Very high background radiation areas of Ramsar, Iran: preliminary biological studies

Jim Conca cited this abstract in PubMed

People in some areas of Ramsar, a city in northern Iran, receive an annual radiation absorbed dose from background radiation that is up to 260 mSv y(-1), substantially higher than the 20 mSv y(-1) that is permitted for radiation workers. Inhabitants of Ramsar have lived for many generations in these high background areas. Cytogenetic studies show no significant differences between people in the high background compared to people in normal background areas. An in vitro challenge dose of 1.5 Gy of gamma rays was administered to the lymphocytes, which showed significantly reduced frequency for chromosome aberrations of people living in high background compared to those in normal background areas in and near Ramsar. Specifically, inhabitants of high background radiation areas had about 56% the average number of induced chromosomal abnormalities of normal background radiation area inhabitants following this exposure. This suggests that adaptive response might be induced by chronic exposure to natural background radiation as opposed to acute exposure to higher (tens of mGy) levels of radiation in the laboratory. There were no differences in laboratory tests of the immune systems, and no noted differences in hematological alterations between these two groups of people.

I found an ungated version of the paper here. Study participants were 14 normal and 21 elevated background persons.

Risks from low levels of ionizing radiation

This is a guest post by physicist Jani-Petri Martikainen @jpjmarti, proprietor of PassiiviIdentiteetti
(This post first appeared on Passiiviidentiteetti October 26, 2014)

This is one branch of the referenced Twitter discussion. 

There was a brief, but interesting discussion in Twitter about risks from exposure to low levels of ionizing radiation. Among pro-nuclear people this discussion erupts with some regularity. For some background there is this really clear discussion by @kasilas which you should read. The thing is that some (I suspect mostly people with engineering background) dislike LNT (linear no threshold) assumption in radiation protection. They say that below a dose of about 100 mSv it doesn’t have observational support and therefore one should not talk about “risk” below some threshold. Such risk is speculative and just gives ammo to anti-nuclear crackpots. On the other hand experts in radiation biology and protection gather around the “party line” and tend to see LNT, if not perfect, then at least good enough and certainly better justified than supposed alternatives. The sane on both sides nevertheless conclude that whatever risk model we use for low doses, the risks will  be small compared to many other risks we face on a routine basis. Both, by and large, hold the opinion that radiation from nuclear power is not an important public health concern relative to more pressing concerns.

Figure 1: Discussing hormesis and how it relates to LNT

Figure 1: Discussing hormesis and how it relates to LNT

I think this discussion is interesting not so much from the scientific perspective, but mainly from the sociological perspective. I suspect that engineering types dislike going through the trouble of minimizing all sources of exposure as much as possible while knowing that it adds to costs and that this work has no observable consequences. They feel that they could be working on much more important things. Radiation protection people on the other wish to protect scientific standards and probably feel a civic duty to maintain and built public trust on experts. Playing fast and loose with radiation risks might undermine that work. They dislike fear mongering by anti-nuclear folks as well as nonchalant attitude to small doses expressed by some pro-nuclear people. They are the doctors trying to keep inmates from running the asylum. (Although this task is complicated by the fact that only pro-nuclear folks have the courtesy to loiter close to the asylum. Antis have always been running free.)

Personally I have sympathy for both sides of this discussion, but I think this is fundamentally not a scientific question, but a question of public perception of risks and how that relates to policies. Due to decades of misinformation many people have fundamentally wrong perception of radiation risks. When we start by saying that radiation dose, no matter how small, poses a risk, we do not question that underlying default setting. We might then continue telling how this risk is nevertheless tiny, but many people have already tuned out. And in any case people are very bad at evaluating risks so they are more than likely to compress the message to “radiation BAD”. The conspiracy minded among the public will of course go even further. When official tells them small amount of radiation has risks, they will conclude that it is in fact deadly and the level that is really safe will be something much much lower. As the safety level is thus adjusted downwards possibilities for exceeding those “safe levels” multiply and the sense of danger will probably go up rather than down. Of course this is a complex issue. If on the other hand we say that the risk is not there, some will simply decide that you are not credible and tune out immediately. You have to adjust your message in response to craziness on the other side and hope they will gradually move to a sensible position. But does anybody know, how nuanced accurate discussion actually influences people whose opinions are at the start of the discussion bizarrely off base? Such discussion certainly is preferable with people whose opinions are more or less sensible to begin with, but with others? I am really not sure and would love to learn of some research on this topic.

Given my background I was (of course) thinking that isn’t this kind of similar to importance of quantum mechanics? We live in an imperfect world where most people do not need Planck’s constant in their daily lives. This natural constant is at the heart of quantum mechanics and indeed our world be inexplicable without it. (In fact some of those who actually need it in their daily lives, define their units in terms of it so that for them Planck’s constant has a value one. Being so down to earth and organic they even call such units “natural”.) However, as a practical matter it doesn’t make sense to incorporate the effects of Planck’s constant into building codes or environmental impact assessments etc. Most people will find it easier to just set Planck’s constant to zero and as a practical tool that is usually perfectly OK, even though it is fundamentally wrong. In fact, if we were to do the opposite, the risk of a backfire would be large. People would not know how to deal with Planck’s constant in practice and if asked about its magnitude they would be off by a large amount. (If we were to give them some additional information such that “Planck’s constant is related to the energy of  particles of radiation”, many would probably increase the value of the constant even more.)

Given the horrendously wrong public perception of radiation risks, I often feel they would be better served if their default settings were based on the idea of zero risk. This is fundamentally wrong, but it is less wrong, in a practical sense, than their current perceptions. Once the lowest order term has been correctly established we could start adding nuance and even move to discussion of such regimes where radiation risk is actually large. Nowadays people start from fears of cities attacked with nuclear weapons and then we expect them to make a reasonable extrapolation of risks into their daily lives. For most people I don’t think that will ever happen. On the other hand, I do not know how that more sensible starting point can be established in practice. Currently people pickup nonsense from NGO:s and media already as children and accurate information gets drowned in the noise.

[The Twitter discussion follows, Ed]:

Amelia Cook (@millysievert)

10/24/14, 3:33 AM

 

According to LNT-influenced guidelines, cancer risk starts to increase at 100mSv, right? Is that an annual dose, or some other duration?

Anders Örbom (@andersorbom)

10/24/14, 3:40 AM

 

@millysievert No, 100 mSv is where increased risk has been observed, but that is due to lack of data, not that 100 mSv is a “limit”.

Amelia Cook (@millysievert)

10/24/14, 3:41 AM

 

@andersorbom No, I understand that, just trying to find it if that assumption is made on an annual dose or some other duration.

Casey (@cthorm)

10/24/14, 4:48 AM

 

@millysievert @andersorbom LNT considers “dose”, not “dose rate,” while dose rate is actually what matters.

Casey (@cthorm)

10/24/14, 4:50 AM

 

@millysievert @andersorbom “accumulation” has no support in the data. Hormesis is observed, biological processes repair slow damage.

Amelia Cook (@millysievert)

10/24/14, 4:55 AM

 

@cthorm @andersorbom Thank you! Looking up ‘hormesis’ now, knew I’d have to do it at some point…

Anders Örbom (@andersorbom)

10/24/14, 4:57 AM

 

@millysievert Or don’t, it’s basically the “cold fusion” of radiobiology. Motivated reasoning and wishful thinking.

Amelia Cook (@millysievert)

10/24/14, 5:01 AM

 

@andersorbom @cthorm Now I don’t know what to believe…

Anders Örbom (@andersorbom)

10/24/14, 5:08 AM

 

@millysievert Believe unbiased trusted sources and the scientific mainstream, not either pro- or anti- activists and fringe researchers.

Janne M. Korhonen (@jmkorhonen)

10/24/14, 6:13 AM

 

@andersorbom @millysievert My heuristic: scientific mainstream is more often right than wrong,and only very rarely totally wrong.

Janne M. Korhonen (@jmkorhonen)

10/24/14, 6:14 AM

 

@andersorbom @millysievert My take after reading quite a bit: LNT model might overestimate cancers but radiation may cause other damage too.

Steve Darden (@stevedarden)

10/25/14, 7:55 AM

 

@jmkorhonen Where is your personal comfort level for annual exposure. E.g., 100mSv/yr? @andersorbom@millysievert

Amelia Cook (@millysievert)

10/26/14, 12:00 AM

 

@stevedarden @jmkorhonen @andersorbom Exactly what I’m trying to figure out! A good question, I’ll put it to more knowledgeable people.

Anders Örbom (@andersorbom)

10/26/14, 12:05 AM

 

@millysievert @stevedarden @jmkorhonen I’m sorry but “comfort level” is just a weird way to think abt it. You shld minimize dose, period.

Jani Martikainen (@jpjmarti)

10/26/14, 3:46 AM

 

@andersorbom @millysievert @stevedarden @jmkorhonen Actually,I disagree.There are risk levels that are too low to worry about. 1/2

Ben Heard (@BenThinkClimate)

10/26/14, 10:24 AM

 

@jpjmarti @andersorbom @millysievert @stevedarden @jmkorhonen Minimising dose beyond evidence of harm leads to costs, creating greater harm

Anders Örbom (@andersorbom)

10/26/14, 10:32 AM

 

@BenThinkClimate @jpjmarti @millysievert @stevedarden @jmkorhonen Weighing risk & benefit does nt req denying risk, and that’s all from me.

Jani Martikainen (@jpjmarti)

10/27/14, 2:19 AM

 

.@andersorbom @BenThinkClimate @millysievert @stevedarden @jmkorhonen I was left wondering…passiiviidentiteetti.wordpress.com/2014/10/26/ris…

Janne M. Korhonen (@jmkorhonen)

10/27/14, 9:06 PM

 

@jpjmarti @andersorbom @BenThinkClimate @millysievert @stevedarden Abandoning LNT politically impossible.Better fight battles we can win.

Jani Martikainen (@jpjmarti)

10/27/14, 9:11 PM

 

@jmkorhonen @andersorbom @BenThinkClimate @millysievert @stevedarden Yes,LNT is not the problem.Misguided perception of risks is the problem

Steve Darden (@stevedarden)

10/27/14, 11:25 PM

 

@jpjmarti Yes, so what can we do to correct mis-perception of risk? @jmkorhonen @andersorbom@BenThinkClimate @millysievert

Scaring The Japanese People With Radiation Is Criminal

I realize many journals and on-line publications need sensational headlines to attract readers. It seems necessary in these times of social media and 24-hour news cycles.

But it becomes unethical to push bad science without doing at least a little due diligence. I understand anti-nuke ideology cares little about science and is never held to any technical standard, but in some cases reporting bad science hurts people who need good science to make personal decisions for themselves and their families.

James Conca explains in depth why the latest instance of media fear mongering is a “textbook case of this malfeasance is the Fukushima-induced thyroid scare in Japanese children”.

Since few in the public read peer-reviewed journals or have the patience to plow through jargon-filled papers, it is the responsibility of scientists to communicate clearly and for journalists to have reputable sources.

Ironically, it has repeatedly been shown that the worst health effects from Fukushima have come from the fear of radiation and the forced evacuations, not from any radiation effects (Gaji 2013;Japan Daily PressWHO ReportNYTimes). Not one person has, or likely will, die from Fukushima radiation. But many people have died from the forced evacuations, fear and depression resulting from both well-intentioned and politically-motivated ignorance on radiation doses and effects following the accident.

Is radiation a must for cells’ normal growth?

This may be important work towards a science-based approach to low level radiation: both studies demonstrated a stress response when cells were grown under reduced radiation conditions

The March, 2011 issue of Health Physics published an interesting paper titled “Exploring Biological Effects of Low Level Radiation from the other Side of Background” summarizing the results from a Low Background Radiation Experiment carried out in Waste Isolation Pilot Plant (WIPP), an underground lab at New Mexico and those from a sister experiment conducted at the Lovelace Respiratory Research Institute, Albuquerque.

This was part of a $150 million, five-year long, low-dose research project recommended by 26 scientists highly regarded in radiobiology research community and representing competing radiation effects hypotheses.

WIPP is located at a depth of 650 metre in the middle of a 610 metre thick ancient salt deposit that has been stable for more than 200 million years. The radioactivity content of the salt deposit is extremely low.

The radiation levels in the lab are ten times lower than the normal natural background radiation levels. The contribution to the background from potassium-40, the only identifiable radionuclide present in the lab can also be reduced further by using a modest amount of shielding. Massive, 650 metre thick, salt reduced the cosmic ray background.

Researchers incubated Deinococcus Radiodurans, a bacterium which is highly resistant to radiation, above-ground and in WIPP in a 15 cm thick pre-world war II steel chamber; that steel is not contaminated by traces of radio-nuclides from nuclear weapons fallout.

(Snip)

The researchers found that shielding cells from natural radiation upregulated ( initiated the process of increasing the response to a stimulus) the expression of two out of three stress proteins and follow on x-ray exposure further upregulated expression.

They obtained similar results with the bronchial epithelial cells. Both studies demonstrated a stress response when cells were grown under reduced radiation conditions. Does it show that radiation is necessary for normal growth of cells?

A few years ago, mainstream scientists should have shown a smirk on their face followed by a grin if they heard this conclusion. Not any more. Many outstanding specialists feel that at the end of five years, they may be able to develop a model based on exposing organisms to near zero levels of radiation, a model based on sound science.

It may lead to increasing the levels of radiation considered safe; it will have a profound impact on the economics of decommissioning nuclear facilities, long term storage of radioactive waste, construction of nuclear power facilities among others. This requires drastic changes in public perception.

 

The REAL reason some people hate nuclear energy

I heard Carl Sagan argue today (in a Science Friday archival interview from May 1996) that entrenched-power is not motivated to encourage critical thinking in the population. I’m afraid Dr. Sagan hit the bulls-eye on that one – the political logic is obvious. 

Today I also read Martin Nicholson’s new and important article at BraveNewClimate on human misperception of risk. Martin’s essay is based on David Ropeik’s essential book How Risky Is It, Really? Human evolution did not prepare us at all for a world where we must make choices amongst imperfect alternatives that have complex future consequences. Evolution did not select for skill at making decisions with century-time-scale impacts. Nor for choosing between alternative risk-benefit pairings. The beginning of Martin’s concluding section makes this clear:

Closing the Perception Gap

Making policy decisions based on fears rather than facts can lead to decisions that feel good (e.g. no nuclear) but increase the overall risk to the population (more deaths and health risks from burning fossil fuels and climate risks from greenhouse gas emissions).

Ropeik tells us that risk perception is an intrinsic, biologically rooted, inescapable part of how the human animal behaves. We need to accept this and use what we know about the way humans respond to risk in order to help ourselves make better, healthier choices. We need to bring the risk perception factors out of the subconscious shadows and use them as practical tools to allow our rational thinking to have more influence in the process.

We need to keep an open mind and give ourselves time to get more information from neutral and reliable sources – those that have no obvious bias. We need to consider all components of our response to the risk – not just the facts. We need to consider the pros and cons of various risk-management options. Why not factor feelings and values into the equation instead of trying to factor them out? Think about which policies will do us the most good.

Poor risk communication from government or agencies that are supposed to protect us like the International Atomic Energy Agency (IAEA) or the World Health Organization (WHO) can sometimes fail to account for people’s risk perceptions. This was a key factor in the long-term social/psychological/economic consequences of Chernobyl. A similar situation may have occurred at Fukushima.

Unfortunately, “feel good” is the most salient feature of politically successful policies. How does this connect to Carl Sagan’s argument? Only our critical thinking skills can save us from “feel good”. One thing we know for sure is that it is rare in western education systems to see critical thinking encouraged.   Read Martin’s essay, you’ll be glad you did.

Fukushima: WHOI senior scientist studies North Pacific Ocean effects

WHOI senior scientist Ken Buesseler

WHOI senior scientist Ken Buesseler began his career in oceanography by studying the spread of radionuclides from Chernobyl in the Black Sea. Not surprisingly, today one of his research interests is the impact of Fukushima contaminants in the North Pacific Ocean. Ken and the WHOI staff have been investing a lot of personal time in science communication — to help the general public better understand whether they need to be worried about Fukushima effects.

Our Radioactive Ocean: Recently they launched the remarkable new website ourradioactiveocean.org. This is almost a “one stop shop” for accurate and accessible information on radioactivity and our oceans. The site is also the home of CMER’s crowd-sourced project to sample and analyze North Pacific Ocean waters. The crowd-sourcing innovation seems to be getting off to an encouraging start — you can see the current results here

CMER Pacific Ocean monitoring

Anyone (you?) can propose a sampling location, take samples of 20 liters of sea water, ship it to CMER at WHOI for analysis – and help raise the funds for the procedure (beginning with the expensive shipping). The fund raising is especially important as Ken’s lab already has more samples than they have budget to analyze. Excerpt from their crowd-sourcing page:

There currently is no U.S. or international agency monitoring the arrival of radioactive water from Fukushima along the West Coast. Although we don’t expect levels to be dangerously high in the ocean or in our seafood as the plume spreads across the Pacific, this is an evolving situation that demands careful, consistent monitoring to make sure predictions are true.

We at the Woods Hole Oceanographic Institution already have dozens of seawater samples from the coast of Japan out to the middle of the Pacific, but now we need new samples—from up and down the West Coast of North America and anywhere else we can get them. The trouble is, these samples are expensive to collect and analyze. That is why we are turning to you, your community, and your social network for help.

If you want to propose a sampling location near you, all you have to do is raise the cost of testing and shipping ($550 to $600 depending on location) and we will send you a sampling kit with everything you need. We’ll also help by setting up a fundraising webpage that you can email to your friends or post on your favorite social media site that will allow you to spread the word and track your progress.

Once you have your kit, sampling is easy (see video). When we get your sample, we will add it to the queue of samples to be analyzed. This isn’t a quick process (it takes 24-48 hours just to measure the radiation in a sample after processing), but we will fast-track samples from people like you. Depending upon how many are ahead of yours, however, it may take 5 to 10 weeks before we send you an email with the results and post your data on our interactive map.

In November 2013 Cape Code Online published a short interview with Dr. Buesseler, where he discussed the new Pacific monitoring initiative:

(…snip…) He predicts the radiation will be so diluted after the long journey across the Pacific that it will pose no threat to American fisheries or recreational activities.

“It’s very much a coastal Japan contaminant problem,” Buesseler said.

But he knows that’s not enough to reassure the public.

Given what’s happened at Fukushima, Buesseler asked, “Wouldn’t you want to have some measurement?”

This effort is science-motivated. But I think there is a science-education benefit that could be important. I predict that the  monitoring results will prove conclusively that the hysteria about the “Fukushima killing the Pacific Ocean” was hype, not science. And these are not results published by “them”, the results will clearly be produced by caring individuals in a completely transparent process. It make another generation to turn around the public radiophobia, but this looks like a solid contribution.

On Twitter you can see the latest updates on the Pacific monitoring project by following @whoi_cmer. Read Ken’s new paper Oceanography paper Fukushima and Ocean Radioactivity {if that link expires, search on the citation: Buesseler, K.O. 2014. Fukushima and Ocean Radioactivity. Oceanography 27(1), http://dx.doi.org/10.5670/oceanog.2014.02}.

Here are some related Seekerblog posts on the public health risks associated with Fukushima contamination. In particular I suggest starting with these:

Do we need to worry about Fukushima contamination in the ocean? (part 1)

Fukushima, radiation and risk: what is scary and what is not

Fukushima contamination “poses no risk” to U.S. West Coast

Tony Barboza writing for the LA Times has a straightforward and accurate account of U.S. West Coast real risks associated with Fukushima contamination. Not every media source is spreading fear, Mr. Barboza is doing an excellent job of sourcing information from real experts such as Nicholas Fisher of Stony Brook University, Kim Martini of University of Washington, and Ken Buesseler, of Woods Hole Oceanographic Institution. Excerpts:

Radiation detected off the U.S. West Coast from the Fukushima Daiichi nuclear plant in Japan has declined since the 2011 tsunami disaster and never approached levels that could pose a risk to human health, seafood or wildlife, scientists say.

Experts have been trying to dispel worries stemming from a burst of online videos and blog posts in recent months that contend radiation from Fukushima is contaminating beaches and seafood and harming sea creatures across the Pacific.

Those assertions are false and the concerns largely unfounded, scientists and government officials said last week, because Fukushima radionuclides in ocean water and marine life are at trace levels and declining — so low that they are trivial compared with what already exists in nature.

“There is no public health risk at California beaches due to radioactivity related to events at Fukushima,” the California Department of Public Health said in a statement.

Even at its worst in the months after the disaster, the dose of radioactivity that Fisher's lab found in tuna caught off California was far lower than what people are exposed to from medical X-rays or eating bananas or other potassium-rich foods, which contain naturally occurring radioactive isotopes.

The latest concerns are mostly driven by online videos, blogs and social media — including a post titled “28 Signs That the West Coast Is Being Absolutely Fried With Nuclear Radiation From Fukushima.”

Kim Martini, an oceanographer at the University of Washington, noticed a surge in outrageous worries about radiation in Seattle last fall, including people who were afraid to go to the beach and stopped eating seafood.

“Every single environmental issue was being blamed on Fukushima,” she said. “And I thought there's no way that can be true.”

Since then she and other scientists have been posting information on the blog Deep Sea News, with posts including “Is the sea floor littered with dead animals due to radiation? No.”

A magnitude 9.0 earthquake off Japan on March 11, 2011, triggered a series of tsunamis that crippled the Fukushima Daiichi nuclear power plant, releasing radiation into the ocean and atmosphere. Studies show that leaks from the facility continue to send radionuclides into the sea. But they dilute quickly in ocean water, scientists say.

Once those contaminants disperse across the Pacific Ocean and reach the West Coast, their concentration will be many thousands of times lower and not of concern, according to an online FAQ by Ken Buesseler, a marine scientist at the Woods Hole Oceanographic Institution.

“This is not to say that we should not be concerned about additional sources of radioactivity in the ocean above the natural sources, but at the levels expected even short distances from Japan, the Pacific will be safe for boating, swimming, etc.,” Buesseler wrote.

Good job Tony!

 

Fukushima, radiation and risk: what is scary and what is not

Thanks to Randall XKCD http://what-if.xkcd.com/29/

The purpose of this post is to communicate why the more you know about radiation the less you worry about nuclear radiation – even the consequences of the terrible accident at Fukushima Daiichi.

To get your skeptical circuits warmed up, let's begin with the above graphic, an excerpt from Randall Munroe's What-If XKCD where Randall “answers your hypothetical questions with physics, every Tuesday”.

What if I took a swim in a typical spent nuclear fuel pool? Would I need to dive to actually experience a fatal amount of radiation? How long could I stay safely at the surface?

Randall's exploration of the question is a useful introduction to how to think about risk and radiation dose – in relation to intensity, exposure time and mediation medium (water in this example). Randall begins

Assuming you’re a reasonably good swimmer, you could probably survive treading water anywhere from 10 to 40 hours. At that point, you would black out from fatigue and drown. This is also true for a pool without nuclear fuel in the bottom.

After you've enjoyed “Spent Fuel Pool“, I recommend Randall's Radiation Dose Chart, which has become a frequently-cited resource for an introduction to radiation dose and risk. The chart is useful for an overview of relative magnitudes. In addition to Randall's chart I recommend that you download for your archive Natural Radioactivity, published by the physics department of Idaho State University. That is “ground truth” on the details of background radiation in the oceans, or land – lots of numbers and units.

With that gentle introduction I hope you are ready to read some resources that go into Fukushima monitoring in a bit more detail. Are you worried about contamination from the Fukushima Daiichi reactors? E.g., turning the Pacific Ocean into a place too dangerous to swim? Too dangerous to eat the Blue Fin Tuna?

First you will find your hard data at Monitoring environmental radiation Nuclear Regulation Authority (NRA), Japan. In particular, you can find the weekly Sea Area Monitoring reports. As I write the latest report is for 10 December, 2013 (PDF).

To make sense out of all the Becquerels/Litre in the NRA tabulations I recommend Putting Fukushima in Perspective: A primer on radioactivity in the Ocean written by University of Victoria marine chemist Jay T. Cullen (@JayTCullen). Dr. Cullen is investing his personal time in science communication to inform the public about the real risks associated with contamination from the Fukushima site. From his primer article:

Talk of plumes of radioactivity being broadcast across the Pacific must take into account that the background radioactivity of seawater is about 14 Bq/L. It is important that although one can detect isotopes from the reactor in the environment the absolute levels are very low and will be lower as the ocean mixes, and the isotope decays.

Dr. Cullen is using 14 Bq/L as the global ocean radioactivity – what does that mean? Well, one Becquerel is that quantity of a radioactive material that will have 1 transformations in one second. So the unit Bq/L tells us there is a concentration of radioactive elements in each litre of ocean that emits at the rate of 1 count per second (cps). We don't know what the material is, but we know a Geiger counter would detect 14 counts/second from a typical litre of sea water. And we know empirically (by swimming in the stuff, eating the Tuna, etc.) that 14 Bq/L is perfectly safe. Even if we don't know exactly what the number means.

Click the thumbnail for full size graphic

So let's examine some of the extensive NRA monitoring, which publishes weekly sampling results from sites immediately around the Fukushima Daiichi breakwater, out to open ocean. The thumbnail to the left shows the worst/highest sample values for Cs-134 and Cs-137 that I could find in the open sea zone (full size).

In the next table I have compared the worst samples to typical ocean background radiation. What we see is that dilution and decay of the cesium isotopes has already reduced the radiation to levels that are insignificant in relation to normal. That indicates that US Pacific coast residents do not need to be alarmed.

 

Some like to use the radioactivity of a banana to make these units more familiar. A typical banana emits about 15 Bq due to the potassium isotope K-40. So radiation-wise eating a banana is similar to drinking a litre of typical ocean, ignoring retention rates. If you are comfortable with bananas and seawater, but are still concerned about the Fukushima contribution, think of it this way. Equivalent to eating that banana, you would have to drink between 3 and 6 cubic meters of pure water contaminated with the measured concentrations of Fukushima cesium. I think I prefer to get my radiation dose from the banana, but I appreciate they are equivalent.

But what about concentration of the insignificant levels by fish and mollusks into dangerous levels if consumed? Good question. I asked the same question, which led me back to Dr. Cullen again for the analysis of that issue, titled What Controls Levels of Fukushima Radioisotopes in Marine Organisms?

Scientists normally report the amount of a radioactive element in an organism in units of concentration where the mass or activity of the radionuclide is given relative to the weight of the organism or its tissue. The units of these measurements are, therefore, either kilogram (kg) or activity in Becquerel (Bq = disintegrations per second) divided by the mass of the organism or tissue (kg/kg or Bq/kg). We want to understand how much radionuclide ends up in the organism relative to the isotopes concentration in seawater which can be reported in either kg per liter of seawater or Bq per liter of seawater (kg/L or Bq/L). By determining the ratio of the concentration of a radionuclide in an organism to the concentration of the isotope in seawater we define the Concentration Factor (CF) which has units of L/kg:

concentrationperunitmass.png

So if the CF for an element in a given organism is a very high number then that radioisotope tends to bioaccumulate and is found at higher concentrations in the organism than in the surrounding marine environment. Conversely, if the CF is low there is little risk of bioaccumulation in the organism.

So what is the bottom line on seafood?

What can we expect on the west coast of North America?

Beginning in the new year we can expect seawater affected by the Fukushima disaster to arrive at our coast in the Pacific northwest. Peak concentrations in the heart of the plume of affected seawater are expected to be on the order of 0.001 to 0.020 Bq/L based on measurements and physical models of ocean circulation. The much lower radionuclide concentrations are the result of mixing and the decay of shorter lived isotopes. Given known CFs for marine organisms these seawater concentrations will result in much lower concentrations of radionuclides in organisms residing on the west coast compared to their Japanese cousins. The radioactive dose to these organisms or consumers of these organisms will be dominated by the naturally occurring radionuclide Po-210.

A confirming evaluation of the food chain question was published in the June 25, 2013 issue of the Proceedings of the National Academy of Sciences Evaluation of radiation doses and associated risk from the Fukushima nuclear accident to marine biota and human consumers of seafood [open access]. Excerpt from the abstract:

To link the radioactivity to possible health impairments, we calculated doses, attributable to the Fukushima-derived and the naturally occurring radionuclides, to both the marine biota and human fish consumers. We showed that 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. Doses to marine biota were about two orders of magnitude below the lowest benchmark protection level proposed for ecosystems (10 µGy⋅h−1).

My bottom line is — if you wish to monitor for any dangers developing when Fukushima seaborne contamination reaches California, then I suggest you subscribe to Dr. Cullen's blog MarineChemist. That's what we do (we subscribe to his RSS feed). If there is anything to worry about then Dr. Cullen will let you know. Or you can just subscribe to Seekerblog!

I promised to also discuss “what is scary?” My answer is the post-antibiotic world where antibiotics don't work any more. That is really, really scary, especially if you are a geezer like me. Climate change is very scary – but antibiotic resistance is spreading as I write. The big hurts from climate change will probably be after-death experiences for me.

Japanese Fisheries Agency samples fish for contamination: most OK “even in the sea near Fukushima”

Japanese Fisheries Agency samples fish for contamination: most OK “even in the sea near Fukushima”
Source Japan Times

The officials from the Fisheries Agency stressed that the monitoring results show that the impact of the nuclear crisis on fish is now subtle even in the sea near Fukushima.

Results from the cesium density test in the first three month after the meltdown catastrophe started in March 2011 showed that 53 percent of fish caught around Fukushima exceeded the legal limit of 100 becquerels per kilogram, but now only 2.2 percent of fish caught top this threshold. Regardless, fish caught within 20 km of Fukushima No. 1 are not shipped to market.

As for fish caught far from Fukushima, more than 14,000 samples have been tested in the past year and only 88 exceeded the legal cesium safety limit of 100 becquerels per kilogram.

Fukushima water leaks:“This is healthwise a big nothing”

Lake Barrett, a former head of the Department of Energy’s Office of Civilian Nuclear Waste Management, spent nearly a decade at the U.S. Nuclear Regulatory Commission and led the clean-up operations after the 1979 partial meltdown at the Three Mile Island nuclear plant. He has been brought in by Tokyo Electric Power (Tepco) to advise it on the lengthy decommissioning process at Fukushima.

He said work should begin now to pump groundwater from the plant before it reaches wrecked reactors – a measure that has been stalled by local opposition.

“They should start pumping as soon as practical,” said Barrett, adding that groundwater would have to be released into the sea along with water that had been treated to remove most radiation – by a system designed by Toshiba Corp.

“I believe in a matter of a few months … early next year … water will be cleaned up and be ready to be discharged,” he said in an interview.

But Barrett, who has said he would feed his grandchildren fish caught off the Fukushima coast if the clean-up proceeds as planned, said Tepco has lost its credibility to reassure a jittery public. “When Tepco says: ‘trust me, this water is safe,’ that’s not enough,” he said.

(…) He said concerns raised by South Korea and China over the continued leaks of radiated water at Fukushima “political posturing.”

“This is healthwise a big nothing,” he said.

Source