Editing Actinide (section)

== Toxicity ==
[[File:Alfa beta gamma radiation penetration.svg|thumb|Schematic illustration of penetration of radiation through sheets of paper, aluminium and lead brick]]
{{Periodic table (transuranium element)}}

Radioactive substances can harm human health via (i) local skin contamination, (ii) internal exposure due to ingestion of radioactive isotopes, and (iii) external overexposure by [[Beta particle|β-activity]] and [[Gamma ray|γ-radiation]]. Together with radium and transuranium elements, actinium is one of the most dangerous radioactive poisons with high specific [[Alpha radiation|α-activity]]. The most important feature of actinium is its ability to accumulate and remain in the surface layer of [[skeleton]]s. At the initial stage of poisoning, actinium accumulates in the [[liver]]. Another danger of actinium is that it undergoes radioactive decay faster than being excreted. [[Adsorption]] from the digestive tract is much smaller (~0.05%) for actinium than radium.<ref name="Himiya aktiniya" />

Protactinium in the body tends to accumulate in the kidneys and bones. The maximum safe dose of protactinium in the human body is 0.03 [[Curie (unit)|μCi]] that corresponds to 0.5 micrograms of <sup>231</sup>Pa. This isotope, which might be present in the air as [[aerosol]], is 2.5{{e|8}} times more toxic than [[hydrocyanic acid]].<ref name="Himiya protaktiniya" />{{page needed|date=August 2024}}

Plutonium, when entering the body through air, food or blood (e.g. a wound), mostly settles in the lungs, liver and bones with only about 10% going to other organs, and remains there for decades. The long residence time of plutonium in the body is partly explained by its poor solubility in water. Some isotopes of plutonium emit ionizing α-radiation, which damages the surrounding cells. The [[median lethal dose]] (LD<sub>50</sub>) for 30 days in dogs after intravenous injection of plutonium is 0.32 milligram per kg of body mass, and thus the lethal dose for humans is approximately 22&nbsp;mg for a person weighing 70&nbsp;kg; the amount for respiratory exposure should be approximately four times greater. Another estimate assumes that plutonium is 50 times less toxic than [[radium]], and thus permissible content of plutonium in the body should be 5&nbsp;μg or 0.3 μCi. Such amount is nearly invisible under microscope. After trials on animals, this maximum permissible dose was reduced to 0.65&nbsp;μg or 0.04 μCi. Studies on animals also revealed that the most dangerous plutonium exposure route is through inhalation, after which 5–25% of inhaled substances is retained in the body. Depending on the particle size and solubility of the plutonium compounds, plutonium is localized either in the lungs or in the [[lymphatic system]], or is absorbed in the blood and then transported to the liver and bones. Contamination via food is the least likely way. In this case, only about 0.05% of soluble and 0.01% of insoluble compounds of plutonium absorbs into blood, and the rest is excreted. Exposure of damaged skin to plutonium would retain nearly 100% of it.<ref name="Plutoniy">{{cite book|editor1=B.A. Nadykto|editor2=L.F.Timofeeva|title=Plutonium|place=Sarov|publisher=VNIIEF|year=2003|volume=1|series=Fundamental Problems|isbn=978-5-9515-0024-3}}</ref>

Using actinides in nuclear fuel, sealed radioactive sources or advanced materials such as self-glowing crystals has many potential benefits. However, a serious concern is the extremely high radiotoxicity of actinides and their migration in the environment.<ref>{{cite book|author1=M. I. Ojovan|author2=W.E. Lee|title=An Introduction to Nuclear Waste Immobilisation|publisher=Elsevier|place=Amsterdam|year=2005|url=https://books.google.com/books?id=vQkQnmo_bE0C|isbn=978-0-08-044462-8}}</ref> Use of chemically unstable forms of actinides in MOX and sealed radioactive sources is not appropriate by modern safety standards. There is a challenge to develop stable and durable actinide-bearing materials, which provide safe storage, use and final disposal. A key need is application of actinide solid solutions in durable crystalline host phases.<ref name=burakov />