The sunscreen which you apply before going for a swim on the beach might be killing coral reefs worldwide, a new research has shown.
According to a study, led by Roberto Danovaro of the Polytechnic University of Marche in Italy, four commonly found sunscreen ingredients can awaken dormant viruses in the symbiotic algae called zooxanthellae that live inside reef-building coral species.
These chemicals cause the viruses to replicate until their algae hosts explode, which results in the spilling of viruses into the surrounding seawater, where they can infect neighbouring coral communities.
Zooxanthellae provide coral with food energy through photosynthesis and contribute to the organisms' vibrant colour. Without them, the coral 'bleaches', turns white, and dies.
"The algae that live in the coral tissue and feed these animals explode or are just released by the tissue, thus leaving naked the skeleton of the coral," National Geographic quoted Danovaro, as saying.
In the study, the researchers studied the effects of sunscreen exposure on coral samples from reefs in the Pacific, Atlantic, and Indian Oceans.
The results showed that, low levels of sunscreen, at or below the typical amount used by swimmers, could activate the algae viruses and completely bleach coral in just four days.
It was also found that the seawater, surrounding coral exposed to sunscreen, contained up to 15 times more viruses than unexposed samples.
Several brands of popular sunscreens were tested and all had four ingredients in common: paraben, cinnamate, benzophenone, and a camphor derivative.
Danovaro said that banning of sunscreen was not necessary and pointed out two simple things swimmers could do to reduce their impact on coral: Use sunscreens with physical filters, which reflect instead of absorb ultraviolet radiation; and use eco-friendly chemical sunscreens.
The study is published in the journal Environmental Health Perspectives.