The question you should have asked about Fukushima, but probably didn’t.

The 2011 Fukushima Dai-ichi nuclear fiasco was a disaster that is still affecting Japan. But it also raised an onslaught of questions about the potential dangers of the leaked radiation back here in the US. Some of the major ones are:

Is Fukushima radiation going to fry the West Coast of the U.S.?!?  No.

It MUST be causing all those sea stars to melt…right? Wrong.

Am I ever going to eat delicious fish from the Pacific ever again?? Yes. Fear not.

Is a giant, radioactive monster going to emerge from the ocean depths and unleash a reign of terror on mankind?!?! Er…Not likely….but even I have to admit…the timing is oddly suspicious on that one.

I’m not a monster.
Source: Kightay

Because the incident was the largest accidental release of radioactive materials in the ocean ever, these concerns are not unwarranted. We should be asking questions about human and ocean health but not ignoring evidence when confronted with it.  However, what I find hugely disconcerting is the one question that is hardly ever asked:

What about the marine life right off the coast of Japan? How did the largest accidental release of radioactive materials in the ocean impact them? 

What about us?

As always, DSN is here to help and shed light on the question you forgot have yet to ask.

Which marine organisms were most affected?

As with many oceanic ‘pollutants’ and your Facebook relationship status, “it’s complicated” is the honest answer here.  There are numerous factors to just how radioactive our watery friends became after the Fukushima catastrophe went down. Distance from point source, is the most obvious. The closest to the power plant, the higher the dose. The farther away…well you know what they say… “dilution is the solution to pollution.”

However, less intuitive forces are also at work. For instance, depth, whether or not you are a demersal (bottom-dwelling) or pelagic (open ocean) critter, how mobile you are, your life stage, and whether you’re a fish, invertebrate, mammal, or seaweed could make a drastic difference on the level of radionuclides you would be susceptible to. Heck, even which radionuclide we are talking about makes a difference (because of the science currently available, I have stuck with Cs-134, -137, and I-131 for the sake of this discussion).

When it comes to radiation, mammals are the most sensitive. Hence why people care so much about…well…people. They will be affected first and this is why the regulatory levels (100 Bq/kg wet) are set at what they are.  This falls under the idea…you protect the most sensitive thing…you protect everything else (an idea not tested in all scenarios). After that, you have the fish and then the invertebrates. Most invertebrates are actually relatively hardy regarding radiation…comes with the territory of living with NATURAL radiation for so many thousands of years.  Not far behind, are the seaweeds. Seaweeds even accumulate some radioactive isotopes like Iodine-131 to higher levels than the seawater.  Accumulated iodine normally acts as an antioxidant, thus they like it cause it saves them from certain oxidation reactions that can be detrimental to their poor seaweedy cells. However, people don’t particularly like it when seaweed accumulates radionuclides…cause people eat lots of seaweed in Japan.

Concentrations of Cs in species around Japan after Fukushima.  I call blue team. Source: Wada 2013
Concentrations of Cs in species around Japan after Fukushima.
I call blue team.
Source: Wada 2013

So how much was marine life influenced by Fukushima radiation? The graph above that looks uncannily like paint ball practice tells us the Cesium concentrations in both pelagic (blue team) and demersal (red team) species. The little black line shows the shift in Japan’s regulatory limit.* Though critters that play in the water column may have received a higher dose at first, that quickly faded. What may catch more of your attention is that red team has piss poor accuracy on the paint ball field has levels that remain relatively constant over time. That is because they live closer to the sediments, where all pollutants go to hang out with other pollutants. Thus, these critters continue to be dosed with radiation and will continue to for decades to come (Don’t forget half life of Cs-137 is about 30 years).

Lastly, and perhaps most importantly, fish can metabolize Cesium relatively quickly (and I-131’s half life is so short that it also rapidly leaves the body). Though fish can accumulate Cesium to about 100 times seawater levels, if they leave a contaminated area the loss rate is pretty high.

To restate, pollutant exposure is a complicated process (no matter which kind of pollutant you are talking about). Variability is the name of the game, but now you know who potentially got the shorter end of the nuclear disaster schtick.

How much radiation can marine critters actually take? 

Source: UNSCEAR 1996
Source: UNSCEAR 1996

For the most part, radiation exposure in marine organisms causes the same damaging effects as radiation in humans. At high doses, fatality occurs. At low doses, carcinogenic maladies and reductions in reproductive capabilities can occur. However, as see in the graph above, it takes orders of magnitude MORE radiation to cause such injuries in marine life than it does in humans. However, we still do not know much on how radiation exposure influences non-human biota at really low doses over longer periods of time, if at all. But groups like UNSCEAR and ERICA are focused on assessing the radiological risk to non-human biota.

How did Fukushima fallout influence local Japanese marine life?

Answer: Not too much. With a conservative approach, models estimated total dose rates much lower than baseline safe levels (10·Ÿ10-3 Gy/day) that would cause population consequences at even chronic exposure conditions for marine life. Doses were estimated at 1.2·Ÿ10-5 Gy/day for pelagic fish, 2.9Ÿ·10-5 Gy/day for molluscs, and 4.1·Ÿ10-5 Gy/day for algae. Don’t forget that these are averages, and there is variability in these numbers based on some of the factors we have already discussed.

Again we caution that more information is needed on how radiation exposure influences marine life and some organisms/species/life stages (like them little fishy babies) and the differences in susceptibility among them. Of course, the biggest issue is the synergy of multiple stressors. What happens when you start to compile global stressors (rising pH, temperatures, extreme water pollution) AND a nuclear meltdown? Organisms that are already dealing with an onslaught of human-derived stressors might be at higher risk from the influence of Fukushima.

*Note* Japanese regulatory limits were some of the strictest in the world before the disaster and were reduced to ensure strictest standards when it comes to monitoring radionuclides in food supply. To see how this level was calculated and why, here is an explanation. These levels are set to minimize human consumption of contaminated seafood and thus exceeding them will result in a fishery closure.


Buesseler, K.O. 2012. Fishing for answers off of Fukushima. Science 338, 480.

Buesseler, K.O. et al. 2013. Fukushima-derived radionuclides in the ocean and biota off Japan. PNAS 109 (16), 5984-5988.

Hinton, T.G. et al. 2004. Effects of radiation on the environment: A need to question old paradigms and enhance collaboration among radiation biologists and radiation ecologists. Radiation Research 162 (3), 332-338.

Kryshev, I.I. et al. 2012. Dynamics of radiation exposure to marine biota in the area of the Fukushima NPP in March-May 2011. Journal of Environmental Radioactivity 114, 157-161.

Schiermeier, Q. 2011. Radiation release will hit marine life. Nature 472, 145-146.

United Nations Scientific Committee on the Effects of Atomic Radiation. 1996. Sources and Effects of Ionizing Radiation.

Wada, T. et al. 2013. Effects of the nuclear disaster on marine products in Fukushima. Journal of Environmental Radioactivity 124, 246-254.



57 Replies to “The question you should have asked about Fukushima, but probably didn’t.”

  1. Here’s another question, that probably can’t be answered yet:

    Have bans on fishing and reduced demand for seafood in the Fukushima region affected marine species richness and abundances?

    Given that the seas around Japan are amongst the most heavily-fished in the world, it would not surprise me at all if sampling over time showed an increase in both richness and abundance in the region, for the same reasons that we observe this in marine protected areas around the world. And without trying to play down the seriousness of the disaster, this is also what has been observed in terrestrial ecosystems in the Chernobyl exclusion zone.

  2. i think you might need to take a look at tritium. it is not talked about much, but it is the most problematic of all these radioactive releases. the lost cores are producing a lot of it, and our geiger counters do not detect the beta particles released. when tritium is in the food or water chain it becomes a serious health risk.

  3. Deep Sea News continues to drive its analysis off assumptions that the radioactivity came from the incidents of March 11-15 2011. Continuous groundwater seeps, direct discharge, and stormwater runoff, all ongoing since then and going forward, have yet to be monitored and modeled. Strontium 90 and Plutonium (from the MOX at Reactor 3) are much more of a long-term concern than the easily-monitored, less dangerous “indicator pollutants” of cesium and iodine. If we don’t know how much of what continues to contribute contamination, how can we know how far and how long dilution will work? And what about the food web – are morbidity, mortality, and teterogenicity being examined? Studies from the Sellafield-Irish Sea nuclear weapons plant showed Stronium-90 accumulating in the shells of macroinvertebrates (lobsters, crabs and the like) as well as seaweed.

    If Deep Sea News recasts their reporting and study design to at least *acknolwedge* this is not just from the March 2011 incident, I’ll stop posting these.

    I am just dismayed that their skewed reporting continues to be re-reported as if they spoke for the health of Pacific marine life.

  4. I agree. I am not a biologist, but one who tested these GE Mark I & II BWR’s decades ago, and left feeling worried.

    I am a former Senior Engineer for Pacific Gas & Electric who does not trust the nuclear industry.

    I also do not trust those who soft-pedal potential dangers of this disaster, when they know nothing about what is really happening. Most information from Japan is now classified as state secrets. You can trust them, since you have less experience in life, but at age 69, I know better.

  5. There are several instruments capable of detecting beta particles and are in use during radiation surveys. Actually the release of tritium is very small and only produced during at-power reactor operations. Tritium exists naturally in the oceans as a result of cosmic ray interaction and in much larger quantities than can ever be released from industrial operations. Also tritium, unlike other solid particle contaminants, does not accumulate in the body.

  6. If you reread our posts you will see that we have acknowledged there are additional leaks. Not sure how many times I have to say it, but the additional radiation from the leakage and seeps is a fraction of the original discharge (see my update at So yeah, this post is spot on looking at the original radiation input and the response to sea life. We haven’t shied away from stating that this is still a problem for Japan, but it’s not for the greater pacific.

    Still not convinced? Take a look at this post by a radiation scientist, who estimates what would happen if all the radiation that is still in the reactor was dumped into the ocean. There might be problems locally, but once it’s diluted it is not a problem.

    I am personally dismayed that you are not looking at the big picture here. Japan still has problems. Radiation isn’t being contained but you also have to realize that what is coming out of the site is only problematic locally and not over the greater pacific. And you are only speculating that all that Plutonium and strontium will be released. After all the science I’ve read on the subject and the fact that radiation levels in both sea water and fish across the pacific are not at harmful levels, I feel pretty confident that we are speaking for marine life. I am sorry you disagree.

  7. Assessing the risk from the data that is out there is not soft-pedaling danger, it’s weighing the evidence and using it to make an informed decision.

    No need to be ageist, we all come with different experiences to this table.

  8. Fukushima: The Ticking Nuclear Bomb. Over 800 Tons of Radioactive Material …

    Global Research, October 31, 2013

    On a test made on 15 dead tuna, all 15 were found to be contaminated with radiation. Of the fish being sold to Canada, in 2012, the Vancouver Sun recorded the number of specimens testing positive for Cesium-137, namely: 100 per cent of monkfish, carp, seaweed and shark; 94% of cod and anchovies; 93% of tuna and eels; 92% of sardines; 91% of halibut; 73% of mackerel.

  9. First of all, I have to thank Kim for this service. I neither disparage nor fail to appreciate the information from a biological professional.

    My opinions come from experience. I learned how to see behind the public fronts while in the service. I learned about radionuclides by writing part of the manual to protect American industry from the effects of nuclear weapons.

    My Master of Science is in Environmental Management, dealing with energy in the environment. As a Research Engineer I tested safety components of those same GE Mark I Boiling Water reactors. Later, I was Senior Engineer for Pacific Gas & Electric, which was then the largest non-governmental power company on Earth. I know how decisions are made, and who influences them. I understand the technology.

    As a generalist, I see this disaster in all its respects.

    Thank you for your needed part in it, but the story has yet to begin.

  10. BTW, be very wary of Global Security, ENE News, and other sites sensationalizing this disaster. They have little to add to the narrative but calls to emotionalism.

  11. TEPCO is talking about trying to get the background levels to 20 milliSeivert /hr, as “normal”. My normal background count here is less than 0.1 microSeivert.

    Is the difference by a factor of 200,000 significant?

  12. I think this addresses the “we’re all gonna die” crowd that thinks there was/is/will be a massive impact on the West Coast from Fukushima radiation, despite the lack of evidence. By that logic, Japan should be a radioactive wasteland and Hawaii should have been crippled.

    The amount of Strontium 90 released is worth further investigation. I wouldn’t automatically assume that it’s either insignificant or calamitous. From what I can tell, the amount released during atmospheric nuclear testing in the 1950s and ’60s was about 1/34,000 the amount released from Sellafield and La Hague. Where does Fukushima fit along that SR-90 producing spectrum?

    This one marine scientist writing on DailyKos has been providing interesting analyses as well as insights into the testing procedures:

  13. Because tritium is an isotope of hydrogen it behaves chemically just like hydrogen, which means the most common chemical form for tritium is water. When water with tritium atoms enter the ocean the dilution is huge, and there is no reconcentration in organism. Tritium does not accumulate like some other isotopes (such as isotopes of iodine in some seaweeds), but moves through the organism like water. In humans tritium has about a 12 day biological half life.

  14. Why would you assume this is “over”? We have hundreds of tons of radioactive blobs in unknown conditions and repose. Three times we got Neutron flux signalling self-criticalities.

    Since then, they have classified information as state secrets. Why would you trust TEPCO or the Japanese government for your information?

  15. If you follow the “15 radioactive tuna” story back to its source (most likely this study:, the original purpose of the research was to determine whether you could determine whether bluefin tuna found in the eastern Pacific had lived in the western Pacific by analyzing the proportions of different cesium isotopes in their bodies. If they had only been in the east, they’d have one mixture; if they’d been in the west, they’d have a mixture influenced by the recent release of cesium from Fukushima — which is what the study found. Explicitly trace levels, explicitly not a health issue, the fish were not “radioactive” or “contaminated.”

    Cesium-137 has been in the Pacific since the nuclear tests of the ’50s and ’60s. It’s not a pleasant thought, but everything in the ocean takes it up to some degree. There’s likely more of a health issue from the non-radioactive contaminants we contributed to our environment — mercury, DDT, and PCBs. If you want to freak out about something…

  16. You have to admitt that it is getting worse, you cant defend Fukushima when it keeps dumping into the ocean.Epigenetic inheritance from even small amounts of Isotopes from Fukushima which there are many and many not spoken about that will be long term in their affects on humans for HUNDREDS OF YEARS…

  17. It’s significant – a significant error in your understanding. The acceptable 20 millsievert dose is per year,not per hour. So what you should be asking about is a factor of 22.

    20 mSv/yr is above pre-existing background in Japan, but is below background radiation levels in many places that are safely inhabited.

  18. Fukushima radiation reaches Pacific Coast: gov’t does nothing to monitor air, food and water – California residents
    22 January 2014 Voice of Russia

    There are indicators that the radiation is reaching California.
    The Japanese government admitted in July 2013 that more radioactive water has been coursing into the Pacific Ocean than the Japanese government first had reported.

    There are signs of radioactivity in California fish. Starfish, Pacific bluefin tunas, sea lions, whales, dolphins, anchovies, and other marine animals either haves radioactive elements from the Fukushima plant, or diseases caused by radiation.

    It took almost 3 years for the radioactive waters to reach the Pacific Ocean.
    The effects of Fukushima will be increasing as the front edge of a large water plume coming from the Fukushima plant will reach California soon and increase over the years.

  19. Again, nothing substantive in your post, almost every item on the supposed impacts of Fukushima radiation has been refuted on this very site:

    There is actually a wildlife bloom going on off the California coast, not a crash. Here’s just one of the many stories:

  20. Hi, Flow. Just a minor correction on equipment. My Geiger-Mullers do indeed detect beta disintegrations. I don’t know about the nifty little pocket-sized detectors these days, mine are clunky big Eberlines. There is a probe shield that blocks beta. Then take the same reading for the same time with the shield open to read both beta and gamma. Subtract the straight gamma reading and that is your beta concentration. Works reasonably well.

  21. It will take about 300 years for the soluble isotopes to ‘dilute’ evenly in the waters of the Pacific. Until then, the concentrations in upper level currents remain surprisingly coherent. And these are the currents of concern for the western coasts of North America.

    Bioaccumulation of isotopes by sea life also serves to concentrate isotopes, and some of them have half-lives longer than a good portion of us have to live on this earth.

    Those are facts. No one is going to get radiation sickness here from eating tuna or salmon, but exposures are cululative in nature and bioaccumulation is a real phenomenon. Levels must be monitored continually, and the public should be informed of what they are.

    Hopefully this will be done. You may have no concerns, but those who do have concerns should have accurate data they can evaluate for themselves.

  22. Tom-

    I agree a very interesting question. One would think, yes, but I do not yet know if the data is out there to prove it. That would be a pretty substantial undertaking.

  23. Ms. Davis-

    I would be interested to see the study you are referring too? Could you send along the reference?

    Also, just for the record, accumulation does not necessarily equate to adverse effects. In fact, many seaweeds are used for this manner. They can accumulate all sorts of pollutants without seemingly damaging effects.

  24. Jeffronicus-

    My thoughts exactly….I believe people might be focusing in on the wrong contaminants. Thank-you for putting that out there.

  25. Alex, my references are based on way too much time spent seeking credible information since TEPCO’s “revelations” of the groundwater seep in late July. I have experience in stormwater/groundwater; persistent toxins in water such as PCBs; and strangely, above-ground storage tanks. Some I have saved as a pdf.; some have (oddly) disappeared since I first found them this summer. You may wish to review:

    Geological Quarterly, 2003, 47 (4): 381–388
    Groundwater conditions along the seawater/freshwater interface on a volcanic island and a depositional area in Japan esp. slides 13, 21, and 25 (pretty expensive for something of small concern)

    TEPCO monitoring: – I cannot find out what the diagonal strike-through line means on Sr90.

  26. It all adds up. Is your toxic stew made magically safe if you simply claim one of the toxic ingredients isn’t “THAT toxic”???

  27. Of course it’s not. Chronic low-level exposure is quite the topic of debate, but keep in mind that linear no-threshold [LNT] is the model upheld by the NAS BIER VII and NCRP and accepted by the NRC despite ALARA necessities and ‘natural’ backgrounds.

    Radiation damage to biological tissues is too specific to be considered ‘harmless’, no part of our immune system defenses against viruses or microbes is effective against it. Just actual healing/housekeeping mechanisms – DNA repair, apopsis-signalling and molecular disintegration signalling (for damaged metabolic molecules with broken/aberrant bonds). There is a wide range of robustness for those, “a little regular harm” doesn’t make them stronger despite what some radiation-lovers like to pretend.

  28. As I said, 20 mSv/yr is below natural background radiation in some parts of the world, and there are no special health problems associated with those regions. So the evidence is that that 20 mSv/yr has no adverse health consequences.

  29. I agree with Kimberly Davis. For the assessment to have any validity it would have to include all of the known elements of the situation. You would need to address the fact that Fukushima has been leaking continuously since 2011 and that the future impact is unknown. This article uses past tense as if there was one release which then stopped. It is misleading. You can’t make an informed decision when you fail to include significant facts of a situation.

    This is kind of like saying beer won’t get you drunk after you’ve evaluated the affect of having one beer.

  30. I forgot to add in my initial comment – thanks for a great article, to complement the rest of the great content of this site – Fukushima-related and otherwise. Cheers.

  31. I’m going to add that I am preparing a post that discusses more recent measurements from 2013 and what they mean. I agree that finding information on this subject is difficult and there are a lot of unanswered questions.

    One of the reasons we focus on the 2011 dump is that is the biggest release and the only one that is affecting the region outside of japan RIGHT NOW. We are trying to asses the risk for people and marine life currently, and these posts are not trying to address what would happen in scenarios that haven’t occurred.

  32. Something similar to that happened in the closure zone around Chernobyl. Turns out that the pressures of living around humans were a bigger threat to wildlife than even a Chernobyl-sized dose of radiation on the landscape.

  33. Thank you. As a 8 year resident of Ibaraki Japan (a prefecture along the coast and directly south of Fukushima) I find your website and content very informative and in depth. A few weeks ago I received the “28 signs” email from a friend back in California. I found it quite alarming at first but also eventually became quite skeptical at the tone. I have two very young children and am married to a Japanese national. I will admit that I hadn’t felt that level of fear and anxiety since the earthquake/tsunami in 2011. We were here before, after and during. I have reiterated this to the many people I have met while researching this topic, the response of the Japanese people and the respect for one another after the disaster only strenghtened my love for this country and its people. I find it strange and so sad that so much has been blamed on Fukushima, and am really upset that such fear mongering is out there. I found an article in popular mechanics about radiation dosage and what it actually translates to. And was actually able to contact the author and eventually found my way here. I find solace and hope in the research of marine biologists, who seem not to posses the the raw emotional charge that often comes when expanding on subject of Nuclear power and radiation. Thank you again for what you do, and please do keep doing what you are doing. Keep informing and passing on knowledge to those that are willing to seek it out.


  34. That’s not a “bloom,” it’s a box canyon wall against which the fauna have been herded by something unusual in their normal waters at the specific time of year that they’re avoiding.

    A concentration of fauna in areas where such concentration is not ‘normal’ behavior doesn’t mean all the critters poofed into existence out of nowhere in the places they are observed.

  35. Citation, please?

    Researcher John McGowan and the other folks at California Cooperative Oceanic Fisheries Investigations (CalCOFI) — which has been monitoring the ocean off California with rigorous time-series since 1949 — have said there is no evidence of any Fukushima impact to the ecosystem.

    Here were the topics for their annual conference in December:

    It’s disingenuous to suggest there is a massive impact to California sealife — from plankton to predators — that hundreds of oceanographic researchers are not seeing in their observations and data.

  36. Washington’s Blog belongs on your list of “sites sensationalizing this disaster” that “have little to add to the narrative but calls to emotionalism.” The above article is typical of such material; parades on beaches do not in fact constitute any kind of evidence.

    Japan’s enactment of restrictions on some state information may be regrettable, but it was not actuated by considerations over Fukushima, contrary to the specious link that is assiduously promoted by some.

  37. You assert: “Japan’s enactment of restrictions on some state information may be regrettable, but it was not actuated by considerations over Fukushima, contrary to the specious link that is assiduously promoted by some.”

    I had a question. Can you prove your assertion? We have to be careful.

    Never mind,we are getting away from the serious points, in which we do not know what is happening, and the company and government do not help.

  38. It’s not really off-topic, in one sense. The unproven assertion here was that the new law in Japan was related to Fukushima, which you are now asserting as the “default position” that needs to be disproven.

    This is a typical twisting of the burden of evidence that has occurred in many claims connected to Fukushima, Somebody makes a claim – see the article – and thereafter certain groups will noisily demand evidence to counter the unfounded claim.

  39. thanks I am a novice but concerned.What I don’t see addressed is the ongoing reactor meltdowns and the potential for reactor 4 overheating and affecting the other storage tanks,that has me really concerned.Still seems like ok for now but far from over with a great potential to be a really big problem the likes of which we cannot imagine thousands of spent fuel assemblies burning seems to be the main worry for the future.If this happens then what?I guess that’s my question.

  40. Reactor 4 was unfueled at the time, but was wrecked by a hydrogen explosion probable from a leak between it and number three.

    The problem with four was the high number of fuel rods int the Spent Fuel Pool, which was damaged.

    Guess what? Fort Lucie NPP, another Three Mile Island clone, has steam generator tube troubles.

    Let’s see if this one is next. The People of the Sacramento Municipal Utility District, which owned Rancho Seco another of these models, shut it down because they no longer trusted the technology or those who were running it for them.

    Let us see what they do with Ft Lucie – wring every last penny out of it and take the chance, or shut it down?

  41. Two items: I called St Lucie Ft Lucie, oops.

    In the reference above, the tons of water that “leaked” was concentrated in radioactivity from the ALPS cleaning unit. They do not tell you, but standing by it for 20 minutes is a fatal act.

  42. I think that would be common sense wouldn’t it George? The article does state “highly radioactive water”. Would it be more clear to call it “murderous radioactive waste”? or would that be misleading people? Also where do you get your measurements for a 20 minute exposure? I am not trying to say that you are lying at all, but as a resident of Japan, I would love to have access to that kind of information…

Comments are closed.