BNC Would sir like a caesium salad with his steak? Barry Brook

Would sir like a caesium salad with his steak? Barry Brook : http://wp.me/piCIJ-1b3

Guest Post by Geoff Russell. Geoff is a mathematician and computer programmer and is a member of Animal Liberation SA. His recently published book is CSIRO Perfidy. To see a list of other BNC posts by Geoff, click here.
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A recent Nature column raised the prospect that the legacy of radiation leaks at Fukushima Daiichi nuclear power plant would be decades of caesium-137 contamination around the plant. After reading this opening, I expected a hysterical beat up similar to that which prompted my last BNC piece. I was wrong. The author is the editor of a substantial book on the aftermath of the Chernobyl disaster and his Nature column ended with a clear and hopeful message summed up in a concluding anecdote about an elderly couple living near a heavily contaminated lake in Belarus. They were growing their own food and eating highly radioactive fish and doing just fine. They were survivors rather than victims. They had aligned their perception of risk with the numbers. The alternative is like the smoker who is terrified of air travel.
The rest of this piece is devoted to doing some risk perception re-alignment but I need to begin with a covering paragraph.
Nothing in this piece should be taken to imply that nuclear reactors should be allowed to become cheap and nasty because we can live with the consequences. Modern reactors with passive safety features are extremely safe and should reduce in price with appropriate modular mass production techniques. There is no need for corner cutting.
There will be two parts to this post. The first part is about the similarities and differences in the way radiation and food shred your DNA and the second describes the practical consequences with a little case study of Japan.

Part I: What exactly does radiation do to your cells?

Caesium-137 (Cs-137) has recently hit the headlines like some kind of scarlet pimpernel. Caesium here, caesium there, where will caesium next appear. Road blocks on Japanese roads now forcibly protect the public against caesium here and caesium there. It causes cancer. So do sake, bacon and steak, but I don't notice road blocks on Tokyo bars or McDonalds.
Here's a picture of what Cs-137 radiation does to your DNA. These come from a recent paper comparing damage from a range of sources and this particular picture is of damage caused by Cs-137.

The right hand image looks a little like a comet. Hence the name comet assay. First some cells were exposed to radiation and then they were chemically busted open to expose the DNA material from the cell nucleus. DNA is normally in coiled braids and when the braids are unbroken, they stay globbed up in a ball like the image on the left. On the right, busted strands of DNA are streaming out of the glob. It's a bloody mess. The cell in this image was hit with 10 Grays. The unit used in most Fukushima publicity has been Sieverts. For the moment, just think of a Gray as another name for a Sievert. So 10 Grays is 10 Sieverts or 10,000 milli-Sieverts. A person receiving a full body dose of just half this amount would have a 50/50 chance of being dead within a couple of months.
What's the difference between a full body 10 Gray dose and a cell being hit by 10 Grays? Don't worry about it ... just accept that this cell nucleus took a monster hit. Imagine blasting a water melon with a shotgun but instead of a shot cartridge with 200 pellets, you are using something with 100,000 really tiny pellets. That's about what happened to this cell nucleus ... the 100,000 is an approximately correct number, I didn't just make it up!
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