Radioactive Phenomena: The Beginnings

An overview of the history of radioactive isotopes in biology and medicine begins in the late 1890s with the discoveries of X-rays by the German physicist Wilhelm Conrad Roentgen, and the French physicist Antoine Henri Becquerel’s who discovered naturally occurring radiations in 1896,  shortly after hearing  of Roentgen’s X-rays at a meeting of the French Academy of Science. Drawing on the work of his father and grandfather on phosphorescence and luminescence, Becquerel discovered naturally occurring radiations from uranium salts while looking for a connection between phosphorescence and Roentgen’s X-rays. Further investigation by Becquerel, Rutherford and others revealed and documented the differences in these radiations including the discovery of alpha, beta, and gamma rays and the radioactive properties of different minerals.

X-rays produced by machines and emanations from naturally occurring materials often penetrated to long distances. This suggested that they  could be used to treat cancers deep within the body, not just for skin tumors using low-energy radiations. New diagnostic and therapeutic uses were rapidly explored and within 5 years published data revealed some of the benefits and hazards of these ionizing radiations.

One of the earliest reports of a misadventure took place at Vanderbilt University where the University Dean lost his scalp hair a few weeks after volunteering as a test subject following an unduly long exposure (Science, April 10, 1896 Dudley, W. Letter to the Editor). Fixed clinical and mobile x-ray units were used in a series of wars, first during the Spanish American War. In World War I, Marie Curie organized and participated in the operation of mobile X-ray systems used by the French Army.

Early investigators using high-energy radiations failed to recognize the danger posed to both the patient, and the unshielded worker. Thus, severe healthy effects were noted especially in  those participating in the earliest experiments (as chronicled in American Martyrs to Science Through the Roentgen Ray, by Percy Brown). Marie Curie herself was amongst the martyrs,  dying at age 66 in 1934 of a plastic anemia, a malignant hematological condition most likely due to  years of exposure to radiations from Radium sources. This occurred while extracting 226Ra from tons of pitchblende (uranium containing ore) from Joachimsthal, Czechoslovakia. She was also known to often carry test tubes containing radioactive isotopes in her pockets and storing them in her desk drawer. Marie and her husband Pierre Curie are best remembered for their research on radiation phenomena, for which they and Becquerel shared the 1903 Nobel Prize in Physics. In 1911, the Curies were awarded a second Noble prize in Chemistry for their discovery of Radium, as the responsible radioactive material. For a fascinating extensive oral and written history of the major people and events responsible for many of the major discoveries, see the American Institute of Physics.

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