You may have heard of the "Banana Equivalent Dose" - but the net dose of a banana is zero.

[bananas]

http://www.boingboing.net/2010/08/27/bananas-are-radioact.html

Bananas are radioactive—But they aren't a good way to explain radiation exposure
Maggie Koerth-Baker at 9:27 AM Friday, Aug 27, 2010

<snip>

The problem is that this system implies that all radioisotopes are created equal—That there's no difference between 520 picocuries of Potassium-40 and a similar intake of, say, radioactive iodine. And that simply isn't true. I contacted Geoff Meggitt—a retired health physicist, and former editor of the Journal of Radiological Protection—to find out more.

Meggitt worked for the United Kingdom Atomic Energy Authority and its later commercial offshoots for 25 years. He says there's an enormous variation in the risks associated with swallowing the same amount of different radioactive materials—and even some difference between the same dose, of the same material, but in different chemical forms.

<snip>

The Potassium-40 in bananas is a particularly poor model isotope to use, Meggitt says, because the potassium content of our bodies seems to be under homeostatic control. When you eat a banana, your body's level of Potassium-40 doesn't increase. You just get rid of some excess Potassium-40. The net dose of a banana is zero.

And that's the difference between a useful educational tool and propaganda. (And I say this as somebody who is emphatically not against nuclear energy.) Bananas aren't really going to give anyone "a more realistic assessment of actual risk", they're just going to further distort the picture.

Thanks to flamingdem for this and more in his post: "143. Ingesting Iodine-134 in Milk is NOT the same as background radiation or x-rays!"

[FBaggins]

1. So what you're saying is....

...that there's more Potassium-40 in your body all the time than what you get from eating a banana?

So... if the dose that, say, drinking 100 gallons of Tokyo water gives you is smaller than even that... it's really not something to be concerned with?

Thanks!

[bananas]

2. Even worse, the calculation was incorrectly based on ...

http://en.wikipedia.org/wiki/Banana_equivalent_dose

The BED calculation probably originated on a nuclear safety mailing list in 1995.<1> However, the calculation was incorrectly<2> based on the dose for ingestion of pure radioactive potassium-40 (40K) , not the natural ratio found in food.
...
The oft-quoted value of the BED is unjustifiably high and was based on incorrectly applying data for the effective dose due to ingestion of radioactive 40K alone. <14>

[jpak]

3. The Happy Talk about exposure to radiation has become quite shrill of late

and preys upon people's ignorance and/or prejudice

yup