In spite of the meltdown of reactor cores in three of the reactors, this was no Chernobyl because the primary reactor containment structures were not destroyed, though they may have been damaged, and the release of radioactivity was limited to three major spikes in the days after the tsunami. The amount of radioactivity released to the air from the three damaged reactors at Fukushima was about 18% of the 1 31I-equivalent radioactivity5 released from Chernobyl, including 500 PBq of 1 31I and 10 PBq of 1 37Cs (compared to 1760 and 85 PBq, respectively, at Chernobyl) (40). 90Sr was not released from the accident, probably because the core temperatures were not high enough to volatilize it (46). There were initial fears that water supplies in Tokyo to the south would be in danger, with 131I testing above Japan’s stringent standards for infants, which are 10 times lower than international standards. However, the level receded below the stan­dard by the next day, so restrictions were lifted (47).

Much of the radioactive cloud was deposited locally around the plant, giving the highest dose levels, but also carried by winds to the northwest of the plant, where it fell in spotty locations from rain, similar to the pattern at Chernobyl. A 20-kilometer (12 mile) mandatory evacuation zone was established with evacuations also from a few communities beyond the 20-kilometer evacuation zone, known as the “deliberate evacuation zone.” The highest levels outside the 20-kilometer evacuation zone were at the village of Iitate, 30 kilometers north­west, which had about 6,000 residents. About 100,000 people were evacuated and will not be able to return for at least six months. None of the people evacuated were exposed to high enough levels of radiation to suffer health consequences. Much of the radioactivity was due to 131I, which decayed away within a couple of months, but soil contamination of 137Cs will remain for years and will have to be cleaned up, and some areas may remain as long-term exclusion zones. However, the highly contaminated areas are much smaller than those near Chernobyl (48). The Japanese government has set a target of reducing the radiation from the acci­dent to below 20 mSv/yr in the evacuation zone and less than 1 mSv/yr in areas such as schools frequented by children (49). As of the end of 2012, about half of the original evacuated area is now accessible without protective gear or monitor­ing (dose rate less than 20 mSv/yr), but overnight stays are not allowed (40).

How many people will die from Fukushima? There were 3 deaths among nuclear plant workers from the earthquake and tsunami. In addition, there were about 15 workers who were injured in the explosions, but none of the injuries was life-threatening. There was much hysteria about the condition of the workers who were responding to the accident under the terrible conditions left by the tsunami and earthquake. Lurid headlines proclaimed that the workers were “suicide work­ers” who would die from the high doses of radiation they were getting. “ ‘I don’t know any other way to say it, but this is like suicide fighters in a war,’ said Keiichi Nakagawa, associate professor in the Department of Radiology at the University of Tokyo Hospital” (50). But this is sheer nonsense. Two workers got radioactive water into their boots while they were working at the plant and were taken to the hospital with great fanfare. They suffered erythema (skin reddening similar to sunburn) from the localized radiation to their feet. They received 2-3 Sv to their feet, which caused the skin reddening (42). To put this into context, the standard radiation treatment for cancer is 2 Sv fractions given five times a week for six weeks. Thus, they received the equivalent of about one radiotherapy treatment to their feet, and the feet are a very radioresistant part of the body, with an allowable dose of 500 mSv per year for radiation workers in the United States.

By the end of 2011, 167 workers had received doses of over 100 mSv, with 135 of them getting between 100-150 mSv, 23 getting between 150-200 mSv, 3 getting between 200-250 mSv, and 6 getting over 250 mSv (51). The normal international allowable dose limit for radiation workers is 50 mSv per year but in an emergency is 500 mSv; under the circumstances, the dose limit was set to 250 mSv for the Japanese workers (52). For adult workers, the risk of dying of cancer is 4% per

Sv, so the workers who got 250 mSv would have about 1% chance of dying of cancer from the radiation. Of course, their normal risk of cancer death is much higher, about 25% (53). These were hardly “suicide workers" In truth, the number of workers exposed to significant levels of radiation is so small that there is likely to be only a single death from cancer.

A year after the accident, the health effects have come into clearer focus as stud­ies on the exposed population were reported. A press briefing in Washington, D. C., on March 2, 2012, by the Health Physics Society, reported that about 20,000 people died from the earthquake and tsunami but none has died from radiation effects. Of 10,000 people nearest the reactors, nearly 60% had doses of less than 1 mSv and 40% had doses of between 1 and 10 mSv. Seventy-one received doses between 10 and 20 mSv, and 2 received doses between 20 and 23 mSv. Recall that the annual average dose for Americans is 6.2 mSv per year (Chapter 8). The doses to the Japanese public from the reactor accident are so low that the increase in cancer incidence is estimated to be about 0.001%. This is so low that there will never be any epidemiological studies that could detect any excess cancer risk (54). The health risks come almost entirely from the stress associated with the wide­spread destruction of homes and towns from the earthquake and tsunami, with fears of radiation on top of that. In short, peoples’ lives have been scrambled, and the ongoing stress contributes to depression and heart disease, the greatest health consequences from the disaster (55).

The World Health Organization (WHO) released a report in early 2013 assess­ing the risks of getting cancer (not dying of cancer) for people in the deliberate evacuation zone. The highest doses were to people in Namie Town, which had about 21,000 people before the accident (56), and Iitate with about 6,000 resi­dents. Using very conservative assumptions that are very likely to overestimate the doses, the average dose to residents of Namie Town was about 25 mSv and Iitate Village residents had about half that (15 mSv). Doses included both external doses and internal doses from eating food, which was assumed to be grown in the same neighborhood, an unlikely assumption. The report also assumed that the DDREF was 1 (see Chapter 7), which likely overestimates the risk. The report con­cluded that male infants in the highest exposed region (Namie Town) could have an additional 7% increase in lifetime risk of leukemia compared to the normal baseline rate, an increase of 6% in breast cancer over baseline for female infants, a 4% increase for all solid cancers in female infants, and a 70% increase in thyroid cancer for female infants. Since the normal thyroid cancer incidence is very low in Japan (0.75%), this represents an increase of only 0.5%. And, of course, thyroid cancer is rarely fatal. Expected cancer risks for older children and adults are lower (46). The report does not specify the number of people in the various age groups.

Let’s think about these estimates to see if they are realistic. Remember that there has been no increase in leukemia or breast cancer in people exposed to higher doses after the Chernobyl accident, so it is likely that the WHO has overestimated the cancer risk. If you use the ICRP risk estimate of 5% per Sv (for low dose radia­tion) for a population that includes children (see Chapter 7), you would expect about 26 additional cancers among the 21,000 people in Namie who were exposed on average to 25 mSv and about 4 additional cancers among the 6,000 people in Iitate. That would compare to a normal expectation of 25% cancer risk, or 5,250 in Namie and 1,500 in Iitate. In other words, the additional cancers expected are such a small number that they will never be measurable.

Both the Chernobyl and the Fukushima nuclear accidents were rated as a 7 (major accident) on the International Nuclear and Radiological Event Scale (INES), a logarithmic scale similar to the Richter scale used for earthquakes (57). However, even though both Chernobyl and Fukushima were major accidents, there are huge differences between them. In Chernobyl, the accident was caused by operator error and faulty reactor design; there were 28 deaths from radiation exposure, 15 deaths from thyroid cancer, 19 deaths from uncertain causes, and a lifetime expectation of 4,000 additional cancer deaths; and there was widespread environmental contami­nation necessitating the evacuation of 336,000 people. In Fukushima, the accident was not due to operator fault or reactor design but was the result of an unprec­edented earthquake and tsunami that killed around 20,000 people; about 18% as much radiation was released as at Chernobyl; there were no deaths from radiation exposure, and there will be only a single cancer death expected in the workers and possibly 25-30 from people in the path of the fallout; there was fairly widespread contamination necessitating the temporary evacuation of 100,000 people but the long-term effects should be confined to a much smaller area. Both were bad acci­dents but the consequences of Fukushima are far less severe.