|are a bit radioactive. When you are flying and passing through all the metal detectors, you expect to be exposed to a small amount of radiation.
However, banana has an isotope of potassium, which makes it radioactive.
This is nothing to worry about, as the body needs the potassium to function normally, and you would need to eat five million bananas at once to get radiation sickness.
So, bananas are just a little bit radioactive, just enough to get them on the charts. (source)