Because a small percentage of potassium consists of an unstable isotope, bananas are technically a radioactive food. However, you would have to eat around five million bananas to experience radiation sickness.
Key Facts In This Video
If the human body is exposed to more than two sieverts of ionizing radiation at once, it will die. (0:50)
As an airplane gains altitude, the level of radiation inside the plane increases. (5:07)
The lungs of smokers are exposed to more ionizing radiation than people living near Fukushima, radiation workers, and astronauts. (9:57)