Dichlorodiphenyltrichloroethane, a colorless crystalline substance, almost completely insoluble in water but very soluble in fats and organic solvents. It was synthesized for the first time in 1874 but its insecticidal properties were not discovered until 1939. After that time, it was widely used by military forces, especially in Italy, to fight against insects carrying malaria and typhus. After the war, it was widely used in agriculture. The WHO (World Health Organization) relied upon DDT in its worldwide program to stamp out malaria in 1955. But during the 1950s, the first doubts began to arise about the effect of DDT on the environment (deaths of birds and fish following spraying with DDT). Gradually, its use in agriculture was prohibited in developed countries during the 1970s and 1980s. The use of DDT is nowadays largely limited, but as for PCBs, it is a very stabile molecule. We can still find a lot of DDT in the environment, notably in the sea.