CORAL-FRIENDLY SUNSCREEN

Chemicals in sunscreen can bleach and harm coral reefs, but a new product on the market hopes to replenish them

- HELEN SCALES

Apply at least 20 minutes before swimming. That's what the sunscreen labels say. But they rarely point out the chemicals that can wash off and harm the environment.

Back in 2008, scientists raised alarms that many of the chemical UV-filters in sunscreens are toxic to sea life. In particular, corals. Oxybenzone is a common ingredient and in lab tests it can induce coral bleaching — the potentially lethal process where stressed corals eject their symbiotic algae and turn white.

The same chemical can damage coral DNA and cause deformities in coral larvae, making them grow a hard exoskeleton before they're ready to settle onto the seabed and flourish into a colony.

Estimates of the amount of chemical sunscreen washing onto coral reefs vary between 4,000 and 14,000 tons every year, both from swimmers and via wastewater systems.

A 2015 study found that a popular tourist hotspot in the US Virgin Islands, Trunk Bay, attracts so many sunscreen-soaked swimmers, it could be preventing coral larvae from settling and harming the corals' ability to heal from wounds. Meanwhile, in a less popular location nearby, Caneel Bay, the coral reefs thrived.

Studies such as these, showing contamination in the sea more than 100 times higher than levels known to damage corals, have prompted bans on oxybenzone sunscreens in the US Virgin Islands, Bonaire, Hawaii and Palau.