Pro-Nuclear Experts Mislead India on Low Radiation Doses

Prof. T. Shivaji Rao

Prof.T.Shivaji Rao is the Director of Center for Environmental Studies,GITAM University, Visakhapatnam (India)

Mr.K.S.Pardhasaradhi, former Secretary of the Atomic Energy Regulatory Board (AERB) in his article in the Hindu dt.24-5-2012 on ‘Needless alarmist views on Low Dose radiation” tried to find fault with the editor of the special articles on low level radiation risks published in the Bulletin of the Atomic Scientists dt.1-5-2012.

He starts the presentation by insisting that while the effects of high radiation doses are clearly known, the effects of low radiation doses contain uncertainties and that the dilemma on the effect of low dose radiation continues. The author blames that rather than offering an unbiased view the bulletin tried its best to show that radiation is riskier than what was thought of so far. The special articles on damaging impacts of low nuclear radiation dose are highly scientific and the authors who were contacted by Mr.Padhasaradhi perhaps thought it not worthwhile to respond to his prejudiced views on safety of low level nuclear radiation because all the International experts know that low non-linear threshold limit (NLT) for radiation dose is scientifically established beyond doubt. The contention of Mr.pardhasaradhi is one sided because he thinks that the bulletin has not provided the complete picture particularly on low dose repair related studies.

The special issue he alleges served to preserve intact the anti-nuclear power credentials of the bulletin which is the scientific stand as proved by the results published by the graphs and scientific reasoning, highlighting the genomic instability and bystander effects that increase radiation risks even at low doses.

The bulletin has rightly put adaptive responses of the cell to low level radiation on a low level key and ignored the existence of cellular repair mechanisms which come into effect only in a few special conditions as indicated below.

When an electron passes through a biological cell the electron releases its energy along its path (called a track) by interacting with the electrons of nearby molecules. The energy thus released is absorbed by atoms near the track causing excitation ( a push in the orbit of an electron to a higher energy level) or ionization (release of an electron from the atom) and the residue unstable atoms are known as radicals and are chemically highly active. X-ray and gamma rays unlike Beta particles release high speed electrons from atoms first. Positively charged particles transfer energy to molecules in the cells electrically uncharged neutrons impact of the nuclei of hydrogen atoms namely protons. Since the masses of the proton and neutron are similar the impact results in an elastic scattering process as occurs in Billiards game. The ejected protons work like charged protons. Ionizations due to radiation act directly on cell molecules or indirectly on water molecules causing water derived radicals which react with nearby molecules causing breakage of chemical bonds or addition of oxygen atoms by oxidation of the affected molecules. The major effect in biological cells is at DNA breaks either in single strand or double strands and the later is important biologically. Single strand breaks can be repaired normally because of the double stranded nature of the DNA(the two strands complement each other so that an intact strand serves as a template for repair of its damaged opposite strand) In case of double strand breaks the repair is more difficult and the erroneous rejoining of broken ends may occur and such misrepairs cause mutations, chromosome abrasions or cell death.

Radiations differ not only by their components like electrons, protons and neutrons but also by their energy. Radiations by neutrons and alpha particles cause dense ionization along their track and are called High Linear Energy Transfer, High LET radiation that is energy released per unit length of the track. Low LET radiations by X-Rays and Gamma rays produce ionizations sparsely along their track and homogeneously within the cell. High LET radiations release energy in a small region of the cell and the localized DNA damage caused by High LET radiations is more difficult to repair than the diffuse DNA damage caused by the sparse ionizations from Low LET radiations. The same radiation dosage produce the same total number of ionizations with the difference that Low LET radiation causes sparse ionizations whose damaging effects can be normally repaired while the High LET radiation causes dense ionization along their track causing double strand breaks which are more difficult for repair and hence are bound to cause cell deaths or mutations resulting in cancer and other forms of illness.

There is nothing like a low level radiation which can be considered to be a safe limit of exposure because such limits have been imposed forcibly over the innocent people of India by the AERB which is highly irresponsible body that works under the guidance of the Department of Atomic Energy and the Prime Minister who are forced to take anti-people’s stand on nuclear issues as they are dictated by the money making nuclear lobby supported by their national political leaders and export killer nuclear power plants to poor developing countries like India where the decision making authorities are not only ecologically illiterate but also violate environmental laws and regulations to promote nuclear plants at any cost even though there are several alternate energy sources like Neyveli lignite coal that provide more than enough electricity at a cheaper cost to several states in India including Tamilnadu where people are being forced to accept an imported killer nuclear plant imported from a foreign country like Russia which has abandoned some nuclear plants long ago. Hence it is evident that in order to understand the impact of even the lowest level of radiation, one must have sufficient background knowledge in biological fields to know that even the low level radiation causes corresponding damaging impacts.





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