Most of the radiation maps of northern Japan are based on external radiation detected in handheld instrument measurements by citizens and scientists, who then link the measurements to GPS coordinates while downloading that data into a massive database. This information about direct, external radiation is certainly important, but it has become the de facto criteria for decision makers in Japan to decide which cities and towns should be repopulated.

We found that this approach only provides limited policy alternatives and serves to minimize potential population exposure for two reasons. First, the Geiger counter data is for external radiation that was deposited on the ground external to human bodies and ignores radiation imbibed or inhaled as “hot particles” into the human body.

Secondly, the external radiation data frequently displayed for northern Japan is based on radiation emitted from only a single radioactive isotope, Cesium-137 (Cs-137), as measured externally. On the other hand, our papers show a wide variety of isotopes that are not detected by handheld Geiger counters or absorbed externally. We show that there is an extensive brew of various isotopes present in radioactive dust that is inhaled or imbibed. Our papers indicate that the radioactive concentration in these dust particles varies widely, by a factor of 1 million, with 5 percent (3 sigma) of these “hot particles” 10,000 times more radioactive than the mean. Our most radioactive dust particle was collected 300 miles from the site of the meltdown.

Furthermore, the data show that alpha, beta and gamma-emitting contaminants in radioactive fallout from the Daiichi meltdowns have not traveled together in lockstep. This means that measuring only beta-emitters like Cesium-137 or only total gamma (as you would with a Geiger counter) is not enough to map the full impact of the fallout. Alpha-emitters must also be measured to protect the public health. This is especially important because of the serious health impacts that can come from exposure to alpha radiation.

2. Northern Japan remains radiologically contaminated.

When a nuclear chain reaction stops, the hazardous remnants of the previously split uranium atoms, euphemistically called “fission products,” are left behind and remain radioactive for centuries. The triple meltdowns and explosions at Fukushima Daiichi Units 1, 2 and 3 in March 2011 released an enormous amount of these fission products into the environment. Wind currents pushed as much as 80 percent of this radiation over the Pacific Ocean, while 20 percent fell on northern Japan, forcing the evacuation of approximately 160,000 Japanese citizens from ancestral lands.

Absent any human intervention, short-lived fission products that originally accounted for more than half of this contamination have already decayed away during the last nine years, while even more has washed into the Pacific from storms and typhoons. Limited cleanup efforts by the Japanese government have further reduced the contamination in a fraction of the populated portion of the devastated Fukushima prefecture. Greater than 10 million tons of radioactive material have been collected and stored in 10 million individual large black bags at hundreds of locations. However, due to mountainous terrain, more than 70 percent of Fukushima prefecture will never be decontaminated.

Absent any human intervention, short-lived fission products that originally accounted for more than half of this contamination have already decayed away during the last nine years, while even more has washed into the Pacific from storms and typhoons. Limited cleanup efforts by the Japanese government have further reduced the contamination in a fraction of the populated portion of the devastated Fukushima prefecture. Greater than 10 million tons of radioactive material have been collected and stored in 10 million individual large black bags at hundreds of locations. However, due to mountainous terrain, more than 70 percent of Fukushima prefecture will never be decontaminated.

As the cost and effort to completely decontaminate the entire land mass of Fukushima prefecture would be prohibitive, the Japanese government has focused on cleaning only populated areas. It also increased the “allowable” radiation limit 20-fold, after an initial partial decontamination, from 1 milli-Sievert to 20 milli-Sieverts per year (100 millirem to 2 rem) to facilitate repopulation of abandoned villages. A 20-fold increase in radiation will create a 20-fold increase in radiation-induced cancers. A significant fraction of residents chose not to return, recognizing the increased risk that these higher approved limits present.

3. Previously “cleaned” areas are becoming radiologically contaminated yet again.

The city of Minamisoma was contaminated and evacuated at the height of the Fukushima disaster. After a period of several years, radiation in the city was remediated and citizens were allowed to return. Minamisoma City Hall was decontaminated, with a new epoxy roof applied after the meltdowns in 2011. The authors collected samples from this previously “clean” fourth-story roof in 2016 and again in 2017, finding high levels of alpha radiation in the relative absence of the normally ubiquitous Cesium isotopes. This can only imply that wind-borne contamination from uncleaned areas is recontaminating those areas determined habitable.

4. Olympic venues in Fukushima prefecture are more contaminated than in Tokyo Olympic venues.

Suburbs of Tokyo are approximately 120 miles from the reactors at Fukushima Daiichi. We found particulate radiation at Olympic venues in Tokyo to be normal compared to other cities worldwide. We found that areas in Japan beyond the Olympic venues were seven times more contaminated than the venues themselves. Contamination at the Olympic venues in Fukushima prefecture, planned to showcase the region’s recovery, were also more contaminated than the Tokyo venues. We found that on average, these northern Olympic venues were two to three times more contaminated with “hot particles” than venues in Tokyo.

We also detected small but statistically significant levels of plutonium at the J-Village national soccer camp in Fukushima prefecture. Even though the Japanese government claims to have thoroughly decontaminated these Fukushima locations, it is not surprising that these Olympic venues remain contaminated. As discussed previously, since the entirety of the prefecture’s area will never be decontaminated, these areas will continue to have wind-borne contamination for centuries.

Science on a Shoestring

As Fukushima was melting down, nuclear advocates in the U.S. were testifying to the Washington State legislature, saying that Japan’s nuclear plants would not be a problem, and that working in a nuclear plant is “safer than working in Toys R Us.” Not surprisingly, those same zealots are now claiming that there will be no increase in cancer fatalities as a result of the three Fukushima meltdowns. However, not including the hot particle contamination my colleagues and I have identified, the UN estimates that thousands of fatalities will occur. Others, including myself, believe the actual cancer increase could result in upwards of 100,000 increased deaths as a result of the radioactive microparticles strewn into the environment.

There is no doubt that radiological conditions in Japan have improved in the decade since the triple meltdowns at Fukushima Daiichi. However, our data show that Japan has not “recovered,” nor can it ever return to pre-meltdown norms. Public relations campaigns by interested parties cannot obscure the recontamination of populated areas in northern Japan that will continue to occur.

Hasegawa, the former head of Maeda Ward in Fukushima prefecture at the time of the Fukushima disaster, sums up the sentiment of most of Japanese citizens in northern Japan: “The nuclear plant took everything.… We are just in the way of the Olympics. In the end, the radiation-affected places like us are just in the way. They are going ahead just wanting to get rid of these places from Japan, to forget.”

There is an old laboratory adage that says, “The best way to clean up a spill is not to have a spill,” and this applies on a much larger scale to the entirety of northern Japan, where cleanup will remain economically unfeasible. Our future plans to further support our hypothesis that Japan remains contaminated will involve testing the shoestrings of Olympic athletes and visitors to northern Japan. Shoestrings are useful, as their woven fabric traps dust which may assist in determining the extent of contamination into populated areas in northern Japan compared to that in Tokyo.