Müller, Paul Hermann (päˈŏl hĕrˈmän mŭlˈər) [key], 1899–1965, Swiss chemist, Ph.D. Univ. of Basel, 1925. He worked as a research scientist with J. R. Geigy A.G. in Basel, Switzerland. Muller won the 1948 Nobel Prize in physiology or medicine for discovering (1939) that DDT was an effective insecticide. Although the use of DDT would be banned in the United States in 1972 due to concerns about its impact on the environment, Müller's discovery was hailed as a public-health breakthrough at the time because DDT and products based on it enabled the control of a number of disease-transmitting pests, including lice and mosquitoes.