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A History of Radioisotopes in Science and Medicine
By ANGELA N. H. CREAGER
THE UNIVERSITY OF CHICAGO PRESSCopyright © 2013 The University of Chicago
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Quite unlike atomic power, radioactive isotopes, tracers, and radiations can be available to science, medicine and technology on a scale adequate to all anticipated needs, and in most cases can be so today.—US Atomic Energy Commission, 1947
At the close of World War II, the nuclear detonations over Hiroshima and Nagasaki demonstrated the devastating power of the atom. As Americans became aware of their country's secret development of nuclear weapons, the US government swiftly turned attention to the peaceful benefits of nuclear knowledge. Foremost was harnessing the energy of atomic fission for electrical power and transportation, but these applications would require time and technology to realize. Another byproduct of atomic energy, however, was ready immediately. Nuclear reactors could be used to generate radioactive isotopes—unstable variants of chemical elements that give off detectable radiation. Scientists began using radioisotopes in biomedical experiments two decades before the atomic age, but their availability remained small-scale until nuclear reactors were developed for the bomb project. In planning for postwar atomic energy, leaders of the Manhattan Project proposed converting a large reactor at Oak Ridge, part of the infrastructure for the bomb project, into a production site for radioisotopes for civilian scientists. The US Atomic Energy Commission (AEC) inherited this plan and oversaw an expansive program making isotopes available for research, therapy, and industry. This book is an account of the uses of radioisotopes as a way to shed new light on the consequences of the "physicists' war" for postwar biology and medicine.
By the end of the war, the Manhattan Engineer District had constructed laboratories and plants at more than a dozen sites throughout the country. On January 1, 1947, these were transferred to the AEC, a civilian agency charged with continuing US atomic weapons production while developing the peaceful uses of atomic energy. Five presidentially appointed Commissioners directed the AEC. The appointees tended to be directors of other agencies, lawyers, businessmen, and physical scientists. The chair of the Commission served as a spokesperson for this group, but decisions were made by majority vote. A general manager oversaw day-today operations. There were limits, both practical and legal, on the civilian orientation of the AEC. Since it produced the growing arsenal of atomic weapons, the agency remained closely tied to the Armed Forces. A Military Liaison Committee provided the organizational interface between the agency and the military, though more extensive interactions developed. The rapid escalation in atomic weapons production and testing through the 1950s, and the shift to thermonuclear bombs, kept the AEC focused heavily on military applications. Even so, the Commission, particularly its first chair David J. Lilienthal, viewed the development of civilian applications of atomic energy as central to the agency's mandate, as well as politically expedient. The Commission's radioisotope distribution program was vital to this mission. In fact, by the late 1940s, the AEC had little else to hold out as evidence of the atom's peaceful benefits; hopes for rapid development of an atomic power industry faded and the nuclear arms race took off with the hardening of the Cold War.
The political value of radioisotopes derived from their scientific and medical utility. Isotopes differ from ordinary atoms by having an alternate (often greater) number of neutrons. Stable isotopes persist indefinitely with this extra nuclear baggage, and can be identified on account of their increased atomic mass. Radioisotopes, by contrast, can be detected when they decay to another—usually stable—form, by emitting at least one of three kinds of radiation. Alpha particles (each made up of two protons and two neutrons) do not go far, and cannot pass through paper. Beta particles (high-energy electrons or positrons) are more penetrating, but can be stopped by wood. Gamma rays have high energy and travel the longest distance in air; they are stopped only by dense materials such as lead or concrete. The radiation hazard associated with each radioisotope depends on how frequently it decays (its half-life), and on the kind and energy of the particles emitted when it does.
Already in the 1930s, scientists and physicians distinguished two ways of using radioisotopes. Like radium or x-ray machines, they could be employed as a source of radiation, such as in cancer therapy. This generally required a significant amount of radioactivity (measured in curies). More innovatively, and generally requiring less radioactivity, radioisotopes could be used as molecular tracers. (So could stable isotopes.) Isotopes gave researchers a way to tag compounds by replacing an ordinary atom with its radioactive sibling. One could then follow the labeled molecule through chemical reactions or biological systems by detecting the radiation emitted as radioisotopic atoms decayed. Consequently, previously imperceptible molecular processes could be traced, leading observers to compare radioisotopes with microscopes. The AEC's 1948 semiannual report emphasized the revolutionary character of radioisotopes: "As tracers, they are proving themselves the most useful new research tool since the invention of the microscope in the 17th Century; in fact, they represent that rarest of all scientific advances, a new mode of perception." A 1952 report reiterated: "Because of the special ability to chart their course through living organisms and intact objects, isotopes have been called the most important scientific tool developed since the microscope."
In contrast to the microscope, however, the aim of using isotopic tracers was not to bring into view anatomical structures so much as dynamic transformations. Biochemists used radioisotopes to reveal the sequence of chemical reactions in metabolism. Physiologists followed the assimilation and turnover of key nutrients and tagged molecules such as insulin to track the movement and activity of hormones. Molecular biologists labeled nucleic acids with radioisotopes to follow the replication and expression of genes. Physicians utilized radioisotopes such as radioiodine and radio-phosphorus to diagnose thyroid function and detect tumors. Ecologists profited as well, using phosphorus-32 to trace nutrient cycling through the living and nonliving parts of aquatic and terrestrial landscapes, giving concrete meaning to the notion of an ecosystem.
Underlying these diverse applications of isotopic tracers was a common tactic. Biologists of all stripes employed radioisotopes to trace out the movement and chemical transformation of key molecules, charting the circulation of materials and energy through cells, organisms, and communities. As labels, radioisotopes could be used to follow compounds through separation techniques (centrifugation, electrophoresis, chromatography) or through biological processes, such as the synthesis of proteins or the movement of phosphorus from phytoplankton into inorganic debris. These tools and their representations—as maps, pathways, and cycles—invited new questions about the economy and regulation of life, informed by the concepts of cybernetics. Radioisotopes were key ingredients of a postwar episteme of understanding life in molecular terms.
By analogy, Life Atomic uses radioisotopes as historical tracers, analyzing how they were introduced into systems of scientific research, how they circulated, and what new developments they enabled. I analyze the movement of radioisotopes through government facilities, laboratories, and clinics, both in the United States and around the world, as a way to make visible key transformations in the politics and epistemology of postwar biology and medicine. The launching of a US government distribution system led to a remarkable penetration of radioisotopes into American laboratories. From 1946 to 1955, the AEC's Oak Ridge contractor sent out nearly 64,000 shipments of radioactive materials to more than 2,400 laboratories, companies, and hospitals. This number underestimates by several-fold the number of ultimate recipients, because many bulk shipments went to companies that sold radiolabeled compounds and radiopharmaceuticals. These radioisotopes were used in more than 10,000 scientific publications during that first decade of the AEC's program. The vast majority of these radioisotopes originated in the Oak Ridge reactor that had been part of the Manhattan Project. (See figure 1.1.)
The availability of this new research tool was tied up with the politics of atomic energy. Most importantly, this is why radioisotope usage took off so quickly—the AEC did everything it could to encourage scientists and physicians to use these "by-products" of the bomb project. By making laboratories, clinics, and companies the beneficiaries of the government's nuclear largesse, the AEC hoped to build public support. In 1950, Commissioner Henry DeWolf Smyth assessed the impact of the isotope distribution program in the following terms:
When [the AEC] is asked, "What are the peacetime uses of atomic energy?" it can reply "Isotopes." Not that they will be useful sometime but that they are already useful. The isotope distribution program is enormously valuable because it reveals the Atomic Energy Commission as more than just a weapons organization. This is true not only in this country, but abroad where the foreign distribution of isotopes has had a very good effect on our foreign relations.
Smyth is remembered chiefly not as an AEC Commissioner, but as the physicist who wrote the official history of the Manhattan Project. The Smyth Report is the starting point for a vast historiography of the atomic bomb oriented around its origins in and consequences for the physical sciences. Life Atomic builds on a more recent scholarship examining how the Manhattan Project and the atomic age shaped postwar biology and medicine. For example, the AEC's interest in understanding radiation damage led to significant funding for genetics research, as well as for studies of Japanese survivors by the Atomic Bomb Casualty Commission. In the 1950s, concerns about the environmental effects of radioactive waste led the AEC's Oak Ridge National Laboratory to organize a large ecology research group, which was instrumental to the development of radioecology. Research into a wide range of biological, medical, and environmental problems took place at the AEC's national laboratories, and at many universities and hospitals with grants from the Commission. Compared with these other AEC initiatives, the radioisotope program is notable for its early origin—the program was established by the Manhattan Project in advance of the Atomic Energy Act of 1946—and the sheer number of research sites that it affected. Though rarely acknowledged, the AEC shaped life science and medicine as profoundly as it did physics and engineering. Hans-Jörg Rheinberger has aptly described the dissemination of radioisotopes as "big science coming in small pieces."
Smyth focused on the important role of the AEC's radioisotope supply in demonstrating that atoms could be helpful as well as harmful. As he indicated, it was not only domestic politics that the agency targeted; the US government saw radioisotope shipments abroad as a key means of aiding diplomacy. Exports were initially justified, over the objections of Congressional critics, as part of the Marshall Plan. By the mid-1950s, the international reach of the isotope program received special attention from President Eisenhower, whose "Atoms for Peace" initiative focused on the foreign development of atomic energy. The United States was competing with other nuclear powers, most notably the Soviet Union, in providing radioisotopes and reactors as a means to wield geopolitical influence. Other Western nations building atomic energy infrastructures launched national companies to supply radioisotopes or develop nuclear power. The AEC, in contrast, was charged with fostering "free enterprise," despite the fact that the 1946 Atomic Energy Act forbade private ownership of fissionable material and most patents on nuclear technologies. This led to a convoluted attempt by the AEC to involve companies in its operations despite the absence of anything like a free market. Moreover, the AEC's national security–related requirements for radioisotope exports put the United States at a disadvantage in comparison with the British and Canadian governments, which sold radioisotopes to foreigners with fewer restrictions.
Although the 1946 Atomic Energy Act made provision for distributing the "by-products" of nuclear reactors, most of the isotopes scientists and physicians desired were not typical fission by-products. Rather, the neutron flux of reactors was employed to irradiate target materials. The specific radioisotopes generated through irradiation were usually chemically purified for sale. Thus the production and distribution of radioisotopes put the US government in a peculiar role, as the manufacturer of a perishable laboratory good. Even as Congressional debates over the appropriate relationship of the federal government to university science delayed the establishment of the National Science Foundation until 1950, AEC-produced radioisotopes represented the support of the US government for scientific research in strikingly tangible terms. The importance of the Cold War in shaping developments in biology and medicine should be understood not only in terms of ideology, but also in terms of infrastructure. The significance of the politics of atomic energy for postwar science, in other words, can be traced using the radioisotopes that left the AEC's nuclear reactors and entered laboratories, clinics, and companies.
Sources and Story
While radioisotopes were important to research and medicine through most of the twentieth century (particularly if natural radioisotopes such s radium-226 are included), the ensuing chapters emphasize developments from 1945 to 1965, when artificial radioisotopes first achieved widespread utilization. This early postwar period was a crucial juncture for the diffusion of radioisotopes as a research technology, for reasons beyond technical utility. After the first atomic weapons were detonated over Japan, the US government's attempts to both exploit and justify atomic energy resulted in the vast uptake of radioisotopes into laboratories, clinics, and the environment. In this sense, by tracing the pathways along which radioisotopes moved, one sees how intertwined were the political, military, economic, and scientific aspects of atomic energy.
That said, there is an important caveat to this book's attempt to narrate postwar science, medicine, and politics through radioisotopes. The AEC generated a massive volume of published and unpublished documents; these provide the main source-base for Life Atomic, undeniably shaping its perspective. The promise and perils of atomic energy presented here are those voiced by government officials and scientists allied with the AEC. To be sure, one finds sharp points of disagreement within this elite group, their vantage points reflecting not only their varying backgrounds, political convictions, and disciplinary affiliations, but also their locations, whether based in Oak Ridge or in Washington, DC, in the AEC's headquarters or on the floors of Congress. Yet they shared, nearly without exception, a commitment to the civilian development of atomic energy and a confidence in the ability of scientists and engineers to safely manage nuclear materials, by-products, and wastes. This underlying consensus is especially important for understanding why the biological hazards and environmental problems associated with radiation, which were not completely unknown, did not sway the government's determination to disseminate radioisotopes and develop nuclear power.
The AEC itself funded extensive research into the biological effects of radiation, which eventually yielded evidence that no dose of ionizing radiation is low enough to be innocuous, yet such investigations occurred alongside, rather than prior to, the development of atomic energy for military, civilian, and industrial use. These studies included human experiments with radioisotopes and radiation sources, many of which remained classified until the 1990s, when new investigative journalism led the Clinton Administration to appoint a panel to evaluate the government's role in these experiments, and to declassify and publicize the relevant government documents they discovered. The Advisory Committee on Human Radiation Experiments (ACHRE) detailed a wide variety of medical experiments using radiation sources, both military and civilian, public and private. Their report contextualizes these diverse activities within the less stringent human subjects guidelines (and lack of federal regulation) that characterized postwar medical research, even as ACHRE criticized researchers who did not follow existing guidelines and government agencies for not providing more oversight. In response, President Clinton offered a formal apology to individuals who were harmed by radiation tests that the US government conducted or supported.
Excerpted from Life Atomic by ANGELA N. H. CREAGER. Copyright © 2013 The University of Chicago. Excerpted by permission of THE UNIVERSITY OF CHICAGO PRESS.
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Table of ContentsPreface
8. Guinea Pigs
9. Beams and Emanations