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As part of an ongoing series documenting the impacts of the Fukushima disaster on the North Pacific and west coast, this diary summarizes a newly published study by Delvan Neville and colleagues in the peer-reviewed journal Environmental Science and Technology. The paper reports measurements of Cesium-134 and Cesium-137 in 26 albacore tuna caught off the west coast of North America between 2008 and summer 2012.  Because of its relatively short half-life (~2 years) 134-Cs is an unambiguous tracer of radionuclides released from the Fukushima Dai-ichi disaster which began in March 2011. Fish collected in 2011 and 2012 had higher 134-Cs and 137-Cs that was due to Fukushima sourced cesium in the Pacific. Fish collected in 2008-2009 had lower 137-Cs activities that largely reflected historic releases of the isotope from atmospheric nuclear weapons testing in the 20th century.  The authors conclude that given the highest levels of Cs isotopes measured in albacore tuna, human consumption of the fish would not not represent a significant increase in annual radiation dose. The corresponding radiological health risk due to Fukushima derived radiocesium in these tuna is, therefore, very small.

As a result of the Tohoku earthquake and subsequent tsunami there were significant releases of radionuclides from the damaged reactors at the Fukushima Dai-ichi Nuclear Power Plant.  Of note were releases of radioactive cesium isotopes (134-Cs with a half-life ~2 years and 137-Cs with a half-life ~30 years) in an approximate ratio of 1:1.  Because of its short half-life legacy 134-Cs from atmospheric weapons testing and the Chernobyl nuclear disaster in 1986 is no longer present in the environment so that this isotope serves as a unique tracer of Fukushima derived isotopes in the environment.

Neville and colleagues measured 134-Cs and 137-Cs in albacore tuna (Thunnus alalunga) collected off the coast of Washington and Oregon between 2008-2012.

Locations where albacore tuna were collected 2008-2012 for subsequent Cs isotope analysis.
Of the 26 fish analyzed all collected in 2008-2009 (before the Fukushima disaster) and 7 of 17 albacore collected in 2012 contained no detectable 134-Cs and had between 0.1-0.3 Bq/kg of 137-Cs (for a brief primer on units used to report radionuclide levels in the environment see here). In 12 of 19 albacore collected in 2011 and 2012, 134-Cs from Fukushima was detected (0.02-0.36 Bq/kg) and 137-Cs was elevated relative to background with activities of 0.23-0.82 Bq/kg.  The figure below summarizes the results of the study with panel a) showing 137-Cs present in tuna over all years, b) showing 134-Cs from Fukushima over time in fish and c) showing non-Fukushima 137-Cs in present in fish owing to legacy 137-Cs present in the environment.
137-Cs and 134-Cs in albacore tuna collected off the west coast of North America between 2008 and 2012 showing the contribution of Fukushima Cs to activities before and after the disaster.
The highest total combined activity of cesium in the most contaminated albacore was 1.18 Bq/kg which is 0.1% of the intervention level of 1200 Bq/kg set by the US Food and Drug administration (FDA).  Consumption of 1 kg of tuna with this level of contamination increases radiation dose to a human consumer by ~20 nanoSievert (10^-9 Sv) or by 0.0006% given average radiation dose from natural sources experienced by the average American. Fukushima derived radionculides in albacore tuna, therefore, are unlikely to represent a significant radiological health threat.  This conclusion is similar to previously published work by others on Pacific bluefin tuna.

An interesting conclusion of the study is that Cs isotopes may allow research scientists to answer outstanding questions with respect to the population biology, distribution and migratory behavior of albacore tuna.  This is because differences in isotope composition of the fish varied with size and age of the albacore measured in the study.

Originally posted to MarineChemist on Tue Apr 29, 2014 at 12:40 PM PDT.

Also republished by SciTech.

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Comment Preferences

  •  +4/Rec'd for showing error bars. /nt (10+ / 0-)

    Happy little moron, Lucky little man.
    I wish I was a moron, MY GOD, Perhaps I am!
    —Spike Milligan

    by polecat on Tue Apr 29, 2014 at 12:54:47 PM PDT

  •  Many thanks, as always. (6+ / 0-)



    Is it true? Is it kind? Is it necessary? . . . and respect the dignity of every human being.

    by Wee Mama on Tue Apr 29, 2014 at 01:35:07 PM PDT

  •  Study Author Nuclear Industry Affiliations (3+ / 0-)
    Recommended by:
    Tinfoil Hat, Jim P, maregug

    What isn't mentioned in Higley, the study creator's relationship with not just the nuclear industry but with their lobbying arm and her long history of trying to whitewash nuclear energy issues. She has some very clear conflicts of interest beyond her job at the university.

    She is on NEI's (nuclear industry lobby group) list of "experts" they hand out to the media. IE: people they know will give the industry talking points for them.

    This has some of Higley's media shenanigans outlined here.  
    http://www.fukuleaks.org/...

    "Katheryn Higley, the other person talking to the press is the head of nuclear engineering at Oregon State and is running a “Partnering With Industry” program to promote nuclear power."

    The timing of the study is also interesting. They look at 2011 and 2012 fish but not 2013 fish. Even with time needed to conclude the study and prepare for publication it seems odd to cut off at 2012 but be making sweeping statements of the situation for fish now. This is a fluid situation where things are expected to change and the worst is expected to be starting now, not to have been back in 2011.

    It should also be noted that albacore were not among the fish with higher uptakes when screened in Japan. The highest I saw was less that 50 bq/kg. This isn't a situation of no contamination but fish that have less ability to absorb and retain cesium.

    So is it information about the situation with fish, yes. Can this one study be used to conclude all Pacific fish is safe to eat and will be in the future? Absolutely not.
    No consumption of cesium 137 or 134 is actually safe. IPPNW is pushing for a food limit of 5 bq/kg in the EU and Japan's intervention level where they pull food off the market is 100 bq/kg. The US 1200 bq/kg level isn't a level of promised safety. It is the level where the govt. will pull food off the market. It is also the highest intervention level in the world.

    •  Hi SDstuck (4+ / 0-)
      Recommended by:
      Wee Mama, palantir, T100R, northstarbarn

      Thanks for your comments.  That one of the authors is recognized as a health physics expert, I think, would reflect a strength rather than a weakness of the study.  

      Samples collected as recently as summer 2013 and analyzed for Cs isotopes by Health Canada did not contain any Fukushima derived 134 or 137.  Species analyzed included chum salmon, halibut, spiny dogfish and sablefish.  The paper is in press and I will report those results when the paper appears in print.

      The authors of this study, nor I, have concluded that all fish or any fish are necessarily safe to eat.  What they did do is determine the radiation dose associated with consuming albacore tuna with maximum Cs isotope activities.  The dose is very, very small compared to other exposures we all experience.

      If you are interested in observed activities in fish the Japanese have been making many measurements.  Dr. Jing Chen of Health Canada considered these measurements in the following open-access paper.  Average concentrations of 137-Cs and 134-Cs were 12 and 26 Bq/kg respectively within 20 km of the Fukushima power plant.

      Based on the activities of 134-Cs and 137-Cs being measured in North Pacific seawater and allowing for bioconcentration of Cs (diary about this here) it is unlikely that fish harvested off the west coast will approach the 5 Bq/kg which you cite above.

      I will report more numbers as they are published.

  •  Higley Listed On NEI Media Contacts (0+ / 0-)

    http://www.nei.org/...

    Higley listed on the media handout NEI gave out in 2011 of their favored experts.

    •  Are we to take from these posts (0+ / 0-)

      that we are to disregard an accomplished scientist's work because of a mere affiliation? That we are to question her integrity because a particular organization recognizes her skills?

      I think Dr. Michael E. Mann might find that a familiar tactic.

    •  curious--how does that change any of the (0+ / 0-)

      measured numbers?

      And if someone else has any measured numbers that are different, where can we see them?

      In the end, reality always wins.

      by Lenny Flank on Tue Apr 29, 2014 at 05:59:01 PM PDT

      [ Parent ]

      •  43 fish over 2 years, and before the main wave (1+ / 0-)
        Recommended by:
        maregug

        hits? Plus then, the objective value of averages?

        A few months ago 37 fish were caught off Southern Japan. One had 137x Japan's 'safe' level, 4 had 2x the safe level, and the rest were below. (Put aside that 'safe level' is a fiction in itself for the moment).

        That one fish ain't caught, and you have an 'average' of the radioactivity in 36 fish that says 'no worries here.'

        But even without that one fish, with 4 of 36 in the gross world of living forms and not mathematical constructs, you have an 11.1% chance of getting a dose that even the government has qualms about. On average.

        When you have, frankly, ludicrous sample sizes by which to promote inferences -- of any sort -- the personal income/status of the person doing the study becomes a consideration.

        There is, after all, an indisputable record of official agents falsifying, misdirecting, and outright lying all up and down the industry, from the ground through the emissions.

        We know for a fact that you can have, as they had in Japan, a SPEEDI station registering nothing at all while a few meters away detectors go to their max instantly. Walk your toddler a few feet this way or that, and you have radically different risks.

        Small samples are clearly non-informative. And practically every study I've seen which says 'no problem here' is based on ... well, I don't know why anyone would cite such inadequate data as indicating anything. 43 fish, 6 fish, 18 fish... seriously?

        Come back with a 43,000 fish sample, and now we're talking science. After all, we can all finish the phrase 'there are lies, damned lies, and...'


        A government is a body of people usually notably ungoverned. -- Firefly

        by Jim P on Tue Apr 29, 2014 at 07:10:06 PM PDT

        [ Parent ]

        •  thanks for that, but it didn't answer my (1+ / 0-)
          Recommended by:
          T100R

          question . . . How does the fact that this person was listed as a media contacts for NEI change any of the measured numbers?

          As for YOUR measured numbers, surely you are aware that southern Japan is not the same as the US west coast. And for someone who just griped for nine paragraphs about "small sample size!!!" (even concluding "come back with a 43,000 fish sample, and now we're talking science"), do you understand why it's hard to take you seriously when YOUR offered sample size is 37 fish?

          In the end, reality always wins.

          by Lenny Flank on Tue Apr 29, 2014 at 07:23:19 PM PDT

          [ Parent ]

          •  I was demonstrating how averages work. (0+ / 0-)

            You didn't really miss that, did you? I wasn't extrapolating to all fish everywhere. If I did that, I would be using the same 'method' I'm criticizing.

            I was showing how 'averages' tell you little to nothing about actual cases with that example. Moreover, how looking at 'averages' on a microscopic-level gives a different message than looking at 'averages' on the level on which we actually live life (actual fish being eaten by actual humans.)

            Think you might have rushed through and not really thought about what you read.

            I take it you acknowledge 47 fish, 6 fish, 18 fish is a ludicrously small sample upon which to assert safety or otherwise.

            As to the other: any appeal to authority has value only insofar as the authority has a track record of being correct. At least in Science, if not Religion.

            Those employed by the nuclear industry have a very very bad track record. When what's being presented plainly can't tell you anything objective, and it's presented by someone with a stake, it's worthy of noting when one is assessing the value of the 'evidence.'

            I don't know. Maybe some people feel 'oh, they've got a certificate, therefore they are correct' but I don't see how that makes inadequate samples suddenly become adequate.


            A government is a body of people usually notably ungoverned. -- Firefly

            by Jim P on Tue Apr 29, 2014 at 07:50:01 PM PDT

            [ Parent ]

            •  and yet again my question goes unanswered . . . (1+ / 0-)
              Recommended by:
              T100R

              And yet again nobody provides any different numbers . . . .

              In the end, reality always wins.

              by Lenny Flank on Tue Apr 29, 2014 at 07:52:36 PM PDT

              [ Parent ]

            •  ps--I have not said a single word about (1+ / 0-)
              Recommended by:
              T100R
              I take it you acknowledge 47 fish, 6 fish, 18 fish is a ludicrously small sample upon which to assert safety or otherwise.
              "safe" or "non-safe". I simply asked why measured numbers would change simply because someone we don't like is associated with them---and where I can see different numbers from anyone who has them.

              And all i got was some silly CT about "we can't trust this or that".

              Fine.  Don't trust them. Show me the numbers from people you DO trust, and show me how those numbers are different.

              In science, data trumps.  Until then, you're just pissing in the wind.  (shrug)

              In the end, reality always wins.

              by Lenny Flank on Tue Apr 29, 2014 at 08:14:32 PM PDT

              [ Parent ]

        •  Hi Jim P (2+ / 0-)
          Recommended by:
          northstarbarn, Jim P

          It takes time and resources to make measurements so I think it is unreasonable to fault the scientific community for not being able to measure everything everywhere. Scientific understanding of the activities of Fukushima derived radionuclides is increasing incrementally.  If you would like to see more measurements made of more species I urge you to lobby your various levels of government to address the problem with more resources.

          That being said, as I indicated above, the Japanese have been making many measurements.  The Japanese Fisheries Agency has made over 39,000 as of November of last year which are detailed online here.  Not quite the 43,000 you have requested but certainly in the right ballpark.

          The percentage of fish registering more than 100 Bq/kg has dropped from 53% to ~2% since 2011 until November 2013 in Fukushima prefecture.  The percentage has dropped to less than 1% from 6.5% in the same time period in other prefectures.  All the data is available for download at the site. These concentrations of Cs in fish result from many orders of magnitude higher activities of Cs in the coastal waters off of Japan immediately after the disaster.  Such activities in seawater here will not occur based on modeling of plume transport and measurements being made in the North Pacific.  

          All available measurements of fish caught off of the west coast of North America thus far suggest that there is little radiological health risk due to Fukushima radionuclides.

          •  Hi MarineChemist (0+ / 0-)

            I don't blame anyone for having a small sample. I do think, however, that possessed of a small sample, one shouldn't mask public relations as science.

            Of course, my '43,000' is not scientifically-based, just a way to give a dramatic indication of the scales required to make any honest evaluation.

            We'll forget for a moment that Japan has engaged -- according to Mayors, Doctors, Hospital Managers, former Prime Ministers and Diet members, Journalists -- in a massive suppression of evidence, and instead let's accept Fisheries' studies as being complete and truthful.

            Again, we are back to averages versus specific cases. 'Averages' are the Achilles Heel of statistical studies.

            Averages can be massively deceptive, as you know. They can't really be relied upon in all areas of life, though they work in some.

            The plaint 'but this is the tool we have' is not the same thing as 'the tool is adequate to the purpose.' The reality that there's clustering of radiation from Fukushima makes appeal to averages weaker than stringent thought requires, imo.

            We can take the case of the infamous 'safe levels.' These are based on studies, and averages, of healthy males in their 20s. But we know that radioactivity has massively more impact on embryos, children (girls particularly), on women, on people with pre-existing troubles, and as some recent research might indicate -- genetic makeup! The standard often referred to is the one which doesn't apply to the majority of humanity.

            Thanks for taking time to answer.


            A government is a body of people usually notably ungoverned. -- Firefly

            by Jim P on Tue Apr 29, 2014 at 09:02:27 PM PDT

            [ Parent ]

            •  Hi Jim P (3+ / 0-)
              Recommended by:
              northstarbarn, T100R, nojay

              All the evidence suggests that the activity of Cs from Fukushima has been decreasing with time in fish caught off the Japanese coast.  Most recent measurements here for Jan. 2014 show 1.6% of ~2000 fish caught at Fukushima prefecture were > 100 Bq/kg.  Effectively 0% from other prefectures exceeded that level (1 fish in ~2,200).  This in Japan where the activity of Cs is seawater from Japan is orders of magnitude greater than what we will experience in N. America.

              This is not a PR exercise but reporting real numbers as they are being generated.  The highest combined 134 and 137 Cs activities in the albacore and other species caught off the west coast are about 1 Bq/kg which result in very, very small doses to people who choose to consume fish.  They actually receive orders of magnitude higher doses from 210-Po naturally present in the fish.

            •  how exactly does Japan stop people from (1+ / 0-)
              Recommended by:
              T100R

              catching fish off the American West Coast and measuring the radioactivity in them.

              Please be as detailed as possible.

              In the end, reality always wins.

              by Lenny Flank on Wed Apr 30, 2014 at 05:04:39 AM PDT

              [ Parent ]

  •  Is cesium the biggest risk to consumers? (3+ / 0-)
    Recommended by:
    palantir, T100R, ladybug53

    I understand that cesium is useful for tracing the radioactive "cloud" and how nutrients move across the Pacific, and isolating the effects of Fukushima.

    But in terms of human risk from consuming fish, is cesium the biggest danger? When I was growing up (before the 1962 atmospheric atomic test ban) what people worried about most was strontium 90, which I gather displaces calcium in bones and teeth.

    I am always skeptical of industry and government claims not to worry, it's entirely safe, nothing to see here just move along. But if this really is good news, that's good.

  •  Pacific Albacore already contains mercury (2+ / 0-)
    Recommended by:
    nojay, northstarbarn

    ...an average of 0.17 milligrams/kilogram.

    That's more than salmon, but less than Atlantic albacore, and way less than swordfish. It's not much - by my calculation, 1 kg of albacore contains 0.0037% of the EPA's annual mercury intake limit for a 160-lb adult.

    I bring this up to put the question of Fukushima into context. Our seafood wasn't "pure" to begin with... and mercury is the greater threat to our health:

    Cesium:  0.0006% of average annual radiation exposure.
    Mercury: 0.004% of the maximum safe annual intake.

    Mercury enters the environment primarily from the extraction and combustion of coal (that's why the concentrations are higher in Atlantic species).

    We have to stop burning coal. But I'm not convinced that we can build enough wind and solar fast enough to avert the worst effects of global warming AND feed 7 billion people.

    I suspect that criticism of research that shows anything less than OMG! levels of radiation crossing the Pacific from Japan is motivated by another agenda... "no nukes, nowhere, no-how".

    There must never be another Fukushima, or another Chernobyl. But to to reduce that risk to zero, by never building another nuclear power plant, compounds the risks of famine, economic collapse and war resulting from climate change + overpopulation.

    So, I'm not willing to take nukes off the table just yet.

    “It is useless to attempt to reason a man out of a thing
    he was never reasoned into” - Jonathan Swift

    by jjohnjj on Wed Apr 30, 2014 at 08:55:47 AM PDT

    •  alas nukes do not have any less a carbon footprint (0+ / 0-)

      than renewables do.

      Nukes simply are not a magic bullet to kill global warming.

      In the end, reality always wins.

      by Lenny Flank on Thu May 01, 2014 at 08:04:07 PM PDT

      [ Parent ]

      •  Not looking for magic bullets. (0+ / 0-)

        I see nuclear power as a crutch - something we may need in the near term, to help the grid keep up with population growth while we replace the fossil infrastructure with green.

        “It is useless to attempt to reason a man out of a thing
        he was never reasoned into” - Jonathan Swift

        by jjohnjj on Thu May 01, 2014 at 09:30:30 PM PDT

        [ Parent ]

        •  alas, it won't work for that either (0+ / 0-)

          It takes years to build a nuke, and their cost has already tripled in just the past five years. That is why companies like Duke Energy have already cancelled their planned nukes.

          In the end, reality always wins.

          by Lenny Flank on Fri May 02, 2014 at 05:35:59 AM PDT

          [ Parent ]

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