The Fukushima Accident

Joel I. Cehn, CHP
Ask the Experts Nuclear Accidents Topic Editor

Would you update me on fallout in the United States from the Fukushima accident?
Wild speculation on the widespread dangers of Fukushima radioactive fallout has been popping up lately, including posts on the Internet with titles like "Holy Fukushima—Radiation From Japan Is Already Killing North Americans." These are thin on facts and create more heat than light. But they do certainly grab our attention. For example, videos and news out of California and Missouri claim that high levels of radiation were detected. What they mean is "higher" levels of ambient radiation. Higher than what? Well, higher than measured elsewhere. Here's the bottom line: natural levels vary a lot. I can see large variations around my own neighborhood. Tenfold differences are not unusual. This is due to a lot of factors, including ground cover, building materials, minerals in the soil, and even weather conditions.

It is true that the 2011 Tohoku earthquake and resulting tsunami wreaked havoc on Japan. It also resulted in the largest nuclear power plant accident since Chernobyl when the tsunami damaged the Fukushima Daiichi Nuclear Power Plant. Radioactive particles were released into the atmosphere and ocean, which effectively closed local Japanese fisheries.

While there were unfortunate effects from the disaster around the Fukushima Power Plant in Japan, the facts show that people in Alaska, Hawaii, and the West Coast of the United States aren't in any danger.

The fuel rods in the Fukushima power plant partially melted and radionuclides were released into the ocean. To a lesser extent, radionuclides were also released into the air and were absorbed by the ocean when they rained down upon it. These two pathways introduced mostly iodine-131, cesium-137, cesium-134, and strontium-90 into the area surrounding the power plant. Only two of those remain today (cesium-137 and strontium-90), because the other two radionuclides have short half-lives and have since decayed away.

We have no accurate estimates of how much of each of these radionuclides was released into the ocean, but the current estimates are above levels released by the Three Mile Island accident, but below levels released by the Chernobyl accident. How much will reach the U.S. West Coast? Answer: not much—certainly not enough to increase radiation levels five- or tenfold. Claims of such increases are the tip-off that facts are being sacrificed for attention. The good news is that factual information is available to those interested, and this Health Physics Society website is a good place to start.

Other information that addresses the recent speculative articles can be found at:
Is it safe to visit northeast Japan after the nuclear accident deposited fallout there?
Many people have posed this question. I believe it is safe. Extensive testing has shown that the ambient radiation levels and the radioactivity levels in food products in major cities have not risen above normal background levels that existed prior to the event. Testing found elevated radiation levels only out to about 80 kilometers from the reactors. Some test results can be seen at the following Nuclear Regulation Authority of Japan website:

Testing of food products that could reach markets is ongoing and effective. Reports to the contrary are just wrong. I feel that the safety limits being used are more than adequate to protect public health, and I do not believe one has to be overly concerned about radiation exposure when visiting Japan.

Finally, my colleagues and I are encouraged by a recent report from a United Nations scientific committee that found the public was exposed to only low levels of radiation (dose). This amounted to less than the dose they received from natural background radiation. And that dose was received in the year of the accident. Today, doses are vanishingly small since fallout levels are greatly reduced and food is monitored.
What studies have been done on the impact of the Fukushima accident?
Several international studies have been done. The most recent and complete study is by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). This study, by 80 leading scientists, drew several conclusions:
  1. On the whole, the exposure of the Japanese population was low, or very low, leading to correspondingly low risks of health effects later in life.
  2. The actions taken to protect the public (evacuation and sheltering) significantly reduced the radiation exposures that would have otherwise been received.
  3. No radiation-related deaths or acute effects have been observed among nearly 25,000 workers involved at the accident site.
The committee specifically looked at risks to children. They looked at measurement data in children and U.S. military personnel and made detailed exposure estimates (doses). The doses were so low that the UNSCEAR committee refrained from projecting hypothetical risks into the future. In practically all instances, these dose levels were far below those where human health effects have been observed. 

The committee concluded, "Radiation exposure following the nuclear accident at Fukushima-Daiichi did not cause any immediate health effects. It is unlikely to be able to attribute any health effects in the future among the general public and the vast majority of workers."
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