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Medicine Correspondence Blog

The Medicine Correspondence Blog allows authors to post Letters to the Editors, Reviews, and other editorial writings that are not considered original research.

Monday, October 3, 2016

Letter to Editor:Increases in perinatal mortality in prefectures contaminated by the Fukushima nuclear power plant accident
Estimated average effective doses to adults, 10-year-old children and 1-year-old infants over the first year after the nuclear power plant (NPP) accident in Japan (2011) in the most contaminated Fukushima prefecture were, respectively, 1.0-4.3, 1.2-5.9 and 2.0-7.5 mSv.[1] Worldwide annual exposures to natural radiation sources are generally expected to be in the range of 1-10 mSv, with 2.4  mSv being the estimate of the central value.[2] Some national averages exceed 10 mSv.[3] In the USA the average exposure to natural radiation is around 3.10, in Japan - 1.5 mSv/year; medical exposures add approximately the same value (in the USA more than in Japan).[4] In Europe, average annual doses from the natural background exposure are above 5 mSv in several countries.[5] Additional doses to the residents of the most contaminated Fukushima prefecture have thus remained during the first year after the accident within the limits of the natural radiation background, being far below the limits for professional exposures.[6] For comparison, a single computed tomographic (CT) examination produces a dose within the range 2-20 mSv, while doses from interventional diagnostic procedures usually range from 5 to 70  mSv.[7] Health risks including perinatal mortality have never been proven for the doses discussed above; an overview is in.[6]

According to the concept discussed previously,[8] with the dose rates tending to the background level, radiation-related risks would tend to zero, and can even fall below zero in some dose range in accordance with hormesis. Although not all animal experiments supported the hormesis concept, current experimental evidence in favor of hormesis is considerable.[9-12] This means that a part of experimental data is at variance with epidemiological studies, including those cited in.[13] However, epidemiological studies of low-dose radiation effects may be prone to biases,[14-16] for example, dose-dependent selection or self-selection, higher participation rates of cases (e.g. cancer patients) compared to controls etc. The better recollection by cases of the facts related to radiation exposure (recall bias)[17] may be conductive to the overestimation of doses in the cases. The selection and self-selection bias is a potentially serious problem of the epidemiological research. It is known e.g. from studies on the low frequency magnetic fields, where, similarly to low-dose low-rate ionizing radiation, there is some epidemiological association with cancer but neither supporting laboratory evidence nor biophysical plausibility.[18-20] In populations exposed to ionizing radiation, the self-selection bias must be stronger than for magnetic fields because carcinogenicity of the former is generally known. People knowing their higher doses would probably come to medical institutions more frequently being given averagely more attention.

It is not surprising that cataclysms with evacuation of people, associated with stress, temporary derangements of perinatal care services, of diets, etc., are accompanied by an increase in the perinatal mortality. Another factor potentially contributing to some reported dose-effect relationships might be an ideological bias and conflicts of interest aimed at the strangulation of nuclear energy,[21] which agrees with the interests of fossil fuel producers. Nuclear power has returned to the agenda because of the concerns over increasing global energy demand and climate changes. NPP emit virtually no greenhouse gases in comparison to fossil fuels. The global development of nuclear energy must be managed by a powerful international executive based in the most developed parts of the world. It would prevent from spreading of nuclear technologies to unstable regions, where conflicts and terrorism are not excluded. It would also permit construction of NPP in optimally suitable places, disregarding national borders, considering socio-political, geological and other preconditions, quality of working by local workers, etc. In this way, nuclear accidents like in Japan (2011), caused by the formidable earthquake and tsunami, or in Chernobyl (1986), favored by disregard for written instructions,[5] would be prevented. Moods and motivations of workers and engineers may be of importance, possibly related to the observation of their human rights. Note that Chernobyl accident coincided with destabilization of the Soviet society.

In conclusion, the study[22] does not prove any dose-effect relationships but creates an exaggerated impression about the consequences of the Fukushima accident. According to the judgment by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), no discernible increased incidence of radiation-related health effects is expected among exposed members of the public or their descendants after the above-named accident.[1] Certainly, radiation exposure of the developing embryo or fetus can cause damage. In addition to the induction of congenital malformations, the central nervous system is particularly affected, which can enhance the prenatal mortality. Mainly on the basis of animal studies and some observations following high-dose exposures of pregnant women, the UNSCEAR considered that there is a threshold for these effects at about 100 mGy[23] i.e. much higher than the doses discussed above. Dose-response relationships at low radiation doses can be further clarified in large-scale animal experiments involving different mammal species, comparable doses and dose rates, reliably shielded from biases and conflicts of interest.

Corresponding author

Sergei V. Jargin
Peoples' Friendship University of Russia
Clementovski per 6–82,
115184 Moscow, Russia
E-mail: sjargin@mail.ru


References

1. UNSCEAR 2013 Report. Annex A: Levels and effects of radiation exposure due to the nuclear accident after the 2011 great east-Japan earthquake and tsunami. New York: United Nations; 2013.

2. UNSCEAR 2000 Report. Annex B. Exposures from natural radiation sources. New York: United Nations; 2000.

3. International Atomic Energy Agency (IAEA). Radiation, people and the environment. Vienna: IAEA; 2004.

4. Background radiation https://en.wikipedia.org/wiki/Background_radiation

5. Mould RF. The Chernobyl record. The definite history of Chernobyl catastrophe. Bristol and Philadelphia: Institute of Physics; 2000.

6. Jargin SV. Hormesis and radiation safety norms. Hum Exp Toxicol 2012; 31(7):671–675.

7. Mettler FA Jr, Huda W, Yoshizumi TT, Mahesh M. Effective doses inradiology and diagnostic nuclear medicine: a catalog. Radiology 2008; 248:254–263.

8. Jargin SV. Dose and dose-rate effectiveness of radiation: first objectivity then conclusions. J Environ Occup Sci 2016; 5(1):25–29.

9. Baldwin J, Grantham V. Radiation hormesis: historical and current perspectives. J Nucl Med Technol 2015; 43(4):242–246.

10. Calabrese EJ. Model uncertainty via the integration of hormesis and LNT as the default in cancer risk assessment. Dose Response 2015; 13(4):1559325815621764.

11. Doss M. Linear no-threshold model vs. radiation hormesis. Dose Response 2013; 11:480–497.

12. Scott BR. It's time for a new low-dose-radiation risk assessment paradigm - one that acknowledges hormesis. Dose Response 2008; 6(4):333–331.

13. Scherb H. Letter to the Editor. Int J Risk Saf Med 2016; 28:177–180.

14. McGeoghegan D, Binks K, Gillies M, et al. The noncancer mortality experience of male workers at British Nuclear Fuels plc, 1946-2005. Int J Epidemiol 2008; 37:506–518.

15. Zablotska LB, Bazyka D, Lubin JH, et al. Radiation and the risk of chronic lymphocytic and other leukemias among chornobyl cleanup workers. Environ Health Perspect 2013; 121:59–65.

16. Watanabe T, Miyao M, Honda R, Yamada Y. Hiroshima survivors exposed to very low doses of A-bomb primary radiation showed a high risk for cancers. Environ Health Prev Med 2008; 13(5):264–270.

17. Kesminiene A, Evrard AS, Ivanov VK, et al. Risk of hematological malignancies among Chernobyl liquidators. Radiat Res 2008; 170:721–735.

18. Mezei G, Kheifets L. Selection bias and its implications for case-control studies: a case study of magnetic field exposure and childhood leukaemia. Int J Epidemiol 2006; 35(2):397–406.

19. Kabuto M, Nitta H, Yamamoto S, et al. Childhood leukemia and magnetic fields in Japan: a case-control study of childhood leukemia and residential power-frequency magnetic fields in Japan. Int J Cancer 2006; 119:643–650.

20. Karipidis KK.  Assessment of bias in a survey of residential magnetic fields in Melbourne, Australia. Radiat Prot Dosimetry 2015; 163(1):92–101.

21. Jaworowski Z. Observations on the Chernobyl disaster and LNT. Dose Response 2010; 8:148–171.

22. Scherb HH, Mori K, Hayashi K. Increases in perinatal mortality in prefectures contaminated by the Fukushima nuclear power plant accident in Japan: A spatially stratified longitudinal study. Medicine (Baltimore) 2016; 95(38):e4958

23. UNSCEAR 2010 Report. Summary of Low-Dose Radiation Effects on Health. New York: United Nations; 2010.​


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