MIT released a new study last week proclaiming that “the guidelines governments use to determine when to evacuate people following a nuclear accident may be too conservative. “
The study by Olipitz et al (aka: MIT mouse study) is being used to advocate for a sweeping downgrade of nuclear safety policy. This is based on a five week low dose external radiation exposure study of mice.
(Werner Olipitz bio)
The MIT promotional announcement of the study included these claims:
- “Current U.S. regulations require that residents of any area that reaches radiation levels eight times higher than background should be evacuated. However,the financial and emotional cost of such relocation may not be worthwhile, the researchers say.”
- ““There are no data that say that’s a dangerous level,” says Yanch, a senior lecturer in MIT’s Department of Nuclear Science and Engineering. “This paper shows that you could go 400 times higher than average background levels and you’re still not detecting genetic damage.”
- “Until now, very few studies have measured the effects of low doses of radiation delivered over a long period of time. This study is the first to measure the genetic damage seen at a level as low as 400 times background (0.0002 centigray per minute, or 105 cGy in a year).”
- “Though the study ended after five weeks, Engelward believes the results would be the same for longer exposures. “My take on this is that this amount of radiation is not creating very many lesions to begin with, and you already have good DNA repair systems. My guess is that you could probably leave the mice there indefinitely and the damage wouldn’t be significant,” she says”
- “However, the researchers say that more studies are needed before evacuation guidelines can be revised.”
One of the two researchers quoted by the MIT press release also predicted less than a month after the start of the Fukushima nuclear disaster, that there would be no or only minimal bad health outcomes from Fukushima. She also went on to make predictions about the workers health outcomes at a time when the exposures and even who some of the workers were was unknown. More on her later in the article.
Some Key Issues With The Study:
- The study was only 5 weeks
- The study looked at external exposure only (ignoring internal exposure), existing evidence shows accident exposures are drastically different than the lab scenario used in the MIT study
- The acute group and the chronic group were irradiated by different methods
- A previous study using a lower rate and longer duration of exposure disputes MIT’s finding
- The numbers of mice in the study groups are extremely low and of a possibly radiation resistant type, a non-standard mouse was also used
- The isotope used, iodine 125 has a considerably different (lower) gamma energy than the common nuclides in an accident.
- Claims that there are very few studies of low dose radiation
As we investigated this MIT mouse study (Olipitz et al) a number of errors and flaws were found. Different methods were used to irradiate the chronic and acute mouse groups. A radiotherapy treatment x-ray machine was used to irradiate the acute group and an iodine 125 phantom was used to irradiate the chronic low dose group. Iodine 125 is not one of the common isotopes in nuclear accidents and not one of the standard isotopes used to examine to biological effects of ionizing radiation. The iodine 125 flood phantom used to irradiate the chronic low dose groups of mice has not been investigated or tested by outside labs. A radiation resistant mouse strain was used in most experiments in the study whereas a genetically altered mouse was used in one sub group. These genetically altered mice have not been tested by any outside group and are not a commonly used research mouse. Extremely disparate numbers of mice existed among the sub-groups raising concerns about the validity of comparing the derived data.
The study only looked at external exposure. Internal exposure is a well established method of exposure in nuclear accidents. The chronic exposure was only 5 weeks. Engelward excuses the short study duration because “she believes” a longer study period wouldn’t show anything. Nothing is cited to support this contention and the evidence in Tanaka et al (2009) proves Engelward false. The 2009 study by Tanaka et al used a lower dose rate for a considerably longer study period of time and found clear evidence of damage at lower dose rate of chronic exposure. The MIT study cites Tanaka yet completely dismisses the study as not proving anything and gives no reasoning for the dismissal of the Tanaka study’s contradiction to their findings. The MIT study also claims there has been little or no research into chronic low dose radiation exposure, this is simply not the case. There is an extensive body of research on this issue.
On top of the errors, questionable methods and misleading statements in the study, the authors use their observations to make the case for reconsidering nuclear evacuation zones. A very limited study on mice is used to then make the gigantic leap to the suggestion we should change the safety policy for people in relation to nuclear accidents is suspect. Dr. Yanch is one of the senior co-authors of the study and the only one from the nuclear department at MIT, though now only a visiting professor. Her track record in her own work and her comments to the media showed a serious effort to promote her idea that nuclear evacuations shouldn’t happen even if the science doesn’t back this up. Yanch is now promoting this flawed MIT study as “evidence” and she is using it quite clearly to advocate that we roll back evacuation zones or simply not even evacuate people.
Five Week Study
The five week study is incredibly short. Mice have a life expectancy of 2-3 years. The study could have easily gone longer and included more mice in the total study to get a more reliable picture of outcomes. Studies on mice and even animals closer to humans frequently do not translate over to an accurate model of human outcomes. In 2004, the FDA reported that 92 out of every 100 drugs that successfully pass animal trials, subsequently fail human trials. Ironically this study came out the same time the NRC has shrunk nuclear evacuation zones in the US and while ongoing exposures in Fukushima are still a major concern. Beagles used in plutonium MOX inhalation studies ran for years, not weeks. A low dose chronic exposure to gamma radiation in mice done in Japan used a 400 day exposure routine.
Comment in our group discussion from Edano:
“I think the most problematic detail in the study is the short exposure period of 5 weeks. bioaccumulation happens over months and years, the mice will consume other contaminated animals and vegetables, and the accumulation will rise exponentially with time.”
External Exposure Only
The study only exposed the mice to external exposure. Mice were exposed to iodine 125 (a relatively weak gamma emitter) through a sealed plexan box underneath their cage that acted as a “flood phantom”. It is well known that in nuclear accidents those exposed get both external and internal exposure. Bandazhevsky looked at children born after the Chernobyl disaster late enough to have not been exposed in utero to the initial radiation. These children lived in contaminated areas of Belarus where residency was still permitted based on radiation levels. At autopsy incredibly high levels of cesium 137 (a strong gamma emitter) were found in the internal organs of these children. This indicated considerable ongoing internal contamination of the victims of this disaster, even those born well after the blast. Rats recently found in Fukushima outside the evacuation zone had considerable internal contamination. This highlighted that even far outside the disaster zone, internal contamination is both a considerable risk and part of the exposure of nuclear disaster victims.
Kawauchi 30km from plant - 3.11 micro sievert/h air dose - 3,100 Becquerel/kg in rats
Kitaibaraki 70km from plant – 0.2 micro sievert/h air dose - 790 Becquerel/kg in rats
Without also factoring in internal exposures what is created is an inadequate model for human accident exposure and certainly not one worthy of altering nuclear evacuation procedures.
Weak external iodine 125 does not compare to strong internal cesium 137, one of the biggest issues in nuclear accidents.
Different Irradiation Methods Used
The acute and the chronic low dose groups of mice were irradiated by different types of radiation and irradiation fields. They used x-ray beams for the acute group and iodine-125 phantoms for the chronic exposure group. This is uncommon for a research study. It is typical to use the same radiation source and method to irradiate all groups in the study in order to be able to draw a conclusion. From the MIT paper:
“For acute exposures, nine week old mice were irradiated for 1.4 min at a dose-rate of 7.1 cGy per minute using a Philips RT250 Xray machine (Philips Medical Systems, Bothell, WA) at 75kV and a 0.2 mm Cu filter in place.”
“For low-dose rate exposures, four week old animals were exposed for five weeks using an 125Iodine (125I) based variable low dose-rate irradiator (Olipitz et al. 2010). Briefly, to create a large, uniform exposure area, commercially available plexan boxes (flood phantoms) were filled with 125I in NaOH buffer. Flood phantoms were placed below the animal cages resulting in a dose-rate of 0.00017 cGy/min ± 0.00002”
The synopsis may be that Olipitz and others (2012) did not find any signs of radiation-related chromosomal damage in mice exposed to external ionizing radiation at a low dose rate, that is 2 mGy/d, over five weeks. By contrast, Tanaka and others (2009) observed dose-related signs of chromosomal damage after up to 615 days of exposure at 1 mGy/d. The discrepancy in findings may be caused by differences in gamma energy of the radionuclides used to produce the field of irradation. Whereas Olipitz and others (2012) used iodine-125 to produce X-rays of 35.5 KeV peak energy, Tanaka and others (2009) employed a major contaminant released in severe nuclear reactor accidents, that is cesium-137 with a peak energy at 662 keV.
Previous Study Disputes MIT Claim
Tanaka et al (2009)showed lower rates and a longer duration study indicated dose rate effects were found as low as .0045 cGy/h. This is lower than the MIT study. Mice were exposed to .0045cGy/h for 400 days and showed clear signs of dose rate effects even at that lowest rate. MIT cites Tanaka et al’s, and claims “although the dose-rate was ~10X higher than that used here.” This is incorrect. Tanaka et al (2009) vs. the MIT study:
Lowest in Tanaka study .045 mGy/h = .0045 cGY/h
Lowest in MIT study 0.0002 cGy/min = .012 cGy/h
Tanaka et al is clearly the lower dose rate of the two studies.
They cite other studies by Tanaka et al (and others) as disputing the MIT work also, but claim “at what dose rate” radiation causes damage is “unclear”. No explanation is given why they think the multiple studies by Tanaka et al don’t prove anything yet their smaller, shorter study somehow does and also warrants changing human evacuation zones. They do nothing to make this case other than to claim it to be true.
A recently released human a-bomb study showed that “zero” is the threshold for exposure threshold. “The estimated lowest dose range with a significant ERR for all solid cancer was 0 to 0.20 Gy, and a formal dose-threshold analysis indicated no threshold; i.e., zero dose was the best estimate of the threshold.”
There is also an error in the citations for the study. The study cites “(Tanaka et al. 2009a)” yet only one Tanaka 2009 study appears in the citations. This indicates that another study was removed from the citations and that this listing for citations was not properly updated in the publication process. Was another Tanaka 2009 study removed from the citations? If so what did it say since the one still in the citations clearly disputes the MIT study? Or was it just an issue of sloppy review?
Test Group Numbers And Mouse Type
The total mice and total numbers in individual test groups also raises problems. The total number of mice in certain types of analysis are very low with as few as 6 mice in a test group. Other groups are considerably disparate.
“Group sizes for base lesion analysis, gene expression analysis, and micronucleus assay were 6, 16 and 6, respectively. Group sizes for the homologous recombination assay were 60 and 24 animals for the continuous radiation and acute exposure experiments, respectively.” (from the MIT study)
6 base lesion analysis
16 gene expression analysis
6 micronucleus assay
60 continuous radiation (homologous recombination)
24 acute exposure experiments (homologous recombination)
Total: 112 test subjects and 112 control mice assuming they had test and control for each.
A comment from Peter Melzer in our group discussion:
“Sample sizes in animal studies can be small depending how difficult it is to harvest the data. The problem is that the sample sizes in this study are greatly disparate. If the sample sizes of two groups in a statistical comparison are not equal, the average of the two is used. With a group composed of six individuals compared to another composed of sixty this average would be 33 which does not do justice to either. The great discrepancy will lead to larger deviations from the mean within the groups, resulting in less likelyhood in finding a statistically significant difference between the groups.”
Depending on the strain of mice, some may be more radiation resistant than others. The strain C57Bl6 were used in the experiment, BALBc mice are far less resistant to radiation in the issue of radiation and certain types of cells and cancers than C57Bl6. The mice selected could have added to the bias in the experiments. The C57Bl6 mice used in the MIT experiment were also further modified by MIT and used in this study. MIT created a mouse dubbed “recombomice” or FYDR mice. These C57Bl6 mice were genetically modified and bred in house by members of the research team. These mice have not be independently tested or verified by any outside institution to assure their reliability or other changes to their properties. A paper was published in 2004 on the FYDR mice. In the paper it cites experiments using this mouse to indicate damage from acute radiation but the experiment and results are unpublished. They also claim “the FYDR mice are currently being exposed to X-rays under long-term low-dose conditions” in 2004 but no paper or results appear to have been published from this work. The MIT researchers also claim this recent 5 week mouse study to be “the first” at 400 fold and how so few studies on low dose radiation have been done. It is rather obvious they have been doing this work but not releasing these specific results.
It was also noted that these FYDR mice and the study only looked at one way DNA damage can occur from radiation exposure. Peter Melzer made this comment on the issue in our group discussions: “Keep in mind these mice can be used to examine only one type of effect that ionizing radiation may exert indirectly. That is, in the attempt to fix radiation damage to DNA using homology directed repair deleterious mutations may occur. The exposed mice may contain an increased number of cells with homologous recombinations indicated by fluorescence. If they don’t, the finding does not rule out that ionizing radiation affects another molecular mechanism of DNA repair.”
The FYDR mice were also only used in one of the DNA test sub-groups, regular C57Bl6 mice were used in the other experiments. It is not clear if differences in the two strains of mice could influence the study because no outside analysis of the FYDR mice has been done.
Iodine 125 was used in the study under the guise that it is similar to cesium 137, a common isotope found in nuclear accident scenarios. Cesium 137 is a much higher energy gamma emitter than iodine 125. Cesium 137 in the 1000 MeV range, iodine 125 in the 10′s of keV range. Iodine 125 would not expose the mice in the way cesium 137 would. The decay mode of iodine-125 is very different from that of cesium-137 or iodine-131. From wiki http://en.wikipedia.org/wiki/Iodine-125 : “The detailed decay mechanism is electron capture to form the nearly-stable nuclide tellurium-125. This is followed by gamma decay at 35.5 keV energies noted, or else internal conversion electron emission, followed by an average of 21 Auger electrons emitted at very low energies (50-500 eV). The internal conversion and Auger electrons from the radioisotope have been found in one study to do little cellular damage, unless the radionuclide is incorporated chemically directly into cellular DNA, which is not the case for present radiopharmaceuticals which use I-125 as the radioactive label nuclide.”
The same MIT researchers admit in their own study that most radiation exposure studies are done with cesium 137 or cobalt 60. Due to them being very penetrating they are harder to handle in a laboratory. They claim since iodine 125 is a lower energy, lower penetration and easily shielded gamma radiation emitter, it can be used without the levels of shielding required with the other isotopes. This also clearly shows why it is considerably different than the commonly found nuclear accident isotopes like cesium 137. Our review of mouse radiation studies showed that iodine 125 was not commonly used, Cobalt 60 was the most common. Most studies used one of the common isotopes found in a nuclear accident.
Number Of Low Dose Studies
One of the authors claims there are “very few” studies of low dose radiation. It was also claimed that their study is the first to study radiation exposure at these low levels for DNA damage.
Both are flat wrong.
The DOE has an entire program to study low dose radiation
Tanaka et al: Dose-Rate Effectiveness for Unstable-Type Chromosome Aberrations Detected in Mice after Continuous Irradiation with Low-Dose-Rate y- Rays (2009)
(lower rates than MIT used)
Lowest in Tanaka study .045 mGy/h = .0045 cGY/h
Lowest in MIT study 0.0002 cGy/min = .012 cGy/h
Nakamura et al: Adiposity in Female B6C3F1 Mice Continuously Irradiated with Low-Dose-Rate γ Rays
Yamamoto, O. et al: Oral administration of tritiated water (HTO) in mouse. III: Low dose-rate irradiation and threshold dose-rate for radiation risk. Int. J. Radiat. Biol73:535–541. 1998. CrossRef, PubMed, CSA
Ina, Y., H. Tanooka et al: Suppression of thymic lymphoma induction by life-long low-dose-rate irradiation accompanied by immune activation in C57BL/6 mice. Radiat. Res 163:153–158.2005. BioOne, PubMed
Saying there are “very few” or that theirs is the first of this type of study is patently false. The studies listed are just a very small sampling of the work already done on this issue.
Questions About Bias
The MIT study contradicts a considerable body of evidence to the contrary and makes no clear case why this other evidence should be ignored in favor of theirs. The short duration and limited scope of the study raises concerns that the study was assembled to provide a desired outcome. Adding to the concerns of bias is the paper by Dr. Jacquelyn Yanch weeks after the Fukushima disaster began, making sweeping speculative claims about the health outcomes of those exposed. Yanch also questioned evacuations (discouraging them) at that time and the researchers involved with this paper continue to do so as seen in the MIT press release.
Yanch is cited as being a member of the MIT nuclear department. Yanch resigned in 2010. No reason is given for the resignation but due to her many years as faculty it is very likely she was tenured. If this is the case, what incident caused MIT to have her resign is of great interest. Usually only things like a conflict of interest or gross misconduct would cause someone to resign or be asked to do so. Yanch started a company called “Ioneyes, Inc.” but no record of this company doing business exists online and no mention of it before 2012. Yanch keeps ties to MIT as a “visiting professor“. Such a thing is usually needed in order to obtain grants. Yanch transferred an NRC grant to another professor in 2010, no reason is given for the grant transfer. Yanch in the days following the March 2011 disaster at Fukushima Daiichi, flaunted her MIT credibility calling herself “professor of nuclear engineering at the Massachusetts Institute of Technology”, failing to mention the whole “visiting” part of it. On March 22, Yanch was in the media desperately trying to downplay and dismiss Fukushima and again on March 31st.
In this paper Yanch again works to try to downplay Fukushima. She accuses people of wasting resources based on fear in Japan and claims food not being distributed is “lightly contaminated”. She also goes on to outright promote radiation hormesis and to reinterpret an old a-bomb study, then cite her unofficial reinterpretation as her source. She cites the NCRP as justification for her wild claims. One of our previous investigative pieces found the NCRP is funded by a who’s who of the commercial nuclear industry including the nuclear industries lobbyist group, NEI. The head of NCRP John Boice is also heavily involved with the Health Physics Society, a group that was busy trying to downplay Fukushima during the 1 year anniversary. Yanch herself has ties to the HPS. She has taught at their conferences, her work and the work of two other researchers on this new MIT study have had their work published in the Health Physics Society’s journal.
One of the other key members of the MIT mouse study Bevin Engelward has had her work published in the HPS journal as has Olipitz.
Other researchers appear to be mostly from the Department of Biological Engineering at MIT.
TEPCO Sponsors MIT Nuclear Department
TEPCO sponsors a professor of nuclear engineering at MIT. As part of this TEPCO also funds research programs in the nuclear engineering department at MIT, though TEPCO is not mentioned as a funder or conflict of interest in the actual paper. The conflict this creates raises questions when department researchers like Dr. Yanch are going to bat for the nuclear industry in her public statements by giving claims favorable to TEPCO’s corporate line. Mujid Kazimi is still listed as the TEPCO sponsored professor today, his career details indicate that the program continues. It is unclear if all of this questionable activity violates MIT’s Ethics and Conduct rules, it certainly doesn’t meet the public standards of being unbiased.
The overarching problem is that this very small and questionable study is being used to justify scaling back nuclear accident evacuation zones. This is clearly stated as the conclusion of the researchers as they state in the MIT article on the study.
Dean made this comment about the MIT study’s leap from a 5 week mouse study to evacuation zones:
“I believe data like this can come out,, however, one does not use this data to establish evacuation zones immediately following an accident… FUKU and TMI has taught us that the potential , based on the reactor accident, exists for much more conservative evacuation zones.. ie: in some instances the rad levels may not be high but the potential that increases will come is extremely high..it’s better evac a larger area and then repopulate than to all of a sudden have a burst of radiation which goes in a plume right over the population that was thought safe based on the MIT therory”
In a fire you evacuate the whole building. Even if the fire is in one room, you want everyone out of the building until the situation is determined and under control. People can be allowed to return as safety is established. The MIT study and the claims made by the researchers who authored it are riddled with flaws and inaccuracies. This along with the very clear pro-industry bias of Yanch, the only nuclear department member on the study, shows some very inappropriate behavior of at least some of the academics involved. When scientific studies are manipulated or science journalism favors propaganda over fact, the public trust is greatly violated. Claiming this MIT mouse study as justification for shrinking US nuclear evacuation zones or downplaying the disaster in Fukushima is that kind of violation.
This article is due to the hard work of the SimplyInfo.org research team. Many members played a role in investigating, researching and analyzing the information involved. Without the efforts and assistance of all of those involved, this in depth work would not be possible. Ian Goddard has done some considerable behind the scenes research on this issue. Peter Melzer, Edano, Dean Wilkie, Nancy Foust and many others have put considerable time into researching this issue. I would also like to thank the various academic experts who were kind enough to share their opinions on this project.
This article would not be possible without the extensive efforts of the SimplyInfo research team
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