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Friday, August 7, 2015

Billions of dollars’ nuclear industry's predicament?


BIER Report VII: Biologic Effects of Ionizing Radiation (BEIR) develops the most up-to-date and comprehensive risk estimates for cancer due to exposure to radiation.

The report which gives results of the life time cancer risk calculation using mathematical models from an exposure of 100 mSv dose to a typical US population. The calculations predicted one individual in 100 persons would be expected to develop solid cancer or leukemia. This can be compared with the expected 42 cancer cases that would be developed in 100 persons spontaneously due to other causes!

Risk is lower at lower exposures. Similar calculations for a lower dose of 10 mSv predict one out of 1000 exposed individual would develop cancer. However, it is very difficult due to statistical limitations, to predict reliable number of cancers at these low levels of exposure. Now, 100 mSv is the occupational dose limit for radiation workers for 5-year period, average of 20 mSv per year. The world average natural background radiation is 2.4 mSv in a year to which all of us are exposed. Average radiation exposure of the occupational workers, in general, is in the range of natural background radiation levels.

Under such situations of uncertainty how one can assume that at low doses, the cancer risk is linearly lower?  It is quite possible that the risks are lower than predicted by LNT model or non-existent or even beneficial to health. There is also no direct evidence of increased risk of non-cancer diseases at low doses.    

Now why at all assume existence of cancer risk at such low levels of radiation and impede progress of the nuclear industry worth billions of dollars? 

[The BIER VII document: Health Risks from Exposure to Low Levels of Ionizing Radiation is available from the National Academies Press, 500 Fifth Street, NW, Washington, DC 20001, 2006]