Thorotrast was a contrast medium used in Germany since 1890. It was used in Japan since 1930,
but it was found that 25 to 30% of people developed liver cancer 20 to 30 years later.
Why does it take so long before cancer develops? Thorotrast is an alpha-radiation nuclide. Alpha radiation injures nearby cells, and the DNA that is harmed most is a gene called "P53".
We now know, thanks to genome science, the entire sequence of human DNA.
However, there are 3 million locations on the DNA that are different from person to person.
So today, it doesn't make sense at all to proceed as if all humans are the same.
The basic principle should be the "personalized medicine" when we look at internal radiation - which DNA is damaged, and what kind of change is taking place.
In case of thorotrast, it is proven that P53 is damaged in the first stage, and it takes 20 to 30 years for the 2nd, 3rd mutations to occur, causing liver cancer and leukemia.
About iodine-131. As you know, iodine accumulates in thyroid gland, and that is most noticeable during the formative phase of thyroid gland, i.e. in small children.
However, when the first researcher in Ukraine was saying in 1991 "There are an increasing number of thyroid cancer",
researchers in Japan and the US were publishing articles in Nature magazine saying "There is no causal relationship between the radiation and thyroid cancer."
Why did they say that? Because there was no data prior to 1986, there was no statistical significance.
The statistical significance was finally noted 20 years later. Why? Because the peak that started in 1986 disappeared.
So even without the data prior to 1986, the occurrence of thyroid cancer and radiation exposure from Chernobyl had the causal relationship.
Epidemiological proof is very difficult. It is impossible to prove until all the cases are done.
Therefore, from the viewpoint of "protecting our children" a completely different approach is required.
Dr. Shoji Fukushima from a national institution called Japan Bioassay Research Center, which researches health effects of chemical compounds,
has been studying diseases involving urinary tract since the Chernobyl accident.
Dr. Fukushima and doctors in Ukraine studied parts of bladders removed during more than 500 cases of prostatic hypertrophy surgery.
They found out that in the highly contaminated area where 6Bq/liter was detected in urine, there was a high frequency of mutation of p53 though 6Bq may sound minuscule.
They also noticed many cases of proliferative precancerous conditions, which we assume was due to the activation of p38 MAP kinase and the signal called "NF-kappa B,"
leading inevitably to proliferative cystitis, with carcinoma in situ occurring with considerable frequency.
Knowing this, I was astounded to hear the report that 2 to 13Bq/liter [of radioactive cesium] was detected from the breast milk of seven mothers in Fukushima.
We at the Radioisotope Center of Tokyo University have been helping to decontaminate Minami-Soma City, sending about 4 people at a time and doing decontamination work for the length of 700km per week.
Again, what's happening to Minami-Soma clearly shows that 20 or 30 kilometer radius [from the nuke plant] doesn't make any sense at all.
You have to measure in more detail like measuring each nursery school.
Right now, from the 20 to 30 kilometer radius area, 1,700 school children are put on the buses to go to school.
Actually in Minami-Soma, the center of the city is located near the ocean, and 70% of the schools have relatively low level of radiation.
Yet, children are forced to get on the school buses to go all the way to schools near Iitate-mura [where radiation is higher], spending 1 million yen everyday for the busing.
I strongly demand that this situation be terminated as soon as possible.
What's most problematic is the government's policy that they will compensate the residents for the moving cost only if their areas are designated as official evacuation zones.
In a recent committee held at the House of Councilors [Upper House], then-President Shimizu of TEPCO and Mr. Kaieda, Minister of Economy, Trade and Industry answered that way.
I ask you to separate the two immediately - compensation criteria issue and children's safety issue.
I strongly ask you to do whatever you can to protect children.
Another thing is, what I strongly feel when I'm doing the decontamination work in Fukushima is that emergency decontamination and permanent decontamination should be dealt with separately.
We've been doing a lot of emergency decontamination work.
For example, if you look at this diagram, you will notice that the bottom of this slide is where small children put their hands on.
Every time the rain stream down the slide, more radioactive materials accumulate.
There can be a difference in radiation level between the right side and the left side. If such difference occurs and if the average radiation of the slide is 1 microsievert, then one side can measure as high as 10 microsieverts.
We should do more emergency decontamination work in such places.
The ground right under the roof gutter is also where children frequently put their hands on. If you use high pressure washer you can reduce the radiation level from 2 microsieverts to 0.5 microsievert.
However, it is extremely difficult to lower the level to less than 0.5microsievert,
because everything is contaminated. Buildings, trees, whole areas. You can lower radiation dose of one place, but very difficult to do that for the whole area.
Then, how much will it cost when you seriously do the decontamination work?
In case of "Itai-Itai Disease" caused by cadmium poisoning, to decontaminate half of cadmium-contaminated area of roughly 3,000 hectare, the government has spent 800 billion yen so far.
How much money will be needed if we have to decontaminate the area 1,000 times as big?
So, I'd like to make four urgent requests.
First, I request that the Japanese government, as a national policy, innovate the way to measure radiation of food, soil, and water, through using the Japan's state-of-the-art technology such as semiconductor imaging detectors.
This is absolutely within Japan's current technological capability.
Second, I request that the government enact a new law as soon as possible in order to reduce children's radiation exposure.
Right now, what I'm doing is all illegal.
The current Radiation Damage Prevention Laws pecifies the amount of radiation and the types of radionuclides that each institution can handle.
Now Tokyo University is mobilizing its workforce in its twenty-seven Radioisotope Centers to help decontaminate Minami-Soma City, but many of the centers don't have a permission to handle cesium.
It's illegal to transport it by cars.
However, we cannot leave highly radioactive materials to mothers and teachers there, so we put them all in drums and bring them back to Tokyo.
To receive them is illegal. Everything is illegal.
The Diet is to blame for leaving such situations as they are.
There are many institutions in Japan, such as Radioisotope Centers at national universities, which have germanium detectors and other state-of-the-art detectors.
But how can we, as the nation, protect our children if these institutions' hands are tied?
This is the result of the gross negligence by the Diet.
Third, I request that the government as a national policy mobilize technological power of the private sector in order to decontaminate the soil.
There are many companies with expertise of radiation decontamination; chemical companies such as Toray and Kurita, decontamination companies such as Chiyoda Technol and Atox, and construction companies such as Takenaka Corporation.
Please mobilize their power to create a decontamination research center in Fukushima as soon as possible.
It will take tens of trillions of yen to do the decontamination work.
I'm gravely concerned that it might become public works project involving concessions.
We don't have the luxury to spare a single second considering the financial condition of the Japanese government.
We must figure out how we really do the decontamination work.
What on earth is the Diet doing, when 70,000 people are forced out of their homes and wandering?
That's all.