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Thursday, January 30, 2014

Plutonium -- it Sticks to Your Bones, and Blasts you with Alpha the Strongest Form of Internal Damage

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QUANTITATIVE PLUTONIUM MICRODISTRIBUTION IN BONE TISSUE OF VERTEBRA FROM A MAYAK WORKER

Abstract

The purpose was to obtain quantitative data on plutonium microdistribution in different structural elements of human bone tissue for local dose assessment and dosimetric models validation. A sample of the thoracic vertebra was obtained from a former Mayak worker with a rather high plutonium burden. Additional information was obtained on occupational and exposure history, medical history, and measured plutonium content in organs. Plutonium was detected in bone sections from its fission tracks in polycarbonate film using neutron-induced autoradiography. Quantitative analysis of randomly selected microscopic fields on one of the autoradiographs was performed. Data included fission fragment tracks in different bone tissue and surface areas. Quantitative information on plutonium microdistribution in human bone tissue was obtained for the first time. From these data, quantitative relationship of plutonium decays in bone volume to decays on bone surface in cortical and trabecular fractions were defined as 2.0 and 0.4, correspondingly. The measured quantitative relationship of decays in bone volume to decays on bone surface does not coincide with recommended models for the cortical bone fraction by the International Commission on Radiological Protection. Biokinetic model parameters of extrapulmonary compartments might need to be adjusted after expansion of the data set on quantitative plutonium microdistribution in other bone types in human as well as other cases with different exposure patterns and types of plutonium.
Keywords: plutonium, skeleton, neutron-induced autoradiography

INTRODUCTION

The skeleton is a repository for many metals and radionuclides () and thus is as risk for radiation effects. Plutonium is of particular importance because it is a potent carcinogen and is used in nuclear weapons and nuclear power engineering, as well as other applications. Once plutonium is in the systemic circulation, for example, it is primarily concentrated in the liver and the skeleton in humans (). Epidemiological studies of plutonium personnel cohort show the presence of a reliable correlation between radiation levels from incorporated plutonium and the risk of skeletal malignant tumors (). Furthermore, these plutonium-induced skeletal tumors tend to appear at skeletal sites that differ from naturally occurring tumors (). Other radionuclides that deposit in bone are also associated with skeletal cancers and include 224Ra, 226Ra, 228Ra, 228Th, 249Cf, and 252Cf ().
Neutron-induced autoradiography (NIAR), also called “fission track autoradiography” (FTA), permits the identification and localization of very small amounts of plutonium in biological tissues (). In animal studies, the fission tracks present in the NIARs and the underlying tissue structures can be quantified resulting in estimates of plutonium concentrations and radiation doses to specific anatomical locations. These include structural bone elements and tissue compartments, (i.e. endosteal surfaces, bone tissue, bone marrow) (; ).
The purpose of this report was to present quantitative data on plutonium microdistribution in different areas of human bone tissue. These tissues were obtained from former workers at the Mayak Production Association, Ozyorsk, Russia. This approach should permit investigators to obtain detailed localization and distribution data for plutonium in the human. These data will allow researchers to make skeletal radiation dose assessment more precise, lead to improved radiation safety standards, and further our understanding of radiation-induced human cancers

MATERIALS AND METHODS

The Southern Ural Biophysics Institute (SUBI) Russian Human Radiobiological Tissue Repository (RHRTR) () was the source of biological material for studying plutonium microdistribution in bone tissue. Bone tissue samples were obtained during the autopsy of former workers from the nuclear fuel cycle plant (Mayak) and are stored in separate storage containers in neutral formalin.
For the present study, the biological material of the case (identification number in the repository is 440) with high plutonium body burden (44 kBq) was selected. Personal medical and dosimetric information including radiation history, medical data, autopsy records as well as postmortem radiometry data of organs and tissues is shown in Table 1. The employee worked at the plutonium plant for 7 years as a chemist-technologist and generally had daily contact with relatively soluble plutonium-nitrate compounds. After being diagnosed with chronic radiation sickness, the individual was transferred to another work location for 6.5 years, but had the potential for contact with insoluble plutonium dioxide aerosols. The records indicated exposures to uranium compounds were not likely. The exposures to plutonium-nitrate compounds helps explain the relatively small fraction of plutonium retained in the lungs relative to other organs of this worker (Table 1).
Table 1
Characteristics of RHRTR case #440.

Preparation of samples

A well-preserved sample of thoracic vertebra was obtained for the study. The sample had been stored in neutral formalin for 12 years. The vertebra was selected because the vertebral column is a site with a higher propensity for plutonium-induced sarcomas in experimental animals (; ) and humans (; ). Additionally, the vertebral bodies have a greater content of plutonium per unit bone mass than most other bones (). The tissue samples were dehydrated in ethyl alcohol at a concentration increasing sequentially from 40 to 100%. The dry bones were infiltrated with methyl methacrylate containing benzoyl peroxide as an activator. Infiltration was enhanced by several applications of vacuum to expel the air from the bone. Specimens were placed in a water bath at 37°C, and the temperature held constant until complete polymerization. Sections through the middle of the vertebral bodies were cut using a low-speed bone saw (Isomet, Buehler), polished with aluminum oxide to about 100 μm in thickness and cleaned in ultrapure water. The sections were soaked for 15 min in a 15% sodium borate solution, again rinsed in ultrapure water and allowed to dry in a dust-free environment.

Neutron-induced autoradiography

Neutron-induced autoradiography has an advantage over conventional autoradiography by decreasing the time necessary to attain a sufficient track density. Rather than waiting for a natural decay of the isotope with the registration of the alpha emission on a photographic film or emulsion, NIAR accelerates this by exposing the sections to thermal neutrons that will cause the 239Pu to fission. The fission fragments are registered on plastic detectors, rather than a photographic film or emulsion, as previously described in greater detail (; ). In addition, use of the NIAR is very practical to study plutonium distribution in bone tissue inasmuch as decalcification is not necessary. Decalcification results in plutonium “wash-out” from bone surfaces.
The bone sections were sandwiched between two Lexan polycarbonate detectors (International Plastics, Poulsbo, WA). The sections with their Lexan detectors were placed in a single container fabricated to fit in the port of the nuclear reactor. The container was then irradiated with thermal neutrons at a flux of 8 × 1012 neutron cm−2 s−1 with a total neutron fluence of 9.6 × 1016 neutron cm−2. This was done at the Massachusetts Institute of Technology Nuclear Reactor Laboratory. After the container was removed from the reactor, it was allowed to “cool” for one week to permit the decay of short-lived isotopes generated during the thermal neutron irradiation. The sections and the polycarbonate detectors were then removed and the detectors were placed in a solution of 5 M KOH at 70°C for 8-12 min with constant mild agitation. The detectors were then rinsed with filtered deionized water and allowed to dry. The plutonium fission fragments from the neutron irradiation create holes in the plastic detectors that appear as dark “tracks”. The sodium borate incorporated into the bone during the preparation step creates a subtle, latent bone image on the detectors through fission of the boron atoms. Selected bone sections used for NIAR were then mounted on plastic slides, polished and stained with a modified Giemsa stain for histological examination.

Analysis of autoradiographs

The algorithm proposed by was used for quantitative analysis of the NIARs. For this purpose, detectors were mounted on slides and every fourth viewing field was randomly selected (at magnification x 40). All 8 viewing fields were photographed using a digital camera Olympus DP 11 (Olympus Optical Co, LTD, Japan) and micrographs were printed. The accompanying histological section permitted precise identification of the different structural elements of bone tissue and their boundaries on the autoradiograph. Endosteal surfaces, bone marrow, Haversian canal lumens and bone tissue of cortical and trabecular fractions were quantified. Trabecular bone fraction was observed in all 8 viewing fields, and cortical bone fraction was registered only in 2 viewing fields. Plutonium localization in bone tissue needs to be precisely determined for dosimetric calculations. It was assumed that the ‘ribbon’ outlining the interface of bone-marrow or bone-Haversian canal lumens relates to endosteum area. For track calculation on endosteal surfaces, the width of this ‘ribbon’ was chosen corresponding to a plutonium fission track length. Based on previous data (), this value was 18 μm, and according to data derived in this study a plutonium fission track length was 15 μm, as measured using a digitizing program (AxioVs40,v. 4.7; Carl Zeiss). Therefore, the ‘ribbon’ width specifying endosteum was chosen as 30 μm (15 μm on each side from interface) for calculation of plutonium fission tracks on endosteal surfaces (Fig. 1a-b, 2a-b). However, the observed histological endosteum width was much less. The width of the endosteum was measured in different areas of the histological section using the same digitizing program. The measured mean endosteum width was 6.2 μm (Table 2)
Fig. 1
Structural elements of trabecular bone in (a) histological image, and (b) neutron-induced autoradiograph. M, Marrow; ES, endosteal surface; BV, bone volume. x40.
Fig. 2
Structural elements of cortical bone (a) histological image, and (b) neutron-induced autoradiograph. ES, endosteal surface; BV, bone volume; EH, endosteum of Haversian canals; lumen of Haversian canal is indicated by an arrow. x40.
Table 2
Endosteum width in different compartments of the vertebral specimen.
For identification purposes, the tracks were considered to be straight and not to exceed 20 μm in length (). If a track crossed an interface (e.g., endosteum-marrow), it was assigned to the endosteum, since the probability of its location in endosteum area is much higher than in bone marrow (; ; ). The authors scored the number of tracks in every structural element of bone tissue manually as well as areas and perimeters of these structures.

RESULTS AND DISCUSSTION

According to the biokinetic model of the extrapulmonary compartment of the International Commission on Radiation Protection (), there are cortical and trabecular fractions in skeleton, and each of these is subdivided into bone surfaces, bone volume and bone cavity compartment containing the bone marrow (Fig. 3). Results of plutonium fission fragment tracks scored in the different structural elements of bone tissue, areas of these regions on the sample and values of plutonium fission fragment tracks density in different structural elements are shown in Table 3. The data show that the plutonium distribution in bone tissue is very nonuniform, and this fact conforms to earlier animal studies (; ; ).
Fig. 3
Diagram of the skeletal ICRP model for plutonium ().
Table 3
Number and density of 239Pu fission fragment tracks in different parts of the bone tissue.

Limitations

There were some limitations in this study. First, there is little available data on potential plutonium wash-out from bone tissue fixed in neutral formalin. However, contains a description of an experiment on rats, whose bone tissues during the part of experiments were processed twice with cold 5% trichloroacetic acid. Her work indicated a small portion of the plutonium was washed-out. Thus, if during the period immediately after radionuclide intake, procedures using powerful chemical reagents, there was an 8% wash-out of the nuclide fixed in the bone. It is reasonable to assume that in the case used in this study (Case #440), where the period between the date of plutonium contact and the date of death was more than 20 years, the plutonium was likely firmly fixed in bone tissue and long-term storage in formalin may not have resulted in significant wash-out. However, we cannot exclude the possibility that some translocation of the plutonium may have occurred during the storage period. This would need to be confirmed with an experimental study.
Another limitation is that when scoring, tracks crossing the interface of endosteum-marrow or endosteum-bone were classified as endosteum both for trabecular and for cortical bones, that results in a bias error.
The third challenge is accounting for the background content of natural uranium in the human skeleton. Because uranium is also fissionable, as is plutonium, it can produce fission fragment tracks on autoradiographs that are indistinguishable from the plutonium tracks. The impact of natural uranium content on the quantification of plutonium in bone can be estimated using the neutron physics of these isotopes. Using the analysis outlined in the ratio of fission events due to target nuclei (239Pu) to total fission events can be mathematically determined. Nuclear reactions are first-order irreversible reactions. In the irradiation process, the following competing fission reactions are taking place:
Pu+nfission239,U+nfission238,U+nfission235.
Each reaction rate is described by eqn (1):
ν=Nϕ,
(1)
where v is reaction rate in interactions (cm−3 s−1), ϕ is neutron-flux density (neutron cm−2 s−1), N is atom density (atom cm−3) and σ is microscopic cross-section (barn). For fission processing system with competing first order reactions the overall reaction rate is given here in eqn (2):
ν=iNiσiΦ.
(2)
The concentration of neutrons is several orders of magnitude greater than that of the fissile atoms; thus, we assume constant flux for all species. After some algebraic manipulation the ratio of fission events due to 239Pu to total fission events is given below in eqn (3):
K239Pu=N239PuσNiσi
(3)
The concentration of 238U in human bone tissue is within the range of 100-200 mBq kg−1 (), for people residing in regions with normal natural radiation background (predominantly as a result of entering through the digestive tract). Average concentration of 238U in cortical and trabecular bones on averaged data of United Nations Scientific Committee on the Effects of Atomic Radiation is 150 kBq kg−1 (). On the basis of the ratio 238U and 235U in isotopic composition of natural uranium, averaged concentration of 235U in human bone tissue is 1.08 kBq kg−1.
The content of 239Pu in the skeleton for case #440 was determined to be 20 kBq. Considering that the skeleton mass of adult man is estimated to be about 10.5 kg (), then the content of 239Pu per kilogram of bone tissue for our case was 1.9 kBq kg−1.
Knowing the content of isotopes in the sample as well as their microscopic cross-section on thermal neutrons, it is possible to find the ratio of fission events due to 239Pu, 235U and 238U to total fission events from eqn (3). Results of calculations are presented in Table 4. As can be seen from the table, the fission events due to 239Pu outnumber all other combined fission events. Thus, the contribution of natural uranium content on the number of fission tracks is negligible and most of the tracks are the result of 239Pu fission events.
Table 4
Calculated ratios between fission events from 239Pu, 235U and 238U, and all fission events in the bone sample.

Testing of ICRP model

For the purposes of dosimetry, the bone cavity compartment is assumed to consist entirely of bone marrow in cortical and trabecular fractions (). However, bone marrow in the cortical fraction is essentially non-existent when evaluated using histological criteria (). Haversian canals exist in mature cortical bone and were observed in the cortical bone in this study (Fig 2a). The Haversian canal is also lined with endosteal-like tissues, but the tracks arising from the Haversian surfaces were assigned to the cortical surface compartment.
The data derived from this study were tested against the biokinetic model recommended by the ICRP for assurance of radiation protection standards. The authors considered the ratio between track number in bone volume and track number on bone surface for cortical and trabecular fractions – q(CV)/q(CS) and q(TV)/q(TS), correspondingly.
Using values of volume and surface of bone tissue for cortical and trabecular fractions of the reference man skeleton (Table 5), the authors approximated the data derived from one slide (Table 3) to the whole skeleton. At the same time, for determination of an elementary volume of bone tissue, in which tracks of fission fragments were scored, the area of track scoring was multiplied by the track length (15 μm), except for the endosteum areas (where it was multiplied by the actual endosteum width in the relevant area). Actual values of these parameters for cortical and trabecular fractions were 2.0 and 0.4, correspondingly. These ratios were calculated for this case at the time of death for two scenarios of intake: acute (intake in the first working day) and chronic (uniform intake over the time of contact with radionuclide) using IMBA Professional Plus program, v. 4.0. Calculated and actual values of the ratios between number of decays in the bone volume and number of decays on the bone surface are presented in Table 6. As can be seen from the table, values of parameters coincide for trabecular bone but significantly differ for cortical bone.
Table 5
Values of volume and surface of bone tissue for cortical and trabecular fractions of the skeleton in Standard Man ().
Table 6
Actual and calculated values of ratio between decay number in bone volume and decay number on bone surface for cortical and trabecular fractions.
It should be noted that track density on bone surfaces is an order of magnitude greater then in bone volume for cortical and trabecular fractions according to scoring data of plutonium fission fragment tracks.
Plutonium is initially deposited on bone surfaces but becomes buried and redistributed with time (). Thus the heavy surface concentrations of 239Pu in the NIAR from the worker would suggest a more recent deposition. There are several possible explanations for this. One is that this worker had a very substantial plutonium exposure shortly before death. This was not considered likely considering the employment history of this worker. Another explanation is that plutonium that is recently resorbed and released during bone remodeling may also redeposit onto bone surfaces, as observed in experimental studies (). In this regard, 241Am was observed on vertebral cancellous bone surfaces 11 years after exposure in a human case (). Another explanation is that there was a late in life translocation of 239Pu from the liver. The liver is the other major deposit of plutonium in the body and data from the RHRTR indicates that in workers with a normal health status and from 2-4 decades after their plutonium exposures, the liver contains about 42% of the total residual amount of plutonium in the body with about 50% in the skeleton (). However, when the late-in-life health of the individual is considered, recent data shows that with diseases that affect the liver (such as hepatitis, cirrhosis, metastatic disease or other degenerative diseases), there is a release of plutonium from the liver, some (or perhaps even most) of which appears to be incorporated into the skeleton (). In several studies on the concentrations of plutonium from fallout in humans, the presence of chronic or acute diseases that affect the liver was reported to result in a decreased retention of plutonium in the liver relative to other organs (; ). In the present study, the worker died from a pulmonary cancer with metastatic disease that involved the liver and this may account for some, or perhaps mosts of relative deposition of 239Pu on bone surfaces for this individual.
Moreover, plutonium burden in bone volume is considerably greater than plutonium burden on bone surfaces (Table 6). The data indicates a considerable underestimation of resorption from bone surfaces to bone volume for cortical fraction. It should be noted that these data are preliminary, and they require further development based on of different types of bones and on other cases.

CONCLUSIONS

  1. Quantitative data for plutonium microdistribution in human bone tissue was obtained for the first time on an sample of a thoracic vertebra specimen;
  2. Plutonium distribution in this specimen was very non-uniform. The track density on endosteal surfaces is the next-higher order of magnitude than in the volume of bone tissue, both in cortical and in trabecular fractions;
  3. Actual ratio between the number of 239Pu decays in bone volume and number of 239Pu decays on the bone surface does not coincide with the ICRP recommended values for cortical bone;
  4. It is possible that biokinetic model parameters of extrapulmonary ICRP compartment might need to be adjusted following further studies on quantitative plutonium microdistribution in other human bone types and in individuals with different exposure patterns and scenarios.

Acknowledgments

Sources of support
The Department of Health and Human Services, National Institutes of Health, National Cancer Institute (Grant #R01 CA66759); Russian Federal Medical and Biological Agency (Government Contract # 11.302.06.0).

Footnotes

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8 comments:

  1. RANGE!
    Plutonium-241 of Fukushima Origin Found 32 Kilometers from the Plant, Says National Institute of Radiological Sciences After Nearly One Year [blogspot.de]
    The level [of plutonium-241] will not affect human health. Plutonium-241 has relatively short half life of 14 years compared to other isotopes of plutonium. It decays into americium-241, which is easily absorbed through soil into legumes.



    Plutonium in bone: a high resolution autoradiographic study using plutonium-241.
    Priest ND, Jackson S.

    Abstract

    Plutonium-241 citrate solution at pH 6-5 was injected intravenously into hamsters and an adult rabbit at a dose of 10 kBq g-1 (260 nCi g-1). The hamsters were killed serially at 15 min, 2 hours, 1 day, 10 days, 1 month and 6 months after injection and the rabbit at 1 week. Their knee-joints or femora were examined for plutonium-241 by autoradiography. Few differences were found between the pattern of plutonium distribution in the hamsters and the rabbit. The results showed that although plutonium is initially distributed on bone surfaces, at long periods after injection it becomes deposited throughout the bone matrix. Plutonium uptake by cells in resorbing areas of periosteum, in active osteoblasts, and in chondrocytes in regions of cartilage mineralization was rapid. Plutonium concentrated more slowly on the resting bone surfaces and at sites of low metabolic activity. In addition, some unlabelled sections of skeletal tissues were immersed in a plutonium-241 citrate solution. When autoradiographed, it was found that plutonium was bound by cell nuclei, tooth enamel matrix, dentine, predentine and bone matrix. Plutonium binding to cartilage matrix was weak. The results are discussed with reference to the literature, and a model is proposed to explain the distribution pattern and fate of plutonium deposits in bone. Int J Radiat Biol Relat Stud Phys Chem Med. 1977 Oct;32(4):325-50.



    ReplyDelete
  2. Health Phys. 2013 Jan;104(1):57-62. doi: 10.1097/HP.0b013e31826e17be.
    Evaluation of (241)Am deposited in different parts of the leg bones and skeleton to justify in vivo measurements of the knee for estimating total skeletal activity.

    Abstract

    The percentage of Am deposited in different parts of leg bones relative to the total leg activity was calculated from radiochemical analysis results from six whole body donors participating in the U.S. Transuranium and Uranium Registries (USTUR). In five of these six USTUR cases, the percentage of Am deposited in the knee region as well as in the entire leg was separately calculated relative to total skeletal activity. The purpose of this study is to find a region in the leg that is both suitable for in vivo measurement of Am deposited in the bones and has a good correlation with the total skeletal Am burden. In all analyzed cases, the femur was the bone with the highest percentage of Am deposited in the leg (48.8%). In the five cases that have complete whole skeletal analysis, the percentage of Am activity in the knee relative to entire skeletal activity was 4.8%, and the average value of its coefficient of variation was 10.6%. The percentage of Am in the leg relative to total skeletal activity was 20% with an average coefficient of variation of 13.63%. The Am activity in the knee as well as in the leg was strongly correlated (R = 99.5% and R = 99.1%, respectively) with the amount of Am activity in the entire skeleton using a simple linear relationship. The highest correlation was found between the amount of Am deposited in the knee and the amount of Am deposited in the entire skeleton. This correlation is important because it might enable an accurate assessment of the total skeletal Am burden to be performed from in vivo monitoring of the knee region. In all analyzed cases, an excellent correlation (R = 99.9%) was found between the amount of Am activity in the knee and the amount of Am activity in the entire leg. The results of this study suggest three simple models: two models to predict the total skeletal activity based on either leg or knee activity, and the third model to predict the total leg activity based on knee activity. The results also suggest that the knee region is a suitable position for in vivo measurements of Am deposited in the bones and also for an accurate and efficient detection system. Detector efficiency should be apparently calibrated based on only the Am burden in the knee region bones instead of Am activity deposited in the entire leg.


    Health Phys. 2013 Jan;104(1):51-6. doi: 10.1097/HP.0b013e318261f1f6.
    A new leg voxel model in two different positions for simulation of the non-uniform distribution of (241)Am in leg bones.
    http://www.ncbi.nlm.nih.gov/pubmed/23192087
    The resulting leg voxel model is now ready for use as an MCNPX input file to simulate in vivo measurement of bone-seeking radionuclides.


    ReplyDelete
  3. RANGE!
    americium-241-found-soil-west-tokyo
    http://enenews.com/alert-americium-241-found-soil-west-tokyo-74-becquerelskg-dangerous-plutonium-241



    Biosorption of americium-241 by immobilized Rhizopus arrihizus
    http://www.sciencedirect.com/science/article/pii/S0969804303002586



    RANGE!
    Nuclear physics
    Americium, Curium and rare earths radionuclides in forest litter samples from Poland
    Jerzy W. Mietelski,
    Bogdan Wa̧s
    The Henryk Niewodniczañski Institute of Nuclear Physics, Radzikowskiego 152 st., Kraków PL-31-342, Poland
    Abstract

    Twenty seven samples of forest litter or humus layers (A0 or A1) collected in 1991 in selected regions of Poland were analysed for the presence of 241Am, Cm isotopes and rare-earth alpha-emitters. Samples were originating from a large research project and were previously analysed for gamma-emitters and plutonium.


    Source
    http://www.sciencedirect.com/science?_ob=ArticleListURL&_method=list&_ArticleListID=-510420180&_sort=r&_st=13&view=c&_acct=C000228598&_version=1&_urlVersion=0&_userid=10&md5=d818b41898f88c631a0c6e063f689eeb&searchtype=a





    ReplyDelete
  4. 2.3 times the strontium, a boiling point higher detection point of molybdenum 99 of 3,232 degrees
    4,682 degrees molybdenum boiling point, 5,150 degrees technetium, plutonium 3,232 degrees, 1,382 degrees strontium.

    From U.S. soil investigation.
    http://inventsolitude.sblo.jp/article/86330286.html


    Molybdenum 99 have also been detected in the Kanto region from the south Tohoku . I shows a similar trend detection and view of the strontium . There is also the point where the Tc-99m of the daughter nuclide has been detected , and there is no point even Arru .

    That this only that they are scattered widely molybdenum 99 , or would not have to mean that there is an event where the temperature rises up to 5,000 degrees or more that technetium is vaporized at least in a nuclear reactor at the Fukushima Daiichi nuclear accident .

    Thus , some would not do than the vaporized at least . Consider also the possibility that the fuel rods are ground in small pieces by the explosion of Unit 3 was severe , especially those of gaseous and particulate is released electrode, and diffused .

    I think in that case , a low boiling point nuclides more , strontium , of course , and he had the opportunity plutonium vaporized more .

    I think where the difference occurs in the behavior of the atmosphere from the differences of the weight , fine flew pole and he is supposed to be higher in the long distance that is detected .

    Is in the gun somewhere or other strontium , plutonium . Because not be lowered uniformly the same cesium some places that are not detected . But there are examples where strontium was detected in no small measure in the Kanagawa Prefecture , or in Tokyo is , I should be going there .

    By examining in detail , so you kind of a situation is perhaps surprising . The United States is measured by using a proportional counter with (γ -ray energy analysis ) gamma spectroscopy a large amount of sample . You do not do it I could as long as there is motivation , because there are circumstances that would not do .

    ( Description modified based on the comments of the first occurrence 2014/1/29 1 /30 reader )

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  5. Vertical distributions of plutonium isotopes in marine sediment cores off the Fukushima coast after the Fukushima Dai-ichi Nuclear Power Plant accident
    http://www.biogeosciences.net/10/2497/2013/bg-10-2497-2013.pdf


    Pu isotopes are more particle reactive than Cs and the sediment-water distribution coefficient (Kd value) of Pu is two orders of magnitude higher than that of Cs (IAEA,
    2004). In mid-April 1986, by a coincidence of timing, IAEA-MEL scientists moored automated time series sediment traps in the Ligurian Sea, and they found that in one month after the accident more than 50 % of the total 239+240Pu inven-
    tory originating from Chernobyl and deposited in that region had transited through 200 m depth, while only 0.2 % of the corresponding 137Cs deposition did so (Povinec et al., 1996). In the North Pacific, the Chernobyl-derived radiocesium was detected in the sinking particles collected at a depth of 780 m two months after the Chernobyl accident (Kusakabe et al., 1988). The resident time of Pu isotopes in
    the North Pacific was much shorter than that of radiocesium (Fowler et al., 1983; Honda et al., 2013). Thus Pu isotopes released from the FNDPP accident could be more quickly incorporated into sediments by the scavenging process than
    Cs, and the determination of Pu isotopes in the sediments should give reliable information about Pu contamination in the marine environment

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  6. Induction of osteosarcoma and acute myeloid leukaemia in CBA/H mice by the alpha-emitting nuclides, uranium-233, plutonium-239 and amercium-241.
    http://www.ncbi.nlm.nih.gov/pubmed/11213349

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    Increasing the number of staff also studied as a department that is independent to the newly established Department of childhood cancer in the Fukushima Medical University Hospital
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    Posted 1月22nd 2014

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    Posted 1月22nd 2014

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    Replies
    1. Thanks for the comments and additional resource macho!

      Delete
  7. The whole ICRP model is a piece of crap. Did you read my article translation ?
    http://fukugeddon.com/?p=37
    Basically, the scientists in this report come to the conclusion that the existing model and the measurement procedures are anything but appropriate need to be re-thought completely. And they conclude that the permitted rates are too high by several powers of ten.

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