gas, is also radioactive. When ingested, 80% of the ingested radium leaves the body through the feces, while the other 20% goes into the bloodstream, mostly accumulating in the bones. This is because the body treats radium as calcium and deposits it in the bones, where radioactivity degrades marrow and can mutate bone cells. Exposure to radium, internal or external, can cause cancer and other disorders, because radium and radon emit alpha and gamma rays upon their decay, which kill and mutate cells. At the time of the Manhattan Project in 1944, the "tolerance dose" for workers was set at 0.1 micrograms of ingested radium. Some of the biological effects of radium include the first case of "radium-dermatitis", reported in 1900, two years after the element's discovery. The French physicist Antoine Becquerel carried a small ampoule of radium in his waistcoat pocket for six hours and reported that his skin became ulcerated. Pierre and Marie Curie were so intrigued by radiation that they sacrificed their own health to learn more about it. Pierre Curie attached a tube filled with radium to his arm for ten hours, which resulted in the appearance of a skin lesion, suggesting the use of radium to attack cancerous tissue as it had attacked healthy tissue. Handling of radium has been blamed for Marie Curie's death due to aplastic anemia. A significant amount of radium's danger comes from its daughter radon: being a gas, it can enter the body far more readily than can its parent radium. , 226Ra is considered to be the most toxic of the quantity radioelements, and it must be handled in tight glove boxes with significant airstream circulation that is then treated to avoid escape of its daughter 222Rn to the environment. Old ampoules containing radium solutions must be opened with care because radiolytic decomposition of water can produce an overpressure of hydrogen and oxygen gas. The world's largest concentration of 226Ra is stored within the Interim Waste Containment Structure, approximately north of Niagara Falls, New York. The Maximum Contaminant Level (MCL) for radium is 5pCi/L for drinking water, however, the OSHA doesn't set a exposure limit, as there is a radiation limit already set up. See also Notes References Bibliography Further reading External links Photos of Radium Water Bath in Oklahoma NLM Hazardous Substances Databank – Radium, Radioactive Annotated bibliography for radium from the Alsos Digital Library for Nuclear Issues