Showing posts with label radioactive silver. Show all posts
Showing posts with label radioactive silver. Show all posts

Friday, January 25, 2013

Japanese Researchers Found Cesium More Concentrated in Calf Than in Mother Cow in the Former Evacuation Zone in #Fukushima Prefecture


and organ-specific high concentration of radioactive silver and tellurium.

In a research paper on an open-access peer-reviewed magazine, the researchers at Tohoku University studying the cattle abandoned in the former "evacuation zone" (20-kilometer radius from Fukushima I Nuclear Power Plant) in Fukushima Prefecture say that calves had 1.5 times as much cesium per kilogram as the mothers.

So far, the popular meme pushed by people like Ms. Kayoko Ikeda (who seemingly started out as a staunch defender of people escaping radiation contamination, and who turned out to be an apologist for the official line) is that there's nothing to worry about radiation contamination because children, with their high metabolism, will expel radioactive materials out of their bodies very quickly.

Now, Tohoku University researchers and the media have timidly started to say, as Kyodo News reports (1/24/2013), that we have have to rethink our premise.

What a surprise. Now what?

From Kyodo News (1/24/2013):

セシウム、母牛より子牛が高濃度 東北大、セシウム調査

Tohoku University's survey reveals that radioactive cesium is more concentrated in calf than in mother

東京電力福島第1原発事故で、原発から半径20キロ圏内にある当時警戒区域に指定されていた福島県南相馬市と川内村に取り残された牛の内部被ばく調査を進める福本学東北大教授(病理学)らの研究グループが、母牛よりも子牛の方に高濃度の放射性セシウムがたまっていたとの研究結果をまとめ、23日付の米オンライン科学誌プロスワンに発表した。

A research group headed by Professor Manabu Fukumoto (pathology) at Tohoku University  has been studying the internal radiation exposure in cows abandoned in part of Minamisoma City and Kawauchi-mura in the 20-kilometer radius evacuation zone because of the Fukushima I Nuclear Power Plant accident. The group published the result on an online science magazine in the US called Plos One on January 23 which the researchers found radioactive cesium was more concentrated in calves than in mothers.

福本教授は、子牛と母牛が全く同じ物を食べていたとは限らないとした上で「代謝が盛んな子どもの方が、放射性物質がたまりにくいとされるが、見直す必要があるのではないか」と話し、今回のデータはメカニズムの解明に向けた基礎データになるとしている。

Professor Fukumoto says calves did not necessarily ate exactly the same food as the mothers, but says "It has been said that children with high metabolism do not retain radioactive materials long, but maybe we need to take a fresh look." The data will be the basis to understand the mechanism [of cesium accumulation], Professor Fukumoto says.


The researchers also found high concentrations of short half-lived radionuclides like Ag-110m (half-life 250 days) in liver and Te-129m (half-life 34 days) in kidney.

Abstract of the paper "Distribution of Artificial Radionuclides in Abandoned Cattle in the Evacuation Zone of the Fukushima Daiichi Nuclear Power Plant", at Plos One (emphasis is mine):

The Fukushima Daiichi Nuclear Power Plant (FNPP) accident released large amounts of radioactive substances into the environment. In order to provide basic information for biokinetics of radionuclides and for dose assessment of internal exposure brought by the FNPP accident, we determined the activity concentration of radionuclides in the organs of 79 cattle within a 20-km radius around the FNPP. In all the specimens examined, deposition of Cesium-134 (134Cs, half-life: 2.065 y) and 137Cs (30.07 y) was observed. Furthermore, organ-specific deposition of radionuclides with relatively short half-lives was detected, such as silver-110m (110mAg, 249.8 d) in the liver and tellurium-129m (129mTe, 33.6 d) in the kidney. Regression analysis showed a linear correlation between the radiocesium activity concentration in whole peripheral blood (PB) and that in each organ. The resulting slopes were organ dependent with the maximum value of 21.3 being obtained for skeletal muscles (R2 = 0.83, standard error (SE) = 0.76). Thus, the activity concentration of 134 Cs and 137Cs in an organ can be estimated from that in PB. The level of radioactive cesium in the organs of fetus and infants were 1.19-fold (R2 = 0.62, SE = 0.12), and 1.51-fold (R2 = 0.70, SE = 0.09) higher than that of the corresponding maternal organ, respectively. Furthermore, radiocesium activity concentration in organs was found to be dependent on the feeding conditions and the geographic location of the cattle. This study is the first to reveal the detailed systemic distribution of radionuclides in cattle attributed to the FNPP accident.


According to the paper, the researchers collected 79 cattle, 27 of which were from Minami-soma city located north and 52 from Kawauchi between August 29 and November 15, 2011.

From the Results and Discussion section:

Before the cattle were euthanized, we noticed 3 mother and infant pairs in Plot 2. We confirmed that these infants were born after the FNPP accident and that they were being weaned at the time. As shown in Figure 2B, most of the points lie on the upper side of the dashed equality line (infant side). The regression analysis showed that radiocesium activity concentration was 1.51 times higher in the infant organs than in the corresponding maternal organs (R2 = 0.70, SE = 0.09). Therefore, we concluded that the deposition of 137Cs in infant organs is correlated with that in the corresponding maternal organs but is higher than that in maternal ones. Shorter half-lives of retention are adopted for infants and children than for adults [12]. Inaba et al. mentioned that water and electrolyte metabolism should differ considerably between newborn and adult, and that potassium contents of the feeding might affect the radiocesium activity concentration [13]. We do not have any data regarding the proportion attributed to milk and grass which the infants were taking at the time of the sacrifice.

In our data, the thyroid showed lower 137Cs deposition compared with other visceral organs (Figures 1 and 2B). Bandazhevsky previously reported that the highest accumulation of radiocesium was found in the endocrine glands, in particular, the thyroid, in humans [14]. Although we need to consider the species difference between humans and cattle, radiocesium is suggested to have little impact on thyroid carcinogenesis.

About Ag-110m in liver:

Radioactive 110mAg is not a fission product but is formed by the neutron capture of stable 109Ag. We detected 110mAg in the liver of all of the cattle except for fetuses examined (Table 1 and Figure 3A). The ratio of deposited radioactivity concentration of 110mAg to 137Cs in the soil of Plot 2 and Plot 3 was lower than 0.5% and that in the grass of Plot 3 was lower than 5% (Table S3). The value in the soil was consistent with the distribution map of radiation doses by MEXT (http://radioactivity.mext.go.jp/old/en/1​750/2011/10/1750_1031e_2.pdf) (MEXT Dose Map) as of June 14, 2011. In the current study, 110mAg activity concentration in the liver did not show Plot dependent difference or association with 137Cs activity concentration (Figure 3A). Both the human evidence and the animal studies indicate substantial deposition of silver in the liver but the retention rate is influenced by the route of intake [12]. It is reported that the liver deposition of 110mAg in sheep and its transfer coefficient to the liver was higher than that of 137Cs in the Chernobyl nuclear accident [16]. These data indicate that the transfer coefficient of 110mAg to the liver is higher than that of 137Cs. Furthermore, post-mortem data on the distribution of 110mAg in a patient 195 days after injection showed the highest uptake in the liver (40%) among all organs [17]. There was no relationship between the activity concentration of 110mAg in PB and in the liver (Figure 3B). Danscher et al. reported that silver predominantly accumulates in lysosome-associated tissues, such as lymph nodes, liver, kidneys and the central nervous system after silver administration in rats and mice. Furthermore, they showed the intense accumulation of silver in Kupper cells of the liver [18]. From these cumulative data and this study, we concluded that the liver is the primary target organ for 110mAg deposition.



The entire paper is available free at the link

Monday, November 7, 2011

#Radiation in Japan: Spiders in Iitate-mura Concentrating Radioactive Silver 1,000 Times

Dr. Bin Mori is a professor emeritus at University of Tokyo, Faculty of Agriculture. Since the beginning of the Fukushima nuclear crisis on March 11, the professor has been writing his blog focusing on the effect of radiation in plants and remediation of agricultural land.

I have featured his autoradiographs of dandelion and horsetail on my blog before.

In his post on October 30, Professor Mori wrote about his discovery, probably the world first, he made in spiders (Nephila clavata) he caught in Iitate-mura, Fukushima Prefecture, where the villagers were forced to evacuate after being designated as "planned evacuation zone". The spiders, he found, had radioactive silver (Ag-110m) at 1,000 times the concentration in the environment.

The following is my translation of Dr. Mori's October 30 blog post, with his express permission:

飯舘村で雨の降る中での植物の採取は困難であったので、竹藪や杉林の中で、網を張っているジョロウグモ(Nephila clavata)を捕獲してきました。

Since it was difficult to collect plants in the rain in Iitate-mura, I caught instead "nephila clavatas" in the bamboo groves and cedar forest.

クモは直接土を食べるかどうかわからないが、網にかかった蝶やアブやカナブンなどを食べて林の中の食物連鎖の上位に位し、放射性セシウムを濃縮しているだろうと考えたからです。

I don't know whether the spiders eat dirt itself, but I thought they may have concentrated radioactive cesium in their bodies as they were at the top of the food chain in the forest, eating butterflies, horseflies, and drone beetles that they caught in their webs.


(Picture 1: Nephila Clavata)

ジョロウグモを4匹一緒にしてGe半導体で、放射性セシウム (Cs-137とCs-134) を分析しました(図1)。すると、Cs-137のエネルギーピークである661.7keVの隣の657.8keVの位置にほぼ等量の未知のエネルギーピークを見いだしました(図2)。

I put 4 nephila cravatas together in the germanium semiconductor detector, and analyzed radioactive cesium (Cs-137 and Cs-134) (Picture 1). Then I noticed an unknown energy peak at 657.8keV, right next to the energy peak of Cs-137 at 661.7keV (Chart 2).


(Chart 2: Ag-110m peak detected next to Cs-137)

これを同定するとAg-110m(銀の核異性体:半減期249.5日)の放出する4つのガンマ線の1つのピークであることがわかりました。他の3つのピークも検出されました(図3)。

When I identified this peak, it turned out to be one of the 4 gamma-ray peaks from Ag-110m (nuclear isomer of silver, half life 249.5 days). The other 3 peaks were also detected (Chart 3).

(Chart 3: 4 peaks of Ag-110m identified)

したがって、ジョロウグモが東電福島原発由来の放射性降下物である超微量の放射性銀(Ag-110m)を濃縮していることがわかりました。

So, the conclusion is that nephila clavatas have concentrated a minute amount of radioactive silver (Ag-110m), which is one of the radioactive fallout materials from Fukushima I Nuclear Power Plant.

クモの放射能の濃度は 

Cs-134(2.9Bq/4匹 )+Cs-137(3.9Bq/4匹) = 3656Bq /kg生体重
に対して
Ag-110m (2.6Bq/4匹)=1397Bq /kg生体重
でした。

The densities of the radioactive materials in the spiders were:

Radioactive cesium:
Cs-134 (2.9 Bq/4 spiders) + Cs-137 (3.9 Bq/4 spiders) = 3,656 Bq/kg live weight 

versus

Radioactive silver:
Ag-110m (2.6 Bq/4 spiders) = 1,397 Bq/kg live weight

この林の汚染土壌のCs(137+134)とAg-110mの存在比は、約2500:1 でしたので、上記の数値を用いて計算すると、ジョロウグモは約1000倍にまで土壌の放射性銀を生体濃縮していたことになります。

In the forest where the spiders were caught, the ratio of radioactive cesium (134+137) to Ag-110m was about 2,500 to 1. Using the above numbers, I calculated that nephila clavatas bio-concentrated the radioactive silver in the soil to about 1,000 times.   

昆虫が銀を高濃度濃縮するという知見はこれが世界で最初の発見です。また、すでに林内で放射能の生物濃縮が始まっているということが明らかです。

This is the first discovery in the world that an insect highly concentrates silver. Also, it is evident that bio-concentration of radioactivity in the forest has already started.

 この研究の詳細は11月26日(土)日本土壌肥料学会関東支部会(松戸の千葉大園芸学部)で発表します。乞御来聴。

I will present the details of my research on Saturday November 26 at the Japanese Society of Science and Plant Nutrition's Kanto Branch meeting (Faculty of Horticulture at Chiba University in Matsudo City, Chiba). Please come.  

付記:計測に際しては、東京大学大学院農学生命科学研究科・田野井慶太朗助教のお世話になりました。

Appendix: I'd like to thank Keitaro Tanoi of University of Tokyo Graduate School of Agricultural and Life Sciences for the measurement.

追記1:ここで用いた生体濃縮の定義は、セシウムに対する比率で計算したものです。詳しくは論じませんが、放射性セシウムの生体濃縮の定義によっては、ジョロウグモの銀の濃縮度は、これよりもけた違いに高くなる可能性があります。

PS: The definition of bio-concentration used here is calculated from the ratio to radioactive cesium. I won't discuss it in details here, but depending on how bio-concentration of radioactive cesium is defined, the concentration ratio of radioactive silver by nephila clavata may be even higher.

In the very last sentence, Professor Mori is literally saying "higher by a digit". But I am not exactly sure whether he means literally or figuratively, or whether he means higher by single digit or more. (I'm asking the professor for clarification.)

Professor Mori says he is planning to write up the paper on the subject in English and submit it, but he says that's secondary. The most important thing, he says, is to disseminate information as wide as possible when it comes to radiation contamination, and he uses his blog to post his own unique discovery like this even before he writes it up as a scientific paper.

(What a difference between him and certain researchers who withhold critical information about radiation contamination in Japan so that their papers get accepted by prestigious foreign papers.)

Monday, August 1, 2011

#Radioactive Fallout in Tokyo in March: Iodine, Cesium, Tellurium, Radioactive Silver

Silver-110m, half life about 250 days, wouldn't have been discovered unless the control rods had melted at Fukushima I Nuclear Power Plant.

There was the news in early April that radioactive silver was detected in South Korea. There was no way the same nuclide wasn't falling in Japan if it could fly all the way to Korea, I thought.

Sure enough.

It was not until 2PM on July 29 that the Ministry of Education and Science announced the "reading of environmental radioactivity level by prefecture [Fallout]" for March 2011.

What's the point of telling us now? Just for the record?

Radioactive materials that were falling in the Kanto region in March, other than iodine-131, cesium-134 and -137, are:

Niobium-95
Tellurium-129
Tellurium-129m
Tellurium-132
Silver-110m
Cesium-136
Lantanium-140
Barium-140

They look to be the nuclides coming out of melted fuel rods. No plutonium, strontium or uranium are mentioned.

The level of radioactive iodine (131) and cesium (134, 137) is also markedly high in Kanto. It is particularly high in Tochigi and Ibaraki Prefectures, and it is higher in Tokyo than in Saitama or Chiba. The area with the elevated level of radioactive fallout includes Shizuoka and Nagano Prefectures. For details for other prefectures, please go to the Ministry of Education website.

March result (part):