Scientists in the US believe the health consequences from the Japanese nuclear accident may have been underestimated

While the Japanese tsunami of March 2011 was devastating in its own right, the long term health consequences because of the damage to the nuclear reactor at Fukushima Daiichi are also of serious concern.

There are a number of factors that have to be considered when assessing the health effects of radiation exposure: for example land decontamination efforts, size of evacuation area, shielding by buildings and terrain and consumption of contaminated food.

Jan Beyea, from the US expert consulting service Consulting in the Public Interest, together with fellow colleagues has been analysing previous calculations of the subsequent nuclear accident in Japan, and believes that the number of predicted future mortalities from cancer is higher than originally predicted. ‘Health consequences predicted for the Fukushima Daiichi accident are dominated by "groundshine" gamma radiation from the decay over several decades of dispersed radioactive caesium. Although an individual's risk is small, the mid-range, predicted number of future mortalities from cancer is closer to 1000 than the 125 figure calculated without considering long-term groundshine [gamma radiation emitted from radioactive materials deposited on the ground].’

A critical part of calculating the consequences of a nuclear accident is the treatment of the gamma ray dose from land contaminated with caesium-134 and caesium-137. Radiocaesium isotopes can also be responsible for extra cancers that can be expected years after the initial exposure. It is these long-term doses in the environment that were not included in the original estimations.

Lynn Anspaugh, from the University of Utah, US, who works in the field of radiology and reconstructing radiation doses and who analysed the Chernobyl accident, agrees that Beyea’s research points out several inaccuracies in the previous work. However, he feels that the real question this work raises regards the future of nuclear power itself. ‘Both accidents had a root cause in poor judgments having been made by humans. If nuclear power is to have a future, its proponents must indicate how they can make such reactors fail safe and how they will assure that siting decisions do indeed take account of possible, or even likely, natural events.’

Beyea hopes that this work will help improve models of accident consequences as well as future emergency planning and response. When discussing the future of this type of research he adds: ‘Quantifying the psychological and physical effects of stress following large releases of radioactivity may be the next frontier in consequence analysis.’