Bananas Are Naturally Radioactive

Bananas contain potassium-40, a radioactive isotope that gives them a tiny, harmless glow of radioactivity.

Bananas are one of the world’s most popular fruits—and one of the most unexpectedly radioactive. They contain potassium-40, a naturally occurring radioactive isotope. But don’t panic—it’s perfectly safe.

In fact, you’d have to eat 10 million bananas at once to suffer radiation poisoning. The “banana equivalent dose” is even used as a tongue-in-cheek unit for explaining radiation safety.