Radiation Exposure from Eating Pacific Bluefin Tuna Affected by Fukushima Nuke Accident Miniscule, US Researchers Say

32 microsieverts per year or 0.032 millisievert per year, for the Japanese people in Japan, 0.9 microsievert per year or 0.0009 millisievert per year for people in the US.

Exposure from radioactive polonium in fish is much greater than radioactive cesium of Fukushima origin, says Professor Nicholas Fisher at Stony Brook University in New York.　(See Table 1 at the bottom of the post.)

He also says the the amount of radioactive cesium in bluefin tuna caught off the coast of San Diego in 2012 dropped in half, compared to the bluefin tuna caught in 2011.

Unlike most of the Japanese media these days, the US media, including CNN below, still talks about radiation in terms of dental X-ray or transcontinental flight. Just give us the number, please.

From CNN (6/3/2013):

Fukushima tuna study finds miniscule health risks

Go ahead, order the sushi.

Levels of radioactivity found in Pacific bluefin tuna that spawned off Japan around the time of the Fukushima Daiichi nuclear accident are far below anything that would pose a health risk and have dropped in fish caught the following year, U.S. researchers reported Monday.

The latest findings follow up on a 2012 study that found radioactive cesium, a nuclear reactor byproduct, in tuna caught off California in the months after the triple meltdown at Fukushima Daiichi. The attention that study received led scientists to take another look at the data, said Nicholas Fisher, a marine science professor at New York's Stony Brook University.

"People did not know how to translate that into a dose, or into what risk do I have from eating that tuna," Fisher said. "The paper that's coming out today addresses that."

They found that anyone who eats the bluefin -- highly prized for sushi and sashimi -- would get about 5% of the radiation they'd get from eating one typical banana, a fruit high in naturally radioactive potassium. The results were released Monday by the journal Proceedings of the National Academy of Sciences.

Even subsistence fishermen, who eat far more fish than the typical American, would receive a dose of radiation from the cesium isotopes released in the meltdown equivalent to a single dental X-ray, Fisher and his colleagues reported. That translates to a "worst-case scenario" of two additional cancer deaths for every 10 million people in that category, he said.

The doses were calculated from fish caught off San Diego in August 2011. A follow-up study with fish caught in 2012 found the amount of cesium-134 and -137 dropped by about half in those tuna, Fisher said.

(Full article at the link)

Japan's Kyodo News says exposure from radioactive polonium in fish is much greater than radioactive cesium of Fukushima origin.

It also says the radiation exposure would be 0.032 millisievert in one year.

The paper abstract:

Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California

Daniel J. Madigan, Zofia Baumann, and Nicholas S. Fisher

Abstract

The Fukushima Dai-ichi release of radionuclides into ocean waters caused significant local and global concern regarding the spread of radioactive material. We report unequivocal evidence that Pacific bluefin tuna, Thunnus orientalis, transported Fukushima-derived radionuclides across the entire North Pacific Ocean. We measured γ-emitting radionuclides in California-caught tunas and found 134Cs (4.0 ± 1.4 Bq kg−1) and elevated 137Cs (6.3 ± 1.5 Bq kg−1) in 15 Pacific bluefin tuna sampled in August 2011. We found no 134Cs and background concentrations (∼1 Bq kg−1) of 137Cs in pre-Fukushima bluefin and post-Fukushima yellowfin tunas, ruling out elevated radiocesium uptake before 2011 or in California waters post-Fukushima. These findings indicate that Pacific bluefin tuna can rapidly transport radionuclides from a point source in Japan to distant ecoregions and demonstrate the importance of migratory animals as transport vectors of radionuclides. Other large, highly migratory marine animals make extensive use of waters around Japan, and these animals may also be transport vectors of Fukushima-derived radionuclides to distant regions of the North and South Pacific Oceans. These results reveal tools to trace migration origin (using the presence of 134Cs) and potentially migration timing (using 134Cs:137Cs ratios) in highly migratory marine species in the Pacific Ocean.

Full paper PDF: http://www.pnas.org/content/early/2013/05/30/1221834110.full.pdf

Part about radiation exposure for Japan and for the US:

Table 1 showing the radiation dose:

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