When they're put into landfill sites, they don't go away. They can stay around for hundreds of years. Environmental groups like Friends of the Earth ask us to think twice before buying plastic which is not biodegradable. This is the sound of rescued birds, which are covered in oil. Often from the enormous ships which carry oil around the world, the supertankers.
Supertankers carry thousands of tonnes of oil around the world.
But there is always the risk of the oil spill. In 1989 the supertanker Exxon Valdez spilled tonnes of oil off the coast of Alaska. The oil spill from the supertanker spread over an area of 12,000 square kilometers. This created an enormous oil slick. Around 35,000 sea birds were killed in the oil slick.