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Fukushima, 6 Years Later: Consequences and Lessons

11.3.2017

[This article has been published in Spanish in Materia-El País by Adelaida Sarukhan and Elisabeth Cardis]

On March 11, 2011, an earthquake of magnitude 9 shook the east of Japan (...) and led to one of the worse nuclear accidents in history

On March 11, 2011, an earthquake of magnitude 9 shook the east of Japan, followed by a 15 meter tsunami that inactivated the electrical and cooling system of three reactors of the Fukushima Daiichi nuclear power plant, and led to one of the worse nuclear accidents in history

Given the vicinity to large cities (Tokyo is just over 200 km away), more than 10 million people could have been exposed to the radiation cloud. Fortunately for the populations (but less so for the coastal ecosystems), much of the radioactivity leaked into the sea. It is estimated that the amount of radiation released into the air was less than 15% of that released by the nuclear accident at Chernobyl. Accordingly, individual dose measurements on workers and evacuees (those that were within a 20-km radius) show that the average accumulated dose per person was 10-fold less than the average dose registered in Chernobyl. Moreover, recent analyses of data obtained from 9,000 dosimeters distributed to children and women living in Date (60 km away from the power plant) show that the radiation they received was lower than the atmospheric radiation levels registered by helicopter.

The consequences

One of the major health consequences of the Chernobyl accident was the significant increase in thyroid cancer cases among children

One of the major health consequences of the Chernobyl accident was the significant increase in thyroid cancer cases among children. In contrast, the increase in cases reported after Fukushima is due to the launching of  a systematic screening programme among potentially exposed children, which has detected cases that very likely would have never evolved or caused clinical symptoms. Dose measurements show that the amount of radioactive iodine absorbed by the thyroid was several orders of magnitude lower than that observed among exposed populations near Chernobyl. This is due in great part due to the lower levels of released radiation, the iodine-rich diet of coastal populations (iodine deficiency favours thyroid uptake of radioactive iodine), and the low milk consumption among the Japanese (radioactive I131 deposits on pastures consumed by cows), as compared to the Chernobyl populations.  

This by no means implies that the accident did not have tragic consequences on the populations living near the power plant. More than 100,000 people were evacuated from their homes for no other reason than the precautionary principle. As of today, there are still many people that cannot return to their homes, with the psychological, social and economic consequences that this entails. 

Although the nuclear accident did not result in any direct death, the evacuation caused more than 1,000 premature deaths, particularly during the first three months and especially among older people that suffered the trauma and stress of leaving their homes and among hospitalized patients in critical condition that had to be evacuated under inadequate conditions. According to the World Nuclear Association, the fact of having maintained the evacuation beyond a precautionary few days was the main cause of deaths and human suffering. 

The lessons (or what to do and not to do in the future)

The Fukushima accident confirms the enormous psychosocial impact of a nuclear accident

According to a WHO report, the greatest health impact of the Chernobyl nuclear accident, that occurred almost 31 years ago, was on mental health. The Fukushima accident, although different in many ways, confirms the enormous psychosocial impact of a nuclear accident. Among the lessons learned from both cases, an overarching conclusion stands out in case of a future nuclear accident: the fundamental ethical principle of doing more good than harm should be central to any decision.     

Evacuation plans must be optimized to reduce the risk of radiation exposure without forgetting the negative effects

Under this principle, thyroid cancer screening in the aftermath of a nuclear accident should be recommended only if the absorbed radiation and the iodine deficiency levels justify it. Thyroid cancer in young people is aggressive, but with good prognosis. The experience in Chernobyl shows that, even without systematic screening, it is easily diagnosed in case of clinical evolution. Out of a population of 2 million children in Belarus (the region most affected by radioactive contamination, where thousands of children received more than 1,000 mGy o megagrays), some 50-60 cases were detected per year. In Fukushima, where the number of exposed children and teenagers (around 300,000) and the radioactive iodine doses absorbed were much lower (100-1000 fold less), one would not expect more than 1 case per year as result of the radiation exposure. Therefore, systematic thyroid screening in children can do more harm than good: the high-sensitivity echography used has allowed the detection of small nodules in more than half the examined children (a similar proportion to that observed in other non-exposed regions in Japan), generating unnecessary anxiety in parents and children, and in some cases leading to needless surgeries, with the associated risks and consequences (e.g. taking thyroid hormone supplementation for the rest of their lives).   

Additionally, evacuation plans must be optimized to reduce the risk of radiation exposure without forgetting the negative effects of evacuation (particularly among fragile populations) and ensuring an adequate medical and psychological support. Moreover, the evacuation orders must be lifted as early as possible in order to protect the physical and mental health of the evacuees. Past nuclear accidents have highlighted how important it is for displaced and /or affected communities to receive counselling and tools to perform radiation measurements on their own, participate in decision-making, and regain, as far as possible, control of their own lives.

These are some of the recommendations that are starting to come out of the European project SHAMISEN

These are some of the recommendations that are starting to come out of the European project SHAMISEN, whose goal is to evaluate the lessons learned from past nuclear accidents, in particular Chernobyl and Fukushima, and improve the preparedness and follow-up of affected populations according to their needs and without generating unnecessary anxiety. The project, coordinated by ISGlobal, brings together experts from 18 institutions in Europe and Japan and will present its final conclusions by the middle of this year.