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* Please be aware that the comments below are in response to the information that was available at the time they were given.

According to information as of March 18 14:42 JST.


Dr Makoto Kondo

Lecturer, Department of Radiology, Keio University School of Medicine.

Q: Are the effects of radiation exposure on an adult different from a child?

 “There is a large difference in radiation effects on adults compared to children.  Even in the case of radiation exposure from CT (X-ray computed tomography) scans, the chances of a child developing cancer is so many times higher than adults.  Children’s bodies are underdeveloped and easily affected by radiation, which could cause cancer or slow body development. It can also affect their brain development.  A developing brain is delicate.  Although this is still under debate, there have been reports of children who had their heads exposed to radiation in an effort to remove angiomas (benign tumours) but later on developed intellectual disabilities in their teens.

"Unborn babies are also undergoing fast developments, so are equally vulnerable to radiation.”


Q: What are the effects on reproductive organs?

  “Along with lymphocytes, the reproductive organs are sensitive to radiation.  A man’s reproductive organs can be affected by a 1Sv dose of radiation.  While depending on the age, ovaries are more tolerant to radiation than testes, and it takes a total of about 15Sv of radiation to stop the ovaries from functioning.  But again, this depends on the age and a 6Sv dose may be enough to impair ovary function in women  around 40 years old."


Q: Do we need to worry about internal radiation right now?

“As long as a significant amount of radioactive material is not being released into the environment, there is nothing to worry about.  The amounts of radiation being recorded in areas further than 30km from the nuclear plant, such as Tokyo, Chiba and Kanagawa prefectures, are such that there is no need to worry about internal radiation damage.


Q: If there are no immediate health effects, what about the possible long-term effects?

“'No immediate effects' means there is no show of immediate symptoms caused by radiation exposure.  The more radiation a person is exposed to, the bigger the chances it will cause cancer in the long run.

“There is an internationally-recognized prediction chart (published by the International Commission on Radiological Protection in 2007) that outlines the likelihood of getting cancer in comparison to the amount of radiation.  According to this, it  predicts that if one million people were exposed to a 10mSv dose of radiation, 500 people would die from cancer.

“At the moment, not a lot of people are being exposed to radiation so there are no long term effects to worry about.  If the current radiation levels can be kept, I think we can return to a normal life soon.”


Q: What conditions would cause immediate health effects?

“Even if a nuclear power plant worker were exposed to their annual 50mSv limit at once, they will make a recovery as long as they keep away from any more radiation.  At the moment there are a few regions that are getting high radiation recordings, but the half-life of the radioactive materials in the air right now are short so the amount of radiation in the air will quickly deplete once the amount being released at the plant goes down.

"But there have been studies that have analysed the data of 400,000 or so nuclear power plant workers in the world, and they have suggested that even radiation exposures to amounts less than 10mSv have led to cancer developments.

“I am not sure whether or not, or how much, the local residents around the power plant are being exposed to radiation, but if it is a similar amount to that of the workers at the power plant, there may be a possibility their health condition has been affected by the exposure.

“In the future, if there is a chance radioactive material is released into the environment, its affects will depend on what type it is.  Gamma ray radiation would be dangerous, but so far there have been no reports that this is being released.  (I am not a nuclear physicist, but I have heard it is very unlikely that) if the reactor went critical and sent cesium and iodine out into the air, absorbing these materials would be extremely dangerous.

“But, no matter what happens, I think I will stay here (at the Keio University Hospital in central Tokyo).”




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