Paul Hermann Müller, also known as Pauly Mueller (12 January 1899 – 13 October 1965), was a Swiss chemist who received the 1948 Nobel prize in Physiology or Medicine for his 1939 discovery of insecticidal qualities and use of DDT in the control of vector diseases such as malaria and yellow fever.
Early life and education Müller was born on 12 January 1899 in Olten, Solothurn, to Gottlieb and Fanny (née Leypoldt or Leypold) Müller. He was the oldest of four children. His father worked for the Swiss Federal Railways and the family first moved to Lenzburg in Aargau and then to Basel. Müller went to the local primary school (volksschule) and later to the lower and upper "realschule". In that time, he had a small laboratory where he developed photographic plates and built radio equipment. In 1916, he left school due to bad grades and started to work as a laboratory assistant at Dreyfus. The next year he became an assistant chemist in the scientific-industrial laboratory of the electrical plant of Lonza AG. Returning to school in 1918, he obtained his secondary school diploma in 1919 and entered the University of Basel in the same year. At the University of Basel he studied chemistry (with a minor in botany and physics) and started to study inorganic chemistry under Friedrich Fichter. In 1922, he continued his studies in the organic chemistry lab of Hans Rupe. While working for Rupe as assistant, he received his PhD writing a dissertation entitled Die chemische und elektrochemische Oxidation des as. m-Xylidins und seines Mono- und Di-Methylderivates (The Chemical and Electrochemical Oxidation of Asymmetrical m-Xylidene and its Mono- and Di-methyl Derivatives) in 1925. He graduated summa cum laude.
Early work at Geigy On 25 May 1925 Müller began working as a research chemist for the dye division of J. R. Geigy AG in Basel. His first research topics at Geigy concerned synthetic and plant-derived dyes and natural tanning agents. This work led to the production of the synthetic tanning agents Irgatan G, Irgatan FL and Irgatan FLT. In 1935, Geigy began research on moth- and plant-protection agents and Müller was specifically interested in plant protection. He said that his love for plants and nature in general, which led him to choose botany as a minor subject at university, brought him to think about plant protection. Specifically, he wanted to start synthesizing chemical plant protection agents himself. In 1937, he patented a technique for synthesizing novel rhodanide- and cyanate-based compounds which showed bactericide and insecticide activity. He then developed the product Graminone, a seed disinfectant which was safer than the mercury-based disinfectants at the time.
Synthesis of DDT After his success with tanning agents and disinfectants, Müller was assigned to develop an insecticide. "At that time," according to The World of Anatomy and Physiology, "the only available insecticides were either expensive natural products or synthetics ineffective against insects; the only compounds that were both effective and inexpensive were arsenic compounds, which were just as poisonous to human beings and other mammals." During the course of his research, Müller found that insects absorbed chemicals differently than mammals. This led him to believe it likely that there are chemicals toxic exclusively to insects. He sought to "synthesize the ideal contact insecticide—one which would have a quick and powerful toxic effect upon the largest possible number of insect species while causing little or no harm to plants and warm-blooded animals." He also made it his goal to create an insecticide that was long-lasting and cheap to produce, along with a high degree of chemical stability. In embracing this goal, Müller was motivated by two events. The first of these was a major food shortage in Switzerland, which underscored the need for a better way to control the infestation of crops by insects. The second was the typhus epidemic in Russia, which was the most extensive and lethal such epidemic in history. He began his search for his insecticide in 1935. He studied all the data he could find on the subject of insecticides, decided which chemical properties the kind of insecticide he was in search of would exhibit, and set out to find a compound that would suit his purposes. Müller spent four years searching and failed 349 times before, in September 1939, he found the compound he was looking for. He placed a fly in a cage laced with one particular compound, and short while later, the fly died. The compound he had placed in the cage was dichlorodiphenyltrichloroethane (DDT), or, more precisely, 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane, which a Viennese pharmacologist named Othmar Zeidler had first synthesized in 1874. Zeidler, while publishing a paper about his synthesis, had not investigated the properties of the new compound, and had thus failed to recognize its extraordinary value as an insecticide. Müller quickly realized that DDT was the chemical he had been searching for. Tests of DDT by the Swiss government and the U.S. Department of Agriculture confirmed its effectiveness against the Colorado potato beetle. Further tests demonstrated its astonishing effectiveness against a wide range of pests, including the mosquito, louse, flea, and sandfly, which, respectively, spread malaria, typhus, the plague, and various tropical diseases.
Application of DDT After taking out a Swiss patent on DDT in 1940 (a U.K. patent followed in 1942 and patents in the U.S. and Australia in 1943), Geigy began to market two DDT-based products, a 5% dust called Gesarol spray insecticide and a 3% dust called Neocid dust insecticide. The name DDT was first employed by the British Ministry of Supply in 1943, and the product was added to U.S. Army supply lists in May of the same year. It was also in 1943 that the first practical tests of DDT as a residual insecticide against adult vector mosquitoes were carried out. The next year, in Italy, tests were performed in which residual DDT was applied to the interior surfaces of all habitations and outbuildings of a community to test its effect on Anopheles vectors and malaria incidence.
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