What are the effects of DDT with animals?

DDT is a pesticide that was used in the past to control insects and to prevent them from damaging crops. The problem with DDT is that it accumulates in the environment and remains in the muscles of animals and fish. When birds consume too much DDT, such as by eating fish, they are unable to make hard shells on their eggs, resulting in very few new babies being born in certain bird populations, such as pelicans.