Furthermore, when plastic breaks up, chemicals are released into the water, and these too remain for a long time. Researchers in Japan have studied watcr from the world's oceans and found that it contains chemicals from plastic. Two of these chemicals, polystyrene and bisphenol A, have also been found in fish. It is not known yet what effect they may have on the fish or on other kinds of marine animals, but they are known to be harmful to human health