Actinium is a silvery radioactive metallic element. It glows blue in the dark due to its intense radioactivity. It has an atomic number of 89. Actinium was discovered in 1899 by André-Louis Debierne, a French chemist, who separated it from pitchblende. Friedrich Otto Giesel independently discovered actinium in 1902. The chemical behavior of actinium is similar to that of the rare earth lanthanum. It is about 150 times as radioactive as radium, making it valuable as a neutron source. Otherwise it has no significant industrial applications. Actinium-225 is used in medicine to produce Bi-213 in a reusable generator or can be used alone as an agent for radio-immunotherapy. Purified actinium-227 comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.773-year half-life. The isotopes of actinium range in atomic weight from 206 amu (206-actinium) to 234 amu (234-actinium). Actinium-227 is extremely radioactive, and in terms of its potential for radiation induced health effects, actinium-227 is about as dangerous as plutonium. Ingesting even small amounts of actinium-227 would represent a serious health hazard. The greatest threat of radioactivity to life as we know it is damage to the gene pool, the genetic make-up of all living species. Genetic damage from radiation exposure is cumulative over lifetimes and generations. There are no uses known for actinium