Bananas are radioactive and you would need 10 million at once

Bananas are naturally radioactive. They contain potassium, and a tiny fraction is potassium-40, an isotope that decays. Each banana emits about 0.1 microsievert of radiation. You would need to eat 10 million at once to get radiation poisoning. Scientists even invented a joking unit, the Banana Equivalent Dose, to explain low radiation risks to the public. Your own body contains about 4,400 becquerels of potassium-40 already, so you are more radioactive than the fruit you are holding.