Bananas are radioactive.

Bananas have naturally high-levels of potassium and a small fraction of all potassium is radioactive. Consuming one banana would deliver a total dose of 0.01 millirem (0.1 microsieverts) of radiation. This is a very small amount of radiation.

http://epa.gov/radtown/natural-radioactivity-food#:~:text=Bananas%20have%20naturally%20high-levels,very%20small%20amount%20of%20radiation.