Radioactive Bananas?

I stumbled upon a number of interesting papers recently, which are in fact genuine scientific investigations into matters we often take for granted, for example -  the radiation level of bananas.

Image: dvice.com

I've read about radioactive bananas(oh by the way, all bananas are radioactive) in my nuclear physics class, and yet I never got bothered by it.
Bananas are radioactive because they contain potassium-40, which is pretty unstable. But you don't have to worry about gulping down the yellowish-radioactive-fruit, because it takes a whopping 37,290,000,000 bananas to kill you, and still, it won't qualify you for the Xavier Institute for Higher Learning.

Image: marcinthewild.com

The paper takes 450mg as the mean amount of potassium contained in a banana. Of this, only a small percentage of the total mass is represented by potassium-40, around 0.0117%(5.27mg). The half-life of this small fraction is around 1.26 billion years, making the decay relatively slow, and hence ensuring a continuous burst of energy throughout your life. A banana equivalent dose (abbreviated BED) is a nonstandard unit of radiation exposure, ostensibly defined as the additional dose a person will absorb from eating one banana.

The concept is based on the fact that bananas, like most organic material, naturally contain a certain amount of radioactive isotopes—even in the absence of any contamination due to human nuclear endeavors. The banana equivalent dose was meant to express the severity of exposure to radiation, such as resulting from nuclear power, nuclear weapons or medical procedures, in terms that would make sense to most people.

The amount of energy released, however, is minute, around 0.0000000000000931 J/s, roughly 0.000000000107 Gray. It takes around 1 Gray to cause radiation sickness in an adult, and it takes 4 times that to have a good chance of killing someone. The simple multiplication that ensues gives 37,290,000,000 bananas.

Assuming that a dude takes a banana a day, oh... he would have to pump his age up to 102 million years in order to acquire enough bananas to kill himself.


http://en.wikipedia.org/wiki/Banana_equivalent_dose
https://physics.le.ac.uk/journals/index.php/pst/article/view/350/190