Editing Protactinium (section)

==Precautions==
Protactinium is both toxic and highly radioactive; thus, it is handled exclusively in a sealed [[glove box]]. Its major isotope <sup>231</sup>Pa has a [[specific activity]] of {{convert|0.048|Ci|GBq|lk=on}} per gram and primarily emits alpha-particles with an energy of 5&nbsp;MeV, which can be stopped by a thin layer of any material. However, it slowly decays, with a half-life of 32,760 years, into <sup>227</sup>Ac, which has a specific activity of {{convert|74|Ci|GBq}} per gram, emits both alpha and beta radiation, and has a much shorter half-life of 22 years. <sup>227</sup>Ac, in turn, decays into lighter isotopes with even shorter half-lives and much greater specific activities (SA).<ref name="ANL" />

{|class="wikitable" style="text-align:center"
!Isotope
|<sup>231</sup>Pa|| <sup>227</sup>Ac|| <sup>227</sup>Th|| <sup>223</sup>Ra|| <sup>219</sup>Rn|| <sup>215</sup>Po||<sup>211</sup>Pb|| <sup>211</sup>Bi || <sup>207</sup>Tl
|-
!SA ([[Curie (unit)|Ci]]/g)
| 0.048|| 73|| 3.1{{e|4}}|| 5.2{{e|4}}|| 1.3{{e|10}}||3{{e|13}}|| 2.5{{e|7}}|| 4.2{{e|8}}||1.9{{e|8}}
|-
!Decay
|α || α, β||α || α ||α ||α ||β||α, β||β
|-
![[Half-life]]
| 33 ka|| 22 a|| 19 days || 11 days|| 4 s|| 1.8 ms|| 36 min|| 2.1 min|| 4.8 min
|}

As protactinium is present in small amounts in most natural products and materials, it is ingested with food or water and inhaled with air. Only about 0.05% of ingested protactinium is absorbed into the blood and the remainder is excreted. From the blood, about 40% of the protactinium
deposits in the bones, about 15% goes to the liver, 2% to the kidneys, and the rest leaves the body. The biological half-life of protactinium is about 50 years in the bones, whereas its biological half-life in other organs has a fast and slow component. For example, 70% of the protactinium in the liver has a biological half-life of 10 days, and the remaining 30% for 60 days. The corresponding values for kidneys are 20% (10 days) and 80% (60 days). In each affected organ, protactinium promotes cancer via its radioactivity.<ref name="ANL" /><ref name="target" /> The maximum safe dose of Pa in the human body is {{convert|0.03|µCi|kBq|abbr=on}}, which corresponds to 0.5 micrograms of <sup>231</sup>Pa.<ref>{{cite book|author = Palshin, E.S. |display-authors = etal|title = Analytical chemistry of protactinium| place =Moscow|publisher = Nauka|date = 1968}}</ref> The maximum allowed concentrations of <sup>231</sup>Pa in the air in Germany is {{val|3|e=-4|u=Bq/m<sup>3</sup>}}.<ref name="target">{{cite journal|doi=10.1016/j.nima.2008.02.084|last1=Grossmann|date=2008|first1=R.|pages=122|volume=590|issue=1–3|last2=Maier|journal=[[Nuclear Instruments and Methods in Physics Research A]] |first2=H.|last3=Szerypo|first3=J.|last4=Friebel|first4=H.|title=Preparation of 231Pa targets|bibcode = 2008NIMPA.590..122G }}</ref>