Marie Curie was present in such minute quantities that they would eventually have to process tons of the ore. In July 1898, Curie and her husband published a joint paper announcing the existence of an element which they named "polonium", in honour of her native Poland, which would for another twenty years remain partitioned among three empires (Russian, Austrian, and Prussian). On 26 December 1898, the Curies announced the existence of a second element, which they named "radium", from the Latin word for "ray". In the course of their research, they also coined the word "radioactivity". To prove their discoveries beyond any
Polonium methylated in living things to create organometallic compounds. Studies investigating the metabolism of polonium-210 in rats have shown that only 0.002 to 0.009% of polonium-210 ingested is excreted as volatile polonium-210. The median lethal dose (LD) for acute radiation exposure is about 4.5 Sv. The committed effective dose equivalent Po is 0.51 µSv/Bq if ingested, and 2.5 µSv/Bq if inhaled. So a fatal 4.5 Sv dose can be caused by ingesting , about 50 nanograms (ng), or inhaling , about 10 ng. One gram of Po could thus in theory poison 20 million people of whom 10 million would die.