The potassium in bananas makes them measurably radioactive. A banana equivalent dose (BED) is often used to convey relative levels of radiation exposure. A chest CT scan delivers about 70,000 BED, while the Three Mile Island accident exposed residents 10 mi away to about 700 BED. Among common foods, bananas are the most radioactive, containing about 3,520 picocuries of radiation per kilogram. Potatoes are a close second with 3,400 pCi/kg.