemones had replaced part of oxybenzone’s chemical structure — a specific hydrogen atom on an alcohol group — with a sugar.
• Replacing hydrogen atoms on alcohol groups with sugars is something that plants and animals commonly do to make chemicals less toxic and more water soluble so they are easier to excrete.
• But when you remove this alcohol group from oxybenzone, oxybenzone ceases to function as a sunscreen.
• Instead, 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 convert oxybenzone into a potent, sunlight-activated toxin.

Sea Anemone:

• Members of the sea anemone genus are often thought of as plants due to their flower-like appearance, but this underwater invertebrate is, in fact, an animal.
• As such, they need a hearty diet to survive.
• All sea anemone species are carnivorous, relying on a variety of proteins to survive and thrive.