Sunscreen is killing coral reefs worldwide. Commonly found sunscreen ingredients -- such as paraben, cinnamate, benzophenone, and camphor derivatives -- can awaken dormant viruses in symbiotic algae called zooxanthellae, which live inside reef-building coral species.

The chemicals cause the viruses to replicate until their algae hosts explode. This spills the viruses into the surrounding seawater, where they infect coral communities. In addition, zooxanthellae provide coral with food through photosynthesis. Without them, the coral "bleaches" (turns white) and dies.

It is estimated that 4,000 to 6,000 metric tons of sunscreen wash off swimmers annually in oceans worldwide. Up to 10 percent of coral reefs are threatened by sunscreen-induced bleaching.