The Swiss chemist Paul Hermann Müller (1899-1965) is noted for his discovery of the insecticidal powers of DDT.
Paul Müller was born on Jan. 12, 1899, at Olten, Switzerland, the son of an official of the Swiss Federal Railways. The family soon moved to Basel. Encouraged by his father, Müller performed experiments at home with chemicals bought at a local pharmacy. After a brief spell as a laboratory technician Müller entered Basel University. In 1925 he was awarded a doctorate for a thesis on the chemical and electrochemical oxidation of a substance known as asymmetrical m-xylidine and some of its derivatives. That year he joined the firm of J.R. Geigy as research chemist.
Müller's first research interest at Geigy was in the field of leather tanning, and he was able to develop several synthetic tans with good fastness to light. He also developed an interest in the conservation of hides and in the associated problem of rendering wool resistant to attack by moths. Although the firm had by this time considerable expertise in mothproofing textiles on an industrial scale, Müller believed that an alternative approach to the problem was necessary. Hitherto the insecticides used had been oral poisons. Müller proposed a search for insecticides that could act by mere contact, and for this he did his own biological testing, which was unusual for a chemist. Realizing that compounds with a—CCL3 group (for example, chloroform) were often lethal to insects, he examined several of these until, in 1939, he came to DDT (dichlorodiphenyltrichloroethane), which, although known since 1873, was now revealed as a far more effective contact insecticide than any other and was easily manufactured.
This discovery came at a crucial moment in history. DDT, with its lethal action on malaria-carrying mosquitoes, played a vital role in maintaining the health of the Allied armies in the Far East. As a routine precaution, the shirts of British and United States troops were impregnated with DDT. Its first use on a large scale was at Naples in 1943, when a typhus epidemic was brought under control within 3 weeks. Today, discovery of pesticide residues in animal bodies has revealed a toxic hazard unsuspected in Müller's day, and controls in the use of DDT and other pesticides are being demanded.
For his discovery Müller received the Nobel Prize for physiology or medicine in 1948. In 1962 he was given an honorary doctorate at Thessalonica (Salonika) in recognition of the valuable effects of DDT in the Mediterranean area.
Müller became deputy chairman of Geigy and assistant research director of its pesticides division. He died in October, 1965.
Further Reading on Paul Hermann Müller
A brief biographical sketch of Müller is in H. Schück and others, Nobel: The Man and His Prizes (trans. 1951; 2d rev. ed. 1962), and Eduard Farber, Great Chemists (1961).