Simple Things – Surprising Histories explained why bananas are safe despite being naturally radioactive. This is because bananas are high in potassium, which contains the isotope potassium-40. In large amounts, this isotope would be harmful, but the amount inside a banana is fairly negligible.
Because bananas are so rich in potassium, they are naturally rich in potassium 40. Every single second, in a standard banana, about 15 atoms of potassium-40 decay and release a microscopic burst of radioactive energy. It’s completely natural, and it’s been happening since the very first banana grew on Earth.
The amount is so small that scientists created an unofficial yet amusing scale, known as the BED or Banana Equivalent Dose, which compares the radiation from bananas to other common radioactive events.
Eating one banana exposes you to about 0.1 micro severs of radiation. To pu that into perspective, just living on planet Earth and absorbing natural background radiation from the ground and the cosmos gives you about 100 bananas’ worth of radiation every single day.
