Isotopes and compounds of plutonium are radioactive poisons that accumulate in bone marrow. Contamination by plutonium oxide (spontaneously oxidized plutonium) has resulted from a number of nuclear disasters and radioactive incidents including military nuclear accidents where nuclear weapons have burned.[86] Studies of the effects of these smaller releases, as well as of the widespread radiation poisoning sickness and death following the Atomic bombings of Hiroshima and Nagasaki, have provided considerable information regarding the dangers, symptoms and prognosis of radioactive poisoning. PMID 19454804
During the decay of plutonium, three types of radiation are released-alpha, beta, and gamma. Alpha particles can travel only a short distance and cannot travel through human skin. Beta particles can penetrate human skin, but they cannot go all the way through the body. Gamma radiation can go all the way through the body.[87] Alpha particles, beta particles, and gamma radiation all expose the body to ionizing radiation. Either acute or longer-term exposure carries a danger of unfavorable health outcomes including radiation sickness, cancer and death. The danger increases with the amount of exposure.
Even though alpha radiation does not penetrate the skin, it does irradiate internal organs if plutonium is inhaled or ingested.[33] The skeleton, where plutonium is absorbed by the bone surface, and the liver, where it collects and becomes concentrated, are at risk.[32] Plutonium is not absorbed into the body efficiently when ingested; only 0.04% of plutonium oxide is absorbed after ingestion.[33] What plutonium is absorbed into the body is excreted very slowly, with a biological half-life of 200 years.[88] Plutonium passes only slowly through cell membranes and intestinal boundaries, so absorption by ingestion and incorporation into bone structure proceeds very slowly.[89][90]
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.[91] 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.[92] 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.[77]
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.[89]
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.[93]
A commonly cited quote by Ralph Nader, states that a pound of plutonium dust spread into the atmosphere would be enough to kill 8 billion people. However, the math shows that only up to 2 million people can be killed by inhaling plutonium. This makes the toxicity of plutonium roughly equivalent with that of nerve gas. [94]
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.[89] "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."[95][96]
プルトニウムの毒性について (スコア:0, すばらしい洞察)
プルトニウムの毒性について武田邦彦氏から問題提起があり、
http://takedanet.com/2011/03/32_f654.html [takedanet.com]
他のアルファ線核種よりも有害である事実がないことが分かり
Wikipediaの記述も訂正されました。
プルトニウム 毒性 [wikipedia.org]
無害ではないですが、他のアルファ線核種と同等程度に有害です。
Re:プルトニウムの毒性について情報操作されましたね。 (スコア:2, すばらしい洞察)
武田邦彦氏ブログ更新が27日
東電のプルトニウム検出発表は28日夜
wikiペディア書換え操作が29日未明!
これは情報操作だね。
↓情報操作以前
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毒性
プルトニウムの同位体および化合物はすべて放射性で有毒である。化学毒性についてはウランに準ずると考えられているが[8]、その化学毒性が現れるよりもはるかに少ない量で放射線障害が生じると予想されるため、化学毒性のみでプルトニウムの毒性を論ずることはできない[9][10]。プルトニウムのような不溶性の化合物は腸で吸収されないが、そういった論とは無縁である。
プルトニウムは重金属の仲間であることから、ウランと同様に腎臓への障害が予想され、その大きさは鉛と同程度と推定される(鉛はプルトニウムよりも人類に馴染みのある元素だが相当に有害な物質でもある。詳しくは鉛またはテトラエチル鉛を参照)。また、ランタノイド元素とアクチノイド元素の同じ順番にある元素は互いに似ている傾向があることから、プルトニウムはランタノイドで同じ順番にあるサマリウムと似ていると考えられている。
毒性と人体への摂取経路 [編集]
京都大学原子炉実験所 小出裕章によれば、プルトニウムは、「人類が初めて作り出した放射性核種」であり、「かつて人類が遭遇した物質のうちでも最高の毒性」を持つとされる[11]。その理由は、プルトニウムがアルファ(α)線を放出すること、比放射能が高いこと、体内での代謝挙動にあるとされる[12]。
プルトニウムは人体には全く不必要な元素である。毒性の強い元素の中には必須ミネラルで微量は人体にとっても必要なものもあるが(例:ヒ素、セレン)、プルトニウムは必須ミネラルでさえない。
体内摂取の経路と排出 [編集]
プルトニウムを嚥下し消化管に入った場合、そのおよそ0.05%程度が吸収され、残りは排泄される[13]。吸収されたプルトニウムは、骨と肝臓にほぼ半々の割合で蓄積される。皮膚との接触については、傷が無い限り吸収されない。
最も重要な取り込み経路は、空気中に粒子状になったプルトニウムの吸入である。気道から吸入された微粒子は、大部分が気道の粘液によって食道へ送り出されるが、残り(4分の1程度)が肺に沈着する。沈着した粒子は肺に留まるか、胸のリンパ節に取り込まれるか、あるいは血管を経由して骨と肝臓に沈着する[14]。
プルトニウムは一度吸収されると体外へ排出されにくいのが特徴である。生物学的半減期はウランやラジウムと比べても非常に長く、骨と肝臓でそれぞれ20年と50年である。吸収線量あたりの有害さは核種や同位体によらずラジウム等と同程度であるが、プルトニウムの扱いに特に注意が必要なのは、まさに排出されにくいという特徴によるものである。
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海外の毒性説明
http://en.wikipedia.org/wiki/Plutonium
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Toxicity
Isotopes and compounds of plutonium are radioactive poisons that accumulate in bone marrow. Contamination by plutonium oxide (spontaneously oxidized plutonium) has resulted from a number of nuclear disasters and radioactive incidents including military nuclear accidents where nuclear weapons have burned.[86] Studies of the effects of these smaller releases, as well as of the widespread radiation poisoning sickness and death following the Atomic bombings of Hiroshima and Nagasaki, have provided considerable information regarding the dangers, symptoms and prognosis of radioactive poisoning. PMID 19454804
During the decay of plutonium, three types of radiation are released-alpha, beta, and gamma. Alpha particles can travel only a short distance and cannot travel through human skin. Beta particles can penetrate human skin, but they cannot go all the way through the body. Gamma radiation can go all the way through the body.[87] Alpha particles, beta particles, and gamma radiation all expose the body to ionizing radiation. Either acute or longer-term exposure carries a danger of unfavorable health outcomes including radiation sickness, cancer and death. The danger increases with the amount of exposure.
Even though alpha radiation does not penetrate the skin, it does irradiate internal organs if plutonium is inhaled or ingested.[33] The skeleton, where plutonium is absorbed by the bone surface, and the liver, where it collects and becomes concentrated, are at risk.[32] Plutonium is not absorbed into the body efficiently when ingested; only 0.04% of plutonium oxide is absorbed after ingestion.[33] What plutonium is absorbed into the body is excreted very slowly, with a biological half-life of 200 years.[88] Plutonium passes only slowly through cell membranes and intestinal boundaries, so absorption by ingestion and incorporation into bone structure proceeds very slowly.[89][90]
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.[91] 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.[92] 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.[77]
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.[89]
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.[93]
A commonly cited quote by Ralph Nader, states that a pound of plutonium dust spread into the atmosphere would be enough to kill 8 billion people. However, the math shows that only up to 2 million people can be killed by inhaling plutonium. This makes the toxicity of plutonium roughly equivalent with that of nerve gas. [94]
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.[89] "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."[95][96]
Plutonium has a metallic taste.
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内容を見比べてほしい。
Re:プルトニウムの毒性について情報操作されましたね。 (スコア:1)
LIVE-GON(リベゴン)