March 30, 2017

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“Pediatric Thyroid Cancer After Fukushima Accident” Press Conference by Professor Toshihide Tsuda at Foreign Correspondents’ Club of Japan

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On October 8, 2015, Professor Toshihide Tsuda of Okayama University held a press conference following the publication of an article in the scholastic journal, Epidemiology.

The article, written by Professor Tsuda and four co-authors, is the result of his epidemiological analysis of the data concerning the rate of thyroid cancer in Fukushima residents who were 18 and under and the time of the accident.

According to his study, Professor Tsuda observed a drastic increase in the rate of thyroid cancer in Fukushima after the accident at the Fukushima Daiichi Nuclear Power Plant. Moreover, he argued that this increase is a direct result of the accident. He went on to say that this increase is happening at a much faster pace than initially predicted by the WHO. He stated that the result observed is very similar to what was seen in the four years following Chernobyl. Further, Professor Tsuda said that he expects that the increase of thyroid cancer patients in Fukushima will draw similar statistical curve to that of Chernobyl.

Although Professor Tsuda’s argument has garnered support among many foreign epidemiologists, some Japanese scholars argue that his report is too premature. Also, knowledge of his report and conclusions are not widespread in Japan. According to Professor Tsuda, this is partially due to the number of epidemiologists in Japan being so much lower than that of European countries and the United States. However, Okayama University where Professor Tsuda is employed, has the most epidemiologists amongst all universities in Japan. During the press conference, he stated that the situation is serious and requires preparations and measures to be taken.

Mary Corbett:

Good afternoon, ladies and gentlemen. Welcome everyone to FCCJ press conference this afternoon. My name is Mary Corbett, I am a director, board of directors of the club. Today, we have with us Dr. Toshihide Tsuda. Professor of graduate school of environmental and life sciences. He is an expert epidemiologist, and he has worked in the past on numerous cases involving environmental pollution which led to diseases and labor problems. Five years after the triple meltdown in Fukushima, there is rising body of evidence that many people exposed to the radiation and under 18 years old at the time are suffering growing incidents of thyroid cancer. The local authorities and government argue that this is the result of better screening, better and wider screening in the area. However, not much of the data collected today of 370,000 of these people exposed who were under 18 at that time has been properly analyzed. Dr. Tsuda has analyzed them, and he is here today to let you know exactly what the numbers are saying. I think we want to have as much time for Q and A. So, let’s go straight into Dr. Tsuda’s talk today.

Professor Tsuda: Good afternoon. My name is Tsuda from Okayama University. Thank you so much for so many of you joining us here today.  Since the March 2011 Fukushima Daiichi Nuclear Power Accident which came after the Great Earthquake and Tsunami, thyroid screening examinations have been started for all Fukushima residents aged 18 or younger at that time as of October 2011.

And the result of both tests have been made in public in both Japanese and English online by Fukushima prefecture and also Fukushima Medical University since February 2013.  

However, because of the fact that there has been no or non sufficient epidemiological analysis carried out on this data which has been released, this has led to extremely insufficient condition for causal inference for public health and clinical planning for future outlook, and also for information disclosure to residents.

Our group, our team at Okayama University uses extremely standard epidemiological methods to analyze this data which has been released by the Fukushima prefecture. We submitted our results of this as an original article to the official journal of the international society of environmental epidemiologists. The journal’s name is also Epidemiology. I would like to report here to you that the article was officially accepted and has been just this week published as an early release online.  

This article has been made available under open access, so it can be accessed by anyone, anytime, anywhere, so I hope that you can all take a look at this. The Japanese translation has not been yet created, but we hope to be doing this as soon as possible and then we will be releasing this in Japanese also.

Within the materials we have distributed today includes the article itself, original article, and also e-appendix which contains various data and information which does not fit into the full published article.  This actually has not been made available yet to the public, but it will hopefully be soon as well. But, these two items has been distributed to those present today.

Within these materials includes also an abstract or  summary of the article which contains the same text as it was included in the original article itself. The structure of format of the article is quite simple.  

The purpose or the aim of this article is to make quantifiable, the various aspects such as radioactive elements released from the Fukushima nuclear power plant after the earthquake and tsunami in March 2011, and also the aspects including the situations, incidents of thyroid cancer among exposed residents and causal influence in relation to this.   

And in regards to the methods of the study, it is based on the ultrasound  thyroid screening screens which was by performed by Fukushima prefecture on all residents of Fukushima who were 18 or younger at the time of the accident.

The data which is included within this study begins from the first screenings which were conducted by Fukushima prefecture from October 2011 through until the second round, December 31st, 2014.

There has been a further announcement of screening results following this on March 31, 2015 and the data and information from this is included within E-Appendix.

In regards to the data which was announced on June 30th of this year, this is included within the slides which has been distributed today also.

Our analysis includes, so these prefecture results from the first two rounds and the comparison of these with the Japanese annual incidents and incidents within Fukushima Prefecture including also by age, and looking at how many times this involves and also the latency period of the cancer.

As well as the comparison with the national averages, we have conducted a comparison of incidents within Fukushima Prefecture. So, in areas with lower and those with higher rates as well. So a comparison within the prefecture was conducted also.

In regards to the comparison with the overall Japanese annual incidents, we have found that in regards to thyroid cancer there can be estimated or assumed up to  50 times the amount of thyroid cancer.

Even in lower areas within around 20 times the incidents.

In the lowest areas of Fukushima, there has not been a single incident of cancer found at this stage.

And in regards to the lowest area of Fukushima Prefecture, if this was to be taken as a point of comparison or reference, actually because it is at zero, this would mean that in comparison with other parts of the prefecture, it will come to unlimited or infinity in terms of results, so rather than taking this particular area, or this district as a reference point, we have used the second point as the lowest area within the prefecture.   

The second lowest area has been shown to have been an area where the radioactive plume actually passed around, so this is meaning that it is relatively lower contaminated area within the prefecture.

So comparing the second lowest area and the highest area within Fukushima, it is around 2.6 times the difference.

So, this is in regards to the first round or the initial screenings which were conducted until 2013, and the announcements of the results from the second round, so the round until 2014 is now under way.

And in regards to the announced results of the second round, even when it is assumed that forms of other thyroid cancer are zero, even with this extreme assumption was being made, we are seeing around ten times the amount of cases in this round of results.

This brings us to the inclusion that as we are seeing such an increase even within this period within Fukushima prefecture. It is a very similar situation to the results of what was being seen in Chernobyl after the first four years or at around the same time following Chernobyl, and as a result of this if we look at what happened in Chernobyl in the fifth year and sixth year for example when there was an extreme or a very much increase seen in the rates this means that this situation will most likely be very difficult to avoid here in Japan also.

In 2013, the assessment issued by the World Health Organization estimated that there would be an increase in thyroid cancer, Leukemia and breast cancer, and other forms of solid cancer even outside of the 20 kilometer zone around the Fukushima nuclear power plant.  However, the results that we are seeing now, actually far exceeds what was estimated by the WHO.

However, this situation in Japan is unfortunately not yet very well understood at all. And there’s also not sufficient preparations being put in place in regards to this to so what is necessary is a full understanding of the situation and what it means and also policies and measures to be implemented in accordance with this.

Even as early as 2013, I announced the data and the results of this at the international conference of the International Society for Environmental Epidemiology which is held in Switzerland, and at that time, this was covered very thoroughly by the local media.

And I also announced their subsequent results at the annual conference which was held in Seattle in 2014.

And also at this year’s annual conference which was held in Brazil.

Within this time, I have also worked both verbally and also through written correspondence conducted various reports and also discussions with experts on this issue.

And their common opinion was that this is a very important issue and so they encouraged me to publish an article showing this data analysis as soon as possible.

Within discussions conducted over mail and directly, with them as well they constantly said that this should be published very soon or published as soon as possible. As a result from entering this year, I decided to move faster to publish this article which brings us here today.

So, this bring us to the conclusion of overview of study of the article that I would like to share with you today. I would like to have as much time as possible for question and answer. So, I will end my presentation here and go into the question time also using some of the slides which I brought today in regards to the data and so on.

Corbette: Thank you, Dr. Tsuda. We will move right into Q and A. The first question from working press only please. If we have time, we take from others as well. Questions? Please give your name and affiliation.  Thank you.

Hodo Station (News Program that airs between Monday and Friday at around 10 pm by TV Asahi, Channel 5)

My name is Hirano form Hodo Station. There was a report yesterday from another scientist saying that the report on this article is too premature, so I would like you to ask your opinion on this evaluation. Also, you mentioned that international experts were encouraging you to publish this article much faster because it is important and yet we hear that in Japan, this is not fully known or understood. I would like to ask if you think that many experts in the field in Japan have the same understanding as you or not in the same evaluation also in regards to your co-authors of this article, and if not then what is the reason for this?

Professor Tsuda: First of all, I would like to say in my exchanges both in discussion and in email with international experts and researchers, there was no single person who said this is too premature.

Rather, there were actually extremely or many opinions and researchers who were saying you need to do this faster, you need to bring this out sooner.

Therefore, I actually think therefore, criticism about why it is slow for this kind of analysis to come out is actually present. I believe that one point is in Japan, especially in comparison with Europe and the United States, the number of experts in epidemiology who conduct analysis on data from other people’s studies are extremely low compared to overseas.

And I believe that this is also the characteristics of Japanese medical or scientific research field. It is related to various particular historical aspect as well. It would be a quite long explanation if I went in it here. But it is written in detail in my book.

Okayama University actually within Japan at least has   relatively the highest number of working epidemiologist.

The reason for so many in Okayama University is also has historical reasons which many of those familiar with Japan are here today are probably aware of the case of Ohara Museum in Kurashiki (Kurashiki city in Okayama Prefecture). However, I would like to say that as well as the four co-authors of this article, there are many other researchers are working in the same field at Okayama University.

And while in comparison with many other research institutes overseas, perhaps it is not as many researchers as on a very regular basis we are carrying out discussions with other researchers in regards to this issue. So, within the researchers at the university, Okayama University, who have been conducting these discussions, there has not been a single person who has said that they are of the opinion that this is too premature. There has also not been a single person who said they do not see any connection between the nuclear power plant and the increase which we are seeing.  So, I hope that answers your question.

-among the working press, there was a request to repeat part of Dr. Tsuda’s initial statement where the microphone was muted temporarily-

Professor Tsuda:

So, first of all, I would like to demonstrate on this slide very simply, we can see written written on the horizontal axis the years from 1977 to 1993.

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And the vertical axis is the number of cases and the number of incidents.

And this is the number of people with thyroid cancer under the age of 14.

So what is often missed in the current discussion at the moment is this small number of increase that we can see here in the circle.

This is an increase which is statistically significant.

So, by not recognizing this statistically significant increase which we can see here in the circle, The Fukushima Medical University and Fukushima prefecture are saying “we do not have an increase.”

So, now here on the slide, it says now “4.1 Years after the accident.”

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But, we are now actually at 4.5 years after the accident. This arrow points to the period that we are at today.

So, here we can see that for those people, Fukushima residents who were 18 years or under at the time of the Fukushima Power Plant disaster, we are seeing increase in  20 to 50 times of the number of the thyroid cancers.

Or this can be estimated, so this situation of increase that we can see in the graph will be very unlikely to be avoided here in Japan.

However, despite the situation, there is no preparation being put in place, and no change in the statements or the way the situation is being presented.

And this is the reason that this article was written in the first place, and also the reason that the academic journal decided to rush to release it so early as well.

From the perspective of disclosure of information as well as very important to make this public earlier.

This is information from Center For Disease Control Prevention (CDC). We can see here that the minimum latency period for  thyroid cancer as to 2.5 years.

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This is the period before it is detected clinically, so actually as a result, the screening it is earlier than this.

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In regards to childhood cancers, it is said that the minimum latency period is one year.  

So, the two point five years refers to adults and one year is for childhood thyroid cancers.

This slide is an overview of the contents and the methods thyroid screenings which were conducted.

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This is an overview of the schedule of the screening.

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In the first year of the screening from October 2011, from mid financial year 2011 through to March 2012, the area which is pink on the slide was tested.スクリーンショット 2016-04-01 18.40.00

And the screenings were conducted in the yellow area from April 2012 through to the end of March 2013.

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And the light blue areas refers to those where the screening tests were conducted  from April 2013 to the end of March 2014.

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And for the year beginning April, 2014, the yellow and pink areas are going through to their second round.

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So now the second round for the light blue area is currently under way.

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Actually, the population density of the Fukushima Prefecture overall is around three times that of Gomel in Belarus which is an area that had very high incidence of thyroid cancer.

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And with more population or higher population exposed to radiation means also a higher number of thyroid cancers to be observed .

This is an explanation of the comparison group and the methodology used in the test.

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The article looks at nine different districts within the prefecture.

The area that I referred to as the highest area so that which could be up to 50 times is number three, the central middle district.

The area I refer to that which has no cases found, no cases detected at this time is or the least contaminated area is the number nine, the northeastern least contaminated district.

The second lowest area which even that still has up to amount of 19 times is listed as number seven is Southeastern Least Contaminated district.

So, this is an outline of the methods of how the comparison or calculation which was being made. It is a very basic method for doing this.   

スクリーンショット (1182)

We can see the comparison between the overall national or Japanese mean annual incidents.

Here is information about internal comparison that was conducted within Fukushima Prefecture showing the second lowest area which was in the Southeastern least contaminated area in terms of the detection of numbers.

スクリーンショット 2016-04-01 19.11.44

So, the program, the package which was used for the calculation, this is very simple epidemiologic package.

Which is a package which was released by the CDC is to the WHO and the researchers all around the world at no cost.

The nine districts can be seen on the map as shown here.

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This is also in the handout which was distributed today.

This shows the numbers from the first round of tests.

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The additional smaller numbers ( +13**, +12**, +25**)which we are being shown now are from the second rounds from the tests.

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The colors in the tables which are shown on the slides correspond with the colors on the map as well. So, we can see here the yellow blocks which are shown correspond with the testing that was conducted from April 2012 to the end of March 2013.

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This area was divided into four districts.

The smaller numbers being brought up to the screen now, are the number of cancer cases which was found in the second round.

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This demonstrates here the four districts from the light blue area on the map which is the area being tested within the April 2013 to the end of March 2014 period.

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And now the second round is still under way at the moment currently, this is why we are not a higher number being brought up in regards to the second round here.

This which is demonstrated on the slide here corresponds with table one in the original article published in the journal. This shows the ratios of the incidence rate.

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And this file table four corresponds to table one in the published article.

The next slide corresponds with table two in the published article.

So, we can see here the number of 50 for the incidents ratio which corresponds with the highest ratio in the result here.

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And the area where there has been no detection is listed here as the zero in the final row.

The second lowest is this one, 19.56.

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We can see here the nearest area which is listed in pink is the area closest to the nuclear power plant and that is close to 30 times in the incident ratio here.

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And the test period for this area, the nearest area was from October 2011 to March 2012.

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This is actually within one year of the disaster. This is less than one year when we consider this in regards to the cancer latency period.

And yet despite the fact that the testing and screening for the nearest area was conducted so soon after disaster, we are still seeing close to 30 times here.

This is an extremely important point to note.

So, in regards to the yellow area, this of course relates to about one to two years latency period or a maximum up to a one year period in this respect and  we are seeing high latency period.

スクリーンショット 2016-04-01 19.51.39

In this respect as well and we are seeing this high latency period.

And the light blue area demonstrates latency period of two to three years.

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Here we can see similar numbers in terms of the 40 times for the yellow and purple areas. But, because of the difference of the latency period, this has a different meaning. So we can see the yellow area is actually likely to be higher.

When we consider this in relation to the latency period, we can say that this is actually higher incidents.  

And this is the ratio from the internal comparison within Fukushima Prefecture.

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So, the area which was the second lowest listed here as one for the prevalence of all ratio.

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So, we can see for the area which is located closest to the power plant, we have the number 2.58 times.

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So, when we consider the latency period in regards to this,  this could  quite easily be explained by its proximity or, its connection to the nuclear power plant.

And this shows the plans for the second round.

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So, this has already announced here, however the  2015 results have almost not at all yet been announced.

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The breakdown of the results from financial year 2014 can be seen on this slide.  

So, within the article, it is actually eight cases within the E-Appendix it is 15, but here we can see 25 in the most recent results.

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So, here when we look at the second round results here we see going up to 55.4, this shows that we are in at the similar trend to that which can be seen in the curve from Chernobyl.

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So, from when the first cases were detected, it could have been estimated that we would see very similar pattern or similar trends to that which did occur in Chernobyl. And when we did look at the results here, that is exactly what we are seeing now.  

Therefore, also we can assume that there will be likely to be a similar curve seen from now as well and also similar increase in result.

However, we are not only seeing no measures put in place we are also seeing no announcements at all in regards to this.

This is of course leading to more mistrust or uncertainty for the residents and also meaning that there is likelihood that the administration of the local government will also not be able to function in response.

Now, we must as soon as possible look at the way to change the way this is referred to and being spoken about to implement measures to deal with this as soon as possible. Thank you.

Corbett: We will take more questions.

Ian Thomas Ash, Documentary Filmmaker

My name is Ian Thomas Ash and I’m a documentary film maker. I’m a member of this club. I made a film called A2-B-C which is three years ago which is about the issue of children’s thyroids and concern of their parents. Three years ago when they expressed a concern about the issue, they were told that they were crazy, they were worrying too much, there was no data to prove anything about their concerns. We all know that it takes years to have these kind of peer reviewed studies. The work that you are doing is extremely important. I’m looking forward to your continuing work. My question to you however is would you have recommended five years ago or four and a half years ago that more was done to protect the children while it was trying to be discovered what was happening. Could this have been predicted?

Professor Tsuda:

Yes. I believe that there are many things which should have been done, could have been done at the time. Even at the time of the disaster, when we looked at what the most experts were saying when we looked at the ratio of number radioactive materials dispersed in the atmosphere in comparison with Fukushima, we could also have at that time assumed that we would probably or likely to see thyroid cancers in Fukushima as well. So, this could have been expected from that time.   

However, we are now seeing an even higher pace being observed now which means that also should be evaluating perhaps there was even more release of the radioactive materials and exposure to the radiation for the people.

However, so when the official announcement was made that the radioactive materials dispersed were 1/10, there were of course many things which could have been done even before that, and things that could have been done at the time this announcement was made.

For example, if iodine had been distributed to children, who were effected at the time exposed then it could have been expected that the number of thyroid cancer could have been reduced by up to half.

Therefore, I think it can be said that the experience of the Chernobyl has not been utilized or barely been utilized at all here in Japan.

In 2012, the WHO conducted their preliminary dose estimate and based on this in 2013 they issued this health risk assessment which can be seen in the slide here, showing the expected increase in thyroid cancer for those who were one year old at the time and the dark blue area on this graph demonstrates the WHO’s assess or expected increase.

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However at the time when the draft for the estimated or preliminary dose estimate was issued by the WHO in 2012 due to lobbying by the Japanese government at that time the dose which was included by the WHO was actually reduced following this.

スクリーンショット 2016-04-01 21.06.16

And according to reporting which was issued on December 7th of last year, so in 2014, as a result of this lobbying by the Japanese government, actually the estimated dose which was included within the WHO assessment was ⅓ or 1/10  less what had originally included in its draft.

Which shows to us that actually this lobbying was doing exactly the opposite of what should have been done at the time what measures should have been put in place.

I believe that it is necessary or the Japanese government should conduct an investigation of what actually really happened and the contents of what was reported at the end of last year. Does this answer your question?

Tokyo Shimbun

I am from Tokyo Shimbun, Tokyo Newspaper. I would like to ask first about Fukushima Prefecture and their committee, is referring to potential overdiagnosis or screening effect in regards to why these numbers are so high. If this is the case what kind of percentage or ratio could be accounted by these kinds of factors? If you have numbers available in regards to this, if this possibility was excluded, what kind of numbers would we be looking at? I would like to ask for the source for the statistics for the national means and also the numbers there too.

Professor Tsuda: 

First of all, I would like to point out that those researchers who are referring to potential screening effects or over diagnosis, I don’t believe that they have actually looked at any kinds of data or articles which could show what kind of ratio could actually be responsible or could these kind of factors to be responsible for.

So, I actually hope that if you, when we hear the researchers talking about potential screening effect or overdiagnosis, we should be actually asking them well if you think that this is actually the case, what kind of ratio do you believe could be expected to be accountable for such factors. And ask them to show the data or research which could demonstrate this.  

The data which is available for this is only showing two to three times, or six to seven times at most, so one digit in regards to what could be accounted for as a result of such factors.   

However, the increase we are seeing in Fukushima Prefecture is up to the levels of 20 to 50 times.

So, it’s actually a whole digit more than this, a whole figure more.  

Therefore, even if a screening effect does exist, it can only account for a very small part of this, a very small percentage, very small ratio.

So, this information on the slide here is included within the abstract, not within the full article, but I would like to refer to a point here.

スクリーンショット 2016-04-01 21.17.24

This slide refers to the screening by ultrasound was conducted in Chernobyl by children who were born one year after the disaster and all in relatively low contaminated areas and there was the total of 47,203 children who were screened this way.

スクリーンショット 2016-04-01 21.21.28

And within this 47203 children who were screened at this time, there was not a single case of thyroid cancer found. This data is included within the latter part of the E-Appendix distributed today.

So, this is being used as the reasoning for claiming that there is not an increase in thyroid cancer for children who were born after the disaster at this time.

However, these figures are screening or this investigation is not being referred to at all here in Japan. We often hear in Japan saying that this is the first time that the screening has been conducted on such a scale of tens of thousands of people. This has not been done anywhere before. However, we can see here actually the number of tens of thousands of people screened in the Chernobyl does very much to show that there is a precedent.

So, the announcements are being made in Japan without learning from the experience of Chernobyl, and also without referring to the kind of the evidence that already exist about the effects of radiation on the human body, human health. Does this answer your question?

Someone in the working press requests Dr. Tsuda to cite the source of the national mean.

And in regards to the source of the information regarding the national mean, this is taken from data by the National Cancer Center of Japan.  It is available on their homepage as well. Which shows that the averages of thyroid cancer for those who are under the age of nineteen is around 2.3 per one million people.

Austrian Newspaper  

I heard, I read that some people say your research is different perhaps more modern than other kind of research. So a result of your research to former research is different, because you use a more modern kind of research.   

Professor Tsuda:

My methods implemented in this research are not any particular modern methods. They are exactly what is written in any kind of textbook about this issue.

Within Japanese people at least, there has not or I have not had anyone who makes direct criticism to me.

If you do hear any criticism of methodology or my studies and so on, I would like to ask you please refer them to me directly and I would be very happy to have any opportunity to discuss with them directly also.

This is what we can say “behind your back.”

This actually relates to issues with the Japanese health and medical policy making methods even in a lot of is based on rumors things happening behind their backs or discussions like this. Things being talked in corridors rather than being based on medical evidence, articles or empirical research and so on. This is one of the reasons for various delays and problems within Japanese health and medical policy situation today also.

Corbett: Is one more question OK?

Freelance Researcher Suzuki:

I’m a freelance researcher. My name is Suzuki. Within researching or reporting on Fukushima, of course while being aware of the dangers there, many people who question about well we have no choice but to continue to living there.

What they should be doing if they are continuing to live in Fukushima?  You mentioned that there are no preparations or measures being made in place to this but unfortunately for many residents of course they have to deal with situation of being in Fukushima, so what would you recommend for them to do as residents and what kind of measures should be put in place.

Professor Tsuda:

Within the field of industrial medicine, there is a legal, it is legally compulsory for any worker when they are taking on a new job to undergo detailed education about the potential risks involved within that work.  

Thus even if no measures are being put in place, even just by making detailed information available to people also reduces by a huge factor, the amount of unnecessary exposure or danger.

However, within Fukushima Prefecture and indeed within Japan as a whole at the moment, the only announcement which is continually being made is that at levels of less than one hundred millisievert per year, there will be no cancer, there is no danger.

There is no detailed explanation of this kind of information being made and kind of information which is everybody is aware of. For example, the impact of radiation on people is more the younger you are is something which is not being explained at all in official announcements.

Even if just this very small, very basic knowledge information could be conveyed, then there are many different detailed things that very small details which can be made as changes at even no cost.

Furthermore, the radiation exposure level varies very much according to the location, according to the place.

Therefore, by investigating and determining those areas which are at a much higher dose higher levels of radiation and as a result deciding to spend less time there, less time in highly contaminated areas can make a huge difference.  

So, there are many many methods to ensure that there would be no unnecessary exposure to radiation and this can be done at no cost, and yet education and implementation of this is completely not happening.

And this kind of information must be given even more to those people who are living in Fukushima or have no choice but to remain in Fukushima, they deserve even more to have access to this kind of information.

Corbette: Last question.


Hello. I am from TBS NEWS23. I have three questions. First of all in regards to the analysis which was announced in this article, I would like to ask if this demonstrates also a linkage between the incidents of cancer and also the dosage or the contamination levels, the next point is in regards to your point that we can expect similar as we seen in Chernobyl, I would like to ask that the reason for this is because of the very high incident rate which was demonstrated or what the reason for expecting the same as occurred in Chernobyl and the third point is I would like to ask specifically if you could name city or  town names which were referred to as 50 times and 19 times and so on.

Professor Tsuda:

In relation to your first question, as it was explained before the latency period is different according to the color of the area, according to the pink, yellow, and blue. Even if the adjustment was made for this, adjustment was made according to the information which is available of the direction of the radioactive plume following the disaster, we can see higher concentration within the southern area and even once we adjust for these particular aspects in regards to the results of analysis we can see actually very clear relationship between the factors of the incidents or the contamination level or dosage.

スクリーンショット 2016-04-01 21.38.59

I do not have those figures available with me today, however in articles which were published in Iwanami publishers scientific journal called Kagaku (Science) there have been two articles published specifically on this issue.

So, first of all, in regards to the Chernobyl curve which was displayed, the case of Chernobyl is only an example of such a large scale exposure to radiation of the whole population of an area, Fukushima is of course the second of such an example.

So, if we compare the incidence of thyroid cancers in Chernobyl in the first four years following the disaster there and in comparison to the case of Fukushima at around the same period, we can see in the case of Japan there is more, actually 20-50 times in comparison to overall Japanese mean.

However, we have not actually reached the average latency period for thyroid cancer we are only still at the minimum latency period.

So, therefore, if we look at the current incidents we are seeing here in Fukushima and compare this with the Chernobyl curve as demonstrated, would there be actually anybody say that there is not likely to be the similar curve or situation observed in Japan?

In regards to the third question regarding the districts, the pink area because it has a lower population density. This was kept as one district  in our research and also.

The yellow and blue area have relatively higher population so they were divided into four areas each.

As you are likely  aware, there are three or four highly populated cities within Fukushima Prefecture.

One is Fukushima city which is here as I am showing.

The second, Koriyama city.

The third being Iwaki city which has the highest population.  

And here is the city of Aizuwakamatsu. This was taken into account in a very straightforward way in terms of dividing the districts. We can see here this one here in the top northern area, the northern middle district has Fukushima city and the two local municipalities north of that.

Koriyama city and Iwaki city both have very high populations of their own so they were taken as single districts in this study. And so the area which is referred to as three central middle district contains two cities and two towns. Sorry to correct that, two cities, one town and one village according to the local determinations. And so I believe of course this shows you clearly clearly which areas this refer to. Number nine although it is not written on this slide refers to Soma city and Shinichi town.

Corbett: So, professor, Unfortunately, I don’t think we can take any more questions. But, I think the professor might have a few minutes of…..Do we have a meeting room or anything? Or while we are cleaning up, maybe the professor can take a few more questions?

Ok, so, If the professor has time, please stay a few minutes, OK?  Professor has some time, so I think he can take some individual questions, but unfortunately we have to clear the room soon, so we have to bring this session to close. I would like to thank the professor very much for very insightful analysis that he brought to us today, and as a tradition, I would like to present Dr. Tsuda with an honorary membership card, and hopefully we can continue this debate, and maybe we can have some of the public officials come and debate here sometimes. We would like to hear the officials’ account for the details  today. Thank you very much.


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