Another Study Estimates Minimal Risk from the Fukushima Disaster

A protestor at the anti-nuclear demonstration in Paris on March 20, 2011. The demonstration was sparked by the Fukushima disaster (Click for credit)

On March 11th of 2011, an earthquake in the Pacific Ocean produced a tsunami that devastated parts of Japan. According to the Japanese National Police agency, at least 15,870 people died in the disaster, and an additional 6,114 were injured. Over 2,000 people were still missing as of September 12, 2012.1 In addition, the tsunami caused multiple meltdowns at the Fukushima Daiichi nuclear power plant. As a result, approximately 900,000 terabecquerels of radiation was released into the surroundings. To give you a sense of what that means, the Chernobyl nuclear disaster that occurred in 1986 spewed an estimated 5.2 million terabecquerels into the surroundings.2 So while the radiation released in the Fukushima disaster was bad, it wasn’t nearly as bad as what happened at Chernobyl.

Of course, the total amount of radiation released isn’t the entire picture. After all, the Chernobyl area wasn’t nearly as densely populated as Japan. So while the Fukushima disaster released less radiation, that smaller amount of radiation could have a larger effect, given the fact that there were so many people who could have been exposed to it. Last year, a study was published in the Journal Energy & Environmental Science, and it indicated that the increased cancer risks caused by the Fukushima disaster would be minimal. Since cancer is the most common long-term consequence of radiation exposure, the report seemed to indicate that the long-term consequences of the disaster would be small.

A new study was recently published by the World Heath Organization (WHO). The authors of the previous study were not involved in this study, and the methodology of the new study is different from that of the previous one. As a result, it seems to me that this is a truly independent assessment compared to the previous one. However, the conclusions are roughly the same.

In the study, the participants examined the specific radioactive isotopes that were released, the patterns of exposure, and the estimated doses to which people were exposed. Those observations and estimates were then extrapolated to produce estimated lifetime organ doses for people in various parts of the world. Those lifetime organ doses were then correlated with cancer risk, and the result was an estimate for the increased risk of specific cancers as well as all solid cancers (which basically means any cancer that produces discernible tumors). The conclusion of the study is summarized as follows:3

This health risk assessment concludes that no discernible increase in health risks from the Fukushima event is expected outside Japan. With respect to Japan, this assessment estimates that the lifetime risk for some cancers may be somewhat elevated above baseline rates in certain age and sex groups that were in the areas most affected.

Specifically, it found that in Japan, the risk for all forms of solid cancer increased by 4% as the result of the Fukushima meltdowns. The largest increase in risk is estimated to be for thyroid cancer, and that increase is 70%. Now what, exactly, do those numbers mean? They represent the increased risk compared to the baseline risk. According to the report, for example, the baseline risk of contracting thyroid cancer in Japan is 0.75%. This means that without the disaster, 0.75% of Japanese people will contract thyroid cancer in their lifetimes. If the increase in risk for thyroid cancer as a result of the disaster has been correctly estimated, now 1.275% of Japanese people will contract thyroid cancer.

So what does this tell us? If these two studies are accurate, then the long-term consequences due to the Fukushima meltdowns are really quite minor. As one of the authors of the WHO study said:

The additional risk is quite small and will probably be hidden by the noise of other (cancer) risks like people’s lifestyle choices and statistical fluctuations…It’s more important not to start smoking than having been in Fukushima.

I hope this study and the previous one find their way into the heads of people who are making energy decisions in Japan. There have been all sorts of protests against nuclear power as a result of the Fukushima disaster, and Japan is seriously considering reducing it use of nuclear power as a result. However, based on all the evidence we have right now, the fact is that the consequences of the Fukushima meltdowns are absurdly small compared to the immediate devastation caused by the tsunami. Does that mean nuclear power is definitely the way to go for Japan? Of course not. It just means that those who are making such decisions better know the real risks associated with each form of power generation so that they make their decisions based on data rather than emotions.


1. National Police Agency of Japan, Damage Situation and Police Countermeasures, September 12, 2012 (available online)
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2. Devil’s Bargain?: Energy Risks and the Public, First Report of Session 2012-13, House of Commons, Great Britain, p. 28
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3. Health risk assessment from the nuclear accident after the 2011 Great East Japan Earthquake and Tsunami based on a preliminary dose estimation, World Health Organization 2013, p. 9 (available online)
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  1. Joel Duff says:

    Thanks for posting these results. This is a good reminder of how fear can be worse the actual danger in many cases. Whenever I lecture on mutations in DNA I include a section in radioactivity and have talked about Fukushima many times. I suggested to my students that the dangers from chemical contaminants in the water and soil will probably end up being worse than radiation dangers. Of course those workers at the plant could have been exposed to dangerous levels, though not anywhere near that of Chernobyl, but as these reports show, the overall dangers for the general public are not that high. There is great danger in radioactivity but our society has taken that to mean that anything that is radioactive is dangerous. This is a helpful chart that puts radioactivity exposure in perspective: I like to point out to students that there is some evidence (I can’t put my finger on the research at the moment) that people that live in areas of higher natural radioactivity may actually have a lower prevalence of cancer. It isn’t intuitive that this should be the case but I liken it to those that grow up in sterile conditions vs being around a lot of allergens. The latter will likely have fewer allergies later in life. I also liken it the dangers of radioactivity to UV sunlight exposure. Our cells have amazing systems for fixing the mutations caused by UV light if exposed in moderation but if we abuse or bodies by massive exposure to the sun we overwhelm the systems design and can do ourselves real damage. Radioactivity in small doses isn’t a problem, its acute exposure that presents the biggest problem. There are chemicals, though, in the environment that in small quantities over long periods of time will accumulate into larger problems which is why I would say that PCBs and other chemicals spilled during the Tsunami probably represent a more significant concern. As you point out, hopefully real evidence like these reports will be used to make future decisions not the misconceptions of the public.

    1. jlwile says:

      Thanks, Joel. That is an excellent chart! I am so glad you linked it!

      You are definitely correct about the fact that chemical contamination from the tsunami will present a more significant long-term concern than the radiation.