Fukushima across the Pacific


This map is from a detailed simulation of the spread of Pacific ocean radiation, and shows the anticipated levels as of Aug. 2013. It looks scary, but the red color indicates that the levels of Cs137 from Fukushima are 10,000 times less than when released in March 2011, while the light blue indicates levels that are less than one-millionth.

Let’s make it clear: the release of radioactive contamination from the Fukushima NPP to the environment — the air, the land, and the ocean — is a massive disaster. There’s no other way to describe it. Radiation in the air spread far and wide, and was even detectable, though barely, on other continents, while radiation in the ocean is spreading more slowly but inexorably. We know that some of the fish caught off Japan have been too contaminated to be sold for human consumption, and that wide expanses of farmland in Japan have been contaminated as well. But what effects can be expected overseas?

Lately there have been quite a few reports of die-offs, dangerously contaminated fish, and other horrors in the Pacific Northwest which have been ascribed to the effects of radioactive contamination in the Pacific ocean from Fukushima. Many people are worried and unsure, others are convinced that these reports are factual, and the stories have found a ready audience, mainly through online media. We’ve addressed and debunked a few of them already. Could it possibly be true that hazardous levels of Fukushima ocean radiation have reached North American Pacific shores? If this hasn’t happened yet, is it likely to happen in the future? The consensus among the many ocean scientists who have been monitoring the phenomenon is that Fukushima radiation is beginning to reach the Pacific coast, the levels will be so low they will only be measurable with extremely sensitive equipment, and that while the risks to people will not be zero, they will be “insignificant.”

Let’s try to understand why.

The ocean has been naturally radioactive since primordial times, and received quite a lot of fallout during the nuclear weapons testing era. Chernobyl added additional radioactive contamination to all of the world’s oceans, though considerably more to the North, Baltic, and Black Seas than to the Pacific. In addition, the Sellafield accident released quite a lot of contamination into the Irish Sea, and nuclear accidents in other locations have contributed as well. Ocean scientists have been measuring and tracking the radiation from all of these sources for decades, and have given us a very good idea of how the radiation found in different parts of the world’s oceans differs, where it came from, and how it moves through the environment.

This historical knowledge has been very useful for understanding the effects Fukushima has had and will continue to have on the Pacific. Many excellent researchers from Japan and abroad have been investigating this closely since March 2011, and anyone who is hoping to know more about what impact Fukushima radiation will have on the ocean far from Japan– in Hawaii, Alaska, or near California, for instance — should become familiar with what Fukushima ocean studies have shown. These researchers’ collaborations have been a model of cooperation among nations and institutions, and while the picture is not yet complete, the outlines — how much radiation is in the ocean, where it will go, and when it will get there — have been fairly well estimated.

These scientists conclude that the the Cs137 levels in the waterborne Fukushima radiation now reaching the North American Pacific coast will peak at between about 0.004 and 0.010 Bq/L, compared to about 0.001-0.002 Bq/L before the accident, will stay that way for a few years, and should start declining again around 2017. Percentage-wise this means 2 to 10 times existing Cs levels, which we could say is a lot, especially since the entire Pacific will be affected. But when one considers that the added radiation represents only about 1/1000 or less of the 7.4 Bq/L of Cs 137 the US EPA allows in drinking water (Japan and the WHO both allow 10 Bq/L), most people would probably conclude that it represents a minuscule health risk if any even if you drank it. The same appears to be true concerning the risks presented by the migratory Pacific bluefin tuna caught off California that had detectable levels of Cs137 as well: someone who ate 2 kg of it a week for a year would raise their risk of fatal cancer by only 0.00002%.

As always, the Devil is in the Details. As a recent press release from the Woods Hole Oceanographic Institute points out, “This is an evolving situation that demands careful, consistent monitoring to make sure predictions are true.” Detailed summaries of the research and the conclusions after the jump.

So who’s checking?
There have been quite a few very informative papers about the impact of Fukushima radiation on the ocean. Some of the most useful include:

Aoyama, et al: Fukushima derived radionuclides in the ocean 

Behrens, et al: Model simulations on the long-term dispersal of 137Cs released into the Pacific Ocean off Fukushima

Rossi, et al: Multi-decadal projections of surface and interior pathways of the Fukushima Cesium-137 radioactive plume

Nakano, et al: Long-term simulations of the 137 Cs dispersion from the Fukushima accident in the world ocean.

Buesseler, et al: Fukushima-derived radionuclides in the ocean and biota off Japan

Buesseler: Fishing for Answers off Fukushima

Radionuclides in the ocean (Ken Buesseler, WHOI)

Dr. Ken Buesseler of The Woods Hole Oceanographic Institute (WHOI) has authored or co-authored several of the most informative studies of Fukushima ocean impacts. The illustration above is from one of his presentations, and shows how Fukushima radioactive releases to the world’s oceans compare to those from Chernobyl and weapons testing, as well as to natural radiation. As you can see, while Fukushima released quite a lot of Cs137 to the oceans, the amount appears to be somewhat less than that from Chernobyl, about 1/10 of that from global testing, and only a tiny fraction of the natural radiation (mainly Uranium 238 and Potassium 40) that has always been there. WHOI is reportedly in the process of testing water samples taken from the ocean offshore off northern California, and hopefully the results will not be long in forthcoming.

The WHOI has several excellent and readable online reports about Fukushima ocean impacts:

FAQ: Radiation from Fukushima

Special Series : Fukushima and the Ocean

How Is Fukushima’s Fallout Affecting Marine Life?

Radioisotopes in the Ocean: What’s there? How much? How long?

And this post at Deep Sea News covers the key points pretty well too:

True Facts about Ocean Radiation and the Fukushima Disaster

The author, an ocean scientist, admits to getting a bit snarky, and we think his assessment of the risk to people is possibly not nuanced enough, but he does a good job of refuting some of the wilder speculation.

How do researchers know what will happen to the North American Pacific coast because of Fukushima, and how reliable are their estimates?

Some of the post-Fukushima Pacific Ocean studies are simulations that begin with estimates of how much radiation was released, where the wind and ocean currents is likely to have taken it, what resulting ocean contamination we can expect, and how that is likely to change over time. Other studies are primarily based on measurements of seawater at different depths, and of the seabed. These are used by researchers doing simulations to cross-check their assumptions and conclusions, and to refine their simulations. Because the methodologies and the aspects taken into consideration vary from study to study, different simulations result in slightly different estimates of the level of ocean contamination the Pacific will experience. But they all agree that while the increase in radioactivity in the ocean off Hawaii, Alaska, and California will be measurable, it will also be minute.

Some of the terminology can be confusing. The amount of radioactivity in a substance, like food, the ground, water, or in people’s bodies, is usually expressed in Becquerels (abbreviated as Bq). This actually refers to how many atomic disintegrations are happening each second (The older unit of Curies — Ci – is still sometimes found and can be easily converted to Bq). Radioactivity in food and other solids is usually expressed per unit of weight, such as Bq/kg, while liquids are give per unit of volume. For drinking water, milk, etc, it’s usually given as Bq/L, but because the concentration of radioactivity in seawater is usually so small, it is commonly expressed as Bq/m3, that is, per 1000 liters (264 gallons). Japanese and WHO guidelines currently allow up to 10 Bq/L of Cesium in drinking water, while the US stipulates a limit of 7.4 Bq/L. For easier comparison, I’ve tried to give both per liter and per cubic meter concentrations in the following discussion.

In the graph above, the black line indicates Cs levels close to Japan, which rose to about 10000 Bq/m3 shortly after the start of the disaster due to the tremendous quantities of radiation directly discharged into the ocean and entering it as fallout from aerial discharges during the first several weeks. The light blue line shows expected levels near Hawaii, red is near the Aleutians, dark blue is Baja California, and green is North America. In the case of Hawaii and the North American coast, ocean C-137 levels are expected to peak at about 0.004 Bq/L, compared to about 0.001-0.002 Bq/L before the accident. Other areas are expected by this team to be less. (Both this study and the one by Nakano, et al, cited above come up with similar predictions, while the one by Rossi, et al, predicts levels about 10 times higher) (From: Behrens, et al : Model simulations on the long-term dispersal of 137Cs released into the Pacific Ocean off Fukushima)

A team of Canadian ocean scientists has been measuring seawater samples gathered along a line which extends out to about 1500 km off of British Columbia since 2011, in order to track the approach of Fukushima radiation:

Smith et al : Radionuclide Transport from Fukushima to Eastern North Pacific

This is nicely summarized by MarineChemist at DailyKos, who has been providing very informed and readable summaries of findings from peer-reviewed literature:

Update on Fukushima Radionuclides in the North Pacific and Off the West Coast of North America

The Canadian team’s conclusions are that so far, the radiation seems to be arriving at the the slightly faster pace Rossi’s simulation predicted, but at levels which fit more closely to the lower estimates given by the simulations of Behrens and Nakano. Only continued measurement will show for sure.

To summarize the findings from the papers linked above:

–The peak Cesium levels in the Pacific before the start of the Fukushima disaster were between 1-2 Bq/m3 (0.001-0.002 Bq/L, again, compared to 7.4 Bq/L allowed in drinking water by the EPA).

–As ocean currents slowly transport the contamination eastward, levels in the ocean near Hawaii and the Aleutians started to climb several months ago, and in Hawaii will peak between 4-30 Bq/m3 (0.004 – 0.030 Bq/L) over the next several years, and should start declining around 2017.

–Detectable Fukushima radiation has started to reach the North American coast, and will peak this year and the next at somewhat lower levels than Hawaii, somwewhere between 2-20 Bq/m3 (0.002 – 0.020 Bq/L). In June 2013, the Canadian team measured 0.3 Bq/m3 (0.0003 Bq/L) from Fukushima close to the coast of British Columbia.

— Again, while so far measurements have suggested that the lower estimates are accurate, we won’t know for sure for some time. Regardless, the levels are 10,000 to 100,000 times lower than in the ocean off Japan in 2011, and while one could calculate a statistical probability of radiation-induced illness to humans who might swim in or drink the seawater off the Pacific Coast of North America, it’s hard to describe it as anything but insignificantly small.

Global ocean radiation levels as of 1990 (WHOI)

The ocean map above is from WHOI, and helps put the expected increases in the Pacific due to Fukushima in perspective. As the captions point out, in 1990 the Baltic had 125Bq/m3 of Cs137, and the Black Sea 52 Bq/m3; these were mainly due to Chernobyl.  The 55Bq/m3 in the Irish Sea was mainly from Sellafield. The rest is mainly from nuclear testing. Several independent reports are due to be presented soon, but Japanese gov’t data indicates that similar levels have not been seen in the ocean 20km off Japan for over a year:

Fukushima Sea Area Monitoring, January 07, 2014

At this point, the overwhelming scientific consensus, with no credible dissenters, is that the consequences for humans in North America will be very small. The scientists themselves use words like “insignificant,” “inconsequential,” “minute,” “undetectable,” or “none.” But while the overall Pacific contamination levels are expected to be much less than seen in the Baltic, Black Sea, or Irish Sea in 1990, or even today, nearly the entire Pacific will be affected, a much bigger expanse of ocean than any of these seas. And, of course, however unlikely, nature could surprise us unpleasantly. We can’t say with absolute certainty that Fukushima Pacific radiation will never pose a danger to humans or the environment around the rest of the Pacific rim, and we should definitely continue to carefully monitor its spread.

What about the radioactive tuna?

Many people are concerned about radioactive cesium from Fukushima that has been detected in migratory Pacific bluefin tuna caught near California, which had approx. 4.0 Bq/kg of Cs 134 and 6.3 Bq/kg of Cs 137 (Japanese regs allow 100 Bq/kg, the EU allows 600 Bq/kg, while the US allows 1200 Bq/kg of Cs 137 and Cs134 combined.

The original study is here:
Madigan, et al: Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California

One of the best sources of information on the risks this contamination poses can be found in this paper:
Fisher, et al: Evaluation of radiation doses and associated risk from the Fukushima nuclear accident to marine biota and human consumers of seafood

Among the important take-aways are:

–“…doses in all cases were dominated by the naturally occurring alpha-emitter 210Po and that Fukushima-derived doses were three to four orders of magnitude below 210Po-derived doses.”

–If a subsistence fisherman, who eats more fish than an average consumer, ate 124 kg of the contaminated tuna that was caught in 2011 over the course of a year, the additional committed effective (i.e. lifetime) dose they would get from the cesium in the fish, even taking the higher risk from internal emitters into account, would be 4.7 μSv (microsieverts). They would get more than 600 times this from the Po210 in the fish, and 2.8 mSv (millisieverts) from all the radiation in the fish, including K40. On the other hand, an average consumer who ate this tuna regularly for a year would receive about a 0.9 μSv lifetime dose.

–Pacific bluefin tuna caught off California in August, 2012 were found to have less than half the levels of Cs of those caught in August, 2011; doses to human consumers would be comparably smaller.

–It is often stated that any dose of radiation, no matter how small, carries a health risk; this can only be estimated statistically because it has been impossible to detect directly at very low doses. Assuming an excess relative risk of fatal cancer of about 5% per Sv of radiation dose, the doses to the fishermen from eating a lot of this fish “…can be estimated to result in two additional fatal cancer cases per 10,000,000 similarly exposed people.” That is, it would increase a person’s probability of fatal cancer by 0.00002%. Some scientists have proposed good reasons to adopt a higher risk coefficient, 10% per Sv instead of 5%, in which case the probability would be 0.00004% instead. Other potential health consequences from Cs would lie in a similar range of probability.

We try to avoid saying what is “safe” or “unsafe,” but this is a vanishingly small risk. These fish and other species need to be continually monitored, however, in the event the contamination increases for some reason. There are important gaps in our understanding of the foodchain interactions as fish cross the Pacific, but the evidence indicates that these tuna spent time in the ocean plume close to Japan in 2011 while it was still very dense and that’s why they ingested as much Cs as they did. Fukushima continues to release contamination to the ocean, but the amount per year as estimated by the scientists cited earlier is about 1/300 of what was released during the first few months after the disaster started in 2011 (about 0.1 Pbq now vs about 30 PBq in 2011).

This continuing release poses an ongoing threat to marine species and the environment off the coast of Japan, one that shows no sign of abating anytime soon. But from what we now know, and particularly taking into account the known rate of bioaccumulaton for fish — they accumulate 50-100 times of the Cs present in the water they swim through– its contribution to radiation in migratory species that reach the US is likely to be imperceptible.

In a later post we will talk about the radioactive contamination in the ocean off Japan itself, which presents a much more painful picture.

15 Comments on “Fukushima across the Pacific

  1. where is the app for Samsung phones? all I see is a app for the old junk iphone, why would you even have that due to the iphones have die in the usa

  2. Hi there Im really concerned about the radiation being in the food, I heard from a few web sites that it was found in milk in states such as oregon and washington and in the beef and chickens. I live on the east coast but everything I buy which is organic for my family is from oregon and washington state. Is it true its in the food already and should I just eat local. I buy everything from costco and they told me they test there meat really good. My second question is I heard that it spread to the east coast as well threw the air and its showing up in pine trees they are dying? So is it that high all ready over here in NC that I should be taking suppliments Im pregnant and just really concerned about my baby and other small children. If these website are false do see it coming over here in the future and getting bad. concerned…
    Thanks Gina

    • Hi Gina, Although fallout from Fukushima did show up in trace amounts in consumables (such as milk) in North America shortly following the disaster, levels soon retreated to non-detect. Even in Japan, the levels of contamination we are seeing, while certainly higher than those in the US, do not pose a significant risk to human health. In short, you have nothing to worry about from Fukushima, even if you are pregnant or have small children. (As the parent of a young daughter here in Japan, lord knows we, as parents, have more than enough other things to worry about!)

      As for the pine trees dying as a result of Fukushima, that doesn’t seem to make any sense. Would you be able to provide a link to your source for this? That might help us debunk it.

  3. Just wanted to say thank you for writing this article. I’ve been looking for something that gave more details instead of the “trust us its safe” articles on the internet. While I’m still a little fearful of the the incoming radiation I now feel confident that I’m not going to start glowing if I visit the west coast and stick my feet in the ocean. Though I’m still going to stay away from the fish for a little bit.

  4. I see references to the EPA and Japanese government “safety standards” but no mention or explanation for why their levels were raised after Fukushima’s troubles.

    It would also be very good of Safecast to do an article like this for air contamination, rather than purely oceanic contamination. It makes no sense to talk about just one or the other. Precipitation and bio accumulation should also be addressed.

    • Hi Nikolas, By “raised” do you mean that the levels were loosened or tightened?

      As for air contamination, do you really mean air contamination (which is nearly zero) or ambient radiation (which is elevated)? As for precipitation, do you mean precipitation as in fallout via rain (in which case, the levels are nearly zero) or precipitation as in the formation of a solid in a solution (from an ocean contamination point of view)?

      As for bio-accumulation, I think the article addressed that.

  5. Really enjoyed your article. Thank you for quelling a lot of sensationalism I have heard from friends of late. There is one thing I want to call your attention to. The EPA does not regulate radiation discharge into our nations sewers. They do not have jurisdiction it is primarily regulated by state environment departments with discharge limits specified in both Federal and State Statutes, and these limits are a product of the Nuclear Regulatory Commission.



    • Royallynn: If you have a link to more info about the EPA policy about this I’d really like to find out more. These jurisdictional issues crop up in so many areas of environmental protection. Even with food and water, the EPA and the FDA basically set separate radiation standards. As far as radionuclides in sewers go, what we’ve seen in Japan has been that medical waste accounts for almost all of it in normal times, and, particularly in the first year after the Fukushima disaster began, a lot of contaminated dead leaves and things like that made their way into the sewers. In Japan, at least, the radiation levels are reported regularly, as are levels found in incinerators etc,. This was true even before the disaster. But you have to know where to find the reports. So that would seem to me to be the main issue: How well are nuclide levels in sewers being reported? What are they checking for, and how often? And how closely in line with EPA standards (which we may want to critique as well) are local standards?

  6. An excellent and thorough article. While there maybe no significant threat to health in the levels of cs-137 contamination found in blue fin tuna on the West coast so far, Nicholas Fisher from Stony Brook University didn’t rule out the possibility of cs-137 concentrations possibly increasing, rather than decreasing over the next couple of years.

    The risks, however, from consuming fish contaminated to the level of 100 bq/kg considered ‘safe’ by Japan fisheries is a different matter. Please read my article on the research of Dr. Yuri Bandazhevsky done on cs-137 contamination and it’s health impact on children that was done after Chernobyl. You can find the article here: http://www.fukushimaresearchgroup.com/radionuclides-in-the-food-chain/

    He found serious conditions in the majority of children he studied at just 50 bg/kg of body weight, showing that cs-137 exposure for children is FAR more dangerous than has been previously been considered.

    • Hi Mark, Thanks for the link. I think you may want to talk to a scientist or someone who is somewhat practiced in the art. Many of the statements in your article are misleading or flat-out not true. Moreover, I have a feeling many of your statements don’t accurately reflect the underlying source, but I have not way to check that without inline references, so it would be great if you could provide those. In addition, I would beware Dr. Bandazhevsky’s research. His results have been pillioried by his colleagues (and rightly so, in my opinion), and even the layman can catch obvious statistical and logical flaws in his work. To say that he represents the fringe of research on this topic would be putting it lightly.

  7. I am curious if the levels of radiation are low, how are these people on the coast and inland in Canada receiving radiation readings four times above normal background levels?

    Are these hoaxes or are the devices set to read out warnings at low levels?

    • Joe: Please post links to the reports you’re referring to. One of the most noticed was from a person who measured a beach in Northern California and posted a video on YouTube. We wrote about it here:
      Short version: It’s from natural sources that have been there for eons (mainly the mineral monazite), well-documented by geologists even decades ago, nothing at all detectable from Fukushima. We do see a lot of hoaxes about this sort of thing, but in this case the guy was just ignorant. Ignorant enough, I’ll add, to set off a widespread panic, not very different from shouting “fire” in a crowded theatre.

  8. Earthquake Nuclear Plants:

    4x Switzerland (all of them)
    all Turkish and Indian Nuclear Plants
    US: Diablo Canyon Nuclear Plant, San Onofre Nuclear Plant, California + 20 Nuclear Plants around the New Madrid Fault Line in the USA
    20 French Nuclear Plants – all down the Rhone Valley incl. largest Nuclear Uranium Factory Pierrelatte / Tricastin 10800 t/yr standing exaclty between 2 vertical fault lines in the Rhone Valley + 4 Blocks Nuclear Power Plant Tricastin – all radioactive water would end up in the emditerranian.

  9. Thanks for all the comments, everyone.

    Saburo: Thanks. I appreciate your reasonable and informed tone.

    Igoddard: Thanks too. You’re right about the estimates by Stohl, et al. And if you look at the WHOI illustration closely, you’ll see that the figures on the little spheres themselves add up to 13-60 PBq, while the legend says 8-45 PBq. Go figure. Buesseler himself said not too long ago that he thinks that as the various estimates are refined, the ocean deposition will work out to about 15-30 PBQ. Meanwhile I guess we have to always try to understand what the consequences could be if the high-end estimates turn out to be accurate. I’ll try to post a graph I found recently showing which shows the current estimate ranges a bit more clearly.

    Mark: Thanks for your post too. I discussed what body burdens of Cs people of different ages could get from eating 100Bq per day every day for a year and what their doses would be in this post:

    Please take a look at it and feel free to comment. Overall, I agree, we should probably try to keep childrens’ Cs body burdens below 50 Bq/body or so, or maybe 10 Bq/kg. Fortunately this looks doable, even in Fukushima. About safety, we should always be wary when someone tells us something is “safe,” because almost nothing really is. For doses, health effects, etc, I wish official agencies used the term “safe enough” and then specified how many people were statistically expected to die or get sick from whatever it was, and made sure that society was aware of it and accepted it. We accept all sorts of risks and deaths from common activities, but almost always tacitly, because we’re rarely required to really think about it.

    About Bandashevsky, I basically agree with Saburo that his conclusions are not as well-founded as is often claimed. He deserves credit, as does Nesterenko, for asking important questions and trying to find out. My caution stems from a number of issues. Keep in mind that Bandashevsky’s research included both studies of children’s cadavers, which cannot be ethically repeated, and in-vivo studies on lab rats.

    –A Japanese researcher who was translating Bandashevsky’s studies (and who was very inclined to support and publicize his findings) showed the slide images to a respected pathologist, who said he suspected poor slide preparation to be the cause of the many “anomalies” that were visible, such as striations and tissue damage. Preparation artifacts like these are likely to appear when the slicing blade is not sharp enough.

    –In 2008, a group of French researchers tried to replicate Bandashevsky’s rat studies, and were unable to. They found a number of effects we should be aware of, but particularly did not find heart tissue damage like Bandashevsky claimed:
    Chronic Contamination of Rats with 137Cesium Radionuclide:
    Impact on the Cardiovascular System

    Gueguen et al; Cardiovascular Toxicology March 2008, Volume 8, Issue 1, pp 33-40

    –The ARCH committee, which was formulating policy proposals for long-term health studies in Chernobyl (and included researchers like Baverstock, Cardis, Kesminiene, and Williams on its core team, none of whom can be described as a nuclear power supporter) contacted Bandashevsky and asked if he would like to defend his papers in light of the new French research. He declined, leading the committee to assume he would retract his papers shortly. He never did. (This is from personal communication with an ARCH committee member)

    –I met Bandashevsky late last year in Tokyo, and was able to discuss his findings a bit and exchanged a number of emails afterward. He was quite a gentleman, etc., but I was shocked to learn that he thought that no food testing was being done in Japan after Fukushima, and that no internal contamination screening was being done either. This is what he had been told by the Japanese person who was “handling” him and controlling his communication as much as possible. I quickly introduced him to other researchers in Japan who were able to show him reliable data about food testing and WBC screening. At first he refused to believe that there are over 40 internal contamination screening centers in the Fukushima area alone. In mid-2013, he uncritically believed what he had been told, that there were none.

    For all of these reasons, I don’t entirely reject his findings, but I take them with a large grain of skepticism.