Beside its highly corrosive character, its main disadvantage is the formation by neutron activation of Bi (and subsequent beta decay) of Po (T '"`UNIQ--templatestyles-0000000F-QINU`"' 1 ⁄ 2 = 138.38 day), a volatile alpha-emitter highly radiotoxic (the highest known radiotoxicity, above that of plutonium).