Banana inflorescence. Image credit:Wikipedia
US citizens can hold off a bit on going internet shopping for potassium iodide to guard against radioactive iodine exposure, leaving the pills for those that might need them first (in Japan for example). Holding the worry aside, first take a moment to see if you and your family might be exposed beyond the Banana Equivalent Dose. Wikipedia explains "Banana Equivalent Dose" so that even a TeeVee anchor could peel it.
A banana equivalent dose (BED) is a concept to place in scale the dangers of radiation by comparing exposures to the radiation generated by a common banana.Three Mile Island produced an overall radiation exposure less than one BED-worth. Thought the TMI comparison might be a steadying bit of info, considering we canned all US nuclear power development over the fear-equivalent of every adult person eating a partial banana. Next Big Future makes a BED comparison to the Japanese exposure here.
Many foods are naturally radioactive, and bananas are particularly so, due to the radioactive potassium-40 they contain. The banana equivalent dose is the radiation exposure received by eating a single banana. By comparing the exposure from these events to a banana equivalent dose, a more intuitive assessment of the actual risk can sometimes be obtained.
The average radioactivity is 130 Bq/kg (3 520 pCi/kg), or roughly 19.2 Bq (520 pCi) per 150 g banana. The equivalent dose for 365 bananas (one per day for a year) is 36 μSv (3.6 mrems).
Bananas are radioactive enough to regularly cause false alarms on radiation sensors used to detect possible illegal smuggling of nuclear material at US ports.
Another way to consider the concept is by comparing the risk from radiation-induced cancer to that from cancer from other sources. For instance, a radiation exposure of 0.1 mSv (10 mrem) increases your risk of death by about one in one million--the same risk as eating 40 tablespoons of peanut butter, or of smoking 1.4 cigarettes.
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