Bananas are slightly radioactive, due to their high levels of potassium, and specifically the isotope potassium-40. Potassium is an essential nutrient for human health, and this isotope occurs naturally in many foods, but bananas have more of it than most. The radioactivity from bananas is so low that it’s not harmful to humans, but it is enough to make them detectable with a Geiger counter. This has even led to the creation of a playful unit of measure known as the banana equivalent dose, used to quantify radiation exposure.

Why Bananas Are Radioactive

Potassium-40 is a naturally occurring isotope of potassium, and because potassium is an essential part of many biological processes, it’s found in abundance in living organisms, including bananas. The radioactivity in bananas comes from the decay of potassium-40, which releases beta particles. While the level of radiation in a banana is minimal and harmless, it serves as an interesting example of how natural elements can emit radiation at very low levels. It also highlights the fact that radiation is present in many things around us, often in forms that we don't realize. Shutdown123