Rate of Radioactive Decay (Rate of Radioactivity):
The original unit used to express the decay rate of a sample of radioactive material. The curie is equal to that quantity of radioactive material in which the number of atoms decaying per second is equal to 37 billion (3.7×1010). It was based on the rate of decay of atoms within one gram of radium. It is named for Marie and Pierre Curie who discovered radium in 1898. The curie is the basic unit of radioactivity used in the system of radiation units in the United States, referred to as “traditional” units.
Source: Health Physics Society, http://hps.org/publicinformation/radterms/radfact50.html
Source: http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=791&tid=154 Toxicological Profile of Radium, US ATDSR, Agency for Toxic Substances & Disease Registry.
Quote: “The most important hazard that arises from the release of nuclear energy are radiations produced directly from fission and subsequently emitted by the resultant fission products and plutonium. The fission products can produce injury either as an external source of radiation or, if they gain entry into the body, by acting as an internal radioactive poison, quite analogous to radium poisoning. This latter consideration is a major concern, since the amounts required within the body to produce injurious effects are minute compared to the quantities necessary to induce damage by external beta and gamma irradiation.
A comparison with the history of the radium industry gives an index of the magnitude of the problem presented by fission products and plutonium to the medical protection program of the Plutonium Project. …. A total of approximately one kilogram of radium has been isolated since its discovery fifty years ago.” end quote
Source: The Metabolism of the Fission Products and the Heaviest Elements
Jos. G. Hamilton, M.D., Division of Medical Physics (Berkeley), Divisions of Medicine and Radiology (San Francisco) University of California, 1946.