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Submitted by Thomas S. Tenforde, National Council on Radiation Protection and Measurements
   Commenting as an individual
Document 2005 ICRP Recommendation
 
Comments on the fundamental ICRP Recommendations – update of Publication 60

I would like to thank the Commission for making the update of radiation exposure limitations described in Publication 60 available for comment worldwide. The following are my comments on this document in which each comment is related to specific paragraph numbers.

1) Para 158-159: The use of natural background as a benchmark for comparison of ICRP’s recommended exposure limits does not seem very meaningful, especially when contributions to background of radon and its progeny are not included. Although radon exposure can be mitigated by ventilation and other engineering measures, it is still not completely controllable and is an inevitable part of the natural background exposure. A more meaningful comparison of the exposure limits would be to the overall average population exposure including radon and medical sources of radiation, which are a major part of the total exposure. It is currently estimated that the average individual in the United States and Europe receives annual doses of about 5 mSv per year on a routine basis. In that context, the public effective dose limit of 1 mSv per year is only a 20% additional contribution above the normal exposure level from common sources. In addition, the occupational effective dose limit of 20 mSv per year (averaged over 5 years) is then only a four-fold increase over the usual exposure of an average member of the population. These comparisons seem more meaningful than just comparing exposure limitations to natural background radiation without the radon contribution or other man-made exposures from medical applications of radiation that have become an integral part of our lives.

(2) Para. 164: The selection of 0.3 mSv per year as a maximum public dose constraint in the case of exposure to multiple dominant sources should be given further explanation. For example, if it is known that the total exposure is less than 1 mSv per year, there is no reason to restrict any of the dominant sources of exposure to 0.3 mSv per year or less. The choice of 0.3 mSv per year as a constraint for a dominant source should also be discussed in depth.

(3) Para. 173: The concepts of age-averaged effective dose coefficients and age-average habits need to be explained more clearly and completely. For example, how many categories of age will be considered? These concepts could introduce unnecessary complexities in estimating radiation exposures and risks.

(4) Para. 185: The rationale for a five-year averaging period should be given. In general, public doses are not measured or recorded, and so imposing a five-year averaging period seems unreasonably precise. Perhaps the intent was to mirror the use of a five-year averaging period for limiting occupational exposure to an average of 20 mSv per year. However, the same level of control does not seem realistic for members of the public.

(5) Para. 225: The statement that the exposure of care givers for nuclear medicine patients should be limited to a few tens of mSv per episode is too vague. For example, in Commentary No. 11 (1995) NCRP provided much more specific guidance for such situations.

(6) Para. 239-240: The discussion of limiting doses from “hot particles” is unnecessarily vague. For example, NCRP has given specific guidance on limiting doses from hot particles in Report No. 130 (1999).

(7) Para. 241-251: The discussion of protection of the environment is very superficial and needs to be greatly amplified to give a more complete description of the methodology that will be used in arriving at recommendations. Unless this is done, I recommend omitting Section 11 and Annex B from the document altogether.

Overall Comments:

This draft document lacks the thorough exposition of the fundamental basis for radiation health protection guidance that was expected in the update of Publication 60. I recommend that the document not be issued until the various foundation documents being prepared by ICRP are drafted and published following a worldwide peer review process. At that point the fundamental basis document should be appropriately revised, subjected to a second round of international review and comments, and published after suitable revisions have been made.


Submitted by Thomas S. Tenforde, Ph.D.
Bethesda, Maryland (USA)
December 31, 2004