New studies have shown that sun tan lotions can be highly toxic to coral reefs. One study in Environmental Health Perspectives has shown that a small amount of sun cream can kill off or ‘bleach’ habitats of the small reef-building animals. The study states “Sunscreens cause the rapid and complete bleaching of hard corals, even at extremely low concentrations.” We may apply just small amounts of sun tan cream when we’re on the beach, but even that small amount can harm the sea life. It all mounts up too when you think of the amount of people on each beach, as they swim off shedding tons of the stuff into the water everyday. An estimated 78 million people have been thought to head to beaches with reefs every year. The researchers have calculated that people leech 4,000 to 6,000 tons of sunblock residue into the sea where reefs live every year. Because people visit relatively small portions of reefs around the world, it’s estimated in the study that roughly 10 per cent of the reefs could be threatened by sun cream. The study also says around 25 per cent of suntan lotion on the average beach goer is washed off within 20 minutes of going in the water. So how does Sun cream bleach Coral Reefs? When sunscreen reaches the corals they cause a fast release of their mucus and this is what the animals use to nourish themselves. Without mucus they become vulnerable, and the effect is combined by how the lotion damages the corals relationship with algae which is called zooxanthellae. The coral and the zooxanthellae have a symbiotic relationship and without their presence and lots of mucus, the corals lose their colour and die off, thus creating the bleaching effect. An average bottle of sunblock contains at least 20 per cent of chemicals including aminobenzoic acid and trolamine salicylate, as well as zinc oxide and titanium dioxide, according to the study. If you want to help the coral reefs then look out for sun cream products which are ‘reef-safe’ and read packaging labels carefully before you decide what to use. Some are also named ‘biodegradable’ which a lot of marine parks recommend putting on when diving around reefs.