To link this to the potential effects on human health of the radioactive emissions from the Fukushima Daiichi accident: the risk of dying of radiation-induced cancer among about a million Fukushima residents is roughly one in two thousand—approximately the lifetime risk of dying in Japan from a violent crime. In other words, the individual radiation-associated cancer risks are small. In terms of the population risks, if we take this one-in-two-thousand risk and multiply it by about a million exposed people, a reasonable estimate of the number of people in Fukushima who will ultimately perish from radiation-associated cancer is five hundred.
While the estimated radiation-related risks to individuals are very small, the estimated radiation-related public health consequence—the death of five hundred people—is calamitous. On the other hand, compare that estimate of five hundred deaths with the number of deaths caused by the earthquake and tsunami—approximately eighteen thousand.
As we think about the significance of the Fukushima accident, we need to think about it at two levels: individual risk and population risk. The individual risks, while probably not zero, are very small because the radiation doses are very small. Nevertheless, there is understandably a huge amount of anxiety in Japan focused on individual radiation-related risks. From the perspective of individual risks, there seems to be an imbalance between what we know about the actual individual risks and the level of concern that individuals in Japan have right now about their individual risks.
The relevant concern, in my view, is about the population risks. Considering that the population risk—the worldwide incidence of radiation-related cancer due to the Fukushima accident may well be several thousand—allows one to start posing policy questions about the risks and benefits of nuclear power. We need to seriously address these questions.
We have let the people of Japan down by confusing these two different ways of looking at risk. The individual radiation risks are very small, and so the individual risk for anybody living in Japan or in Fukushima will be small—not zero, but comparable with many other risks that people naturally take in their everyday lives.
We have a responsibility to be more careful about talking about the radiation risks associated with the Fukushima accident. Education is the way to do this. We need to talk to people and explain what the nature of radiation-related risk actually is; we need to explain what we know and what we do not know.
In April 2011, the artists and crew of the Metropolitan Opera in New York City and the American Ballet Theatre were about to embark on tours of Japan. Naturally there was a great deal of concern from everyone about whether they should proceed. I went to the Metropolitan Opera and talked for several hours about what radiation and the risk associated with low doses of radiation are. I tried to be as candid as I could and to express what uncertainties there were. We had an hour of questions, and in the end, the Metropolitan Opera and the American Ballet Theater did go to Japan. If you are willing to sit down and carefully talk to an audience and explain what you know and what you don’t know, you can get people to understand what the nature of the risks actually is.
The other part of the story and the reason there is such angst in Japan is the incredible, but not unreasonable, skepticism regarding the information that people are given. Anyone who goes to Japan will see there is such disbelief when it comes to what the authorities are saying about the doses of radiation. We do know what the doses really were—within limits—and we have to reassure people that these were low.
If you could measure everyone’s radiation dose directly, you would be able to identify anybody exposed to high doses of radiation. They could then be monitored and treated. It would also reassure the great majority of people who received very low doses or no doses at all. There are many studies to show that if you perform a test, people are more willing to believe the outcome than they are when a person in a white lab coat says, “Don’t worry.” At Columbia University, we have developed a very high-throughput biodosimetry tool, which is based on the same finger stick that diabetics use. Through this means, we can look at very large populations of, for example, thirty thousand samples a day. In principle, this is one methodology that might reassure people that they are not receiving very high doses and that there is no great conspiracy under way.
At Fukushima there is no doubt that the individual risks are very small, and we must do more to inform and reassure individuals in Fukushima who have been exposed to radiation. Yet there is also no doubt that there will be potentially significant population risks. We therefore need to improve the way we quantify these population risks, because that is the only way we can have a serious conversation about the societal risks and benefits of nuclear power.
8
The Initial Health Effects at Fukushima
Ian Fairlie
On March 11, 2011, following the Great Tohoku Earthquake, a tsunami hit the Fukushima Daiichi nuclear power plant on the east coast of Japan. The resulting surge was over forty feet high at the plant’s seawall; it flooded the plant, causing the failures of cooling pumps and diesel electricity generators. During the following days, explosions occurred at Unit 1 on March 12 and at Unit 3 on March 14, which were videotaped and widely broadcast. On March 15, an “explosive event” in Unit 2 was followed by another in the spent-fuel pond of Unit 4 a few minutes later. Finally, on March 16, a major explosion occurred in Unit 4. The latter three explosions were not videotaped because it was dark and the TV crews were not recording at the time.
In sum, three explosions and two explosion-type events destroyed the reactors at Units 1, 2, and 3 and the spent-fuel pool of Unit 4. The spent fuel stored in the pools of all four units overheated as water levels dropped and a fire occurred in the Unit 4 pool. Reactor core meltdowns also occurred in Units 1, 2, and 3. Seven people were killed by the explosions and around 12,000 workers were exposed to more than 250 millisieverts of radiation. Approximately 86,000 people were evacuated from areas near the stricken plant, 76,000 of whom lived within a twenty-kilometer radius. About 8 percent of Japan’s surface area was contaminated by the fallout from radioactive plumes emitted by the plant, contaminating food and water.
U.S. military helicopters measured surface levels of cesium-134 and cesium-137 and found plumes of radiation had contaminated some high-population areas, including parts of Tokyo. Even if the approximately 30 million residents of Tokyo received an average of dose of only one millisievert, the resulting population dose of thirty thousand person-sieverts is still a very large collective dose.
Although the accidents at Chornobyl and Fukushima were both catastrophic, the atmospheric bomb tests in the 1950s and 1960s were actually worse in terms of the amounts of radioactivity released into the atmosphere. The fallout from Chornobyl resulted in higher nuclide concentrations over larger land areas compared to that from Fukushima. The highest concentrations were in the Ukraine, Belarus, and the former Soviet Union, but 60 percent of the fallout reached Western Europe, including Britain and France; the latter had unwisely declared that it was beyond the Chornobyl fallout.
In contrast, about 80 percent of the fallout from Fukushima fell on the sea. But the population densities in Japan are much higher than in the Ukraine, Belarus, and the Soviet Union. Thirty-six petabecquerels (1 petabecquerel = 1015 becquerels) of both cesium-134 and cesium-137 were released into the air from Fukushima. Several other estimates—both higher and lower—were made. Japanese estimates, which are perhaps less rigorous, were around 10 petabecquerels.