DDT was banned in the United States in 1972, but provisions exist for its use in public health crises caused by diseases spread by insects. It may also be used to control body lice.
DDT was first created in 1874, but its properties as an insecticide weren't discovered until 1939. The chemical was used successfully during WWII to control malaria, typhus, body lice and bubonic plague. Paul Hermann Muller, the chemist who discovered it's use an insecticide, was awarded the Nobel Prize in Physiology or Medicine in 1948.
Over the next three decades, DDT was discovered to be linked to certain kinds of cancers in humans and widespread ecological damage to plants and animals. A handful of countries still use the chemical for agricultural and insect-control applications but most have banned widespread use of the insecticide.