It has been discovered that one marine mammal had 50 such bags in its stomach. All of it is harmful. Plastic bottle caps, straws, string and security tabs are all swallowed by sea turtles along with plastic pens and cups, which can break into small harmful pieces and have been found accumulated in animal stomachs in large quantities. Many plastics contain harmful organochloride compounds, such as PCB's, which once ingested, can damage reproduction and the animals' ability to resist disease. These substances remain in the body so that when the animal is eaten, the plastics are passed on up the food chain and can be found in predators, such as seals and dolphins, who are affected the most.
Plastics also maintain air bubbles and prevent turtles diving successfully for their food.
In addition to these plastics there are even smaller items which cause equal amounts of damage. Plastic and foil sweet wrappers, amongst others, can be consumed in mistake for small fish or small Crustaceans. Once in the animal's gut they will accumulate there and although the animal feels full, in reality it is dying of hunger. All these items only represent a fraction of what is dumped without thought by beach users, in addition to all the above problems, many items are washed up on the beaches through illegal dumping, by fishing fleets, cruise liners and the Navy. Obviously little can be done about the past, but there is now an opportunity for all of us to have a radical reappraisal of our garbage problem.