The Windscale fire in 1957 caused between 12 and 240 cancer deaths, according to research undertaken in the 1980s by Greenpeace UK. The Three Mile Island accident in 1979 caused the release of unknown amounts of radioactivity with unknown health effects, required a bn clean up and precipitated a three decade long hiatus in nuclear power plant construction in the USA. The number of deaths from radiation exposure caused by the Chernobyl nuclear disaster in 1986 has been hotly disputed for thirty years but official estimates from 2005 presented to the International Atomic Energy Agency and World Health Organisation stated 9,000 deaths, later revised upwards to 16,000.
With the Fukushima disaster in Japan in 2011, official estimates by the United Nations Scientific Committee on the Effects of Radiation of the collective dose (48,000 person Sv) in Japan are remarkably similar to those by independent experts. When the conventional 10% per Sievert risk factor is applied, this collective dose means around 5,000 future cancer deaths in Japan.
However, after Fukushima many governments (notably the UK, eager to protect its nascent nuclear renaissance from public antipathy) rushed to reassure citizens around the world that radiation exposure rates were 'insignificant' at the same time as we witnessed heartbreaking photographs of Japanese children being checked for contamination by a radiation worker clad in head-to-toe protective clothing. The Japanese authorities, when confronted with the news that children were being exposed to as much as 20 times the 'permitted' level of radiation simply raised the authorised limits. The radioactivity from the Fukushima disaster is still circling the Earth and its eventual global health impacts will take decades to emerge.
The health impacts of exposure to radiation remain an area of great uncertainty and much controversy. It is a controversy which was heightened to fever pitch in 2008 when a report commissioned by the German government's Radiation Protection Agency demonstrated that within a 5 km radius of every nuclear power station in Germany there was a 60% increase in the incidence of leukaemia in children aged under five. These cancers were not linked to medical or other radiation exposures or to high levels of radioactivity from previous nuclear disasters, as the study unequivocally demonstrated a strong association between increased childhood leukemias and proximity to nuclear reactors. The study prompted the governments of the UK, France and Switzerland to immediately carry out similar studies, which all showed increased child leukemias near their nuclear reactors. When a metastudy was conducted on these plus a similar German study, the result was a statistically significant 37% increase in child leukemias within 5 km of all the nuclear reactors in these four countries. The inference was, and remains, that these cancers are caused by routine discharges from nuclear power stations, and that the consequences for health in the host community are most readily registered in the health of young children and the unborn as they are known to be far more radiosensitive than adults.
The debate around low levels of radiation exposure and its effect has dogged the nuclear industry for decades. Current methods for setting limits for exposure are based on cancer data collected from the victims of the atomic bombs dropped on Hiroshima and Nagasaki in 1945. Essentially, the yardsticks developed from that data have not changed in 70 years. They amount to 'the larger the dose, the greater the impact' – a 'linear' theory describing the relationship between dose and health impact. But there has been uncertainty about the situation at very low doses where data is scarcest. Is there a threshold level at which exposure has no effect?
The scientific evidence from epidemiology studies and radiation theory is overwhelmingly clear: there is no threshold. Many recent studies, for example, clearly show risks even from background radiation. The problem is not the science but the refusal or inability of some journalists and pro-nuclear scientists to accept it.
Nevertheless, doubt and controversy remain about what happens at very low dose rates. Critics of the industry and its processes for assessing the safety or otherwise of its 'authorised limits' for exposure to host populations cite the work of several independent scientists which shows that existing limits are unsafe. In addition, the European Committee on Radiation Risk (ECRR) argues that the traditional method of using the concept of 'dose' to measure the resulting level of 'risk' is outdated, discredited and entirely without foundation. For example, a tiny 'dose', perhaps from a microscopic particle of plutonium or another alpha-emitting radioisotope, can lead to a significant risk which is not reflected in current official estimates. This is because harm may result from internal exposure to radiation which has entered the body, and is in close proximity to sensitive organs, unlike the external exposures received at Nagasaki and Hiroshima. The CERRIE Report published in 2004 showed very large uncertainties in official dose estimates from internal emitters. Should a particle lodge in the lung after inhalation, or in the stomach after ingestion, the cancer risk is higher than that estimated using external risk factors derived from Nagasaki and Hiroshima.
So 'low estimated dose' does not mean 'low risk'. In addition, the ECRR argues that as a foetus in the womb is highly radiosensitive, genetic damaged linked to the development of cancer can be triggered by an initial 'hit' of radiation. Exposure to radiation in this way can be experienced when a nuclear reactor is refuelled and a large 'spike' in the plant's radioactive emission profile occurs when the reactor is opened to permit the renewal of fuel rods. This very large increase in aerial radioactive emissions (consisting of up to 80% of annual emissions) can lead to high exposures via inhalation of radioactive gases or ingestion of food and water contaminated by radioactive water vapour during outages when reactors are re-fuelled.
Repeated attempts to require the industry's advisory body, the Committee on the Medical Aspects of Radiation in the Environment (CoMARE) to engage in meaningful, scientific and expert-to-expert debates with their critics to arrive at an agreed position on this subject have failed. This is perhaps not surprising given the Government’s vehement support for nuclear power.
The latest attempt to narrow the gulf between polarised positions, an attempt which has secured the support of the Department of Energy and Climate Change (DECC) as well as that of the Office of Nuclear Regulation, arose from the series of meetings held between DECC and non-governmental organisations which have been taking place for the last three years, but even with these powerful forces behind the initiative, CoMARE is reluctant to engage and has since deferred the issue to the former government Chief Scientist, Professor John Beddington, a fisheries expert, and DECC's own chief scientist, Dr David McKay. Unless and until the industry acknowledges these uncertainties and unless and until the industry's health and radiation advisory agencies are forced to engage with their critics in order to arrive at a more consensual view, public concerns over exposure to radiation – arising from decommissioning activities, from routine operation, from spent fuel movements, from waste management and from the inevitable accidents – will continue and host communities will be left to wonder and worry about the effects of living in close proximity to nuclear facilities long into the future.
Belatedly, however, a glimmer of light appears at the end of the low level radiation tunnel. Speaking during a panel session at the World Nuclear Association's (WNA) 2014 Symposium, Roger Coates, vice president of the International Radiation Protection Association (IRPA), said that the nuclear industry and governments "have not been honest in presenting the risks of radiation at low levels". He suggested the nuclear industry should encourage its radiation protection practitioners to join the debate on presenting the risks of radiation. "If we express risks of radiation in what is defined as 'normal' … we will be in a more honest and better situation," Coates said, rather confusingly.
Perhaps more revealingly, Willie Harris, Director of Radiation Protection at the US utility Exelon Nuclear, stated that the nuclear industry "does not have a significant amount of research in low-dose areas" in its studies and concepts, and that, in some cases, there had been a 'mis-communication' of radiation risks. These are small and, some would say, insignificant concessions from the industry which go only a small way in acknowledging that the uncertainties in the knowledge base upon which radiation limits, and thus public reassurance, are founded are fundamentally flawed. But it gives the critics a toe-hold in the debate. From the acknowledgements at the WNA symposium, we can now mount a legitimate challenge to the unfounded and entirely placatory platitudes regularly trotted out from the industry about the risks from a nuclear facility being 'one in a million', or that a dose of 1 millisieverts is 'safe', or that impacts from routine discharges are 'insignificant'.