Autoradiography of soil samples from near the Fukushima nuclear plant revealed hotspots of radioactivity caused by cesium microparticles. Satoshi Utsunomiya
On March 14 and 15, 2011—three days after the Great East Japan Earthquake and its resulting tsunami hit the Fukushima nuclear power plant—explosions at two of the plant’s reactor buildings released a huge amount of invisible radioactivity. These radioactive plumes were blown away by the wind, descending over the surrounding area and into the ocean. Eventually, the radiation emitted from the Fukushima plants spread over the entire Northern Hemisphere. It also spread to Japan’s capital, Tokyo.
Following the explosions, Japanese researchers rushed to collect and study radioactive materials from the soil and the air to find out what had happened inside the reactors, believed now to have melted down because their cooling systems failed. On March 13, the Tokyo Metropolitan Industrial Technology Research Institute, the agency responsible for measuring the air quality of particulate matter in the Tokyo area, started to collect air samples more frequently. This effort was part of the Tokyo metropolitan government’s emergency monitoring program for environmental radiation, which aimed to detect gamma-emitting nuclides in airborne dust. The filters revealed that at around 10 a.m. on March 15, 2011, a large plume of radioactivity reached Tokyo, some 240 kilometers (149 miles) south of Fukushima. All samples taken on March 14 and March 15 showed spikes in radioactivity.
The institute’s researchers published their first results in the journal of the Japan Radioisotope Association in June 2011 (Nagakawa et al. 2011); they estimated the total exposure dose to humans from radioactive substances, including iodine 131 and cesium 137 found in airborne dust, foodstuffs, and drinking water from the Setagaya ward in the old Tokyo City. Extrapolating from their measurements from March 13 to May 31, they calculated the corresponding annual cumulative dose of radiation in that part of Tokyo as being 425.1 microsieverts, which is less than half the annual dose limit to the public recommended by the International Commission on Radiological Protection. In a second conference publication in English (Nagakawa et al. 2012), the researchers extended their monitoring period to October and estimated that the total annual effective dose due to inhalation for adults in the Tokyo metropolitan area from the Fukushima radioactive plumes was far lower, at 25 microsieverts.
But two years after the accident, Japanese scientists discovered a new type of highly radioactive microparticle in the exclusion zone around the Fukushima plant. The microparticles, which had been ejected from the Fukushima reactors, contained extremely high concentrations of cesium 137—a radioactive element that can cause burns, acute radiation sickness, and even death. Satoshi Utsunomiya, an environmental radiochemist from Kyushu University in southwestern Japan, soon found that these particles were also present in air filter samples collected in Tokyo in the aftermath of the Fukushima accident.
The controversy surrounding his attempts to publish his findings nearly cost him his career and prevented his results from being widely known by the Japanese public ahead of the 2020 Summer Olympics in Tokyo.[1] Scientists still don’t know if these highly radioactive microparticles present significant danger to people, and Satoshi is one of the very few scientists who is focused on trying to find out. “We have the measurements now that tell that the particles did pass over population centers and were being deposited in places,” Gareth Law, a radiochemist from the University of Helsinki, told me. “We should answer the question.”
A view of the Fukushima nuclear plant on March 14, 2011 after the reactor failures. Hydrogen explosions in units 1 and 3 may have contributed to the dispersal of cesium microparticles into the atmosphere. Photo12 / Ann Ronan Picture Library
Model of the radioactive plume from the reactor meltdowns at the Fukushima Daiichi nuclear plant, March 11-16, 2011. (Katata et al. 2012)
The skyline of Setagaya Ward in Tokyo, Japan, captured on Feb. 16, 2018. Air filters gathered from this neighborhood in the hours and days after the March 11, 2011 meltdown of the Fukushima nuclear reactors revealed a new kind of radioactive particle present in the capital city, some 150 miles away. Shawn.ccf
The discovery
In May 2012, Toshihiko Ohnuki, an accomplished environmental radiochemist then at the Japan Atomic Energy Agency (JAEA), visited Yoshiyasu Nagakawa at the Tokyo Metropolitan Industrial Technology Research Institute, also known as TIRI. Nagakawa was the first author of two TIRI studies on radiation exposure in Tokyo, and Ohnuki asked Nagakawa if he could obtain some air samples for further analysis. Ohnuki had already studied how radioactive cesium fallout from Fukushima reacted with components of contaminated soil. Now, he wanted to do the same with the airborne dust samples from Tokyo.
Nagakawa gave Ohnuki five small filters that had been collected from the Setagaya ward in old Tokyo City at different times on March 15, 2011—the day the radioactive plume reached Tokyo. Ohnuki received the samples without restriction on their use, and no written agreement was made.[2]
Air filters collected in Tokyo’s Setagaya Ward were provided to Toshihiko Ohnuki by Yoshiyasu Nagakawa at TIRI. Imaging of the filters (bottom row) revealed a spike in the rate of ionizing radiation on the morning of March 15, 2011. The bulk radioactivity on each sample was measured in counts per minute (CPM). Toshihiko Ohnuki
Back in his laboratory at JAEA, Ohnuki performed autoradiography of the five samples, revealing many radioactive spots on all of them. The bulk radioactivity on each sample was measured to be between 300 counts per minute for the filter that covered the midnight to 7 a.m. period and 10,500 counts per minute between 10 a.m. and 11 a.m. on March 15.[3] The radiation rate was so high that Ohnuki had to cut some of the filters into small pieces, less than one square centimeter, to keep from saturating the scanning electron microscope. Ohnuki stored the unexamined filters for future analysis.
Months later, in August 2013, four researchers from the Meteorological Research Institute in Japan reported for the first time about a new type of spherical radioactive cesium-bearing particle that had been ejected in the early days of the Fukushima accident (Adachi et al. 2013). The researchers had collected air samples on quartz fiber filters at their institute in Tsukuba, located 170 kilometers southwest of the Fukushima plant. Their findings, published in Scientific Reports, were about to revolutionize the way environmental radiochemists understood the radioactive fallout from Fukushima.
Back in the lab, the researchers placed the filters on an imaging plate and inserted them into a portable radiography scanner. The images revealed many black dots, which indicated the presence of radioactive materials on the filters, with a maximum radioactivity level measured on the sample at 9:10 a.m. on March 15, 2011, four days after the Fukushima accident began. The researchers placed this sample under a scanning electron microscope and then into an energy-dispersive X-ray spectrometer to directly observe the shape and composition of the radioactive materials on the filters. What they saw stunned them.
The first electron microscope view of the previously unknown radioactive cesium microparticle, from air filter samples collected in Tsukuba, about 100 miles from the Fukushima nuclear plant. (Adachi et al. 2013)
The microscope images showed that the particles containing radioactive cesium were perfectly spherical, one of them measured as having a diameter of 2.6 microns (millionths of a meter). Scientists had found spherical cesium-bearing particles already, but these were different. They were larger and contained other elements, including oxygen, silicon, chlorine, manganese, iron, and zinc. Most important, these particles appeared to be insoluble in water, at least under atmospheric conditions.
Before this discovery, Japanese scientists did not know the exact physical and chemical properties of the radioactive materials ejected from the Fukushima nuclear plant. “People thought that those hot spots [on soil samples] were just evidence of the very high concentration of water droplets, but it was not a reasonable explanation because cesium was always known to be very soluble in water,” Satoshi said. “We were puzzled at that point.”
After the Meteorological Research Institute study was published, Ohnuki remembered the air filters from Tokyo that he had obtained from Nagakawa. He went on to reanalyze the samples to see if they contained these newly found cesium-bearing microparticles. But Ohnuki soon stopped, deciding to hand four small pieces he had cut from the samples to Satoshi. Ohnuki and Satoshi were already collaborating on a study of the occurrence of cesium in soils contaminated by the Fukushima accident (Kaneko et al. 2015). He knew Satoshi could help by using high-resolution transmission electron microscopy, a powerful technique to study the properties of materials at the atomic scale—exactly the tool needed to observe these microparticles.[4]
Kyushu University professor Satoshi Utsunomiya gathers soil samples with a colleague in the vicinity of the Fukushima nuclear plant. Courtesy Satoshi Utsunomiya
Satoshi Utsunomiya and members of his research team used electron microscopes like this one to gather images of the newly discovered cesium microparticle. Courtesy Satoshi Utsunomiya
Shocking results
The newly discovered entities were initially called spherical cesium-bearing particles, but Satoshi and his co-workers coined the term cesium-rich microparticles, or CsMPs, in 2017, which is now what researchers call them generally (Furuki et al. 2017). CsMPs had not been noted in earlier major reactor accidents.
Scientists knew the microparticles came from the Fukushima reactors because their isotopic ratio between cesium 134 and cesium 137 matched the average ratio for the three damaged reactors calculated by the Oak Ridge National Laboratory.[5] Because these particles emanated from the Fukushima reactors, Satoshi and the other scientists studying them thought that they may contain evidence about reactions that occurred during the accident. But the environmental radiochemist’s curiosity was also triggered by the unique features of these microparticles: Their size is very small, typically two to three microns, even smaller than one micron in some cases.[6] And the cesium concentration in each of the particles is very high relative to their size.
After Satoshi obtained four small pieces of the Tokyo air filters, he designed what he calls “a very simple procedure” to find out whether the filters contained cesium-rich microparticles. In April 2015, he took autoradiograph images of the four pieces, confirming what Ohnuki had already seen with a digital microscope at JAEA. Then Satoshi moved to characterize the structural and chemical properties of the particles using scanning electron microscopy (SEM) and atomic-resolution transmission electron microscopy (TEM). Although the procedure’s design was simple, executing these steps would prove to be extremely difficult.
A page from Satoshi’s lab notes compares an autoradiograph he took in April 2015 (top) with a photograph of an air filter sample previously taken by Toshihiko Ohnuki (bottom). The red areas indicate positions of radioactive particles. Courtesy Satoshi Utsunomiya
One of Satoshi’s graduate students found the first CsMP on July 14, 2015—after four months of working “extremely hard” to establish an isolation protocol by trying different SEM methods. “We were very excited by the successful isolation of CsMPs, but we were even more excited by looking at the inner structure of these particles by TEM because there was no TEM data at the time,” Satoshi said. He had a vision: Once they established the method of isolating CsMPs, they could further investigate in detail and obtain important information on the reactor meltdown process and the properties of fuel debris remaining in the reactors.
Now that they knew how to isolate the microparticles, Satoshi and his lab members divided their work into two separate efforts: Two filter pieces would be used to confirm under the electron microscope if these highly radioactive particles were indeed CsMPs, and the two other pieces would be used for dissolution experiments, to confirm if the particles were insoluble in water.
The team struggled again, this time with the atomic-resolution transmission electron microscopy. TEM is a powerful technique that enables researchers to investigate the structural and chemical properties of particles at scales ranging from microns to sub-angstrom.[7] But to observe the inner structure of particles, the transmission electron microscope requires very thin samples, typically 100 nanometers or thinner.[8] It took about three months for Satoshi and his lab members to successfully make their first TEM observation of a cesium-rich microparticle on the thin foils they had made. Using several TEM techniques, the team was able to produce high-resolution images of exceptional quality showing the shape and main elemental constituents of several CsMPs from the Tokyo air filters.
Transmission electron microscopy (TEM) enabled Satoshi’s team to capture atomic-resolution images of cesium microparticles (including these four particles) discovered on the Tokyo air filter samples provided by Toshihiko Ohnuki. Next to each TEM image, elemental maps of the major constituents of the particles, visualized on secondary electron (SE) images obtained through high-angle annular dark-field scanning transmission electron microscopy (known as HAADF-STEM), including oxygen (O), silicon (Si), iron (Fe), cesium (Cs), and zinc (Zn). (Utsunomiya et al. 2019)
In July 2015, as Satoshi was busy working on the Tokyo air filters in his lab at Kyushu University, Ohnuki received a note from Nagakawa, the TIRI researcher who had provided the samples, asking him to return them so they could be reanalyzed. In his e-mail, Nagakawa did not specify the motive for his request, which appeared innocuous: “Please return at least some of the materials we gave you for reanalysis … if the location is unknown, it can't be helped.”
Ohnuki immediately sent Nagakawa two filters from March 15, including the filter from 10 a.m. to 11 a.m. that had the highest level of radioactivity and contained the largest number of radioactive spots. Ohnuki added that he had discarded the other three filters after he analyzed them in 2013.
Nagakawa also asked Ohnuki whether he was planning to publish papers based on the samples. Ohnuki explained that he stopped analyzing them after his inconclusive attempts in 2013, but did not mention he had given Satoshi part of the filters for study.[9]
In April and June 2016, Satoshi conducted dissolution experiments and quickly confirmed that the CsMPs were insoluble in water. The experiments also showed that most of the cesium activity on these filters came from CsMPs. In fact, up to 90 percent of the cesium radioactivity came from these microparticles, not from soluble forms of cesium—meaning that most of the cesium radioactivity detected during the March 15 plume in Tokyo was from CsMPs.
Satoshi was now ready to publish his results in a scientific journal. These were important findings that the scientific community needed to know. But Satoshi also understood that they could create a public relations crisis in Japan because his findings contradicted previous statements that played down the implications for public health of Fukushima fallout in Tokyo.
The Goldschmidt Conference—the foremost such international meeting on geochemistry—that year was held in the Japanese city of Yokohama. Satoshi was invited to give a plenary talk and present his research on environmental contamination from the Fukushima disaster (Utsunomiya 2016). During the talk, he presented his new findings on the Tokyo air filters. His talk received a lot of attention and was even reported by several Japanese and international newspapers. After his presentation, the scientific chair of the conference, Hisayoshi Yurimoto, said: “Very interesting results. And also very shocking results.”[10]
Satoshi Utsunomiya delivers a plenary address at the 2016 Goldschmidt conference in Yokohama, Japan. The presentation, which covered his new findings on the Tokyo air filter microparticles, caught the attention of international media. Gaël Kazaz / Goldschmidt
Scientists go on trial
Between 2016 and 2019, a Kafkaesque sequence of events circled about Ohnuki, the former JAEA researcher who gave Satoshi the Tokyo air filter samples, and Satoshi. During that sequence of events, Satoshi’s research paper was accepted for publication by a prestigious scientific journal after peer review—but the journal delayed publication of the paper for years, eventually deciding not to publish it based on mysterious accusations of misconduct that, it turned out, were unwarranted. As a result, Satoshi’s findings were not made widely known, saving the Japanese authorities a possible public relations crisis as the summer Olympics in Tokyo neared. Because of the controversy surrounding Satoshi’s paper and the lack of research on the health impacts of these particles, it remains unclear to what extent Tokyo residents have been exposed to dangerous radiation levels as a result of the Fukushima accident.
I worked to reconstruct the sequence of events related to Satoshi’s research paper to find out whether the controversy over its publication was the result of some unethical practice on his part; competition between research laboratories; or attempted suppression of scientific results. The account that follows is based on the review of dozens of e-mails, letters, reports, and transcripts of phone conversations the Bulletin has obtained, as well as on multiple interviews with people directly involved in the events.
In August 2016, the leader of Nagakawa’s research group at TIRI, Noboru Sakurai, sent an e-mail to Ohnuki urging him to return filter samples he had earlier obtained from TIRI to the Tokyo Institute of Technology, where Ohnuki was now employed. Ohnuki responded that the filters had already been sent, but Sakurai maintained they had not received them. Ohnuki had asked a staff member of the research group he used to work in at the Japan Atomic Energy Agency to send the samples he had left there, but the samples were not sent. Because the samples were studied in a controlled area, theymay have been disposed of together with other Fukushima-related samples that had been stored at JAEA.
In July 2015, three years after giving Ohnuki the five air filters from Tokyo that Satoshi showed contained cesium microparticles, TIRI’s Yoshiyashu Nagakawa asked for them back. His request reads, in part: “We are currently considering reanalyzing the filters collected at the time of the accident. So, we would like to ask you to return the filters we gave you (if there are any left over).”
In October, as Ohnuki dealt with insistent requests that he return the filter samples, Satoshi submitted two research manuscripts to the journal Scientific Reports, one on the first successful isotopic analysis of individual cesium-rich microparticles based on soil samples collected from the exclusion zone at Fukushima, and one on the first characterization of the CsMPs from the Tokyo air filter samples that he had presented during his talk in Yokohama. Both articles were accepted in early January 2017 after peer review.[11]
The Tokyo paper, titled “Caesium fallout in Tokyo on 15th March, 2011 is dominated by highly radioactive, caesium-rich microparticles,” was co-authored by three graduate students from Satoshi’s lab—Jumpei Imoto, Genki Furuki, and Asumi Ochiai, who conducted the experiments—and three Japanese collaborators: Shinya Yamasaki from the University of Tsukuba who contributed to the measurement of samples; Kenji Nanba of Fukushima University, who contributed to the collection of samples; and Toshihiko Ohnuki, who had obtained the samples. The paper included two international collaborators who were world experts in the study of radioactive materials, Bernd Grambow of the French National Center for Scientific Research at the University of Nantes in France and Rodney C. Ewing of Stanford University, who contributed to the research ideas and participated in the analysis of the data. Satoshi was the lead author of the study.
On January 27, just days after the Tokyo paper was accepted for publication, Yuichi Moriguchi, a prominent professor at the University of Tokyo who regularly appeared on national TV programs, visited Ohnuki at Tokyo Tech ahead of a meeting of the Atomic Energy Society of Japan.[12] Moriguchi was joined by Yasuhito Igarashi, a professor at Kyoto University and a co-author of the 2013 paper about the discovery of the CsMPs. Ohnuki would later write in an e-mail that he showed the two visitors copies of the preprint of the accepted Tokyo paper. Moriguchi was very surprised to learn about this paper and that it was about to be published. He, too, was working on the Tokyo samples, and he had an ongoing collaboration with TIRI (Ebihara et al. 2017; Oura et al. 2017). “We were competitors,” Moriguchi told me in an interview for this story. “Of course, there are several more groups that study the [cesium] microparticles in the other media, but for atmospheric pollution, I think we have only two major groups in Japan.”[13]
On the day of the visit, Moriguchi sent an e-mail to Ohnuki, pressing him to inform TIRI about the planned publication. “This type of information makes government agencies very sensitive,” Moriguchi wrote. “If the results obtained from these valuable sample collections conducted at a research institute under the administration were to incur the displeasure of government agencies and it becomes difficult to obtain cooperation from research institutions, we are concerned that this could hinder future research using these types of samples.” Their meeting revealed differing interpretations of using the TIRI samples for research. In an interview for this story, Moriguchi confirmed his concerns and said he had contacted Sakurai at TIRI after seeing the paper. In his e-mail to Sakurai, which I have viewed, Moriguchi wrote: “Professor Onuki and his colleagues’ research is of great significance in terms of scientifically clarifying the effects of the accident and leaving a legacy for future generations, so I wonder if some kind of compromise can be found, but would that be difficult?”
The old headquarters of the Tokyo Metropolitan Industrial Technology Research Institute (TIRI), as seen in 2009 in Kita Ward, Tokyo. This was the main headquarters at the time of the Fukushima accident in March 2011. Kamemaru2000
After the Fukushima disaster, TIRI moved in October 2011 to a new, larger research facility. TIRI
The day after the visit, not realizing the huge controversy it would generate, Ohnuki sent a PDF file of the preprint paper to Sakurai, informing him about the upcoming publication. Sakurai was not happy: He anticipated the political implications of these new findings, which came from samples that someone from his institute had given to another researcher. Also, Sakurai and his research group at TIRI had already analyzed these samples in 2011 and did not detect—let alone characterize—the microparticles (Nagakawa et al. 2011). Should Ohnuki and Satoshi’s paper be published, it could be a blow to his and his research group’s credibility. Almost immediately, Sakurai moved to block the publication, according to e-mails obtained by the Bulletin.
On February 1, Rafal Marszalek, the then-deputy managing editor of Scientific Reports, wrote to Satoshi telling him that the journal had been contacted by a researcher raising concerns regarding the provenance of the air samples analyzed in the manuscript. Marszalek gave Satoshi a couple of days to clarify how the samples were collected.
Scientific Reports first informed Satoshi on February 1, 2017, that the journal had received a complaint about the samples he used in the paper.
Satoshi had no idea what this complaint asserted or who the complaining researcher was. So he asked Ohnuki, who told him that he had sent the paper to TIRI. E-mails show that Sakurai contacted Scientific Reports to inform the journal of TIRI’s concerns over the sample’s provenance. As Satoshi was still trying to contain the controversy, his second paper was published on February 15, 2017 (Furuki et al. 2017). Meanwhile, the journal kept the Tokyo paper on hold.
Ohnuki explained to Satoshi that when he obtained the samples in 2012, it was understood that they were meant to be used for research to better understand the environmental behavior of radioactive cesium. There was no other reason to give a radiochemist samples that were known to contain radioactive material. So, according to Ohnuki, no formal agreement was needed.[14] Satoshi attempted to explain this to Scientific Reports, but the editor was not convinced and told Satoshi that he could not verify if Nakagawa was authorized to share the samples with Ohnuki. He therefore asked that Satoshi and Sakurai resolve the supposed provenance issue before publication.
The co-authors were skeptical that the journal would publish the paper, even if they acknowledged TIRI had provided the sample or included some TIRI researchers as co-authors. They felt trapped—and started to see a conspiracy.
Satoshi emailed Sakurai asking for details of the complaint, but Sakurai did not respond. Satoshi even wrote to the director of TIRI, Tsugunori Okumura, who also declined to disclose details of the accusation and explained that this was an issue between TIRI and the Japan Atomic Energy Agency, where Ohnuki was working at the time of the experiments.
In July 2017, TIRI increased the pressure by sending a formal complaint to the Tokyo Institute of Technology, where Ohnuki was now employed. In a letter that the researchers were not able to see until a year after it was sent, TIRI accused Ohnuki of “suspected acts violating internal regulations, researcher’s ethics and code of conduct” in providing Satoshi with samples from TIRI without the institute’s consent.
Toshihiko Ohnuki at a 2016 workshop on radioactive waste treatment and remediation hosted by the Japan Atomic Energy Agency. JAEA
As the issue became more political and involved more institutions, Satoshi continued his research on CsMPs and presented two other papers about Fukushima at the next Goldschmidt Conference in Paris in August 2017. Later that month, under pressure from the Tokyo Metropolitan Institute of Industrial Technology, the Tokyo Institute of Technology opened a formal investigation of Ohnuki on suspicion of improper research activities with Satoshi. “It was like a court,” Satoshi said of being called before the compliance committee. Except that, unlike in a trial, he did not know the exact terms of what they were accused of. “The team at TIRI didn’t even allow Kyushu University to show me this letter,” Satoshi said. “So at that point, I didn’t understand what the problem was.”
Satoshi thought that TIRI was complaining about the sample provenance: “I clearly said to the committee members that the sample they provided us was for research. But they were claiming that they just lent us the sample.” For Satoshi, it was a very unreasonable accusation.
The misconduct investigation occurred in the middle of a series of scandals involving several Japanese universities in the 2010s, including a notorious stem cell scandal in 2014 during which researcher Haruko Obokata fabricated results that allowed her to claim to have developed a groundbreaking method to create stem cells easily. Following this and other scandals, the science and technology ministry in Japan issued a set of guidelines on research misconduct, including penalties for researchers who engaged in falsification, fabrication, and plagiarism, among other scientific wrongdoing. Satoshi and Ohnuki’s was one of the first cases in Japan to go through a trial-like investigation based on the guidelines.
“There was an investigation, a very detailed investigation, involving lawyers,” Satoshi said. “It’s so stupid, you know. Lawyers for a research study as simple as this.”
After months of proceedings, the investigation ended on December 22, 2017. The final report of the investigation, which I have viewed and was sent by Tokyo Tech President Yoshinao Mishima to Kyushu University President Chiharu Kubo, states that Ohnuki and Satoshi—referred to respectively as “the suspect” and “the co-author” in the report—had been found not guilty of scientific misconduct. Although no written agreement between TIRI and JAEA clarified the conditions under which the samples were given to Ohnuki, the use of the filters and the data extracted from them could not, in itself, be considered the intellectual property of TIRI. Therefore, the case could not be considered as theft or plagiarism.
The investigation also concluded that both institutions had been “sloppy,” TIRI for not having clarified the conditions under which it supplied the samples and JAEA for not having adequate procedures for their storage and disposal. Although Ohnuki and Satoshi were cleared of misconduct accusations, the committee recommended that the two researchers be blamed by their universities for their mishandling of samples.
The Tokyo Tech investigation committee’s cover letter for the three-page report “on the suspicion of improper research activities.” The committee found that neither Ohnuki and Satoshi were guilty of scientific misconduct.
Cleared but still harassed
During the investigation, Satoshi almost gave up on publishing the paper based on examination of the filters in Tokyo. He told the committee members that he would probably withdraw the paper, then “in press,” from Scientific Reports. Both the committee members and TIRI were pleased. “But then I talked to Rod [Ewing], and we did something clever,” Satoshi explained. They would not withdraw the paper; instead, they would keep it “in press” until the investigation was over. In February 2018, with the report from the investigation that cleared the two co-authors in hand, Ewing asked the editor at Scientific Reports to release the paper for publication. But the editor contacted TIRI again to confirm whether the issue was resolved. “Of course, they were very upset because they thought that the paper had already been withdrawn by me,” Satoshi said.
It is not clear why, at this point, Tokyo Tech did not consider the issue resolved. Satoshi had provided pictures of the four samples and the autoradiograph images he had made in 2015. Tokyo Tech could have easily compared the shape of the small pieces to their associated filters as well as their radioactive hotspot distribution from the images to confirm that these sample pieces were from the same Tokyo air filters.
Instead, Tokyo Tech initiated a pressure campaign against Ohnuki and Satoshi to get the samples back. (TIRI seems not to have taken part.) Under direct pressure from the president of his institute, Kazuya Masu, Ohnuki returned the last samples he still had—the samples from which he had cut the small pieces that Satoshi had studied. Now, Satoshi was the last person to still have parts of these samples, and Ohnuki was asking his collaborator to give them back. Tokyo Tech said they needed to verify if the small pieces were the same samples as those that Ohnuki had obtained from TIRI.
Satoshi did not want to give the samples away. “These are the only evidence to prove our article,” he said. Satoshi feared that once Tokyo Tech had received the specimens, it would claim they were not from the samples collected in Tokyo on March 15, 2011, thereby discrediting their study. Satoshi was also worried that, once he sent the samples, he would never be able to retrieve them. Also, relinquishing the samples would have been a violation of his own university’s rules that require preserving samples for possible reanalysis.
In Focus
Why more study of cesium-rich microparticles is needed
Since their discovery over a decade ago, CsMPs have generated a lot of interest from radiochemists who have studied their chemical and physical properties extensively. But while these new microparticles are now well understood, little is known about their fate in the environment and their impacts on human health. Continue reading
Mothers march in Tokyo against radiation exposure risks on March 5, 2016.
Photo by Maxime Polleri
On September 6, the editor of Scientific Reports asked Tokyo Tech once again if there was any update regarding the issue. Tokyo Tech asked Kyushu University to respond to the journal, and decided to disengage. On September 12, Satoshi was feeling powerless and trapped, not sure how longer he could keep both the samples and his job. That’s when he decided to send the samples to Ewing at Stanford University.
“I sent all the samples to Stanford,” Satoshi said. Satoshi sent the air filter samples through regular postal services “in a UPS package.”[15] On September 13, Kyushu University’s executive vice president, Koji Inoue, called Satoshi to his office and yelled at him, urging him to give back the samples. Satoshi told Inoue that it was too late; he had already sent the samples to Stanford “for further investigation.”
Now the samples were secured, but Satoshi still needed his paper to be published.
Understanding that the matter had grown even more political, Satoshi made an audacious effort of last resort, sending a letter to then-Governor of Tokyo Yuriko Koike, seeking her permission to publish the paper. Satoshi hoped that, because the city of Tokyo controls the Tokyo Metropolitan Industrial Technology Research Institute, the governor could help settle the issue by allowing the paper to be published.
The move apparently backfired.
Soon thereafter, Satoshi said, “It became very difficult for me to get research funding. That was the biggest impact on me.” The controversial fate of this “very simple paper” was starting to take a toll on his scientific career.
As the paper remained “in press” at Scientific Reports, Andrea Thompson, a reporter from Scientific American who was preparing a piece about CsMPs for the eighth anniversary of the Fukushima disaster, contacted Ewing at Stanford University. Ewing and Satoshi told the reporter about the controversy surrounding their paper, although not in full detail. In late February, Thomson contacted the editor of Scientific Reports to find out what was happening with the paper.
On March 8, 2019, the editor told the authors that Scientific Reports had rejected the paper—more than two years after receiving the first complaint. In his rejection letter, the editor explained that the journal had “now received further communication from TIRI regarding the sample ownership [and] related claims” and shared the claims with the co-authors:
- Tokyo Metropolitan Industrial Technology Research Institute (TIRI) did lend the samples to Dr. Ohnuki of JAERI in May 2012, but did not lend them directly to Dr. Utsunomiya. TIRI just found in January 2017 that the samples may have been transferred to the research team of Kyushu University.
- TIRI has not yet identified the sample described in the article of Science Reports is the sample which originally TIRI lent to Dr. Ohnuki. Therefore, TIRI cannot agree with the description in the article the sample stemmed from TIRI.
That was the first time they had seen the actual language of TIRI’s complaint to the journal. In addition, TIRI had told the journal that it considered the issue not resolved. In the rejection letter, the editor said the journal could not proceed to publication while there was an ongoing dispute regarding sample ownership and was therefore “formally rescinding the offer of publication.” The editor, Marszalek, declined to comment for this story.
Thompson’s article in Scientific American was published on March 11, 2019, mentioning the fact that the paper had been rejected (Thompson 2019).
In June 2019, Satoshi and his co-authors posted their paper on arXiv (Utsunomiya et al. 2019), thereby making the findings public—two-and-a-half years after its acceptance by Scientific Reports. Ohnuki’s name does not appear in the list of co-authors on the arXiv paper, and Satoshi did not acknowledge TIRI for providing the samples.
ArXiv is an open-source online repository where researchers can post their not-peer-reviewed papers before they are published in a scientific journal, a common practice in the fields of physics, mathematics, and computer science. Bernd Grambow, a co-author of the study, suggested that he upload the PDF of the article to arXiv himself to prevent Satoshi from being accused by some authorities of making the paper public. The co-authors agreed.
Posting a paper on a repository is not ideal; researchers need publishers and peer review processes to ensure scientific quality and integrity. In this case, however, the paper had already gone through the peer review process of a top journal and been accepted. As Ewing had told Scientific American about the battle with Scientific Reports, TIRI, and other institutions, “[T]here’s never, in any of the discussion, been concern about our scientific results.”
During our conversation, Moriguchi tried to minimize the novelty of Satoshi’s findings. “The fact that the plume containing these cesium microparticles arrived in Tokyo is not surprising at all for us. We have known that factor for quite an early stage. … The Meteorological Research Institute [had] published that cesium microparticles came to [the] Kanto area.” However, Moriguchi and his research group published their study mapping the distribution of CsMPs over the Kanto region, including the Tokyo metropolitan area, in 2021 (Abe et al. 2021), whereas Satoshi’s study was presented at a conference in 2016 and posted online in 2019. In their paper, Moriguchi and his co-authors acknowledged the importance of Satoshi’s findings: “As first reported by Utsunomiya et al. (2019), it is already-known fact that air parcels containing type A CsMPs passed over Tokyo City at some point on 15 March. Our results strongly support their pioneering report.”
After the paper was made public, the researchers received some attention, but not the visibility commensurate with the implications that the study had for public health in Japan.[16] The three institutions—TIRI, Tokyo Tech, and Kyushu University—were all “very happy,” Satoshi said. “People may think that we lost, but for me, we actually protected science.“
Fukushima’s unit 3 reactor building explodes on March 14, 2011. Nippon TV
Exposed rebar in a 2022 view of the submerged unit 1 reactor base. Research suggests that the cesium microparticles were created when molten material in damaged units 1 and 3 impacted the reactor’s underlying concrete base. TEPCO
New risks
In the early days after the Fukushima accident, radiochemists thought that the situation was very different from Chernobyl. The three reactor-core damage events at Fukushima were considered to be of low energy, meaning that no actual explosion of the reactors had occurred, as was the case for Chernobyl. This led radiochemists to assume that radioactive particles probably had not come out of the reactors or, at least, not in large volume. A lot of the early post-accident research, therefore, focused on the traditional environmental radiochemist approach of collecting soils and sediments, doing bulk analysis, and learning from that.
It was only after scientists discovered the existence of cesium-rich microparticles that researchers, including Satoshi, realized that particles had actually been ejected from the reactors. Gareth Law, a radiochemist from the University of Helsinki who first met Satoshi at the Goldschmidt Conference in 2016, told me he was perhaps too naive at the beginning of his research into Fukushima. Law came to this research from his background in environmental radioactivity in the United Kingdom. “We’ve had a nuclear accident at the Windscale plant in the 1950s and we’ve had a long history of materials being discharged from Sellafield [the new name for the Windscale nuclear site] into the Irish Sea, which have resulted in radioactive particles coming back to British beaches and salt marshes and so on.” Like many other radiochemists, Law was interested in learning how his previous study techniques could apply to the Fukushima research. At that time, CsMPs had just been discovered, and it was still unknown whether these had been produced in the reactors or if suspended cesium had simply condensed around already present airborne particles.
However, as researchers progressed in understanding the unique features and properties of CsMPs, they came to realize that they are very different from the general concept of radioactive cesium released as soluble forms into the environment. Characterizing the microparticles required different techniques. “Looking back on it now, you realize that it takes a lot of time to confirm these things,” Law said.
Because they were unknown until recently, CsMPs pose new risks that are still underappreciated by the research community and public authorities.
Once formed, radioactive cesium 137 has a half-life of about 30 years, after which half of the nuclides will have decayed into stable barium 137, whereas the other half will remain radioactive. CsMPs tend to accumulate, forming hotspots that contain many of the particles.[17] Hotspots of the microparticles have been found inside and outside abandoned buildings in the Fukushima exclusion zone and in other places (Fueda et al. 2023; Ikenoue et al. 2021; Utsunomiya 2024a). “They’re actually there in great numbers in many places, and then that's when the health questions start to come in,” Law said. Despite their great numbers and potential risks, hotspots of CsMPs have not been systematically mapped around Fukushima. “When we visited the exclusion zone, we could still see some hot spot occurrences on the roadside without any protection,” Satoshi said. “We shouldn’t be able to access freely that kind of hot spots.”
Satoshi takes radiation readings in the Fukushima exclusion zone. Courtesy Satoshi Utsunomiya
Because CsMPs are so small, typically two microns or less in diameter, if humans breathe them, they could potentially reach the bottom of the lung, and be lodged into sacs known as alveoli, where the lung generally cannot expel them.[18] Scientists don’t know what would happen then. For instance, a typical immune system response would consist of some kind of clearance mechanism that seeks out foreign bodies and tries to either envelop or dissolve them. But it is still unknown how exactly CsMPs would dissolve in lung fluids.
Most knowledge about breathing and radioactive particulates is based on the assumption that particles dissolve, and researchers have calculated the rates for their dissolution in the human body. But because CsMPs don’t dissolve easily, once inhaled, they will likely stay longer in the human body. Researchers believe that, because CsMPs are so slow to dissolve, they may stay much longer—certainly for several months, maybe longer—in the body, compared to hours or days for suspended cesium.[19]
By unit of mass, CsMPs are much more radioactive than even spent reactor fuel. Some researchers from the Japan Atomic Energy Agency have shown that cultured cells exposed to the radiation from suspended CsMPs display a stronger local impact compared to what is known from previous radiological simulation studies using soluble radionuclides (Matsuya et al. 2022). Scientists are only now seeing some emerging evidence that the point-source nature of the radioactivity from CsMPs could lead to damage to cell systems. This is qualitatively different from the conventional estimate of internal radiation dose at the organ level based on uniform exposure to soluble cesium.
Despite the new risks that CsMPs might pose, the study of their impacts has received little interest.
Nearly six years after it was made public, it is not clear if Satoshi’s paper on the CsMPs on the Tokyo air filters has had any meaningful impact on the research conducted at Japanese universities and institutes. “There is nobody really taking care of it,” Grambow said. “Today, the microparticles are common-sense. Everybody knows that there are lots of microparticles close to Fukushima. Also, JAEA is studying these microparticles, and they try to analyze [them] better. … There are many publications on this. But that’s not necessarily the case for the transport of [CsMPs] all the way to Tokyo. There are some publications. But [Satoshi’s] was on real filters [from the city].”
A lot of the CsMPs that arrived in the city of Tokyo on March 15, 2011, probably have now been washed away in rain, draining into the city’s sewer system and then into the ocean. But in the days and weeks that followed the Fukushima accident, many citizens of Tokyo may have inhaled microparticles. In addition, many hotspots of CsMPs are still spread across the Fukushima exclusion zone.
A close-up of the autoradiograph pictured at the beginning of this article. Hotspots of radioactive cesium like this one appear in soil samples taken from the Fukushima exclusion zone. Satoshi Utsunomiya / Goldschmidt
Satoshi and Law are two of only a handful of scientists trying to find out the extent of the health impacts of CsMPs, despite their potential to be produced in any nuclear accident during which a molten core-concrete interaction occurs.[20] But they have encountered difficulty in funding their research. “A problem in many countries is that funding agencies don't fund things that are very applied to the nuclear industry,” Law said. “Funding agencies believe the nuclear industry should fund that type of research, and you get caught between a rock and a hard place. The nuclear industry probably doesn't want to fund things that are perceived to have a very low chance of an accident ever happening.”
Satoshi and his collaborators are doing the research anyway. “Once you start asking questions and making discoveries, then you shouldn't stop asking,” Law said. “You follow the trail of evidence.”
It is difficult to explain with certainty the motives behind the fierce controversy surrounding Satoshi’s paper on the Tokyo air filters. Was Satoshi so driven by scientific curiosity that he skipped some of the basic principles of ethics and ownership? Was Ohnuki too naive in showing the paper’s preprint to the two professors who were clear competitors? Did Moriguchi genuinely want to resolve the dispute as he told me or did he want to stop this publication so his research group could be the first to report about cesium-rich microparticles on the Tokyo air filters? Were Tokyo Tech and Kyushu University too zealous in investigating their own employees, Ohnuki and Satoshi, based on accusations made by another institution? Was the editor of a scientific journal too cautious in not releasing the accepted paper for publication after Ohnuki and Satoshi were cleared of wrongdoing? Was TIRI really concerned about ownership and origin of the Tokyo samples, or was it more concerned about the huge public relations crisis that would have followed if the paper had been published ahead of the 2020 Summer Olympics in Tokyo?
In short, was it some form of conspiracy or just an unfortunate chain of events that prevented the true extent of the radiation fallout in Tokyo from being known to the public? The answer is far from evident. Maybe it includes a little bit of all of these considerations.
Liz Sikes, president of the Geochemical Society, presents the Clair C. Patterson Award to Satoshi Utsunomiya at the Goldschmidt conference in Chicago, August 19, 2024, in recognition of his contribution to the understanding of cesium microparticles. Gaël Kazaz / Goldschmidt
Satoshi’s vindication
After the Tokyo paper was made public, Satoshi and Ohnuki continued to collaborate on research until Ohnuki retired from Tokyo Tech a few years later. Ohnuki did not answer multiple requests for comment.
Sakurai, who initiated the complaint to the scientific journal, transferred from TIRI to the Tokyo Metropolitan University and retired a few years later. Nagakawa, who gave the samples to Ohnuki, is still employed at the Tokyo Metropolitan Industrial Technology Research Institute. Sakurai and Nagakawa did not respond to my request for comment.
Moriguchi, the prominent professor from the University of Tokyo who had visited Ohnuki and obtained the preprint of the paper on Tokyo and cesium-rich microparticles, said during our conversation that he tried to resolve the issue between the TIRI and Satoshi’s group and have the paper published. Even though Ohnuki and Satoshi have been officially cleared of misconduct, Moriguchi continued to assert that “Prof. Ohnuki’s attitude in handling of the filter sample provided by TIRI was against research ethics, and if the paper had been published [in] Scientific Reports, it could have been retracted, upon claim by TIRI. I wanted to prevent such unhappy process for Prof. [Satoshi] Utsunomiya’s group.” Moriguchi retired from the University of Tokyo in 2021. He is now the vice president of Japan’s National Institute for Environmental Studies in Tsukuba, where he has essentially a governing role. Moriguchi and Satoshi never met in person.
Satoshi continues to study CsMPs actively and regularly presents his results to the Goldschmidt Conference and publishes his results in scientific journals. He and his collaborators work relentlessly to understand better the fate of CsMPs in the environment and their impacts on human health. In 2024, Satoshi received the Geochemical Society’s Clair C. Patterson Award in recognition of his innovative contributions to the understanding of CsMPs.[21]
“I feel like our persistence has paid off,” Satoshi told me. “The Patterson Award is much more meaningful to me than the Nobel Prize. Patterson’s research [on lead contamination] helped the world, whereas Nobel’s invention [of dynamite] has killed millions of people.”
François Diaz-Maurin is the associate editor for nuclear affairs at the Bulletin of the Atomic Scientists.
Previously, Diaz-Maurin was a... Read More
François Diaz-Maurin
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[1] The 2020 Summer Olympics were postponed until 2021 because of the COVID-19 pandemic.
[2] Obtaining samples was not out of the ordinary, Satoshi, the radiochemist from Kyushu University who later studied the samples, told me in an interview: “Just after the Fukushima accident, everything was chaotic. People were trying to promote a lot of research regarding the Fukushima accident. So at that time, it was easy to get samples even from Tokyo.”
[3] Counts per minute is a standard measure of the detection rate of ionizing radiation corresponding to the number of emitted particles detected per minute.
[4] Satoshi had learned this advanced technique during his postdoctoral years at the University of Michigan, where he studied under nuclear materials expert Rod Ewing. Ewing subsequently moved to Stanford University’s Center for International Security and Cooperation and became a member of the Bulletin’s Science and Security Board.
[5] Isotopic ratios are unique signatures used to track the origin of radiation plumes detected in the environment, either coming from reactor accidents or nuclear weapon explosions. Cesium 134 and 137 are two radioactive forms of cesium produced during the fission reactions in a nuclear reactor, with half-lives of 2.1 and 30 years, respectively.
[6] A micron is one one-thousandth of a millimeter, or one one-millionth of a meter.
[7] An angstrom is a unit of length equal to a hundred millionth of a centimeter. For comparison, a hydrogen atom has a width of about 1.1 angstroms.
[8] These thin foils were made using a focused ion beam (FIB), a nanometer-scale precision technique in which a finely focused beam of ions is used to detect an area of interest in a sample, extract it, and prepare it for the TEM analysis. A nanometer is one-billionth of a meter.
[9] In November 2015, Nagakawa contacted Ohnuki again, insisting that he return the missing samples. Ohnuki explained again that he could not find them. In early 2016, Ohnuki retired from the JAEA and became a professor at the Tokyo Institute of Technology, also known as Tokyo Tech.
[10] See, https://www.youtube.com/watch?v=aPDvRYK_3pU (at 48:05). During the question and answer session after his presentation, some researchers questioned whether Satoshi’s high-resolution methods to detect cesium were necessary. “Aren’t existing methods good enough to detect these particles?” one attendee asked. Satoshi explained that conventional electron microscopy would be enough to detect CsMPs. But to understand their behavior in the environment—and the human body—sometimes at very low concentrations, scientists needed these high-resolution techniques. Satoshi emphasized the need for other research groups to use these new techniques. Ewing, by then a professor at Stanford University and collaborator of Satoshi, would later say of Satoshi’s research about the CsMPs in Tokyo: “It is very difficult to find and characterize these particles. Considering the full literature and efforts by others as well as our team, the results are impressive. It is rare to have both the TEM characterization and the isotopic data” (see Brown 2019).
[11] The accepted article on the Tokyo air filters was given the manuscript number SREP-17-16385A.
[12] Moriguchi led a research group on atmospheric dispersion modeling and industrial ecology. Despite not being a radiochemist, he was interested in the study of environmental radioactivity from the Fukushima disaster. At the Goldschmidt Conference in 2016, three days after Satoshi’s plenary talk, Moriguchi and a group of other researchers from Tokyo presented a paper mapping the spatial and temporal distribution of atmospheric radionuclides from the reactors using the air pollution monitoring network of eastern Japan, including that of the Tokyo metropolitan area (Tsuruta et al. 2016). Moriguchi’s group would report on the distribution of CsMPs in that area only in 2021 (Abe et al. 2021).
[13] Moriguchi explained that one is Satoshi’s group, and the other group is composed of professors Nakai and Abe of the Tokyo University of Science, as well as Adachi and Igarashi of the Meteorological Research Institute. “We are in the same group.”
[14] Moriguchi disagrees that an agreement was not needed. “When we use materials, like filters provided by others, before publishing the result, we need to get consent from the provider,” he said. “I believe that is the common sense of researchers.” In 2003, a Japanese researcher proposed the systematic use in Japan of a Material Transfer Agreement, a contract that handles the transfer of research materials that are the subject of further research by another institution (Hirai 2003). The agreement is meant to facilitate collaboration between industry, academia, and government, although the author acknowledged that very few such agreements had been used so far in Japan, “especially in the academic field.”
[15] The one-by-one square centimeter pieces and TEM thin foils were not radioactive enough to need special shielding, Satoshi said. They contained only a small number of CsMPs each.
[16] Moriguchi said that the public had been informed about cesium-rich microparticles in Tokyo. “Even then, I have [been] interviewed, and even the NHK TV broadcasted such issues. So the Tokyo residents also know about that fact, but there is no strong reaction against that.” It is not clear what information Tokyo residents were given about the specific risks from CsMPs, given their exact impact on health is still not well known.
[17] Because of their relatively large size, CsMPs don’t easily migrate through the environment. For instance, CsMPs have been found to stay in the top five centimeters of soil. In addition, CsMPs don’t react easily with minerals in the environment because of their glassy, capsule-like form.
[18] Hotspots of CsMPs could pose significant risks because they make large amounts of highly radioactive particles readily available for inhalation. Particles below five microns can penetrate to the bottom of the lung, into sacs known as alveoli. Once there, it is extremely difficult for particulates to get back out again. After first breathing particles, ciliated cells that make up the tissues of the upper parts of the lung cause one to sneeze or cough, thereby ejecting these particles from the airways. If particles get down deeper, mucus-producing cells will try to push the material back up into the digestive system or up enough so the person can blow their nose or cough it out. At the very bottom of the lung system, however, there is no such natural protection mechanism that can transport material out.
[19] Work with rats exposed to inhaled uranium dioxide particles has shown very long residence times are possible (Morris, Khanna, and Batchelor 1990; Morris, Townsend, and Batchelor 1989). Research by Satoshi’s group on CsMP dissolution and simple modeling shows possibilities for multiyear existence (Suetake et al. 2019). But “this work is simplistic in the grand scheme; more work in more realistic models is needed to say anything with confidence,” explained Law. “The recipe for exposure and long residence times are there, but the work to prove risk is yet to be properly done.”
[20] In 2019, Moriguchi helped fund a study estimating the internal dose from CsMPs (Manabe and Matsumoto 2019). The study was based on Monte Carlo simulations of a stochastic model of the possible pathway of CsMPs throughout the human body to estimate the possible probability of internal doses. The study did not include in vitro or in vivo experiments and was done before the physical and chemical properties of CsMPs came to be known. Satoshi and Gareth Law’s research shows that the study of the health impacts of CsMPs requires a multidisciplinary effort by chemists, geochemists, radiochemists, and toxicologists, as well as access to advanced techniques for characterization of CsMPs in biological models (Suetake et al. 2019).
[21] See https://www.geochemsoc.org/news/2024/02/19/satoshi-utsunomiya-named-2024-clair-c-patterson-medalist; also Utsunomiya 2024b.
Abe, Yoshinari, Seika Onozaki, Izumi Nakai, Kouji Adachi, Yasuhito Igarashi, Yasuji Oura, Mitsuru Ebihara, et al. 2021. “Widespread Distribution of Radiocesium-Bearing Microparticles over the Greater Kanto Region Resulting from the Fukushima Nuclear Accident.” Progress in Earth and Planetary Science 8(1): 13. doi:10.1186/s40645-020-00403-6.
Adachi, Kouji, Mizuo Kajino, Yuji Zaizen, and Yasuhito Igarashi. 2013. “Emission of Spherical Cesium-Bearing Particles from an Early Stage of the Fukushima Nuclear Accident.” Scientific Reports 3(1): 2554. doi:10.1038/srep02554.
Brown, Azby. 2019. “Fukushima Cesium-Enriched Microparticle (CSMP) Update (Interview with Rod Ewing).” CISAC, Stanford University. https://fsi.stanford.edu/news/fukushima-cesium-enriched-microparticle-csmp-update-interview-rod-ewing.
Ebihara, M, Y Oura, N Shirai, Y Nagakawa, N Sakurai, H Haba, H Matsuzaki, H Tsuruta, and Y Moriguchi. 2017. “A New Approach for Reconstructing the 131I-Spreading Triggered by the FDNPS Accident in 2011.” In Goldschmidt Abstracts, 1022. https://goldschmidtabstracts.info/abstracts/abstractView?id=2017004623.
Fueda, Kazuki, Tatsuki Komiya, Kenta Minomo, Kenji Horie, Mami Takehara, Shinya Yamasaki, Hiroyuki Shiotsu, et al. 2023. “Occurrence of Radioactive Cesium-Rich Micro-Particles (CsMPs) in a School Building Located 2.8 Km South-West of the Fukushima Daiichi Nuclear Power Plant.” Chemosphere 328: 138566. doi:10.1016/j.chemosphere.2023.138566.
Furuki, Genki, Junpei Imoto, Asumi Ochiai, Shinya Yamasaki, Kenji Nanba, Toshihiko Ohnuki, Bernd Grambow, Rodney C. Ewing, and Satoshi Utsunomiya. 2017. “Caesium-Rich Micro-Particles: A Window into the Meltdown Events at the Fukushima Daiichi Nuclear Power Plant.” Scientific Reports 7: 42731. doi:10.1038/srep42731.
Hirai, Akihiko. 2003. “Material Transfer Agreement.” Information Management 45(12): 858–67. doi:10.1241/johokanri.45.858. (In Japanese)
Ikenoue, Takahito, Masato Takehara, Kazuya Morooka, Eitaro Kurihara, Ryu Takami, Nobuyoshi Ishii, Natsumi Kudo, and Satoshi Utsunomiya. 2021. “Occurrence of Highly Radioactive Microparticles in the Seafloor Sediment from the Pacific Coast 35 Km Northeast of the Fukushima Daiichi Nuclear Power Plant.” Chemosphere 267: 128907. doi:10.1016/j.chemosphere.2020.128907.
Kaneko, Makoto, Hajime Iwata, Hiroyuki Shiotsu, Shota Masaki, Yuji Kawamoto, Shinya Yamasaki, Yuki Nakamatsu, et al. 2015. “Radioactive Cs in the Severely Contaminated Soils Near the Fukushima Daiichi Nuclear Power Plant.” Frontiers in Energy Research 3. doi:10.3389/fenrg.2015.00037.
Katata, Genki, Masakazu Ota, Hiroaki Terada, Masamichi Chino, and Haruyasu Nagai. 2012. “Atmospheric Discharge and Dispersion of Radionuclides during the Fukushima Dai-Ichi Nuclear Power Plant Accident. Part I: Source Term Estimation and Local-Scale Atmospheric Dispersion in Early Phase of the Accident.” Journal of Environmental Radioactivity 109: 103–13. doi:10.1016/j.jenvrad.2012.02.006.
Manabe, Kentaro, and Masaki Matsumoto. 2019. “Development of a Stochastic Biokinetic Method and Its Application to Internal Dose Estimation for Insoluble Cesium-Bearing Particles.” Journal of Nuclear Science and Technology 56(1): 78–86. doi:10.1080/00223131.2018.1523756.
Matsuya, Yusuke, Nobuyuki Hamada, Yoshie Yachi, Yukihiko Satou, Masayori Ishikawa, Hiroyuki Date, and Tatsuhiko Sato. 2022. “Inflammatory Signaling and DNA Damage Responses after Local Exposure to an Insoluble Radioactive Microparticle.” Cancers 14(4): 1045. doi:10.3390/cancers14041045.
Morris, K. J., P. Khanna, and A. L. Batchelor. 1990. “Long-Term Clearance of Inhaled UO2 Particles from the Pulmonary Region of the Rat.” Health Physics 58(4): 477. doi:10.1097/00004032-199004000-00010.
Morris, K. J., K. M. S. Townsend, and A. L. Batchelor. 1989. “Studies of Alveolar Cell Morphometry and Mass Clearance in the Rat Lung Following Inhalation of an Enriched Uranium Dioxide Aerosol.” Radiation and Environmental Biophysics 28(2): 141–54. doi:10.1007/BF01210298.
Nagakawa, Yoshiyasu, Takashi Suzuki, Yasuhito Kinjo, Noriyuki Miyazaki, Masayuki Sekiguchi, Noboru Sakurai, and Hiroaki Ise. 2011. “Measurement of the Ambient Radioactivity and Estimation of Human Radiation Exposure Dose in Tokyo with Regard to the Radioactive Substance Leakage Due to the Fukushima Daiichi Nuclear Power Plant Accident.” Radioisotopes 60(11): 467–72. doi:10.3769/radioisotopes.60.467.
Nagakawa, Yoshiyasu, Takashi Suzuki, Yasuhito Kinjo, Noboru Sakurai, Takahiro Sotodate, and Hiroaki Ise. 2012. “Measurement of Radioactivity in Airborne Dust and Estimation of Public Dose in Tokyo after the Fukushima Daiichi Nuclear Power Plant Accident.” In Proceedings of the International Symposium on Environmental Monitoring and Dose Estimation of Residents after Accident of TEPCO’s Fukushima Daiichi Nuclear Power Station,.
Oura, Y, M Ebihara, N Shirai, H Tsuruta, T Nakajima, Y Moriguchi, T Ohara, et al. 2017. “129I/137Cs Ratios for Atmospheric Particular Matters Collected Just after TEPCO FDNPP Accident.” In Goldschmidt Abstracts, 3015. https://goldschmidtabstracts.info/abstracts/abstractView?id=2017005167.
Suetake, Mizuki, Yuriko Nakano, Genki Furuki, Ryohei Ikehara, Tatsuki Komiya, Eitaro Kurihara, Kazuya Morooka, et al. 2019. “Dissolution of Radioactive, Cesium-Rich Microparticles Released from the Fukushima Daiichi Nuclear Power Plant in Simulated Lung Fluid, Pure-Water, and Seawater.” Chemosphere 233: 633–44. doi:10.1016/j.chemosphere.2019.05.248.
Thompson, Andrea. 2019. “Radioactive Glass Beads May Tell the Terrible Tale of How the Fukushima Meltdown Unfolded.” Scientific American. https://www.scientificamerican.com/article/radioactive-glass-beads-may-tell-the-terrible-tale-of-how-the-fukushima-meltdown-unfolded/.
Tsuruta, H, Y Oura, M Ebihara, T Ohara, Y Moriguchi, and T Nakajima. 2016. “Comprehensive Retrieval of Spatio-Temporal Distribution of Atmospheric Radionuclides Just after the Fukushima Accident by Analyzing Filter-Tapes of Operational Air Pollution Monitoring Stations.” In Goldschmidt Abstracts, 3198. https://goldschmidtabstracts.info/abstracts/abstractView?id=2016003632.
Utsunomiya, Satoshi. 2016. “Challenging Radionuclides in Environment at the Atomic Scale: Issues in Waste Disposal and Fukushima.” In Goldschmidt Abstracts, 3238. https://goldschmidtabstracts.info/abstracts/abstractView?id=2016000095.
Utsunomiya, Satoshi. 2024a. “Cesium-Rich Microparticles from Fukushima Daiichi: Tiny Ejecta Informing a Severe Nuclear Disaster - C.C. Patterson Award Lecture.” In Goldschmidt Conference 2024. https://conf.goldschmidt.info/goldschmidt/2024/meetingapp.cgi/Paper/21418
Utsunomiya, Satoshi. 2024b. “Acceptance for the 2024 C. C. Patterson Award to Satoshi Utsunomiya.” Geochimica et Cosmochimica Acta 388:318. doi:10.1016/j.gca.2024.10.034.
Utsunomiya, Satoshi, Genki Furuki, Asumi Ochiai, Shinya Yamasaki, Kenji Nanba, Bernd Grambow, and Rodney C. Ewing. 2019. “Caesium Fallout in Tokyo on 15th March, 2011 Is Dominated by Highly Radioactive, Caesium-Rich Microparticles.” doi:10.48550/arXiv.1906.00212.
Bulletin Daily
The cover-up of Fukushima damage extends across the Pacific. In the month following the reactor incident, on the west coast of Canada, we had multiple instances of intestinal cancers in rabbits which also involved the abdominal wall, in a facility which collected and filtered rainwater for drinking. These results were dismissed as anecdotal and coincidental but never occurred again.
We at Safecast are glad to see this renewed interest in this important issue, which we covered through interviews with Profs Utsunomia and Ewng in Aug. 2019 (see website link). The research is solid and significant, and the politicized attempts to prevent publication are unforgivable.