（以下材料是科普材料，在正式科学杂志上不被引用的，仅供初级知识介绍，读者明鉴。 在具体过程，更需听从在场的专家指导）
为什么钚的毒性这么强? （http://zhidao.baidu.com/question/62473096.html
钚 plutonium
一种化学元素。化学符号 Pu，原子序数 94 ，属周期系ⅢB族，为锕系元素的成员和人工放射性元素。半衰期最长的同位素是钚244。1940年美国G.T.西博格、E.M.麦克米伦、J.W.肯尼迪和A.C.沃尔用152.4厘米回旋加速器加速的16兆电子伏氘核轰击铀时发现钚 238。第二年又发现钚的最重要的同位素钚 239。在自然界中只找到两种钚同位素，一种是从氟碳铈镧矿中找到的微量钚 244，它具有足够长的半衰期，可能是地球上原始存在的。另一种是从含铀矿物中找到的钚239，是铀238吸收自然界里的中子而形成的。其他钚同位素都是通过人工核反应合成的。已发现的有质量数232～246的钚同位素。
钚是银白色金属，熔点640℃，沸点 3234℃。在干燥的空气中，表面的氧化膜起保护作用，氧化缓慢，但有水气存在下氧化膜被破坏，容易被氧化。钚溶于盐酸、磷酸，但不溶于硝酸和浓硫酸，原因是发生钝化作用。钚的氧化态为＋3、＋4、＋5、＋6、＋7，以＋4价化合物最稳定。钚的氯化物、硝酸盐、硫酸盐易溶于水，氧化物、氢氧化物、草酸盐碳酸盐不溶于水。钚有剧毒，操作时应严密保护。
金属钚是银白色的，与氧气、水蒸气和酸作用，但不与碱反应。它和铀一样用于核燃料和核武器。现在已经可以获得成吨的钚。
1945年，西博格比较了镎和钚，认为它们与铀的性质相似，同时又与稀土元素中钐相似，在1945年发表了他编排的元素周期表，建立了与镧系元素相同的锕系元素，把它们一起放置在元素周期表的下方，成为今天形式的元素周期表，并留下94号元素以后一系列的空位留待发现。
另外，钚是世界上最毒的物质。一片阿斯匹林大小的钚，足以毒死2亿人，5克的钚足以毒死人类。钚的毒性比砒霜大4．86亿倍，它的威力胜过核武器。
钚的大规模制备是通过反应堆中的核反应进行的，由铀238 吸收中子后生成，再用溶剂萃取和离子交换纯化。钚是易裂变的放射性元素，能用作核燃料，用于制造核武器。钚用作快中子增殖反应堆燃料时，新形成的钚比消耗的钚还要多，可使铀238转变为钚而加以充分利用。钚238用于制造同位素电池，用作宇宙飞船、人造卫星、航标灯的电源。
下面是维基上有关钚毒性科普介绍（http://en.wikipedia.org/wiki/Plutonium）
Toxicity of Plutonium
Isotopes and compounds of plutonium are dangerous due to their radioactivity. Contamination by plutonium oxide (spontaneously oxidized plutonium) has resulted from a number of military nuclear accidents where nuclear weapons have burned.[85]
The alpha radiation plutonium emits does not penetrate the skin but can irradiate internal organs when plutonium is inhaled or ingested.[32] The skeleton, where plutonium is absorbed by the bone surface, and the liver, where it collects and becomes concentrated, are at risk.[31] Plutonium is not absorbed into the body efficiently when ingested; only 0.04% of plutonium oxide is absorbed after ingestion.[32] What plutonium is absorbed into the body is excreted very slowly, with a biological half-life of 200 years.[86] Plutonium passes only slowly through cell membranes and intestinal boundaries, so absorption by ingestion and incorporation into bone structure proceeds very slowly.[87][88]
Plutonium is more dangerous when inhaled than when ingested. The risk of lung cancer increases once the total dose equivalent of inhaled radiation exceeds 400 mSv.[89] The U.S. Department of Energy estimates that the lifetime cancer risk for inhaling 5,000 plutonium particles, each about 3 microns wide, to be 1% over the background U.S. average.[90] Ingestion or inhalation of large amounts may cause acute radiation poisoning and death; no human is known to have died because of inhaling or ingesting plutonium, and many people have measurable amounts of plutonium in their bodies.
The "hot particle" theory in which a particle of plutonium dust radiates a localized spot of lung tissue has been tested and found false – such particles are more mobile than originally thought and toxicity is not measurably increased due to particulate form.[87] However, when inhaled, plutonium can pass into the bloodstream. Once in the bloodstream, plutonium moves throughout the body and into the bones, liver, or other body organs. Plutonium that reaches body organs generally stays in the body for decades and continues to expose the surrounding tissue to radiation and thus may cause cancer. [91]
Several populations of people who have been exposed to plutonium dust (e.g. people living down-wind of Nevada test sites, Hiroshima survivors, nuclear facility workers, and "terminally ill" patients injected with Pu in 1945–46 to study Pu metabolism) have been carefully followed and analyzed.
These studies generally do not show especially high plutonium toxicity or plutonium-induced cancer results.[87] "There were about 25 workers from Los Alamos National Laboratory who inhaled a considerable amount of plutonium dust during the 1940's; according to the hot-particle theory, each of them has a 99.5% chance of being dead from lung cancer by now, but there has not been a single lung cancer among them."[92][93] Plutonium has a metallic taste.[94]
Criticality potential
Toxicity issues aside, care must be taken to avoid the accumulation of amounts of plutonium which approach critical mass, particularly because plutonium's critical mass is only a third of that of uranium-235.[7] A critical mass of plutonium emits lethal amounts of neutrons and gamma rays.[95] Plutonium in solution is more likely to form a critical mass than the solid form due to moderation by the hydrogen in water.[13]
Criticality accidents have occurred in the past, some of them with lethal consequences. Careless handling of tungsten carbide bricks around a 6.2 kg plutonium sphere resulted in a fatal dose of radiation at Los Alamos on August 21, 1945, when scientist Harry K. Daghlian, Jr. received a dose estimated to be 5.1 Sievert (510 rems) and died 28 days later.[96] Nine months later, another Los Alamos scientist, Louis Slotin, died from a similar accident involving a beryllium reflector and the same plutonium core (the so-called "demon core") that had previously claimed the life of Daghlian.[97] These incidents were fictionalized in the 1989 film Fat Man and Little Boy.
In December 1958, during a process of purifying plutonium at Los Alamos, a critical mass was formed in a mixing vessel, which resulted in the death of a crane operator named Cecil Kelley.[98] Other nuclear accidents have occurred in the Soviet Union, Japan, and many other countries.[98]
Flammability of plutonium
Metallic plutonium is a fire hazard, especially if the material is finely divided. In a moist environment, plutonium forms hydrides on its surface, which are pyrophoric and may ignite in air at room temperature. Plutonium expands up to 70% in volume as it oxidizes and thus may break its container.[99] The radioactivity of the burning material is an additional hazard. Magnesium oxide sand is probably the most effective material for extinguishing a plutonium fire. It cools the burning material, acting as a heat sink, and also blocks off oxygen. Special precautions are necessary to store or handle plutonium in any form; generally a dry inert gas atmosphere is required.[99][100][note 11]
