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Small head size and delayed body weight growth in wild Japanese monkey fetuses after the Fukushima Daiichi nuclear disaster



To evaluate the biological effect of the Fukushima Daiichi nuclear disaster, relative differences in the growth of wild Japanese monkeys (Macaca fuscata) were measured before and after the disaster of 2011 in Fukushima City, which is approximately 70 km from the nuclear power plant, by performing external measurements on fetuses collected from 2008 to 2016. Comparing the relative growth of 31 fetuses conceived prior to the disaster and 31 fetuses conceived after the disaster in terms of body weight and head size (product of the occipital frontal diameter and biparietal diameter) to crown-rump length ratio revealed that body weight growth rate and proportional head size were significantly lower in fetuses conceived after the disaster. No significant difference was observed in nutritional indicators for the fetuses’ mothers. Accordingly, radiation exposure could be one factor contributed to the observed growth delay in this study.


The Fukushima Daiichi nuclear power plant (NPP) disaster that occurred in March 2011 exposed a large number of humans and wild animals to radioactive substances. Several studies of wild animals in Fukushima investigated health effects of the disaster, such as morphological abnormalities in gall-forming aphids (Tetraneura sorini, T. nigriabdominalis)1 and pale grass blue butterfly (Zizeeria maha)2, hematological abnormalities in carp (Cyprinus carpio)3, and chromosomal aberrations in wild mice (Apodemus argenteus, Mus musculus)4. However, there is no research investigating long-term exposure to radiation on mammals that typically have long life-span to date. This study is the first report to observe long-term biological effects of the pre- and post-NPP disaster on non-human primates in Fukushima.

We previously studied radioactive exposure and its effect on health of Japanese monkeys (Macaca fuscata) inhabiting Fukushima City, which is located approximately 70 km from the Fukushima Daiichi NPP5, 6. After the NPP disaster, the range of radiocesium soil concentrations in Fukushima City was 10,000–300,000 Bq/m2. Hayama et al.5 investigated chronological changes in muscle radiocesium concentrations in monkeys inhabiting Fukushima City from April 2011 to June 2012. The cesium concentration in monkeys’ muscle captured at locations with 100,000–300,000 Bq/m2 was 6000–25,000 Bq/kg in April 2011 and decreased over 3 months to approximately 1000 Bq/kg. However, the concentration increased again to 2000–3000 Bq/kg in some animals during and after December 2011, before returning to 1000 Bq/kg in April 2012, after which it remained constant.

Fukushima monkeys had significantly lower white and red blood cell counts, hemoglobin, and hematocrit, and the white blood cell count in immature monkeys showed a significant negative correlation with muscle cesium concentration6. These results suggested that the short-term exposure to some form of radioactive material resulted in hematological changes in Fukushima monkey

The effects associated with long-term low-dose radiation exposure on fetuses are among the many health concerns. Children born to atomic bomb survivors from Hiroshima and Nagasaki showed low birth weight, high rates of microcephaly7, and reduced intelligence due to abnormal brain development8. Experiments with pregnant mice or rats and radiation exposure had been reported to cause low birth weight9, 10, microcephaly11,12,13, or both14, 15. We identified one similar study on wild animals16, which reported that the brains of birds captured in the vicinity of the Chernobyl NPP weighted lower compared to those of birds captured elsewhere.

The population of Japanese monkeys in Fukushima City had been systematically managed since 2008 according to a management plan based on law and regulated by Fukushima Prefecture to reduce damage to agricultural crops. Our research group studied the reproductive and nutritional status of the Japanese monkey population by performing autopsies on individuals captured and euthanized by Fukushima City17. These Japanese monkeys were the first wild primate population exposed to radiation as result of nuclear disaster. However, there was no other study either in Chernobyl or Fukushima that followed fetal development over time or compared fetal development before and after long-term radiation exposure in the same wild animal populations.

The objectives of this study were to compare changes in the fetal development of Japanese monkeys in Fukushima City before and after the NPP disaster to determine evidence of developmental delay in Japanese monkey fetuses.


Radiocesium was detected in mothers’ muscle that had conceived after the NPP disaster (Table 1). Mean muscle radiocesium concentration was 1059 Bq/kg for mothers that mated in 2011 and gave birth in 2012 (n = 14), although the concentration decreased gradually in subsequent years up to 22 Bq/kg for mothers that gave birth in 2016 (n = 3). Because muscle tissue was not available prior to the NPP disaster, muscle radiocesium concentrations for individuals captured pre-disaster could not be measured. However, muscle radiocesium concentrations in wild Japanese monkeys captured in 2012 in Aomori Prefecture, which is also located in the Tōhoku region 400 km north from the NPP, were below the detection limit2, therefore, we assumed that the muscle radiocesium concentrations in the Japanese monkeys in Fukushima City prior to the disaster were also below the detection limit.

Similarly, although the air dose in the area of Fukushima City inhabited by the Japanese monkeys was 1.1 to 1.2 µSv/h in April, 2011, it has decreased, reaching 0.10 to 0.13 µSv/h in May, 2016 (Table 2). Based on these measurements, it is estimated that monkeys in this area received accumulated air doses of at least 12 mSv over the five years since the NPP disaster.

The descriptive statistics for Japanese monkey fetuses in Fukushima were shown in Table 3. The median body weight (g) and median body weight growth rate (g/mm) were significantly different between pre- and post-disaster groups (p = 0.032 and 0.0083, respectively). The mean biparietal diameter (mm), occipital frontal diameter (mm), head size (mm2), and proportional head size (mm) were significantly different between pre- and post-disaster groups (p = 0.046, 0.018, 0.014, and 0.0002, respectively). CRL was not significantly different between the two groups. Regression lines describing association of body weight and CRL in pre- and post-disaster groups were described in Fig. 1. Post-disaster regression line was significantly lower than pre-disaster regression line (p < 0.0001) (Table 4). Regression lines describing association of head size and CRL in pre- and post-disaster groups were described in Fig. 2. Post-disaster regression line was significantly lower than pre-disaster regression line (p < 0.0001) (Table 5).

The body fat index for the mothers of these fetuses was not significantly different before and after the NPP disaster (Z = 1.213; P = 0.219).


Body weight and head size relative to the CRL were lower in fetuses conceived after the NPP disaster compared with fetuses conceived prior to the NPP disaster. Japanese monkeys in Fukushima City first conceive in fall when they were five years old and gave birth in spring when they were six years old17. Thus, we assumed that all the mothers we examined that conceived babies after the NPP disaster were continuously exposed to radiation from at the time of the disaster in 2011.

Growth retardation of the fetuses could be caused by the deterioration of the mothers’ nutritional status. However, we did not observe any difference in the body fat index of mothers pre- and post-NPP disaster. Therefore, the growth retardation of the fetuses was unlikely to be associated with to the mothers’ nutritional status. Other factors such as climate changes or food nutrient components might have affected the growth of fetuses. The limitations of this study were that we were not able to obtain samples to look at histological change that might have contributed to the cause of delayed fatal growth and the sample size were relatively small because of the nature of the sampling collection. It might have been ideal to compare monkeys from the evacuation order area to monkeys from the non-contaminated area of Fukushima; however, there was no other area such besides the one in this study that performed systematic large-scale capturing aimed at seizing hundreds of monkeys. In addition, there had been access limitations beyond the evacuation order area. For these reasons, it is impossible to replicate an equivalent study elsewhere at this time.

In experiments using mice and rats, radiation exposure has been reported to cause reduced fetal weight, microcephaly, and reduced brain mass9,10,11,12,13,14,15. However, most of these experiments involved exposing the mother to a single radiation dose at a fetal age of 10 days or later when the brain undergoes development. Such exposure may be qualitatively different from the low-dose, long-term exposure following an NPP disaster. The radiation doses in these experiments varied substantially. Hande et al.9 exposed mice to 9 mGy of 70 kilo-Volt peak X-rays at fetal ages of 3.5, 6.5, and 11.5 days, and found that birth weight was reduced relative to the control mice in all cases. Uma Devi et al.15 exposed mice to 0.25 Gy at a fetal age of 11.5 days and observed reduced head size at birth. In addition, they observed negative correlation between radiation dose and head size in fetuses exposed to 0.05 to 0.15 Gy.

The number of low birthweight children born to residents of some highly contaminated areas of Belarus increased between 1982 and 1990, after the Chernobyl NPP disaster18. Hujuel et al.19 conducted a longitudinal survey of women exposed to radiation through dental treatment who subsequently gave birth. They reported that women exposed to 0.4 mGy or more had increased risk (odds ratio 2.27) of giving birth to a child weighing 2500 g or less. Goldberg et al.20 elucidated the relationship between the level of radiation exposure as a result of medical exams prior to conception and birthweight, and found that birthweight decreased by 37.6 g for every cGy of exposure. Such medical exposure is believed to affect the mother’s gonads and endocrine glands rather than the fetus itself. There is still uncertainly to determine whether the retarded growth we observed was a direct effect of the radiation exposure.

Otake and Schull8 conducted a temporal variation study of mothers exposed to radiation by the atomic bombs in Hiroshima and Nagasaki. They did not observe any effect in newborns that had been exposed between fetal ages of 0 to 8 weeks, and the highest rates of microcephaly and other brain damage occurred in newborns exposed between fetal ages of 8 to 15 weeks. Given that the latter period was when the human brain undergoes rapid development, damage due to radiation exposure during this period might cause severe effect on fetuses.

The previous research suggested that the low birthweight and small head sizes observed in fetuses conceived after the NPP disaster were result of radiation exposure. However, we were not able to quantify the external and internal radiation dose in individual wild animals. Although radiocesium was detected in the muscles of all individuals captured after the NPP disaster, the cumulative exposure was unclear since the biological half-life of radiocesium in monkeys was approximately 3 weeks5. Furthermore, because of the small sample size, it was difficult to determine the causal relationship of exposure dosage and the effect on fetuses.

Although we showed that fetal proportional head size reduced after the NPP disaster, it was not possible to identify anatomically which part of the brain was developmentally retarded. Hossain et al.12 studied the brains of 6- to 12-month-old mice that were exposed to cobalt 60 at a fetal age of 14 days. Brain weight decreased at exposure rates of 0.5 to 1.5 Gy and the number of neurons in the hypothalamus in the CA3 region decreased significantly. We started to perform histological examination brain of fetuses and juvenile monkeys conceived after the NPP disaster to identify the regions of the brain that were developmentally retarded and the effect of retarded growth on post-natal development for further study.


1, Akimoto, S. I. Morphological abnormalities in gall-forming aphids in a radiation-contaminated area near Fukushima Daiichi: selective impact of fallout? Ecology and Evolution. 4, 355–369 (2014).

2, Hiyama, A. et al. The biological impacts of the Fukushima nuclear accident on the pale grass blue butterfly. Scientific Reports. 2, 570, doi:10.1038/srep00570 (2012).

3, Suzuki, Y. Influences of radiation on carp from farm ponds in Fukushima. Journal of Radiation Research. 56, i19–23, doi:10.1093/jrr/rrv076 (2015).

4, Kubota, Y. et al. Chromosomal aberrations in wild mice captured in areas differentially contaminated by the Fukushima Dai-Ichi nuclear power plant accident. Environ. Sci. Technol. 49, 10074–10083 (2015).

5, Hayama, S. et al. Concentration of radiocesium in the wild Japanese monkey (Macaca fuscata) 15 months after the Fukushima Daiichi nuclear disaster. PLoS ONE. 8, e68530 (2013).

6, Ochiai, K. et al. Low blood cell counts in wild Japanese monkeys after the Fukushima Daiichi nuclear disaster. Scientific Reports. 4, 5793, doi:10.1038/srep05793 (2014).

7, Miller, R. W. & Blot, W. J. Small head size after in-utero exposure to atomic radiation. Lancet. 2, 784–787 (1972).

8, Otake, M. & Schull, W. J. In utero exposure to A-bomb radiation and mental retardation; a reassessment. Bri. J. Rdiol. 57, 409–414 (1984).

9, Hande, M. P., Uma Devi, P. & Jageta, G. C. Effect of “in utero” exposure to low dose energy X-rays on the postnatal development of mouse. J. Radiat. Res. 31, 354–360 (1990).

11, Uma Devi, P., Hossain, M. & Bisht, K. S. Effect of gamma radiation on fetal haemopoietic system in the mouse. Int. J. Radiat. Bio. 74, 639–646 (1998).

12, Bang, D.-w. et al. Dose-induce relationships on the prenatal effects of gamme-radiation in mice. J. Vet. Sci. 3, 7–11 (2002).

13, Hossain, M., Chetane, M. & Uma Devi, P. Late effect of prenatal irradiation on the hippocampal histology and brain weight in adult mice. Int. J. Devl. Neuroscience. 23, 307–313 (2005).

14, Uma Devi, P. & Hossain, M. Effect of early fetal irradiation on the postnatal development of mouse. Teratology. 64, 45–50 (2001).

15, Kim, S. H. et al. Dependance of malformation upon gestational age and exposed dose of gamma radiation. J. Radiat. 42, 255–264 (2001).

16, Uma Devi, P., Baskar, R. & Hande, M. P. Effect of exposure to low dose gamma radiation during late organogenesis in the mouse fetus. Radiat. Res. 138, 133–138 (1994).

17, Møller, A. P., Bonissoil-Alquati, A., Rudolfsen, G. & Mousseau, T. A. Chernobyl birds have smaller brains. PLoS ONE. 6, e16862 (2011).

18, Hayama, S., Nakiri, S. & Konno, F. Pregnancy rate and conception date in a wild population of Japanese monkeys. J. Vet. Med. Sci. 73, 809–812 (2011).

19, Peterova, A. et al. Morbidity in large cohort study of children born to mothers exposed to radiation from Chelnobyl. Stem Cells. 15(suppl 2), 141–150 (1997).

20, Hujoel, P. P., Bollen, A. M., Noonan, C. J. & del Aguila, M. A. Antepartum dental radiography and infant low birth weight. JAMA. 291, 1987–1993 (2004).

21, Goldberg, M. S., Mayo, N. E., Levy, A. R., Scott, S. C. & Poitras, B. Adverse reproductive outcomes among women exposed to low levels of ionizing radiation from diagnostic radiography for adolescent idiopathic scoliosis. Epidemiology. 9, 271–278 (1998).

22, Primate Research Institute, Kyoto University Guideline for fieled reserch for nonhuman primates. Accessed 28 January, 2017.

23, Japanese Ministry of Environment. 2012 Japanese Red List. Accessed 28 January, 2017.

24, Newell-Morris, L. L. Age determination in Macaque fetuses and neonates. Nursery care of nonhuman primates (ed. Ruppenthal, G. C.) 93–115 (Plenum Press, 1979).

25, Hayama, S., Mizutani, N., Morimitsu, Y., Shirai, K. & Nigi, H. Indices of body fat deposition in wild Japanese monkeys. Primate Res 14, 1–6 (1998).

26, Fukushima Prefecture website. Available: Results of air dose rate monitoring survey by Fukushima Prefecture. Accessed 20 January, 2017.

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July 14, 2017 Posted by | Fukushima 2017, Reference | , | 1 Comment

Radiation levels exceeding state-set limit found on grounds of five Chiba schools

n-kashiwa-a-20170614-870x580.jpgRadiation levels exceeding the state safety limit have been detected on the grounds of five schools in Kashiwa, Chiba Prefecture.


Radiation levels exceeding the government-set safety limit of 0.23 microsieverts per hour have been detected on the grounds of five schools in the city of Kashiwa, Chiba Prefecture, the prefectural board of education said Monday.

Between late April and mid-May, the board officials detected radiation levels of up to 0.72 microsieverts per hour in certain areas of the schools, including Kashiwa High School and Kashiwa Chuo High School. The areas — including soil near a school swimming pool and drainage gutters — are not frequented by students, but the board closed them off and will work to quickly decontaminate them, the officials said.

Kashiwa has been one of the areas with high radiation readings since the 2011 nuclear disaster at Tokyo Electric Power Company Holdings Inc.’s Fukushima No. 1 power plant.

According to NHK, the board of education had been checking the soil on the school premises in Kashiwa after radiation levels beyond the state limit were detected in shrubbery near the city’s public gymnasium. The board will announce the results of radiation tests at other schools in the prefecture around the end of July, NHK reported.

June 13, 2017 Posted by | Japan | , , , | Leave a comment

0.24 to 0.72 microsievert per hour at five schools in Kashiwa city, 47km from Tokyo

Capture du 2017-06-12 17-21-21


In January 2017, the Chiba Prefectural Board of Education was notified that radiation above the national standard level was measured at the Kashiwa city central gymnasium.

Following that report the Chiba Prefectural Board of Education conducted an investigation in Kashiwa city from late April to the middle of May 2017.

A radiation level exceeding the national standard of 0.23 microsievert per hour was detected on the premises of five schools in Kashiwa City, The radiation measured at 1 meter above ground level ranged from 0.24 to 0.72 microsievert.

At Kashiwa High School, Higashi Tsukuba High School and Middle School, Kashiwa Chuo High School, Kashiwanami High School and Kusanami Takayanagi High School, at places where usually no one enters: near a pool, at the back of a bicycle parking lot, etc..

The prefectural Board of Education decided to cordon those hot spots, to prohibit the entry and to decontaminate those places by soil removal.

They are also planning to conduct a radiation levels survey to the schools outside of Kashiwa city.


Capture du 2017-06-12 20-07-17

Kashiwa city, 47.1km from Tokyo

June 12, 2017 Posted by | Japan | , , , | Leave a comment

Fukushima Radiation, What Prospects for Humanity : a Conversation with Helen Caldicott


Do not go to Japan. Do not under any circumstances take your children to Japan, because you don’t know what you’re eating and where the food is sourced…

And the Japanese are trying now to export their radioactive food to London and elsewhere. Taiwan has refused to receive it. But, it’s dangerous and it’s going to continue to be dangerous for the rest of time. It’s sad.Dr. Helen Caldicott (from this week’s interview.)



Length (59:09)

Click to download audio (MP3 format)

Arnie Gundersen, a nuclear educator and former nuclear industry senior vice president, has referred to it as “the biggest industrial catastrophe in the history of mankind.” [1]

Six years ago this week, a tsunami, triggered by a category 9.0 earthquake, slammed into the site of the Fukushima Daiichi nuclear facility on the north east coast of the Japanese island of Honshu. The natural disaster resulted in the failure of systems keeping the reactor cores and spent fuel rods cool, leading to core meltdowns in three of the plant’s reactors, as well as damage from consequent hydrogen explosions. [2]

Enormous quantities of radioactive particles were released into the atmosphere and the water table leading to the Pacific Ocean. Approximately 170,000 people in the vicinity of the plant were immediately evacuated.

The World Health Organization downplayed the health risks from the catastrophe, concluding in their 2013 Health Risk Assessment from the nuclear accident that the risks of contracting certain cancers in certain sex and age groups were only “somewhat elevated.” The report also concluded “no discernable increase in health risks from the Fukushima event is expected outside Japan.” [3]

Nevertheless, a health management survey examining 38,000 children in Fukushima found three children diagnosed with thyroid cancer. The natural incidence is one in one million. [4]

Further, a December 2011 peer-reviewed report in the International Journal of Health Sciences found that in the 14 weeks immediately following the event, there were 14,000 excess deaths in the United States connected with radio-active fall-out from the Fukushima meltdowns. [5]

 The Japanese government has been so successful in its efforts to assuage the concerns of the wider public that Prime Minister Abe was able to secure Tokyo as the site for the 2020 Olympic Summer Games! As of this month, the Abe government ends its housing subsidies to people evacuated from the area proximate to the nuclear facility, forcing those fearful of the lingering radiation to fend for themselves abroad. [6][7]

The nuclear accident may have profound consequences for all humanity, and possibly all life on Earth, yet the severity of the situation doesn’t seem to merit major headlines.

On this, the sixth anniversary of the start of the Fukushima crisis, we spend the hour with world renowned nuclear watchdog, Dr. Helen Caldicott.

 In this interview, conducted and recorded on International Women’s Day, Dr. Caldicott talks about the high radiation reading recently recorded at Unit 2, efforts to contain the radioactive water spilling out of the facility, projected health risks from the cesium, tritium, strontium and other isotopes spewing from the site and much, much more. Caldicott also extends the discussion to talk about Canada’s role in nuclear proliferation and the threats posed by the new Trump Administration and Cold War atmosphere in which it is situated.

 Dr. Helen Caldicott is a physician and co-founder of Physicians for Social Responsibility. She is a nominee for the Nobel Peace Prize, the recipient of the 2003 Lannan Prize for Cultural Freedom, and author or editor of several books including Nuclear Madness: What You Can Do (1979), If You Love This Planet: A Plan to Heal The Earth (1992)The New Nuclear Danger: George W. Bush’s Military-Industrial Complex(2001), and Crisis Without End -The Medical and Ecological Consequences of the Fukushima Nuclear Catastrophe (2014). She is currently the president of the Helen Caldicott Foundation ( Her latest book, Sleepwalking to Armaggedon: The Threat of Nuclear Annihilation will be available in bookstores in July, 2017.

March 15, 2017 Posted by | Fukushima 2017 | , | 1 Comment

15,550 Bq / kg radioactive cesium school rooftop sludge in Chiba prefecture


Noda city (Noda-shi on the map) is located in Chiba prefecture, at the northern doorstep of Tokyo.

Noda City announced on January 24 that more than 15,550 Becquerel of radioactive cesium exceeded the criteria of designated waste (more than 8,000 bq per 1 kilogram) from the rooftop sludge of Municipal Nittsuka Elementary School. It is the first time that sludge exceeded the standard value in the city. The city already removed the sludge, in accordance with procedures as specified waste based on the Special Measures Law.

In response to the high radiation dose measurements found in Kashiwa city public property site this month, the city started inspection of sludge etc. and dose measurement at 300 public facilities. The country’s decontamination standard is 0.23 microsieverts per hour with a measurement height of 1 meter (50 centimeters for children-related facilities), but the city has independently set the measurement height to be a more severe 5 cm. There are no places that have exceeded city standards so far.

Meanwhile, on the 14th and 15th, they measured sludge on the roof of 12 elementary and junior high schools that were the subjects of solar panel roofing projects. As a result, they found doses exceeding city standards at five schools, up to 0.85 micro-Sievert was measured. City removed the sludge and checked radioactive cesium concentration. Only the sludge of Yotsuka-sho, had concentration of cesium exceeding the standard value of designated waste.

The removed sludge is temporarily stored at a temporary storage place surrounded by containers on the city hall premises. Approximately 5 cubic meters of targeted waste is treated, and four schools sludge which cesium concentration was found within the standard value were treated as general waste.

Translated from Japanese by Hervé Courtois

February 26, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

February 2017: 184 Thyroid Cancer Suspected/Confirmed (1 Additional Case)


  • One more case of suspected thyroid cancer was diagnosed by cytology since the last report.
  • No additional surgeries since the last report: the number of confirmed cancer cases remains at 145 (101 in the first round and 44 in the second round)
  • Total number of confirmed/suspected thyroid cancer diagnosed (excluding a single case of benign tumor) is 184 (115 in the first round and 69 in the second round)
  • The second round screening data is still not final (confirmatory examination still ongoing).
  • Thyroid Examination Evaluation Subcommittee will be convened in May or June 2017 to evaluate the results of the second round screening.

On February 20, 2017, less than two months since the last report, the 26th Oversight Committee for Fukushima Health Management Survey convened in Fukushima City, Fukushima Prefecture. Among other information, the Oversight Committee released the latest results (as of December 31, 2016) of the second and third rounds of the Thyroid Ultrasound Examination (TUE). Official English translation of the results will be posted here. The narrative below presents basic facts of TUE and its current results in perspective, including information covered during the committee meeting and the subsequent press conference.

As of December 31, 2016, there is only 1 more case with cancer or suspicion of cancer from the second round, making a grand total of 184 (185 including the single case of post-surgically confirmed benign nodule) for the first and second round screening results combined. The number of surgically confirmed cancer cases, excluding the aforementioned case of benign nodule, did not change from the previous report (101 from the first round and 44 from the second round), and the remaining 38 (14 from the first round and 24 from the second round) continue to be under observation.

The second round screening (the first Full-Scale screening) was originally scheduled to be conducted from April 2014 through March 2016, and the primary examination (with the participation rate of 70.9% and the progress rate of 100.0%), is essentially complete. But the confirmatory examination (with the participation rate of 79.5% and the progress rate of 95.0%) is still ongoing.

The third round screening (the second Full-Scale Screening) began on May 1, 2016 and is scheduled to run through March 2018–the end of Fiscal Year 2018. As of December 31, 2016, 87,217 out of the survey population of 336,623 residents have participated in the ongoing primary examination at the participation rate of 25.9%. The confirmatory examination began on October 1, 2016, with the participation rate of 29.6% so far.

Full-Scale Screening (first and second)
To be conducted every 2 years until age 20 and every 5 years after age 20, the Full-Scale screening began with the second round screening (the first Full-Scale Screening) in April 2014, including those who were born in the first year after the accident. There are 381,282 eligible individuals born between April 2, 1992 and April 1, 2012. As of December 31, 2016, 270,489 actually participated in the primary examination.

The participation rate remained the same as 3 months earlier at 70.9% but lower than 81.7% from the first round screening. Results of the primary examination have been finalized in 270,468 participants, and 2,226 (increased by 4 since the last Oversight Committee meeting) turned out to require the confirmatory examination.

The confirmatory examination is still ongoing for the second round. Of 2,226 requiring the confirmatory examination, 1,770 have participated at the participation rate of 79.5% (increased from the previous 75.8% but still lower than 92.8% from the first round screening). So far 1,681 have received final results including 95 that underwent fine needle aspiration cytology (FNAC) which revealed 69 cases suspicious for cancer.

Confirmation of thyroid cancer requires pathological examination of the resected thyroid tissue obtained during surgery. There has been no additional surgical case since the last reporting. As of December 31, 2016, 44 underwent surgery and 43 were confirmed to have papillary thyroid cancer. One remaining case was confirmed to have “other thyroid cancer” according to the classification in the seventh revision of Japan’s unique thyroid cancer diagnostic guidelines. A specific diagnosis was not revealed, but it has been reported as a differentiated thyroid cancer that is not known to be related to radiation exposure and it is allegedly neither poorly differentiated thyroid cancer nor medullary cancer.

The third round screening or the second Full-Scale Screening has covered 87,217 or 25.9% of the survey population of 336,623. The primary examination results have been finalized in 71,083 or 81.5% of the participants, revealing 483 to require the confirmatory examination. Results of the confirmatory examination have been finalized in 64 of 143 (29.6%) that have been examined. FNAC was conducted in one person with a negative result: No cancer case has been diagnosed from the third round as of now.

Confusing issues
Conducted every 2 years up to age 20, the TUE transitions at age 25 to milestone screenings to be conducted every 5 years. Some residents are beginning to participate in the age 25 milestone screening, and if they have never participated in the TUE, their milestone screening results will be added to the second round screening results. Thus the number of the second round screening participants is expected to increase even though the screening period technically ended in March 2016.

However, the third round screening survey population excludes the age 25 milestone screening participants: their results will be tallied up separately.

Also in some cases, confirmatory examinations from the second and third rounds might be simultaneously ongoing, or there could be significant delays in conducting confirmatory examinations due to logistical issues such as the lack of manpower. A two-year screening period originally designed for subsequent rounds of the Full-Scale Screening is essentially spread over a longer time period, overlapping with the next round of screening. A precise interpretation of results from each round of screening might be nearly impossible.

A newly diagnosed case in the second round
In the second round, only 1 case was newly diagnosed by FNAC with suspicion of cancer. It is a female from Koriyama-City who was 17 years old at the time of the March 2011 disaster. Her first round screening result was A1.

Prior diagnostic status of the cases newly diagnosed with cancer in the second round
Of 69 total cases suspected or confirmed with cancer in the second round, 32 were A1, 31 were A2, and 5 were B in the first round. One remaining case never underwent the first round screening (no information such as age, sex or place or residence, is available regarding this case).

Thirty-two cases that were A1 in the first round, by definition, had no ultrasound findings of cysts or nodules, whereas 7 of 31 cases that were previously diagnosed as A2 had nodules with the remaining 24 being cysts. All 5 cases that were previously diagnosed as B were nodules, and at least 2 of them had undergone the confirmatory examination in the first round.

This means 56 (32 “A1” and 24 “A2 cysts”)of 69 cases had no nodules detected by ultrasound in the first round which could have developed into cancer. This is 81% of the second round cases suspected or confirmed with cancer. It has been speculated by some that these 56 cases were new onset since the first round, suggesting the cancer began to form in 2 to 3 years after the first round screening, conflicting with the common notion that thyroid cancer in general is slow growing.

Akira Ohtsuru, the head of the TUE, explained that even though some of the small nodules are very easy to detect by ultrasound, exceptions arise when 1) the border of the lesion is ambiguous, 2) the density of the lesion is so low that it blends into the normal tissue, or 3) the lesion resembles the normal tissue. Thus, it is not because the nodules newly formed since the first round screening, but because the nodules were simply not detected even though they were there, that cases which previously had no nodules are now being diagnosed with cancer. Ohtsuru said that when such previously undetected nodules become relatively large enough to become detectable by ultrasound, they might look as if they suddenly appeared. Ohtsuru added that nodules that have already been detected by ultrasound do not to appear to grow very rapidly in general.

This is a better, more legitimate explanation than the previous ones he offered that stated the nodules were present in the first round albeit invisible. However, 56 out of 69 cases seem like a lot to be explained by this.

An issue of the female to male ratio
The female to male ratio of cancer cases warrants a special attention. For thyroid cancer, the female to male ratio is nearly 1:1 in the very young, but it is known to increase with age and decrease with radiation exposure. (See below Slide 2 in this post for more information). In the second round, the female to male ratio has been ranging from 1.19:1 to 1.44:1 overall, but the FY2015 municipalities have consistently shown a higher number of males than females with the most recent female to male ratio of 0.7:1.

What Ohtsuru said about the the female to male ratio boils down to the following:

The female to male ratio for thyroid cancer is influenced by the reason for diagnosis and the age. When the confirmatory examination of the second round screening is completed, the data will be analyzed by adjusting for age and participation rates by sex. The female to male ratio in Japan’s cancer registry data, including all ages, is around 3:1, but it used to be bigger at 4:1 or 6:1 in the 1980’s and earlier. In Fukushima, the TUE was conducted in asymptomatic youth around puberty–a different condition than the cancer registry. Yet even in the cancer registry, the female to male ratio tends to be close to 1:1 up to the puberty. Autopsy data of occult thyroid cancer in individuals who died of causes other than thyroid cancer show the female to male ratio of 1:1 or smaller (more males) in adults. This fact indicates that thyroid cancer screening would yield the female to male ratio close to 1:1 even in adults. Thus, it is scientifically expected that thyroid cancer screening in general leads to a smaller female to male ratio.

He is claiming that thyroid cancer diagnosed by cancer screening before becoming symptomatic–as opposed to symptomatic thyroid cancer diagnosed clinically–is expected to show the female to male ratio near 1:1 or smaller, i.e., as many males are diagnosed as females, or more males are diagnosed than females.

To say the least, calling extrapolation from autopsy data to screening “scientific” seems a bit of a stretch. Furthermore, Ohtsuru’s claim does not add up scientifically. South Korea, where active screening increased the incidence of thyroid cancer, did not observe a smaller female to male ratio as shown in the table of thyroid cancer incidence by sex and age group compiled from Ahn et al. (2016). It is obvious the female incidence is much higher than the male incidence without actually calculating the ratio.

Thyroid cancer incidence by sex and age group per 100,000 
in the 16 administrative regions in Korea
 Compiled from Supplementary Tables 2 & 3 in Ahn et al. (2016) Thyroid Cancer Screening in South Korea Increases Detection of Papillary Cancers with No Impact on Other Subtypes or Thyroid Cancer Mortality (link)

Furthermore, Ohtsuru’s claim that the female to male ratio tends to be close to 1:1 up to the puberty in the cancer registry is not corroborated by the actual data. The table below was compiled from the National estimates of cancer incidence based on cancer registries. The number of thyroid cancer cases for each sex was listed side-by-side for each year and age group. Then a total from 2000 to 2012 was tallied for each sex and age group to obtain the female to male ratio, because the number of cases varies from year to year. Even without knowing exactly which age range Ohtsuru meant by “up to the puberty,” it is clear that the female to male ratio is not at all close to 1:1.

The number of thyroid cancer cases by sex and age group from 2000 to 2012
Compiled from the National estimates of cancer incidence based on cancer registries in Japan (link)

According to this study, the female to male ratio peaks at puberty and declines with age, as excerpted below:

The increased F:M ratio in thyroid cancer incidence does not remain static with age. Female predominance peaks at puberty. […] This pattern occurs as the thyroid cancer incidence begins to increase at an earlier age in females than in males, leading to a rise in the F:M ratio. The ratio starts to decline as the male incidence rate begins to increase and, concurrently, the rate of increase in female incidence rate slows down. The steady decrease in F:M ratio with age continues, and the peak male rate does not occur until between 65 and 69 years of age, compared with the earlier peak female rate between 45 and 49 years of age, just before the mean age of menopause at 50 years.

An issue of the participation rate
The primary examination participation rate of 70.9% in the second round screening is lower than 81.7% in the first round. Most notable is the participation rate of the oldest age group: 52.7% for ages 16-18 (age at exposure) in the first round plummeted to 25.7% for ages 18-22 (age at examination) in the second round. It is 6.6% for ages 18-24 (age at examination) for the ongoing third round so far.

Younger age groups in school have maintained pretty high participation rates thanks to the school-based screening. The older age group often leave the prefecture for college or jobs, and it becomes increasingly difficult to get them to participate, especially with their interests fading in their busy lives.

The status of the new third-party committee
The “international, third-party, neutral, scientific, up-to-date and evidence-based” expert committee proposed by Chairman Hokuto Hoshi at the last committee meeting is being discussed at the prefectural level in consultation with the central government. The prefectural official admitted that the plan was to establish an independent entity that will offer, from a neutral standpoint, latest knowledge of thyroid cancer needed by the Oversight Committee.

A committee member Tamami Umeda from the Ministry of Health, Labour and Welfare elaborated on her vision of the third-party committee as an entity to review and organize the latest clinical and epidemiological knowledge and studies. It would be separate from the Thyroid Examination Evaluation Subcommittee that is intended to evaluate and analyze the status of the TUE, including the evaluation of radiation effects. (Note: In reality, the Thyroid Examination Evaluation Subcommittee has been far from being effective in analyzing the TUE data due to lack of information released by Fukushima Medical University on the premise of protecting personal clinical data).

Explaining that international organizations frequently separate a scientific review process from discussions relating to policy making in order to maintain neutrality, Umeda said she thought a similar process might be useful for the Fukushima Health Management Survey. This comment drew questions from committee members as well as the press about the status of the Oversight Committee itself: Is it a policy-making body? Is it not scientific enough?

It would make more sense to invite experts to join the Thyroid Examination Evaluation Subcommittee to incorporate knowledge gained from the latest research on thyroid cancer. Why it has to be an “international” committee is unclear other than to say that it was recommended by the Organizing Committee of 5th International Expert Symposium in Fukushima on Radiation and Health, including Shunichi Yamashita. A former chair to the Oversight Committee, Yamashita resigned from the position in March 2013 amid controversies surrounding “secret meetings.” Although no longer involved with the Oversight Committee, he has maintained ties with the Survey as Founding Senior Director of the Radiation Medical Science Center for the Fukushima Health Management Survey, the Office of International Cooperation for the Survey.

February 25, 2017 Posted by | Fukushima 2017 | , | Leave a comment

China warns nationals visiting Japan over high radiation levels in Fukushima



The Chinese Embassy in Japan on Sunday issued an alert to its nationals who have plans to travel in Japan, reminding them of the high-level radiation inside a damaged reactor of the Fukushima Daiichi nuclear plant.

Tokyo Electric Power Company (TEPCO), the facility’s operator, announced last week that the radiation levels detected inside the plant’s No. 2 reactor had reached 650 Sieverts per hour, even higher than the previous record of 530 Sieverts per hour in January.

Even with a 30 percent margin of error, the reading is described by many experts as “unimaginable.” It is much higher than the 73 Sieverts an hour, which was detected in 2012, one year after the nuclear plant’s collapse. Under such exposure, a person would only be able to survive a few minutes at most.

The TEPCO on Thursday sent a remotely controlled robot into the reactor, equipped with a camera that is designed to withstand up to 1,000 Sieverts of cumulative exposure. The robot was pulled out after it broke down only two hours into the probe.

The company is planning to send better robots to conduct more detailed probes. However, it insists that radiation has not leaked outside the reactor.

Last week, Chinese Foreign Ministry spokesman Lu Kang said China has issued safety alerts to its nationals over the high-level radiation. He added that China hopes that the Japanese government could clarify how they are going to thoroughly eliminate the impact caused by the nuclear accident.

Six years have now passed after three reactors at Fukushima’s nuclear power plant were damaged by a devastating 9.0-magnitude earthquake and a subsequent tsunami on March 11, 2011. After the accident, the local government ordered residents living within 30-kilometer radius around the Fukushima nuclear plant to evacuate.

February 13, 2017 Posted by | Fukushima 2017 | , , | 1 Comment

“Abita”, an animated film about the plight of 360,000 Fukushima Children


This is an animation from 2013 made by a japanese student living in Germany. A girl living in Fukushima suffers fron radiation exposure.

“Abita”, is an animated short film about Fukushima children who can’t play outside because of the radioactivity. About their dreams and realities.


Abita 2013.jpg

Children in Fukushima can no longer play in nature due to radioactive radiation.
For nature is not 100% decontaminable.
This is just a story of 360,000 children who stay at home and dream of their freedom in nature and experience reality.

Abita was given many international prize, but this not reported in Japan. Sad country!!

Best Animated Film, International Uranium Filmfestival, Rio de Janeiro, 2013
Special Mention, Back-up Filmfestival, Weimar, 2013

Upcoming Competitions:
Eco-Filmtour, Potsdam, 2014 (nominated)
Winter Film Awards, New York City, 2014 (nominated)

International Festival of Animated Film ITFS 2013, BW-Rolle
Japanese Symposium, Bonn, 2013
Nippon Connection, 2013
International Uranium Filmfestival, Rio de Janeiro, 2013
International Uranium Filmfestival, Munich, 2013
International Uranium Filmfestival, New Mexico, 2013
International Uranium Filmfestival, Arizona, 2013
International Uranium Filmfestival, Washington DC, 2013
International Uranium Filmfestival, New York City, 2013
Back-up Filmfestival, Weimar, 2013
Mediafestival, Tübingen, 2013
zwergWERK – Oldenburg Short Film Days, 2013
Konstanzer Filmfestspiele, 2013
Green Citizen’s Action Alliance GCAA, Taipei, Taiwan, 2013
Stuttgart Night, Cinema, 2013
Yerevan, Armenien, ReAnimania, 2013
Minshar for Art, The Israel Animation College, Tel Aviv, Israel, 2013
IAD, Warschau, Gdansk, Wroclaw/Polen, 2013
IAD (BW-Rolle, Best of IC, Best of TFK) Sofia, Bulgarien, 2013
05. November 2013: Stuttgart Stadtbibliothek (BW-Rolle) , 2013
PISAF Puchon, Southkorea, (BW-Rolle, Best of IC, Best of TFK) , 2013
Freiburg, Trickfilm-Abend im Kommunalen Kino (BW-Rolle), Freiburg, 2013
Zimbabwe, ZIMFAIA (BW-Rolle, Best of IC, Best of TFK), Zimbabwe, 2013

Upcoming Screenings:
18. Dezember 2013: Böblingen – Kunstverein Böblingen (BW-Rolle)
21.-22. Dezember 2013: Schorndorf – Kino Kleine Fluchten (BW-Rolle, Best of IC, Best of TFK)
27. August 2014: Künzelsau – Galerie am Kocher (BW-Rolle)
Movie Night for the anniversary of the Fukushima desaster,Zurich, 2014

February 10, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Up to 20µSv/h at Namie Junior High School, Fukushima

Namie Junior High School, Namie, Futaba, Fukushima prefecture.
Measures taken on February 5, 2017, on March 31, 2017 the japanese government will lift the evacuation order in Namie, for its inhabitants to return….

At 1m above the ground : 3.5μSv/h


At 50cm above the ground : 6μSv/h


At 5cm above the ground 20μSv/h


Measurement location

February 8, 2017 Posted by | Fukushima 2017 | , , , | 3 Comments

Food contamination fears after 3/11 make the invisible visible



Radiation brain” was a pun that made the social media circuit after March 11, 2011, deriding people whose brains () had become unduly contaminated with fears about radiation after the disaster at Tokyo Electric Power Company Holdings Inc.’s Fukushima No. 1 nuclear power plant. They had, people claimed, “radiation brains” (hoshanō), a kind of soft-minded hysteria that made them figures of fun but also figures of potential danger to society and the economy. Their lack of confidence in government regulation of foodstuffs, people argued, became the source of harmful rumors that hurt farmers and dairy producers in disaster-affected areas. Such citizens, usually mothers in charge of providing meals for their children, were reckless in their caution.

Aya Hirata Kimura, a sociologist and professor of women’s studies at the University of Hawaii at Manoa, presents case studies of mothers with such anxieties and examines citizens grappling with post-Fukushima food safety concerns in “Radiation Brain Moms and Citizen Scientists: The Gender Politics of Food Contamination After Fukushima.” Kimura does not make claims about the extent of actual dangers to the food supply, but she does argue that the reality of the post-disaster threat is far from certain. The government, in other words, may be right about the limited health risks posed by irradiated produce, dairy, and meat; but skepticism on the part of citizens is a rational, rather than a hysterical, response. She also examines the various constraints that made many citizens — mothers, in particular — turn to scientific activities such as running citizen radiation-measuring organizations rather than engaging in out-and-out criticism of government and industry responses to safety concerns.

Immediately after the disaster, many expected a surge of specifically anti-nuclear political activism in Japan, and indeed protests and demonstrations flourished in the spring and summer of 2011. However, just five years on from the worst nuclear disaster in decades, political activism remains a fringe activity. Part of what interested Kimura was why citizens seemed to be “more concerned than outraged.” As she noted recently, “so many seem to be perplexed why Japan, after the major nuclear accident, has not seen transformative politics.” Her book offers some answers to that question.

Kimura makes the point that avoiding confrontational politics and direct dissent is not, as is often claimed, a characteristic particular to Japanese culture. It’s a characteristic particular to neoliberalism. Neoliberalism is one of the key concepts that guides Kimura’s analysis, and she traces how the neoliberal shift to limited government, rule of the free market, and individualism has determined what kinds of demands citizens in post-Fukushima Japan can make of their government. In a neoliberal society, the government is no longer responsible for ensuring citizens’ rights to safety, economic factors rule in cost-benefit analyses and the good neoliberal citizen is willing to take on individual risk and make individual choices, while they are less willing to act collectively.

Alongside neoliberalism, Kimura introduces us to the concepts of scientism and post-feminism. Scientism indicates a tendency in which science holds authority in society to determine the “reality” of controversial and uncertain situations, although culture and society influence the creation and application of science itself. Post-feminism is the idea that systematic oppression of women has been eliminated and collective feminist activism is no longer necessary, since motivated individual women can empower themselves.

An example of how these three larger forces of neoliberalism, scientism and post-feminism play out in post-3/11 society and constrain citizen activism is the case of fūryōhigai, or harmful rumors. The term “fūryōhigai” apparently originated in the 1980s, and indicated a decline in seafood sales because of nuclear reactor accidents. After agricultural producers in areas near the distressed Fukushima No. 1 plant suffered economic losses, the term gained new currency and shifted blame onto concerned consumers, particularly “radiation brain” moms, and away from government and business interests. The prioritization of economic recovery and the individual consumer’s responsibility to participate in this effort reflected neoliberal priorities. The view of scientism insisted on the scientific authority of nuclear experts, although many of those experts had an interest in promoting nuclear power, and the science of post-Fukushima health impacts remains contested. Contradictory demands placed women at the center of controversies about food safety as mothers responsible for the health of their families but also as targets of gendered stereotypes of women as particularly unscientific and irrational, while the post-feminist social context deterred them from making collective political demands of the powers that be.

The role these three ideologies play in Kimura’s analysis might put off a nonacademic reader, but Kimura employs them to make the power dynamics to which we are all subject visible, much as her citizen scientists labor to make the invisible threat of radiation visible. Speaking about her book, Kimura noted that “all these ‘-isms’ tend to be normalized and taken for granted.” So scientism, for example, makes science’s objective authority something that is taken for granted in spite of the fact that science is shaped by social forces. Kimura works to make the ideologies of neoliberalism, scientism and post-feminism visible, because “invisibility is at the crux of their power. The more they are named, the less they can masquerade as apolitical.” Just because we cannot see these forces does not mean that they do not impact our world, and they are very real in their consequences for potential political activism.

Radiation Brain Moms and Citizen Scientists, by Aya Hirata Kimura. 224 pages Duke University Press.


Workers at a consumer safety center in the city of Fukushima prepare to conduct radiation checks in March 2012 on vegetables brought in by residents

February 5, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

All Fukushima seafood samples pass safety tests for radioactivity


Fish caught during test fishing operations are sold at the Iwaki City Central Wholesale Market on Jan. 13. (Kazumasa Sugimura)


IWAKI, Fukushima Prefecture–For the first time, radioactivity levels were lower than the government’s safety limit in every seafood sample caught off Fukushima Prefecture for an entire year, officials said.

The Fukushima Prefectural Fisheries Experimental Station said 8,502 fish and shellfish samples were tested in 2016, and all recorded radioactivity readings under the safety standard of 100 becquerels per kilogram.

Ninety-five percent of them tested below the detection limit of around 15 becquerels per kilogram.

It was also the first time more than 90 percent of samples were below the detection threshold since the disaster at the Fukushima No. 1 nuclear plant started in March 2011, according to the officials.

People in the local fishing industry hope the numbers will help lead to a return to normal operations, although they say it is difficult to gauge the impact of harmful rumors about Fukushima seafood because prices depend on multiple factors, including quantity and quality.

Test fishing is, after all, test fishing,” said Yuji Kanari, a managing director with seafood wholesaler Iwaki Gyorui KK. “Turning that into full fishing operations like before (the disaster) will emerge as a major challenge this year.

I hope that local consumption of locally produced goods that was disrupted by the nuclear disaster will soon be back.”

The hauls from test fishing, which began in June 2012, have grown from year to year.

Preliminary figures show last year’s catch at 2,072 tons, up 560 tons from 2015, but still only 7.9 percent of the annual catch of 26,050 tons averaged over the decade preceding the 2011 disaster.

Ninety-four species are eligible for this year’s test fishing, which the Soma-Futaba fisheries cooperative association started on Jan. 10 and the Iwaki city fisheries cooperative association began on Jan. 12.


February 3, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Gov’t plan to cut back radiation tests on produce draws mixed reactions



The national government suggested it would scale back radiation tests on produce from Tokyo and 16 other prefectures affected by the Fukushima nuclear disaster, at a citizen-oriented event in Tokyo on Feb. 2, drawing mixed reactions from those in attendance.
A draft policy was put together by government bodies including the Ministry of Agriculture, Forestry and Fisheries and the Consumer Affairs Agency and calls for allowing reduction of the tests from the 2017 fiscal year. The plan was influenced by the fact that there are now almost no cases of agricultural products that exceed the regulatory limit for radioactive cesium of 100 becquerels per kilogram. Under the draft policy, the Tokyo Metropolitan Government or any of the affected prefectural governments whose agricultural products were at half or less of the limit for the past three years could choose to scale back their tests.

Representatives from consumer groups and Fukushima producers were present at the Feb. 2 meeting. There were many voices of opposition against the draft policy, saying it was too early to cut back the tests, or that the requirement for scaling them back should be stricter than half or less of the regulatory limit. On the other hand, another attendee said that over the last five years the tests had cost around 4 billion yen and the money should “be spent toward more meaningful goals.”

According to the testing results from fiscal 2011 through fiscal 2015, during the first two years the percentage of products like vegetables, fruits, tubers and meats from these areas with radioactive cesium in excess of the regulatory limit was between 0.1 percent and 5.9 percent, but since 2013 no excessive radiation has been detected.

The central government plans to hold an event to exchange ideas on the matter on Feb. 17 and get a better understanding of public opinion, before deciding on whether to actually downsize the testing.



February 3, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Fukushima ice cream sales “immune” to fears of radiation

If you tell a lie big enough and keep repeating it, people will eventually come to believe it. The lie can be maintained only for such time as the State can shield the people from the political, economic and/or military consequences of the lie. It thus becomes vitally important for the State to use all of its powers to repress dissent, for the truth is the mortal enemy of the lie, and thus by extension, the truth is the greatest enemy of the State.”  Paul Joseph Goebbels (29 October 18971 May 1945) was Adolf Hitler‘s Propaganda Minister in Nazi Germany.

The town of Koriyama in Fukushima Prefecture was one of the towns most severely hit by the Fukushima Daiichi March 2011 plume. Though not evacuated as it is located outside of the 30km radius evacuation zone decided by the Japanese government, it remains quite contaminated and has many radioactive hotspots.


Winter sales have been strong for Rakuou Cafe au Lait Ice Cream produced in Fukushima Prefecture.


KORIYAMA, Fukushima Prefecture–A dairy company here that has withstood fears and rumors about radiation has produced a hot-selling item in the middle of winter.

Within two weeks in November, the initial 6,000 cups of Rakuou Cafe au Lait Ice Cream, produced by Rakuounyugyou Co. in Koriyama, were nearly sold out.

The company, founded in 1975, shipped out an additional lot of around 18,000 cups in December, but this supply has also run short.

Rakuounyugyou shipped 25,000 more cups, mostly to outlets in Fukushima Prefecture, in mid-January, and plans to ship an additional 24,000 within this month.

Perhaps our ice cream is being seen as more of a premium product,” a sales official at the company said.

Rakuounyugyou’s Rakuou Cafe au Lait, a mild-flavored lactic drink containing at least 50 percent raw milk from Fukushima Prefecture, has an entrenched fan base both in and outside the prefecture.

The company maintained its sales levels in the aftermath of the 2011 Fukushima nuclear disaster, while its competitors suffered losses due to radiation fears and rumors among the public.

Rakuounyugyou developed the ice cream product to commemorate the 40th anniversary of the release of Rakuou Cafe au Lait. The ice cream contains at least 10 percent Rakuou Cafe au Lait and at least 10 percent milk.

We exercised trial and error because we absolutely didn’t want to disappoint fans of our Cafe au Lait,” the sales official said.

The ice cream was initially sold mainly at sightseeing facilities and expressway service areas in Fukushima Prefecture. Demand was high even though the company did little in the way of a sales campaign.

The spreading popularity of the product can be attributed to Twitter.

Tweets about the ice cream can sound like a hunt for a rare Pokemon on the “Pokemon Go” game app.

Where could I get one?” one post said. “I got one!” said another.

It is not the first time the social networking service has helped the dairy company; tweets of encouragement spread in the aftermath of the nuclear disaster.

Be what may, the Rakuou Cafe au Lait tastes so good,” said one particularly popular tweet at that time.

Cafe au Lait is being shipped to a growing number of retailers, most of them in the greater Tokyo area. Sales of the product are up 10 percent from pre-disaster levels.

Word of our ice cream has also been spread by our fans,” the sales official said. “We are so grateful that we are reduced to tears.”



January 29, 2017 Posted by | Fukushima 2017 | , , , , , | Leave a comment

Radiocesium Transfer in Forest Insect Communities after the Fukushima Dai-ichi Nuclear Power Plant Accident


To understand radiocesium transfer in the forest insect food web, we investigated the activity concentrations of radiocesium in forest insects in the Fukushima and Ibaraki Prefectures approximately 1.5–2.5 years after the Fukushima Dai-ichi Nuclear Power Plant. We analyzed 34 species of insects sampled from 4 orders and 4 feeding functional groups (herbivore, carnivore, omnivore, and detritivore) from three sites in each prefecture. 137Cs activity concentrations were lowest in herbivorous species and were especially high in detritivorous and omnivorous species that feed on forest litter and fungi. Radiocesium activity concentrations in any given species reflected the degree of contamination of that species’ primary food sources since radiocesium activity concentrations were found to be the lowest in leaves and grass and the highest in litter, bark, and fungi. This study confirmed that litter and other highly contaminated forest components such as fungi, decaying wood, bryophytes, and lichens serve as sources of 137Cs transfer into the forest insect community.


The forest ecosystems of Fukushima and its adjacent prefectures were severely contaminated with radionuclides after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident on 11 March 2011 [1,2]. For decades to come, the most biologically important radionuclide will be radiocesium because of its long half-life (30.1 years for 137Cs, 2.1 years for 134Cs) [2,3]. Many studies have reported that most of the Chernobyl radiocesium fallout still resides in surface layers in bioavailable form and continues to be a major potential source for transfer into living organisms even several decades after deposition [4,5]. Similarly, in Fukushima, radiocesium is expected to remain in the litter and upper soil layers of the forest floor for the long term [3].

Entry of radiocesium into forest ecosystems can potentially occur through two different pathways: the plant-based food chain and the detritus-based food chain. In the plant-based food chain, radiocesium in living plants moves into grazing herbivores and then into carnivores. In the detritus-based food chain, radiocesium enters the ecosystem via organisms feeding on litter and detritus (detritivores) and carnivores. Previous studies have reported highly contaminated litter to be the primary source of radiocesium in the forest ecosystem [68]. A survey of the forest invertebrate communities in the United Kingdom found the highest activity concentrations of 137Cs in invertebrate detritivores, such as earthworms (Oligochaetes) and woodlice (Isopoda) [8]. By broadly sampling organisms in forests and adjacent streams, including both vertebrates and invertebrates (fish, amphibian, reptile, arthropod, earthworms, etc.), Murakami et al. [6] found that detritivores are more contaminated with 137Cs than herbivores and carnivores at Fukushima.

The forest insect community constitutes a major route of radiocesium transfer to higher trophic organisms such as small mammals and birds. The highly varied feeding habits, life histories, and habitats of insects permit investigation of how radiocesium transfer from forest components into higher organisms occurs. There is particular concern for the effects of radiation on wildlife, including insects, as a result of the FDNPP accident [911]. However, compared with the numerous studies examining radioactive contamination of organisms used for human consumption, such as fish and game, only a few studies have been published about radionuclide accumulation in insects after the accident [12]. Previous studies conducted in European countries have reported on radionuclide transfer and accumulation of insects and other invertebrates [8,1317], but it remains unclear how 137Cs uptake occurs in the entire insect food web and in relation to insect feeding habits.

In this study, we focused on radiocesium transfer in insect communities by investigating 137Cs activity concentrationsg in forest insects in the Fukushima and Ibaraki Prefectures over a period of 1.5–2.5 years after the Fukushima Dai-ichi reactor accident. To assess the distribution of radiocesium across insect communities and the influence of feeding ecology on radiocesium uptake, we collected insect samples from a wide range of insect species: We sampled species from four taxonomic orders (Coleoptera, Hemiptera, Lepidoptera, Orthoptera) and four feeding functional groups within those orders (herbivore, omnivore, carnivore, detritivore). To assess 137Cs uptake across different levels of contamination, we collected samples from a high-contamination area in Fukushima and from a low-contamination area in Ibaraki (137Cs deposition was 130–270 kBq m−2 at the Fukushima area and 13 kBq m−2 at the Ibaraki area according to the 4th Airborne Radiation Monitoring by Ministry of Education, Culture, Sports, Science and Technology in 2011) [18]. To assess the distribution of radiocesium in insect food sources, we also sampled forest floor litter, tree leaves, grasses, bark, fungi, and bryophytes in both study areas.

Materials and Methods

Study area and sampling locations

Fig 1 shows the locations of the two forest study areas in the Ibaraki Prefecture (sites A–C) and in the Fukushima Prefecture (sites D–F). The Ibaraki study area was located approximately 160 km southwest of the FDNPP, close to Mt. Tsukuba. Two sites were located in secondary forest dominated by deciduous trees (sites A, B) and the third was located in a Japanese cedar (Cryptomeria japonica) plantation (site C). The Fukushima study sites were located 39 km northwest of the FDNPP, near Lake Udagawa. Sites D and F were secondary forest dominated by deciduous trees. Site E was a small open area surrounded by both deciduous and Japanese cedar forests. Light traps were used in the open area, and pitfall traps were set on the floor of the Japanese cedar forest. These traps are described in greater detail below. Permission was granted for the field study by the Kanto regional forest office and the Tohoku regional forest office of the Forest Agency.


Fig 1. Locations of Study Sites in the Fukushima and Ibaraki Prefectures.

Left panel shows 137Cs deposition (Bq m−2) in eastern Japan (The map was generated from the Distribution Map of Radiation Dose by MEXT, Japan, Right panels are the aerial photographs provided by the Geographical Survey Institute (, with red squares showing locations of study sites in the Ibaraki Prefecture (A, B, C) and Fukushima Prefecture (D, E, F).


Sampling and specimen processing

Insect sampling was conducted during the summers of 2012 and 2013. Pitfall traps were used for ground-dwelling beetles, and light traps were used for moths and other flying insects. Grasshoppers were collected using a sweep net. For pitfall traps, circular 180-mL plastic drinking cups (7.5-cm diameter) containing acetic acid as bait were used. For each site, 60–150 traps were placed on the forest floor, and sampling took place for 2–28 days from June to September (see Table 1 for collection dates). Light trapping was conducted in the open area of site E in the Fukushima study area. For light traps, a white sheet (1.5 × 1.5 m) was hung behind two light sources (160-W mercury vapor and 20-W fluorescent UV), and insects were captured by hand. Light trapping was conducted for approximately 2 h between 18:00–21:00 h. Light trapping was conducted only at the Fukushima sites because we were unable to collect sufficient biomass for analysis in the Ibaraki sites because of the low 137Cs activity concentrations in samples in the preliminary test results. Sweep net sampling was conducted in an open area close to site D in 2013.


Table 1. Details of study Site.

137Cs activity concentrations and counting errors in Litter Samples are shown for each study site.


Insect samples were sorted and identified to the species level. Several samples were identified only to the family level because of difficulties in species identification and because insufficient biomass was available for 137Cs determination if sorted to the species level. After measurement of fresh weight, samples were dried for >48 h at 60°C, then dry weights were determined. Individual samples of each species were combined and homogenized intact using a food processor. 137Cs concentration is reported for dry weight rather than wet because samples collected from pitfall traps vary greatly in fresh weight because of variations in acetic acid absorption.

Forest components, such as litter, tree leaves, grasses, barks, fungi, bryophytes were also sampled in 2012. Because fungi and bryophytes show a sporadic distribution, we sampled them only in the Fukushima sites in 2012. Leaf and grass samples were washed with water, dried at 70°C, weighed, and powdered using a food processor (see [19] for details). Litter, bark, fungi, and bryophytes were not washed but were dried and powdered similarly to leaves and grass.

Radiocesium measurements

All samples were stored in plastic containers (U8 container, diameter = 50 mm, height = 62 mm). 137Cs activity concentrations were measured using germanium coaxial detectors (GC2518Canberra Japan, Tokyo, Japan; SEG-EMS GEM 35–70, Seiko EG&G Co. Ltd., Tokyo, Japan). Most samples were measured for <10% of the error counts per net area counts, and samples containing only a few becquerels of activity were measured for <15% of the error counts per net area counts. Standardized sources for calibrating the detectors were MX033U8PP (Japan Radioisotope Association, Tokyo, Japan) and EG-ML (Eckert & Ziegler Isotope Products, Valencia, CA, USA). The software Gamma Studio (SEIKO EG&G, Tokyo, Japan) was used to analyze γ-ray spectra. Activities of samples were corrected for radioactive decay to the date of sample collection and were expressed as Bq/kg. S1 and S2 Tables show the 137Cs activity concentrations (Bq kg−1 dry weight) in sampled insect species and forest components, respectively.

Data analysis

After excluding values that fell below the detection limit of the instrumentation, data from 68 insect samples consisting of 34 species were used for the analysis of insect 137Cs activity concentrations. 137Cs activity concentrations tend to be lognormally distributed [20], so the 137Cs activity concentrations in insect and litter samples were log-transformed to fulfill requirements of normal distribution and homogeneity of variance. Whether 137Cs activity concentrations differed across feeding functional groups was assessed using a generalized linear mixed-effects model (GLMM). GLMM is an extension of the generalized linear model that takes into account both fixed and random effects [21]. In this study, the dependent variable was the 137Cs activity concentration in a given insect species. Fixed effects were functional feeding group, the 137Cs activity concentration in litter, sampling year (2012, 2013), and forest type (cedar vs. deciduous forest). Random effects were sampling site (A–F) and insect species. The functional feeding group to which a particular species was assigned (herbivore, carnivore, omnivore, detritivore) was based on its predominant food source. To determine the best model, we used likelihood ratio tests to compare the full model with nested models in which one of the predictor variables was omitted. If the omitted variable had no significant effect on the model, then that variable was removed from the model. This model was also selected as the best model using AIC (Akaike’s Information Criterion) from models using all combinations of variables. Because we were interested in the differences between functional feeding groups, Tukey–Kramer post hoc tests were conducted to test multiple pairwise comparisons [22].

To compare the transfer of 137Cs into insects across different contamination levels in Fukushima and Ibaraki Prefecture, a concentration ratio (CR) was calculated for each species as Bq kg−1 dry weight of insect/Bq kg−1 dry weight of litter. Although different definitions of transfer have been developed for different purposes, we standardized 137Cs transfer into insect species to 137Cs activity concentrations in forest litter because litter is the most basal food resource in forest ecosystems.

All statistical analyses were performed with the software R, ver. 3.1.1 [23], using the optional package lme4 for GLMM analysis and the multcomp package for multiple comparisons.

Results and Discussion

137Cs distribution in forest components

137Cs activity concentrations in the various forest components are shown in Fig 2. As expected, 137Cs mostly accumulated in the litter layer. Living leaves and grass had much lower 137Cs activity concentrations than litter in both study areas, and this was the case for both cedar and deciduous forests. 137Cs activity concentrations were higher in the litter and leaves of cedar forests than in those of deciduous forests. The reported higher 137Cs activity concentrations in evergreen species than in deciduous species have been attributed to the expansion of the foliar parts of the former, but not of those of the latter, at the time of fallout [24]. The finding that litter has a higher activity concentrations of 137Cs than leaves is also consistent with previous studies, which reported that most of the radioactive cesium deposited in Fukushima forests was rapidly transported to the forest floor within 1–2 years after deposition [25,26]. Although the samples from Fukushima had an order of magnitude higher activity of 137Cs than those from Ibaraki, the pattern of distribution of 137Cs among forest components was similar in both areas. The relatively lower levels in leaves and grass reflects a low rate of uptake from the soil by living plants.


Fig 2. 137Cs activity concentrations in Forest Components and Insects.

137Cs activity concentrations are shown for study sites in Fukushima (upper panel) and Ibaraki (lower panel) in 2012. Litter and leaf samples are shown separately for Japanese cedar forests (Litter_e and Leaf_e) and deciduous forests (Litter_d and Leaf_d). Dark horizontal lines represent the mean, with the box representing the 25th and 75th percentiles, the whiskers the 5th and 95th percentiles, and dots indicating outliers.


In contrast to leaves and grass, bark, bryophytes, and fungi were highly contaminated. Previous investigators have found that fungi strongly accumulate radiocesium and play an important role in the uptake and retention of radiocesium in the organic layers of forest ecosystems [5,27]. Bryophytes and lichens are also known to passively accumulate high levels of radiocesium and retain radionuclides for long time periods because of their long life spans [2830]. Thus, these forest components provide insect species not only a highly contaminated diet but also a contaminated habitat causing external radiation exposure.

The 137Cs activity concentrations in detritivorous insects were 1–2 orders of magnitude lower than the activity concentrations in litter in both the Ibaraki and Fukushima areas. Activity concentrations of 137Cs in herbivorous insects were similar to those in tree leaves and grass at Fukushima (no herbivorous insect samples were collected at Ibaraki.)

Effect of insect feeding habit on 137Cs uptake

Fig 3 presents a scatterplot of 137Cs activity concentrations in various insect species within the four functional feeding groups in relation to the 137Cs activity concentrations in litter contamination at the site where they were collected.


Fig 3. 137Cs Activity Concentrations in Insect Feeding Functional Groups.

137Cs activity concentrations of insect species are shown in relation to the 137Cs activity concentrations in litter at the site. Colors indicate the functional feeding group to which species belongs: green, herbivore; yellow, omnivore; gray, carnivore; red, detritivore. Symbols indicate the sampling area: circle, Fukushima; triangle, Ibaraki.


The GLMM analysis of the contribution of each variable to insect 137Cs contaminations indicated a significant effect of litter 137Cs activity concentration and functional feeding group, whereas no significant effect was found for both sampling year and forest type (Table 2). In the final model (Table 3), 137Cs activity concentrations in insect samples were positively correlated with those in litter (P < .001). Thus, the 137Cs activity concentrations in insects reflected the degree of contamination of litter at the study sites. 137Cs activity concentrations of litter are heterogeneous and are known to redistribute with time on the forest floor [31]. On average, 137Cs concentrations in both the litter and the ground beetle Carabus albrecht were lower in 2013 than in 2012 (Table 1, S2 Table). However, at site F, the 137Cs activity concentration of litter was higher in 2013 than in 2012 (Table 1). Although the mechanism is not entirely clear, the lateral transport of heterogeneously contaminated litter might have caused an increase in 137Cs activity concentrations because site F was located near the bottom of a hillslope [31]. In association with the increase in 137Cs activity concentration in the litter, 137Cs activity concentrations in C. albrecht also increased from 242.5 Bq kg−1 to 459.3 Bq kg−1 and 473.0 Bq kg−1 at site F (S2 Table). This confirms that 137Cs activity concentrations in insects reflected the degree of contamination of litter; therefore, CR values calculated from 137Cs activity concentrations in litter are appropriate to compare the transfer of 137Cs into insects despite heterogeneous distribution of 137Cs on the forest floor.


Table 2. Model selectionof GLMM for the 137Cs activity concentrations in insects.

The effect of separately omitting each variable from the full model showing both AIC and chi-square test statistics.


Table 3. The final model of GLMM for the 137Cs activity concentrations in insectsshowing estimates, standard errors, and P-values.

Coefficients in bold indicate significant effects (P < .05).


GLMM analysis also revealed the significant effect of functional feeding groups on insect 137Cs activity concentrations. Multiple comparison analysis showed that herbivores had significantly lower 137Cs activity concentrations than detritivores (P = .004), carnivores (P = .03), and omnivores (P = .05), but no significant differences were observed in its activity concentrations when the latter three functional groups were compared with one another (Table 3).

Fig 4 shows the CR for each insect species/order collected. Values ranged from 0.003 to 0.89.


Fig 4. Concentration Ratio of 137Cs in Sampled Insect Species.

CRs were calculated as Bq kg−1 insect dry weight/(Bq kg−1 litter dry weight. Species are grouped by the orders to which they belong (Coleoptera, Hemiptera, Lepdoptera, Orthoptera) with lines separating the orders. Colors indicate the functional feeding group to which species belongs: green, herbivore; yellow, omnivore, gray, carnivore; red, detritivore. Symbols indicate the sampling area: circle, Fukushima; triangle, Ibaraki.


Although we have data on 137Cs activity concentrations for only carnivores and detritivores in Ibaraki sites, the CR values for the collected insect species were similar between Ibaraki and Fukushima sites. For example, CRs of the samples of C. albrechti, which were collected in large quantities at all sites, were similar between the Ibaraki and Fukushima sites (t-test, t = 0.01, df = 16, P = .99). These results suggest that uptake rate of 137Cs can be consistent regardless of amount of 137Cs depositions.

Comparing CRs across functional groups, herbivores showed the lowest values. Sampled herbivores included moths (Lepidoptera), herbivorous flying beetles (Coleoptera), stinging bugs (Hemiptera), and grasshoppers (Orthoptera). The low CRs for herbivorous insects reflect their diet of living plant tissues, which were found to contain relatively low activity concentrations of 137Cs compared to litter (Fig 2). The three herbivores with slightly higher CRs (Lithosia quadra, Eilema deplana, E. vestusa) are members lichen moth family Arctiidae. The CRs were likely higher because the larvae of these moth species feed on highly contaminated lichen and algae growing on trees or stones.

The CRs in carnivore species were overall higher than those in herbivores. Predominant carnivore species in the sample were ground-dwelling beetles of the family Carabidae. Ground beetles capture and consume a wide range of other soil-dwelling organisms, including detritivorous invertebrates and earthworms.

The higher CR values for carnivore species relative to herbivore species reflect the high contamination levels of the organisms in their diets. We did not investigate 137Cs activity concentrations in earthworms and soil invertebrates, but earthworms and detritivorous soil invertebrates such as springtails (Collembola) and woodlice (Isopoda) were consistently found to have higher 137Cs activity concentrations than other invertebrate groups [8,15]. Copplestone et al. [15] also standardized the activity concentration of 137Cs in living organisms to those in litter, reported ratios of 0.9–1.33 for earthworms showing relatively high CR value compared with carnivores in Fig 4. The snail-feeding Carabidae beetle, Damaster blaptoides, had the highest CR of all carnivore species collected, which also likely resulted from the contamination of terrestrial snails. Some species of terrestrial snails whose diet contain algae, lichens and fungi have been reported to accumulate relatively high amount of radiocesium than other herbivorous species [8,32].

Among detritivores and omnivores, high CR values were found for species that feed on fungi or litter, and relatively low values were found for carrion feeders. In this study, four species of Coleopteran beetles were classified as detritivores. Nicrophorus quadripunctatus and N. concolor are both carrion beetles of the family Silphidae, which feeds on vertebrate carcasses. Their 137Cs activity concentrations were similar to carnivore Carabidae beetles. On the other hand, the dung beetle, Geotrupes laevistriatus, and the giant weevil, Sipalinus gigas, showed high 137Cs activity concentrations. The larvae of these species and adult dung beetles feed on the dung of mammals, and adults are also attracted to decaying carrion and fungi. In study of radioactive contamination in insect species in Poland, Mietelski et al. [13,33] suggested the forest dung beetle as a suitable species for biomonitoring of radioactive contamination because it has high 137Cs concentrations compared to herbivores. The larvae of giant weevils feed on dead or decaying wood. It is possible that giant weevils have high levels 137Cs because decaying wood accumulates 137Cs because of the presence of wood-decaying fungi.

Among omnivorous insects, the camel cricket, Diestrammena ssp. had especially large CR values. This species is eats a wide variety of organic materials on the forest floor, including litter, fungi, and other invertebrate species. The CR values of detritivores and omnivores varied highly across sampling sites, likely indicating the nonuniform nature of 137Cs accumulation in fungi and decaying organic materials, as well as the varied diet of individual insect species [12,15].

137Cs transfer in the forest insect food web

In this study, litter and other forest components that were highly contaminated with 137Cs, such as fungi, decaying wood, bryophytes, and lichens were considered to be primary sources of 137Cs transfer into the forest insect community. Detritivores showed higher 137Cs accumulation than herbivores, confirming that uptake of 137Cs into insect ecosystems occurs through the detritus-based food chain and not through the plant-based food chain as previous studies have suggested [6,7].

With regard to 137Cs transfer through trophic levels, 137Cs activity concentrations of carnivorous insects were higher than those of herbivores but not higher than those of detritivores. Because carnivorous insects were represented by ground-dwelling beetles in this study, a significant proportion of their diet might have comprised detritivorous organisms. Therefore, this result might indicate a decrease in 137Cs activity concentrations in carnivores compared with that in detritivores. Rudge et al. [8] reported similar findings in a study of grassland invertebrate communities in the United Kingdom after the Chernobyl accident and suggested that 137Cs activity concentrations decrease up the food chain. Using stable carbon and nitrogen isotope ratio analysis of organisms in a terrestrial and stream ecosystem, Sakai et al. (2016) likewise observed dilution of 137Cs as it moved from lower to higher trophic levels [7]. These findings are the opposite of what has been observed regarding the bioaccumulation of 137C in fish species. In general, fish species at higher trophic levels will have higher activity concentrations of radiocesium than those farther down the food chain [34,35].

Our results do not provide clear evidence to support the idea of dilution of radiocesium as it moves up the food chain because we did not collect insect species that had a direct predator–prey relationship and because our measurements possibly overestimated the 137Cs activity concentrations in detritivores. We measured insect whole-body 137Cs activity concentrations similar to the reported insect 137Cs activity concentrations in previous studies because of the difficulty in collecting sufficient biomass for 137Cs measurements from dissected individual tissue types [8,1217]. Thus, the high 137Cs concentrations measured in detritivorous insects may have been partly due to the presence of highly contaminated organic matter and soils in the digestive systems of sampled insects. Mietelski et al. (2003) found that measurement of 137Cs in dung beetles could be influenced by food remains in the digestive system. In addition, studies on the assimilation of radiocesium by earthworms have shown that little absorption occurs from contaminated gut contents [36], with radioactivity concentrations in earthworm tissues being far lower than those in the gut [8,37]. However, 137Cs activity concentrations of fish typically have been measured in dissected muscular tissues, so there was no contamination by gut contents. Therefore, the overestimation of 137Cs activity concentrations of whole-body samples should be taken into account when evaluating the 137Cs transfer through the detritus-based food chain and accumulation/dilution of 137Cs. Future studies that focus on137Cs activity concentrations in predator–prey relationships and on the bioavailability of soil-associated and litter-associated 137Cs for tissue incorporation will lead to better understanding of the transfer of 137Cs through the food web.

137Cs contaminations of arthropods are expected to gradually decrease as 137Cs decline activity concentrations in forest litter [3]. Because most herbivorous insect species have a reproductive cycle of 1 year or less, their 137Cs activity concentrations should reflect the level of contamination of their diet of the year in which they reproduced. In other functional feeding groups, members of some species may live for several years; for example, the life expectancy of Carabidae adults is 1 to 4 years. However, in the invertebrates that constitute their diet, the biological half-life of 137Cs is typically several days to a month [32]. Thus, the radiocesium concentration in insects of this species would also reflect the current contamination levels of the organisms that constitute their diet.


Understanding the movement of 137Cs through ecosystems is essential for the management of radiation contamination and risk assessment in forest environments. This study investigated 137Cs transfer in forest insect communities in areas contaminated by the Fukushima Dai-ichi Nuclear Power Plant Accident. The results showed that 137Cs activity concentrations were lowest in herbivores and highest in carnivores, detritivores, and omnivores. The level of contamination in each of the four functional feeding groups of insects reflected the level of contamination of the materials and organisms that constitute their diets. Detritorivorous species had the highest levels of contamination, confirming findings of previous studies that these species play a significant role in 137Cs transfer into the forest ecosystem via consumption of highly contaminated forest litter. The nonuniform distribution of 137Cs in the forest environment is not only because of litter but also because of other forest components that may have high levels of 137Cs contamination, including fungi, decaying wood, bryophytes, and lichens. Insect species that have high CR values or that live in highly contaminated substrates, such as dung beetles, camel crickets, and lichen moths, would be appropriate species for monitoring radiocesium activity concentrations or for studies of radiation effects on wildlife.

Supporting Information

S1 Table. Details of samples of forest components.

137Cs values and counting errors are shown.



S2 Table. Details of samples of insect components.

137Cs values and counting errors are shown.




We thank M Takeda for insect sampling, identification, and technical advice about their ecology and Dr. K Hosaka and Dr. A Takenaka for identifying samples of fungi and plants, respectively.

Author Contributions

  1. Conceptualization: YI SH NT.
  2. Formal analysis: YI.
  3. Investigation: YI.
  4. Writing – original draft: YI.
  5. Writing – review & editing: SH NT.


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Source :

Citation: Ishii Y, Hayashi S, Takamura N (2017) Radiocesium Transfer in Forest Insect Communities after the Fukushima Dai-ichi Nuclear Power Plant Accident. PLoS ONE 12(1): e0171133. doi:10.1371/journal.pone.0171133

Editor: Hideyuki Doi, University of Hyogo, JAPAN


January 27, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

7 Times More Leukemia in 2015 than 2014, 80% in Eastern Japan

Warning, this is not the result of an official study but the findings of the personal study of Kikko, a blogger who took as a base the number of hospitalized patients. But again we cannot expect the Japanese government to officially advertize it: “The number of patients diagnosed with leukemia in 2015 was about 7 times higher than the previous year.”



From June 2015

Sharp increase in leukemia patients ~ Number of patients is about 7 times more than last year ~ Fukushima, Ibaraki, Tochigi, Tokyo

According to the statistics of the National Public Medical Association from the hospitals of each prefecture, from April to October 2015, the number of patients diagnosed as “leukemia” was about seven times higher than in 2014.

About 60% or more of patients diagnosed with leukemia are acute leukemia,
Since 1978 when they began taking statistics, such high proportion never occured before.

About 80% of the patients are in the Tohoku and Kanto regions. Fukushima Prefecture is the largest, next, Ibaraki, Tochigi and Tokyo in that order.

Strontium 90 is the most probable cause. It acts inside the body as calcium so that it can be stored in bones and brain. It takes 2-3 years until symptoms develop. People inhaling it or ingesting it in foods such as milk, fish and meat.

January 16, 2017 Posted by | Fukushima 2015 | , | Leave a comment