Needless alarmist views on low dose radiation

K.S. PARTHASARATHY

Former Secretary, Atomic Energy Regulatory Board

 

On May 1, this year, The Bulletin of Atomic Scientists published a Special Issue on low level radiation risks. Radiation risk has a bearing on dose limits to radiation workers, guidelines for evacuation of public from areas of contamination and in optimisation of radiation dose in medical radiation procedures.

The effects of high radiation doses are clearly known; at low doses there are uncertainties. The dilemma on the effect of low dose radiation continues.

The Special Issue contains seven articles and an editorial. Rather than offering an unbiased view, the Bulletin tried its best to show that radiation is riskier than what was thought of so far.

Dr Beyea, the Guest Editor reviewed three epidemiological studies including the 15 nation nuclear workers study covering years 1943-2000. They showed some increase in cancer rates at low doses. Each of these studies has infirmities.

Unlike his claim, the 15-nation study did not shock the radiation protection community. Currently, doses to nuclear workers are relatively low.

The present dose limits with the provision that the doses to workers should be As Low As Reasonably Achievable (ALARA) ensure adequate protection effortlessly.

Studies in the High Back Ground Radiation Areas of Kerala showed that there is no cancer risk attributable to radiation. Dr.Bayea did not agree.

“For a more positive view of these types of studies, see Boice et al. (2010),” Dr Beyea suggested. Dr Boice who heads the National Council on Radiation Protection and Measurements did not respond to my e-mail query.

The Bulletin which criticized others who held different views, seldom based it on science. It upbraided the French Academy of Sciences for the relationship of some of its members with the French nuclear industry and medical practice and Electric Power Research Institute with U.S. nuclear industry.

The Bulletin argued that the reports of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) would not say that some risk continues up to zero dose, as the Committee, a product of the United Nations, must be cognizant of national politics in UN countries! Some sort of conspiracy theory!

Protective mechanisms

A paper published in the European Heart Journal (2011) demonstrated that at low doses there might be protective mechanisms at work. In theProceedings of the National Academy of Sciences (2011),researchers showed that cell repair mechanisms were effective in dealing with exposure to low doses of radiation.

A contributor, Dr Colin Hill, University of Southern California skillfully highlighted genomic instability and bystander effects (phenomena which may increase radiation risk), put adaptive response on a low key and ignored the existence of cellular repair mechanisms.

Dr Beyea uncritically accepted the high per capita medical dose (often unwanted) in developed countries as a starting point for millions of people and worried about any exposure to radioactive releases from nuclear accident (Fukushima) as contributing to their delayed cancer risk. He ignored the risks from unwanted medical doses which are often much higher.

The hesitation

Based on one paper, Dr Beyea invoked the so called “supra-linear” concept to argue that low dose radiation is much more dangerous than what was thought of till now; though the authors themselves hesitated to do so.

Dr Hill and Dr Richardson, two contributors, did not respond to the queries of this writer. After protracted correspondence, Dr Beyea wanted me to consider quoting the following from his article.

“It should be noted that all of these cellular effects, including bystander effect, genomic instability, and adaptive response, some of which are thought to have effects working in opposite directions, could already be incorporated into the linear human dose-response curve (Morgan and Sowa, 2009), making the debate much ado about nothing.” The observations claiming enhanced radiation risks had many un-highlighted frailties.

The Guest Editor faced difficulties in compiling the Issue. “Yes, it should be no secret who was asked to contribute to the special issue.” Dr Beyea confided in response to my query.

Dr. John Boice did not have the time, given his new responsibilities. Dr Fred Mettler, Professor Emeritus at the University of New Mexico School of Medicine declined. Dr.Michael Stabin, Adjunct Professor of physics at the Illinois Institute of Technology refused. I was not surprised.

The criticism in this review applies only to the articles, which explain radiobiological concepts. The “sophisticated update” promised by Beyea in the Editorial became one sided. The Bulletin has been less than neutral in its approach; it did not provide the complete picture, particularly on low dose repair related studies.

A reader whose knowledge is confined only to the special issue will not be ready to join the debate armed with a broadbased view. The Issue served to preserve intact, the antinuclear power credentials of the Bulletin! 

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(Special thanks to Dr. Parthasarathy for his contribution and permission to share his above work.)