Radium
Hazards

Radium is highly radioactive, as is its immediate decay product, radon gas. 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 the 1940s, the "tolerance level" 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 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, which as a gas can enter the body far more readily than can its parent radium.

As of 2015, Ra 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 Rn 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 Ra is stored within the Interim Waste Containment Structure, approximately 9.6 mi (15.4 km) north of Niagara Falls, New York.

In the United States, the Environmental Protection Agency -defined Maximum Contaminant Level for radium is 5 pCi/L for drinking water; the Occupational Safety and Health Administration does not specifically set exposure limits for radium, and instead limits ionizing radiation exposure in units of roentgen equivalent man based on the exposed area of the body. Radioactive material exposure is regulated more closely by the Nuclear Regulatory Commission, which sets the exposure limit to Ra at 0.01 μCi. Outside of the United States, exposure to radium is regulated by the International Commission on Radiological Protection and the World Health Organization.
startend:end_checker, oulipo:avoid_letter[e]