What is the banana equivalent dose?

The banana equivalent dose is an informal educational measurement used to compare radiation exposure to the radioactivity found in an average-sized banana. One banana equivalent dose is roughly equivalent to 0.1 microsieverts, primarily driven by naturally occurring potassium-40. However, it is not a formally adopted measurement because the human body excretes dietary potassium to maintain homeostasis, meaning the dose is not strictly cumulative.

What we know

• The banana equivalent dose is an informal unit of measurement for ionizing radiation exposure used as an educational example. [1, 2]
• One banana equivalent dose correlates to approximately 10 to the power of minus 7 sieverts, or 0.1 microsieverts. [1, 2]
• Radioactivity in bananas comes from naturally occurring isotopes like potassium-40. [2, 3]
• The radiation dose from eating a banana is not cumulative because potassium in foods is excreted in urine to maintain homeostasis. [2]

Where to go next

• how it workedWhy is potassium-40 radioactive?
• the bigger pictureHow does the sievert measure radiation health effects?
• compared withWhat is the flight-time equivalent dose?
• what caused itWhy are radioactive doses from food not cumulative in the body?
• how we knowHow much background radiation do humans receive daily?
• an unexpected connectionHow does eating bananas explain the atmosphere of Earth?The electron capture decay of potassium-40, the same isotope that gives bananas their radioactivity, accounts for the large abundance of argon in the Earth's atmosphere.

Sources

• [1]banana equivalent dose (Wikidata Q2630196) · CC0 1.0
• [2]Banana equivalent dose · CC BY-SA 4.0
• [3]Potassium-40 · CC BY-SA 4.0
• [4]Equivalent dose · CC BY-SA 4.0
• [5]Flight-time equivalent dose · CC BY-SA 4.0