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Bananas and radiation – the nuclear lobby’s favourite lie

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.

Bananas aren’t really going to give anyone “a more realistic assessment of actual risk”, they’re just going to further distort the picture. 

Fukushima: Think Low Level Radiation Is Harmless? Think Again… UKIAH BLOG  In Around the web on August 25, 2013Time to combat radiation threat From WASHINGTON’S BLOG

 ”…………Nuclear apologists pretend that people are exposed to more radiation from bananas than from Fukushima.

But unlike low-levels of radioactive potassium found in bananas – which our bodies have adapted to over many years – cesium-137 and iodine 131 are brand new, extremely dangerous substances.

The EPA explains:

The human body is born with potassium-40 [the type of radiation found in bananas] in its tissues and it is the most common radionuclide in human tissues and in food. We evolved in the presence of potassium-40 and our bodies have well-developed repair mechanisms to respond to its effects. The concentration of potassium-40 in the human body is constant and not affected by concentrations in the environment.

Wikipedia notes:

The amount of potassium (and therefore of 40K) in the human body is fairly constant because of homeostatsis, so that any excess absorbed from food is quickly compensated by the elimination of an equal amount.

It follows that the additional radiation exposure due to eating a banana lasts only for a few hours after ingestion, namely the time it takes for the normal potassium contents of the body to be restored by the kidneys.

BoingBoing reports:

A lot of things you might not suspect of being radioactive are, including Brazil nuts, and your own body. And this fact is sometimes used to downplay the impact of exposure to radiation via medical treatments or accidental intake.

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.

It all depends on two factors:

1) The physical characteristics of the radioactivity—i.e, What’s its half-life? Is the radiation emitted alpha, beta or gamma?

2) The way the the radioactivity travels around and is taken up by the body—i.e., How much is absorbed by the blood stream? What tissues does this specific isotope tend to accumulate in?

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.

http://ukiahcommunityblog.wordpress.com/2013/08/25/fukushima-think-low-level-radiation-is-harmless-think-again/#comments

August 27, 2013 - Posted by Christina Macpherson | 2 WORLD, radiation, Reference