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Submitted by Akira Suzuki, Japan Nuclear Fuel Limited
   Commenting on behalf of the organisation
Document Low-dose Extrapolation of Radiation-Related Cancer Risk
 
Comment-1
Concerning the very low dose level (effective dose on the order of 1mSv), it should be treated as g the dose level which has no considerable risk h, apart from g the threshold h or g the liner no-threshold h hypothesis and not by just applying the liner no-threshold hypothesis based on the fact that the evidence of the threshold hypothesis does not exist.

[Explanation]
The draft report shows in the descriptions that g there is no direct credible epidemiological evidence of a radiation-related risk associated with exposures on the order of 1 mGy h and on the other hand g undetectable risk should not be deemed as a evidence of zero risk h as the arguments made against LNT hypothesis. Although, g very low dose h is regarded as substantially g the dose level which has no considerable risk h in comparison with the dose from natural background. So it should be treated as g the dose level which has no considerable risk h apart from each hypothesis. (do not regard the liner no-threshold hypothesis on the basis that there are no evidence for each hypothesis )

Comment-2
Regarding article 7. Conclusions No.2, there is a statement saying that g There is , however, epidemiological evidence, unlikely on the whole to be an artifact of random variation, linking increased cancer risk to exposures at dose on the order of 10 mGy g. This should be presented separately, based on the study of population of children exposed in utero.

[Explanation]
There is a statement saying that g There is, however, epidemiological evidence, unlikely on the whole to be an artifact of random variation, linking increased cancer risk to exposures at dose on the order of 10 mGy h in article 7. Conclusions No.2, and referring to the evidence of the studies of leukemia and solid cancers among populations of children exposed in utero. Therefore, it should be described separately and clearly that it is based on the study of exposed in utero. Also, the cohort studies of breast cancer which is referring to another example, exposed to the order of 10mGy. But in this case, 10 mGy is fractionally dose and cumulative doses up to hundreds or even thousands of mGy (chapter 2.4.3). Therefore, it is not suitable to preset as a evidence of increased cancer risk to exposure at dose on the order of 10 mGy.

Comment-3
There is not so effective to discuss applying a liner no-threshold hypothesis to extremely low risk less than other carcinogens risk. It should be balanced with other risks to some extent.