In the early 1930s, it became possible to start using the tracer technique biologically and this led, among other things, to the discovery of bones as a living organism. In 1944, George de Hevesy receives one of the world’s highest honours in physics, the Nobel Prize, based on his research at the University of Copenhagen.
From 1935 onwards, the group’s knowledge about radioactive tracers for identifying biological and physiological mechanisms exploded.
Radium as a gift from the nation
George de Hevesy worked closely with the respected scientist August Krogh, who was a Nobel Prize winner in 1920 and head of the famous Zoophysiological Laboratory.
Krogh and Hevesy worked with studies of membrane permeability with heavy water and radioactive isotopes.
Niels Bohr, August Krogh and George de Hevesy developed the technique – first via the radium-beryllium source, which Bohr received a 50th birthday present: 100,000 kr for 1 gram of radium collected from the Danish population so that more experiments could be carries out.
Pioneering work
Later on, Krogh, Hevesy and Bohr worked together to acquire a cyclotron for the production of radioactive isotopes. Nuclear physicist and Nobel Laureate Ernest Lawrence in the United States had invented the so-called ‘cyclotron’ in 1932 for the production of large amounts of radioactive isotopes for experiments and they wanted a similar apparatus in Copenhagen.
The cyclotron was granted by The Rockefeller Foundation, which funded the research with several donations to the institute in Copenhagen. The cyclotron should of course be used for physics experiments at the Institute for Theoretical Physics, but also to produce isotopes for biological and medical applications. It was first used in 1938 and was in operation until 1993.
They carried out experiments with the elucidation of plant and animal physiology, odontology and for medical use.
The first conference on the biological use of radioactive isotopes took place in Copenhagen in 1938. It had a particular focus on exchange studies in the bones, studies of permeability across membranes and radioactively marked red blood cells.
George de Hevesy’s assistant, Hilde Levi, describes how a cat escaped from the laboratory and out onto Fælled Park and so began the wild cat chase.
Cat hunting in Fælled Park
Today, our knowledge about the harmful effects of radioactive materials and with radiation protection and ethics committees, we shudder a bit over how poorly protected the researchers were. But they were people who knew what they had in their hands, it was very few people and it was pioneering work.
In her biography of George de Hevesy (1985), Hilde Levi vividly describes an experiment where a cat injected with phosphorus-32 jumped out of the window and escaped into Fælled Park.
Everyone involved had to go out to look for the animal for several houses and all of the cats that were caught got a cotton swab in the mouth, which was then tested with a Geiger counter. It took a long time before they found the right cat and the experiment could continue.
Hevesy receives the Nobel Prize
Hevesy worked in Copenhagen until the fall of 1943, when he had to travel to Stockholm due to the changed circumstances in Denmark, where the Nazi regime once more made it impossible for him.
Hevesy lived in Stockholm for the rest of his life and in 1944 received the 1943 Nobel Prize in Chemistry for the development of the tracer principle. The Prize is credited to the University of Copenhagen because it was given for the year 1943 and for research carried out at the Niels Bohr Institute.
Hilde Levi writes in her Hevesy biography that Hevesy would rather have received the Nobel Prize for the discovery of hafnium in 1922.
This observation was confirmed at the opening of the Hevesy Laboratory at Risø in 2005, which Hevesy’s daughter Jenny Hevesy attended. Hevesy’s daughter and son-in-law confirmed that there were other honours Hevesy was more pleased with.
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