DDT introduced

DDT hand-spraying

USDA Forest Service/Bugwood.org (CC BY 2.0)

DDT first arrives in the United States (1945 treatment shown), with immediate implications for curbing the spread of insect-borne diseases. In 1972, amid concerns of its toxicity to humans and other animals, William Ruckelshaus, Environmental Protection Agency administrator, announces the cancellation of all uses of DDT in the United States.