DDT is banned because

DDT is banned because long persistence in the environment.
Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. DDT is similar in structure to the insecticide methoxychlor and the acaricide dicofol.
DDT became a prime target of the growing anti-chemical and anti-pesticide movements, and in 1967 a group of scientists and lawyers founded Environmental Defense with the specific goal of enacting a ban on DDT.