"The Plutonium Files: America's Secret Medical Experiments in the Cold War is a 1999 book by Eileen Welsome. It is a history of U.S. government-engineered radiation experiments on unwitting Americans, based on the Pulitzer Prize--winning series Welsome wrote for the Albuquerque Tribune.
The purpose of the experiments was to assess the effect of radioactivity on the human body. For example, between April 1945 and July 1947, 18 people were injected with plutonium by doctors associated with the Manhattan Project. None of these men, women, and children were told what was being done, and none gave informed consent. Most of the subjects, Welsome writes, "were the poor, the powerless, and the sick -- the very people who count most on the government to protect them".