Plutonium (Pu) is a synthetic, silvery-gray element (atomic number 94) primarily recognized for its role in nuclear energy and weapons. It does not occur naturally in significant quantities, making its creation and study a hallmark of mid-20th-century science. As a radioactive substance, its handling was often shrouded in secrecy and speculation, which fostered a number of urban legends about its early research. The intense curiosity about this element, especially during the development of the atomic bomb, led to a dangerous lack of caution. This environment of rapid discovery and limited knowledge is the setting for the infamous story of a scientist who inadvertently tasted this manufactured element.
The Infamous Story of Ingestion
The most detailed and confirmed account of a scientist ingesting plutonium occurred during the Manhattan Project, the top-secret effort to develop the first atomic weapons. Chemist Donald Mastick, then 23 years old, was working at the Los Alamos laboratory in August 1944 when the accident took place. Mastick was handling a small, sealed glass vial containing a solution of plutonium chloride, a highly concentrated form of the element. The element’s alpha decay had created internal pressure from helium gas buildup inside the tiny container, a property the scientists had not fully anticipated.
When Mastick attempted to snap open the thin neck of the vial, the built-up pressure caused the container to explode. A purplish-colored, acid-based solution, which contained the dissolved plutonium, sprayed directly onto his face and into his mouth. Mastick immediately reported experiencing a distinct, metallic taste. He was quickly taken to the site’s medical director, where his face was scrubbed and a stomach pump was used to remove the ingested material.
The incident was a stark illustration of the lax safety protocols common in the early days of nuclear research. While fellow scientist Egon Bretscher is sometimes anecdotally associated with the idea of tasting plutonium, Mastick’s accidental ingestion is the documented case. Despite the immediate medical intervention, trace amounts of the element remained detectable in Mastick’s body for decades afterward, though he survived until the age of 87.
Toxicity of Ingested Plutonium
The reason the story of accidental ingestion is so alarming lies in the specific radiological properties of plutonium, particularly the isotope plutonium-239. Plutonium is an alpha-emitter, meaning it releases heavy, positively charged alpha particles as it decays. These particles are incapable of penetrating the dead outer layer of skin, making external contact relatively harmless. However, if the element enters the body, the particles can cause intense, localized damage to living tissue.
Upon ingestion, the body’s gastrointestinal tract absorbs only a small fraction of the element, typically estimated to be about 0.05% of the total amount swallowed. The majority of the material passes through the digestive system and is excreted from the body. This low absorption rate is the primary reason why accidental ingestion is considered less hazardous than inhalation, which allows a much greater percentage of the material to be absorbed directly into the bloodstream.
Any amount that is absorbed into the bloodstream becomes extremely hazardous due to its tendency to accumulate in specific organs. Once absorbed, roughly 50% of the circulating plutonium relocates to the bone tissue, and approximately 30% is deposited in the liver. In the bone, the element can remain for up to 100 years, continuously bombarding surrounding cells with alpha radiation and significantly elevating the risk of bone cancer. The concentration in the liver also increases the long-term potential for liver cancer and other tissue damage.
Historical Human Exposure Experiments
The lack of early understanding regarding plutonium’s internal movement and retention led to a separate, darker chapter in its history involving deliberate human exposure. Between 1945 and 1947, a series of human experiments were conducted under the auspices of the U.S. government’s Manhattan Project and its successor, the Atomic Energy Commission. These studies involved injecting small, tracer amounts of plutonium directly into the bodies of 18 unsuspecting patients.
These experiments took place at various hospitals across the country, including facilities in Rochester, Chicago, and San Francisco. The individuals selected for the injections were often patients already hospitalized with chronic or terminal illnesses, though the radioactive injection was not a form of treatment. The purpose of these tests was purely to study the element’s metabolism—how it was distributed, retained, and excreted—to establish safety standards for nuclear workers.
The subjects were not informed that they were being injected with a highly toxic, synthetic radioactive element. This lack of consent and the non-therapeutic nature of the procedures represent a severe ethical violation in medical research. The data gathered helped scientists determine the biological half-life of plutonium in the body, but the long-term effects on the subjects remained largely unknown, highlighting the recklessness that characterized early research with this powerful, man-made element.