Radium seventh of a gram of radium. One kilogram of the Earth's crust contains about 900 picograms of radium, and one liter of sea water contains about 89 femtograms of radium. Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite (pitchblende) sample. While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive. They separated out an element similar to bismuth from pitchblende in July 1898, that turned out to be polonium. They then separated out a radioactive mixture consisting mostly of two
Radium Girls for living dial painters. The project also focused on collection of information and, in some cases, tissue samples from the radium dial painters. When the project ended in 1993, detailed information of 2,403 cases had been collected. This led to a book on the effects of radium on humans. The book suggests that radium-228 exposure is more harmful to health than exposure to radium-226. Radium-228 is more able to cause cancer of the bone as the shorter half life of the radon-220 product compared to radon-222 causes the daughter nuclides of radium-228 to deliver a greater dose of alpha radiation