The apparent murder of former Russian intelligence officer Alexander Litvinenko through polonium poisoning seemed like an outlandish innovation in crime. But it was not the first time that polonium had been deliberately administered to human subjects.
In 1944 at the University of Rochester in New York, “tracer amounts of radioactive polonium-210 were injected into four hospitalized humans and ingested by a fifth,” according to a 1995 retrospective account (pdf).
Four men and one women who were already suffering from a variety of cancers reportedly volunteered for the dangerous experiment. One patient died from his cancer six days after the injection.
See “Polonium Human-Injection Experiments,” Los Alamos Science, Number 23, 1995.
That polonium article appeared as a sidebar in a larger paper called “The Human Plutonium Injection Experiments” (pdf) by William Moss and Roger Eckhardt, which follows on the work of reporter Eileen Welsome, builds on the declassification activities of Energy Secretary Hazel O’Leary, and complements the research of the Advisory Committee on Human Radiation Experiments. See the Moss and Eckhardt paper from Los Alamos Science here.
Polonium was classified in July 1945, the authors note, and given the code name “postum.”
The basic chemistry and physics of polonium were declassified in 1946. The fact that polonium-210 was used in nuclear weapon initiators was declassified in 1967, according to a Department of Energy historical account.