Sunscreen is an important way to prevent sun cancer. It is also putting the ocean’s corals at risk.

In a new joint Israeli-American study, researchers at Tel Aviv University, Ben Gurion University of the Negev, Haereticus Environmental Laboratory in Virginia, US National Aquarium and US National Oceanic & Atmospheric Administration, found that a common chemical found in sunscreen, oxybenzone, is killing off already threatened coral.

“The chemical, oxybenzone (benzophenone-3), is found in more than 3,500 sunscreen products worldwide, including mascara, lipstick and shampoo,” Dr. Omri Bronstein of Tel Aviv University explained.

It can also make its way into the ocean even when the wearer is nowhere near the water.

“Oxybenzone pollution predominantly occurs in swimming areas, but it also occurs on reefs 5-20 miles from the coastline as a result of submarine freshwater seeps that can be contaminated with sewage,” Bronstein continued.”It pollutes coral reefs via swimmers who wear sunscreen or wastewater discharges from municipal sewage outfalls [after it is washed off by the wearer] and coastal septic systems.”

Oxybenzone causes coral to bleach making it more vulnerable to the rising ocean temperatures. The chemical also interferes with the coral’s DNA, impacting their ability to reproduce.

This is particularly concerning in areas where tourism is high and coral reefs are disappearing at an alarming rate.

“We have lost at least 80% of the coral reefs in the Caribbean. Any small effort to reduce oxybenzone pollution could mean that a coral reef survives a long, hot summer, or that a degraded area recovers,” Dr. Craig Downs of Haereticus Environmental Laboratory in Virginia said.

Downs added that if use of the chemical is not reduced then other coral conservation efforts will have little impact.

“Everyone wants to build coral nurseries for reef restoration, but this will achieve little if the factors that originally killed off the reef remain or intensify in the environment.”