Paul Muller Swiss chemist, Nobel laureate in physiology or medicine 1948 Date of Birth: 12.01.1899 Country: Switzerland

Biography of Paul Müller

Paul Hermann Müller was a Swiss chemist and Nobel laureate in Physiology or Medicine in 1948. He was born in Olten, Switzerland, to Gottlieb Müller, a Swiss railway employee, and Fanny (Leipoldt) Müller. He spent his early years in Lenzburg, his father's hometown. When he turned five, his family moved to Basel, where Paul received his education in a local school. After completing school at the age of seventeen, he started working at a chemical plant, and the following year became an assistant chemist in the laboratory of the J.R. Geigy company. Inspired by this research experience, Müller enrolled at the University of Basel in 1919 to study chemistry. He obtained his Ph.D. in 1925 with a dissertation on the organic chemistry of dyes.

After completing his studies, Müller joined the J.R. Geigy company, one of the largest chemical corporations, in Basel. While in Basel, he developed little interest in botany, but at J.R. Geigy, his first task was to study the properties of natural plant products. Over the next three years, Müller obtained several valuable tanning substances. His attention was then drawn to insecticides primarily used for seed protection. In 1935, he began researching insecticides. Despite the abundance of scientific literature and recommendations on their use, there were no insecticides available for sale. Müller sought to develop a synthetic insecticide that would be lethal to insects upon contact but non-toxic to humans and plants, affordable, and chemically stable.

A group of researchers led by Müller conducted biological studies, including testing the insecticidal properties of hundreds of chemical compounds. They synthesized one compound after another, attempting unsuccessfully to predict the insecticidal activity based on their structure. By September 1939, they created dichlorodiphenyltrichloroethane (DDT), a substance in which two benzene rings are linked by a carbon atom with three chlorine atoms attached to it. This compound proved to be an effective contact insecticide, and its chemical structure was stable. Müller knew that similar compounds containing sulfur instead of the central carbon atom were potent oral poisons when the chlorine atoms were located adjacent to each other. In line with this, he synthesized 4,4'-dichlorodiphenyltrichloroethane (DDT) in 1939. The J.R. Geigy company patented the compound in 1940, conducted field trials, and it was made available for sale in 1942.

During World War II, natural insecticide supplies to the Allied powers, most of which were produced in tropical countries, were reduced or completely halted, while the need for them was acute. Malaria and typhus, transmitted by insects, were the two major medical challenges faced by the Allies, as there were no vaccines against these diseases. Research conducted by Ronald Ross and Charles Nicolle showed that the spread of malaria and typhus could be halted by limiting the population of mosquitoes and lice, which were carriers of these diseases. The new insecticide DDT seemed ideal for this purpose. Its low toxicity to humans allowed it to be sprayed directly on the body to prevent typhus. It was also inexpensive, enabling the use of DDT to spray entire islands in the Pacific before the US military landed, thereby preventing malaria infection. DDT was so persistent that a single application remained effective for several months. The successful use of DDT during the war to combat malaria and typhus made Müller a leading candidate for the Nobel Prize in Physiology or Medicine, which he received in 1948 for the discovery of DDT's high efficacy as a contact poison.

For the next two decades, the unparalleled value of DDT as an insecticide was repeatedly confirmed, especially through its use in tropical countries. It not only prevented the occurrence of malaria, the most common tropical disease but also significantly increased the productivity of new agricultural crops developed by Norman Borlaug. However, the adverse effects of DDT were later discovered. One of the initial attractive features of this substance, its stability compared to natural plant insecticides, turned out to be a potential danger. Müller was aware from the beginning that this stability carried certain risks. DDT does not gradually decompose into harmless components but accumulates in soil, water, and the bodies of animals. Moreover, the compound is a broad-spectrum insecticide, killing both pests and beneficial insects, such as bees. Concerns about the side effects of DDT grew during the 1960s, and in 1972, its widespread use in the United States was banned. The detrimental consequences of DDT use and the harm caused by this powerful insecticide to the environment led to the publication of Rachel Carson's book "Silent Spring."

In 1927, Müller married Friedel Rüegg, and they had two sons and a daughter. He resigned from the J.R. Geigy company in 1961 and spent the next four years working in a private laboratory he set up in his home in Oberwil, near Basel. He passed away on October 13, 1965, after a brief illness. Müller received an honorary doctorate from the University of Thessaloniki in Greece and was a member of the Paris Society of Industrial Chemistry and an honorary member of the Swiss Society for Research in Nature.