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):
Tohoku University's survey reveals that radioactive cesium is more concentrated in calf than in mother
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.
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:
About Ag-110m in liver:
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 . 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 . 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 . Although we need to consider the species difference between humans and cattle, radiocesium is suggested to have little impact on thyroid carcinogenesis.
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/1750/2011/10/1750_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 . 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 . 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 . 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 . 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