Bangkok--25 Feb--eTurboNews Ingredients in many sunscreen brands cause rapid and complete bleaching of corals, say scientists. Tourists who wear sunscreens may be contributing to the death of the Great Barrier Reef and other coral reefs around the world, new research has revealed. Scientists in Italy believe that up to 10 per cent of coral reefs are threatened by bleaching caused by chemicals in widely-used creams that are sold to protect users from the suns damaging UV rays. Between 4,000 and 6,000 tons of sunscreen wash off swimmers annually in oceans worldwide, mostly in warm tropical climates where reefs are popular tourist attractions. But scientists at Marche Polytechnic University in Ancona found that many brands of sunscreen contain ingredients that can stimulate viruses in the algae, known as zooxanthellae, which live within corals. Zooxanthellae play an essential role in providing the vibrant color associated with corals by supplying food energy through photosynthesis.