The Gastrointestinal Absorption of Organically Bound Forms of Plutonium in Fed and Fasted Hamsters

Summary

Values of about 0·005–0·01 per cent were obtained for the absorption in fed hamsters of plutonium ingested as Pu⁴⁺ citrate, isocitrate, phytate and malate complexes and Pu³⁺ ascorbate compared with about 0·003–0·004 per cent for Pu⁴⁺ nitrate. Replacing drinking water with tea did not affect the result for Pu⁴⁺ nitrate. Fasting hamsters for 8 h before the administration of plutonium citrate increased absorption to 0·1–0·2 per cent. An extra period of fasting for 4 h after administration did not lead to a further increase in absorption. Similar values were also obtained when plutonium citrate was administered after a 24 h fast, followed either by immediate access to food or a further 4 h fast. In hamsters fasted for 24 h before administration of either Pu³⁺ ascorbate or Pu⁴⁺ nitrate, about 6–7 per cent of the ingested plutonium was retained in the gastrointestinal tract after one week. At three weeks after ingestion of Pu³⁺ ascorbate, gastrointestinal retention had fallen 100-fold without an increase in absorption.     

吸入氧化钚在肺和胸淋巴结的代谢动态观察

本研究用放射自显影和液闪测定法观察了吸入氧化钚在大鼠肺和胸淋巴结的代谢动态特点,并用数学模式描述了钚在肺和淋巴结内的蓄积、分布和廓清规律.结果表明,钚在肺内分布随吸入时间而异,有逐渐向肺边缘集中的趋势.在淋巴结内的分布也不均匀,主要分布于副皮质区.半月后出现集中趋势,有的在腺体一端,有的沿小粱分布.钚在整个淋巴结内的分布规律,可用多项指数式表示.     

Postdetonation nuclear debris for attribution

On the morning of July 16, 1945, the first atomic bomb was exploded in New Mexico on the White Sands Proving Ground. The device was a plutonium implosion device similar to the device that destroyed Nagasaki, Japan, on August 9 of that same year. Recently, with the enactment of US public law 111-140, the "Nuclear Forensics and Attribution Act," scientists in the government and academia have been able, in earnest, to consider what type of forensic-style information may be obtained after a nuclear detonation. To conduct a robust attribution process for an exploded device placed by a nonstate actor, forensic analysis must yield information about not only the nuclear material in the device but about other materials that went into its construction. We have performed an investigation of glassed ground debris from the first nuclear test showing correlations among multiple analytical techniques. Surprisingly, there is strong evidence, obtainable only through microanalysis, that secondary materials used in the device can be identified and positively associated with the nuclear material.     

吸入239PuO2致癌危险度实验中的剂量计算

钚在肺中的初始沉积量,钚在呼吸道的代谢规律以及靶器官质量是吸入²³⁹PuO₂致癌危险度实验研究中器官剂量计算的三要素。本文作者提出了大鼠暇入²³⁹PuO₂后肺、肺门淋巴结剂量计算公式 。此公式因考虑到靶器官质量变化规律, 优于国外算法,使器官剂量估算更合理。     

Predicting Plutonium Decorporation Efficacy after Intravenous Administration of DTPA Formulations: Study of Pharmacokinetic–Pharmacodynamic Relationships in Rats

Purpose The objectives of this study were: 1) to assess the relationship between plutonium decorporation (increased excretion and reduced retention in main organs of deposition) induced by intravenous liposome formulations of the chelating agent diethylene triamine pentaacetic acid (DTPA) and its pharmacokinetics, and 2) to model the renal excretion of plutonium after treatment with liposome-encapsulated DTPA in order to predict its efficacy and to optimise treatment schedules.Materials and Methods Pharmacokinetic parameters from plasma or urinary data (days 0–16 sample collections) were modelled versus decorporation efficacy, and best correlations were selected for their goodness of fit.Results The plutonium decorporation enhancement by DTPA liposomal formulations was well described by logistic models and the best correlation was observed with the area under the DTPA concentration curve of each formulation. The plutonium urinary excretion rates decreased mono-exponentially as a function of time after a single dose and the proposed model allowed a simple determination of the elimination half-life of the Pu–DTPA complex, a reasonably good approximation of the long-term efficacy of the treatments from truncated urinary data.Conclusions Both liposomal formulations of chelating agents and pharmacokinetic approaches to plutonium decorporation should be helpful in optimising treatment protocols.     

放化分离α谱分析在钚内照射个人剂量监测应用中的探讨

目的 探讨尿钚放化分离结合α谱分析的监测方法作为职业人员吸入钚所致内照射个人剂量监测的适宜性,为核工业职业卫生管理和钚设施单位开展尿钚监测提供参考。方法 以美国能源局（DOE）核设施单位的钚化合物组成为例,使用模拟计算的方法,分别推导了急性和慢性吸入钚化合物致个人有效剂量分别为1 mSv时的尿钚水平,并与放化分离后α谱分析的典型探测限进行比较,分析尿钚监测用于个人剂量估算的适用性。结果 仅对于吸入M类钚化合物后10 d内使用放化分离α谱分析进行尿钚监测可以满足1 mSv探测限要求。结论 制定人员尿钚内照射个人剂量监测计划,须考虑监测方法的探测限,必要时通过工作场所监测结合受照时间等对工作人员的职业受照进行评价。     

Chromosome aberrations determined by sFISH and G-banding in lymphocytes from workers with internal deposits of plutonium

Purpose: To examine the influence of α-particle radiation exposure from internally deposited plutonium on chromosome aberration frequencies in peripheral blood lymphocytes of workers from the Sellafield nuclear facility, UK. Materials and methods: Chromosome aberration data from historical single colour fluorescence in situ hybridization (sFISH) and Giemsa banding (G-banding) analyses, together with more recent sFISH results, were assessed using common aberration analysis criteria and revised radiation dosimetry. The combined sFISH group comprised 29 men with a mean internal red bone marrow dose of 21.0 mGy and a mean external γ-ray dose of 541 mGy. The G-banding group comprised 23 men with a mean internal red bone marrow dose of 23.0 mGy and a mean external γ-ray dose of 315 mGy. Results: Observed translocation frequencies corresponded to expectations based on age and external γ-ray dose with no need to postulate a contribution from α-particle irradiation of the red bone marrow by internally deposited plutonium. Frequencies of stable cells with complex aberrations, including insertions, were similar to those in a group of controls and a group of workers with external radiation exposure only, who were studied concurrently. In a similar comparison there is some suggestion of an increase in cells with unstable complex aberrations and this may reflect recent direct exposure to circulating lymphocytes. Conclusions: Reference to in vitro dose response data for the induction of stable aberrant cells by α-particle irradiation indicates that the low red bone marrow α-particle radiation doses received by the Sellafield workers would not result in a discernible increase in translocations, thus supporting the in vivo findings. Therefore, the greater risk from occupational radiation exposure of the bone marrow resulting in viable chromosomally aberrant cells comes from, in general, much larger γ-ray exposure in comparison to α-particle exposure from plutonium.     

Uptake of 59Fe and 239Pu by Rat Liver Cells and Human Hepatoma Cells

Summary

The accumulation of ⁵⁹Fe and ²³⁹Pu was studied in rat hepatocytes in primary culture and in human hepatoma cells (Hep-G2 cells) and was compared with the uptake in isolated perfused rat liver and in rat liver in vivo. With respect to iron uptake from citrate both cell types react similarly: time and concentration dependence as well as the influence of temperature point to a non-specific but energy-dependent uptake mechanism. Pu shows similar behaviour except that a relatively large fraction remains bound to the cell membrane and uptake is lower. This is much more pronounced in Hep-G2 cells than in hepatocytes. If the metals are bound to transferrin, uptake into both cell lines, as well as into isolated perfused rat liver, is very low. After intravenous injection of ²³⁹Pu-citrate, accumulation in the rat liver is very rapid during the first 10 min and much slower after that. The role of citrate in metal uptake is discussed.     

Lung, liver and bone cancer mortality in Mayak workers

Workers at the Mayak nuclear facility in the Russian Federation offer the only adequate human data for evaluating cancer risks from exposure to plutonium. Risks of mortality from cancers of the lung, liver and bone, the organs receiving the largest doses from plutonium, were evaluated in a cohort of 17,740 workers initially hired 1948-1972 using, for the first time, recently improved individual organ dose estimates. Excess relative risk (ERR) models were used to evaluate risks as functions of internal (plutonium) dose, external (primarily gamma) dose, gender, attained age and smoking. By December 31, 2003, 681 lung cancer deaths, 75 liver cancer deaths and 30 bone cancer deaths had occurred. Of these 786 deaths, 239 (30%) were attributed to plutonium exposure. Significant plutonium dose-response relationships (p < 0.001) were observed for all 3 endpoints, with lung and liver cancer risks reasonably described by linear functions. At attained age 60, the ERRs per Gy for lung cancer were 7.1 for males and 15 for females; the averaged-attained age ERRs for liver cancer were 2.6 and 29 for males and females, respectively; those for bone cancer were 0.76 and 3.4. This study is the first to present and compare dose-response analyses for cancers of all 3 organs. The unique Mayak cohort with its high exposures and well characterized doses has allowed quantification of the plutonium dose-response for lung, liver and bone cancer risks based on direct human data. These results will play an important role in plutonium risk assessment.