Don’t take it out on the tuna

I was recently confronted with this image on a social networking site:


Part of its tagline read “The medias [sic] latest distraction is working nicely. Meanwhile, our entire planet is flooding with extremely high levels of radiation and it keeps getting worse by the day. Something must be done.”

I have no problems agreeing with the sentiment of the statement about Miley Cyrus’s antics and their ability to captivate audiences.  Frivolous nonsense aside though, this is a deeply misleading image.  The dramatic colours permeating the Pacific supposedly represent  the extent of radioactive material leakage from the Fukushima nuclear power facility in Japan.

You may be inclined to think, that’s a lot of radioactive stuff, and it’s gone very far.  For half a moment I did.  Then I remembered not to blindly believe the message being portrayed, and looked more deeply into it…  Hang about, that scale is in centimetres – a unit of length, not radioactivity.

That’s because this map has nothing to do with radioactive leakage – it doesn’t even have any direct relation to Fukushima.  It’s the projection onto a 2D map of this image from the US National Oceanic and Atmospheric Administration, showing the 2011 tsunami’s maximum wave height.

I’m curious as to whether or not the person who produced this drivel knew the mistake they were making.  If I had to guess, it would be no – I can easily imagine someone involuntarily spitting their organic antioxidant-rich superfood cereal bar over their laptop after having googled ‘Fukushima’ and seen this, then feeling duty-bound to share it with the world.  Dishonest intentions or not, when faced with an image like this it’s easy to come to one’s own conclusions a little quicker than one should.

Unfortunately, discussion about Fukushima is littered with this kind of fear-mongering.  Take for instance the headline-grabbing reports about radioactive fish near Fukushima waters.  Many west-coast Americans are now afraid to eat tuna caught in the Pacific for fear they’ll grow another limb if they do.  The situation is explained perfectly here; what none of these reports tell you is that elevated levels of radioisotopes by no means necessarily constitute hazardous levels of radioisotopes.

You may also have read about the ‘300 tonnes of radioactive water’ leaking into the Pacific every day since the crisis.  Judging by the vastly-conflicting media reports I personally think that number is a little dubious.  Nonetheless, it does sound like a lot – to use the classic unit favoured by journalists the world over, that’s a 2-metre deep Olympic pool every 8 days.  It’s important to get a perspective on the scale of dilution going on here though.  1OP emptying into the Pacific Ocean, which has a volume of 6.6×10^17 m^3 (cheers Wolfram), every 8 days, for 2.5 years, represents 0.0000000004% of the ocean’s content originating from the site.  Ok, this is very much a ballpark figure, and that water is nowhere near evenly-distributed throughout the ocean, but hopefully it gives you an idea of how long it would actually take for the ocean to have any meaningful content of radioactive material.

The problem the nuclear industry has where public opinion is concerned is that so many people hold irrational opinions about the risk of radiation.  It’s important to remember that we come into contact with it every day.  Walls, food, even people have a small level of radioactivity.  The xkcd comic-writers have wonderfully illustrated this with a radiation dose chart which worth bearing a look at. Aside from the Olympic Pool, one of my favourite units is the Banana Equivalent Dose.  The average banana has an activity of roughly 15 Becquerels (15Bq), i.e. every second around 15 potassium-40 nuclei in your lunchbox decay, producing radiation (this isn’t quite the same as a BED, which takes into account the source and way in which the radiation is absorbed by the body).

Some figures released by Tepco in August show that there are 50,000-80,000 Bq (roughly 3000-5000 bananas) per cubic centimetre in the highly contaminated water collecting in the basements of the facility.  This is collected and treated, though it’s thought a lot leaks into the ground. Post-treatment, the water has levels of activity which are orders of magnitude lower. That which makes it into the groundwater contributes to the aforementioned ‘300 tons per day’, though again my dilution point applies: Put a litre (or 300 tons, you choose) of highly-radioactive water into an ocean of clean water, and you’ll get… an ocean of clean water (or, a negligibly differing amount of radioactivity, if you understand the concept of negligible).

Also, what none of the fact-scarce media reports have pointed out is that nearly 100% of the radiation detected at on-site storage leaks is beta radiation.  If you’ll cast your mind back to GCSE Physics, beta radiation is the emission of a single electron, and is absorbed by say, a sheet of paper, or two metres of air.  It is nearly impossible for a beta-emitter to cause a lethal dose in a human, no matter how strong, unless it is ingested.

Some of the more absurd claims about How Much Danger You’re In tend to come from websites such as ‘’ and ‘’, with the former enlightening us all with ‘11 facts about the ongoing Fukushima nuclear holocaust that are almost too horrifying to believe’.  Amongst this reputable list you’ll find truths such as ‘Something is causing fish along the west coast of Canada to bleed from their gills, bellies and eyeballs.  Could Fukushima be responsible?’ (no), or ‘150 former sailors and Marines say that they now have radiation sickness as a result of serving on U.S. Navy ships near Fukushima and they are suing for damages.’

To conclude, the point of my post is this: You are not in danger because of Fukushima.  Do not let anyone tell you otherwise, and treat misinformed media reports (even mainstream ones), with a healthy dose of scepticism.

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