Bananas are technically radioactive — and scientists really do measure things in this unit

Bananas are rich in potassium, and a small, constant fraction of all naturally occurring potassium on Earth is the radioactive isotope potassium-40 — it has been slowly decaying and emitting radiation for as long as our planet has existed.

Eating a banana means absorbing a microscopic dose of radiation. It's so tiny that physicists coined the informal "banana equivalent dose," sometimes used to illustrate just how small typical everyday radiation doses actually are.

For comparison: to get a radiation dose comparable to a chest X-ray, you'd have to eat thousands of bananas at once — and even then it wouldn't have time to harm you, because the body constantly flushes out excess potassium.

The human body itself is mildly radioactive for the very same reason — potassium-40 is present in every one of our cells, regardless of diet.