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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Bluefin Tuna Off Aomori Prefecture Fetches 155 Million Yen in First Auction of the Year at Tsukiji Fish Market in Tokyo

It is the highest ever price fetched. The bluefin tuna was caught off the coast of Ooma, Aomori Prefecture. A nuclear power plant is being constructed in Ooma.

The construction was halted after the Fukushima I Nuclear Power Plant accident, but Yukio Edano, then-Minister of Economy, Trade and Industry, allowed the restart of construction at Ooi in September last year.

The town of Ooma is very famous for its excellent tuna, and part of the opposition to the nuclear power plant there is because of potential danger the exhaust water from the plant may pose to marine life.

Oh well. Aomori Prefecture is solidly an LDP territory, with Higashidori Nuclear Power Plant and Rokkasho Reprocessing Plant already in place. They want more nuclear subsidies. So what the prized tuna fish goes bust?

From Nikkei Shinbun (1/5/2012):

新春恒例の初セリが５日、東京・築地市場で開かれ、青森・大間産のクロマグロが１キロあたり70万円、１匹１億5540万円の史上最高値で競り落とされた。これまでの最高値は昨年の5649万円（キロ21万円）。落札者は昨年に続き、すし専門店「すしざんまい」を展開する喜代村（東京・中央）。

The first auction of the year was held at Tsukiji Market in Tokyo on January 5. Fluefin tuna caught in Ooma, Aomori fetched 700,000 yen [US$8,000] per kilogram, or 155.4 million yen [US$1.78 million] for the whole fish, the highest ever in history. Before this year, 56.49 million yen per fish (210,000 yen per kilo) was the highest. The winning bidder was the same as the last year's winning bidder, sushi shop Kiyomura (Chuo-ku, Tokyo) with "Sushizanmai" sushi chain.

This is the photo of the 155 million yen tuna (from Nikkei article above):

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Russia Today News Insinuates Fishing Is Banned on West Coast of the US Because of Radiation Contamination from #Fukushima Nuke Accident, and Japanese Freak Out

This has been one of the most "popular" pieces of "news" circulating furiously on Twitter in the past few days. Looking at the date of the news video uploaded onto Youtube by Russia Today (July 21, 2012), RT seems to be the source of the "news". The story is reported by RT's Madina Kochenova, according to the video description.

The video has a catchy title (literally): "Fishy Catch: Fukushima fins spotted on US shores".

Many Japanese people in Japan on Twitter are so distressed (or feigning distress) that the fishing is banned in California because of radiation contamination. Oh My God, look at that sign, it does say "No fishing"! OMG, what do we do when the US demands compensation? We're eating fish here in Japan, and over there they have banned fishing! Radiation contamination must be really bad there, but it cannot be as bad as in Japan, so we are made to eat highly contaminated fish that are caught and sold freely in Japan! And on and on and on.

After having seen the retweet on this "news" today for nth time, I finally happened on the source material, the video by RT. Here's the screen shot that has freaked the Japanese and spawned endless tweets and retweets on radiation contamination scare and speculations about compensation money that will be demanded by the US: "No fishing" sign at a port.

RT's reporter Ms. Madina Kochenova in Los Angeles doesn't outright say (of course not) the sign has to do with the radiation contamination in fish caught and hauled at the port because of the Fukushima accident. But RT strongly insinuates that fishing is banned because of the radiation contamination, making little room for the viewers to come to any other conclusion. Ms. Kochenova says:

"This summer California fishermen are ready to inspect their catch closer than ever before."

As she says this, the "No fishing" sign is shown. Then, she apparently talks to a fisherman, who says:

"The word "radiation" creates a fear in people."

Uh.. yes, so? The fisherman may as well be answering to the reporter's question, "So tell me, what do you think of when you hear the word "radiation"?"

From this, many in Japan have connected the dots - fish in California are contaminated with radioactive materials from Fukushima, and they have banned fishing because of that, and see, the fisherman is afraid, and the US government will demand compensation from Japan!

In the 2 minutes and 50 seconds news clip, RT shows photographs of damages from last year's earthquake/tsunami/nuclear accident, then the soundbites from the US media when they reported back in May on the Stanford researchers' findings of small amount of radioactive cesium in bluefin tuna off the coast of California (10 Bq/kg or so, or about 5 times the background) last year.

I've never heard of fishing ban on the west coast of the US or Canada or Mexico anywhere because of radiation. This is fishy, I thought. Then, looking at the screen shot of the "No fishing" sign, I noticed letters and numbers on the sign: "L.B.M. .16.08.460". Hmmm. Let's run these letters and numbers...

As far as my quick search goes, "L.B.M. 16.08.460" is one of the sections in the Long Beach Municipal Code, and it is about fishing restrictions. The section has been there in the Code, it has been amended numerous times (here is one of them, here's another). The sign that RT used in the background of the news report is probably the sign to tell recreational anglers that they cannot fish at that location.

Almost 17 months since the start of the nuclear accident, we are no wiser.

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(UPDATED) Stanford Researchers Found Radioactive Cesium of #Fukushima Origin in Pacific Bluefin Tuna Off California Coast

(UPDATE) The paper as posted in the Proceedings of the National Academy of Sciences (PNAS):

http://www.pnas.org/content/early/2012/05/22/1204859109.abstract?sid=92ce1d87-a1c1-4fd4-a674-2db99d7bf957

(H/T karl)

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The researchers from Stanford University, California caught 15 tuna fish off the coast of southern California last August and measured radioactive cesium-134 and -137. Nine months later, it is in the news now that their research paper has finally been published in The Proceedings of the National Academy of Sciences.

Neither the Wall Street Journal article below, or Reuters', mentions the exact numbers for radioactive cesium, but Japan's Kyodo News does:

Cesium-134: 4 Bq/kg
Cesium-137: 6.3 Bq/kg

The Stanford researchers think the fish were in the Japanese water about a month after the accident started. Daniel Madigan, who led the study, said they were surprised to find cesium at all, and that it was found in all samples they collected and tested.

Wall Street Journal says the added radioactivity is about 3% of the naturally occurring radioactivity in the fish, and Reuters converts becquerels into curie to put things in perspective saying "It takes 37 billion becquerels to equal 1 curie".

Well, at least the Japanese media, MSM or alternative, has gotten comfortable over the last year quoting the measured numbers instead of trying to put them in perspective without mentioning the numbers.

From Wall Street Journal (5/28/2012; emphasis is mine):

Tuna Carried Fukushima Radioactivity to U.S. Coast

By ROBERT LEE HOTZ

Pacific bluefin tuna migrating last year from coastal Japan to the waters off Southern California contained radioactive cesium isotopes from the Fukushima nuclear disaster, scientists reported Monday.

The amount of radioactivity in the fish was one-tenth the level the U.S. and Japan consider dangerous, and likely posed no public health hazard or risk to people who ate the seafood, the scientists said. But the study showed for the first time that migrating sea life rapidly brought traces of radioactive elements from the damaged Fukushima Daiichi nuclear reactors across vast distances.

"The tuna packaged it up and brought it across the world's largest ocean," said marine ecologist Daniel Madigan at Stanford University, who led the study team. "We were definitely surprised to see it at all and even more surprised to see it in every one we measured."

Their findings raise the possibility that other wide-ranging sea-life that foraged near Japan, such as turtles, sharks and seabirds, may also have carried low levels of radioactive cesium from the accident around the Pacific basin. The scientists expect to conduct more tests on migrating bluefin tuna as well as albacore tuna, sea turtles, and several shark species this summer.

Their research was published Monday in The Proceedings of the National Academy of Sciences.

Prized as a sushi delicacy in Japan and around the world, Pacific bluefin tuna spawn in the Sea of Japan, among other locales. As they grow, the fish usually travel around the southern tip of Japan and follow the Kurishio Current up the country's east coast, past the scene of the nuclear accident, before migrating over 6,000 nautical miles to the eastern Pacific. The fish eventually return to their birth waters to spawn.

In their study, Mr. Madigan and his colleagues tested tissue from 15 young Pacific bluefin tuna caught by recreational fisherman off the coast of San Diego in August 2011, about five months after an earthquake and a tsunami severely damaged the Fukushima reactors, triggering the largest known accidental release of radioactivity into the ocean.

For weeks after the accident, levels of radioactivity were up to 10,000 times normal in the coastal waters off eastern Japan, where the bluefin tuna spend their early life before migrating across the ocean.

In the young bluefin tuna that reached California, the researchers found slightly elevated levels of cesium-137 and cesium-134, two primary products of nuclear fission that tend to concentrate in muscle tissue. The amount of cesium 137 was five times as much as the background level, leftover from nuclear weapons testing decades ago. Prior to the Fukushima accident, cesium-134, which has a half-life of about two years, was undetectable in seawater or marine life.

Overall, the levels were just enough to raise the naturally occurring radioactivity of the fish by about 3%, the scientists said.

"We found that absolutely every one of them had comparable concentrations of cesium-134 and cesium-137," said marine biologist Nicholas Fisher at Stony Brook University in New York state, who was part of the study group. "It is crystal-clear data."

For comparison, the researchers also tested tissue from yellowfin tuna caught at the same time last August and tissue preserved from bluefin tuna caught in 2008, three years before the nuclear accident. Yellowfin tuna typically spend their entire lives in the sea off the coast of California.

In both the yellowfin and the tissue of the 2008 bluefin, the scientists didn't find any cesium-134 and detected only the expected background levels of cesium-137.

Write to Robert Lee Hotz at sciencejournal@wsj.com

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