"Tonight, find out why you could be putting your whole family at risk by serving foods high in radioactivity. That's right, radioactivity. Find out more about this shocking, potentially lethal news here on KEOW tonight at 10 o'clock."
Let's just go ahead and beat the 10 o'clock news to the punch -- frankly, I'm surprised it hasn't been done yet somewhere (or maybe it has?) -- and get to the meat of the matter: Yes, that banana you're eating is radioactive.
Bananas are just one of many foods that we eat on a daily basis which, thanks to ingredients like potassium and radium, produce naturally-occurring and measurable amounts of radiation. In fact, that banana is so good at producing a constant, easily measurable amount of radiation that it's used as a convenient yardstick for measuring radioactivity, which is normally measured in extremely small units called "picocuries." (Yes, after Marie Curie.)
An average banana contains about 520 picocuries, due to the high amount of potassium present in the fruit. All potassium also contains the naturally occurring radionuclide potassium-40. Since many people don't have any concept of how large or small a picocurie is, the "banana equivalent dose" is often used to explain how radioactive a given object is.
For example, the average person's exposure to radioactive isotopes in the aftermath of the Three Mile Island disaster -- within a 10 mile radius from the site -- was 8 millirems, a little less than the average chest X-ray. If you ate a banana every day for a year, your exposure to radioactive potassium-40 would be about 3.6 millirems. So the banana equivalent dose (BED) for the average Three Mile Island survivor was 2.22 BED. Taking circumstances into consideration, that would be the equivalent of eating 810 bananas in one day. (No, this is not a suggested hazing ritual, college kids.)
The fact of the matter is that naturally present radiation is everywhere, even in our own bodies. The average human is comprised, at least in part, of radionuclides like carbon-14 and uranium. So any fuss over foods that contain naturally occurring levels of radiation is just silly. But that doesn't mean it isn't interesting. Below are eight foods that are radioactive. Combine them all in one power-packed meal to gain superpowers! (Superpowers not guaranteed.)
1. Bananas: As mentioned above, bananas contain about 3,520 picocuries of radiation per kilogram (pCi/kg). They are one of the more radioactive foods we eat on a daily basis.
2. Potatoes: Your average white potato contains 3,400 pCi/kg.
3. Carrots: Carrots and potatoes together will net you 6,800 pCi/kg, as carrots carry an equivalent amount of radioactive potassium to potatoes.
4. Lima Beans: Lima beans, like kidney beans, contain 4,640 pCi/kg due to high levels of potassium (as well as a little bit of radium for good measure). Kids, this likely won't be a valid argument against eating them, however.
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5. Red Meat: Again, potassium is the culprit here. That steak will get you about 3,000 pCi/kg.
6. Low-sodium Salt: Because it's made with potassium chloride instead of straight sodium, low-sodium salt also contains roughly 3,000 pCi/kg.
7. Beer: Yes, beer. Stay strong, though, as beer only contains a trifling amount -- only 390 pCi/kg -- that's about 10 times less that of a banana.
8. Brazil Nuts: At more than 6,600 pCi/kg, Brazil nuts are the most radioactive food the average person consumes due to their high levels of radium present in the tree's root system, as well as high levels of potassium. Not to fear, though: The human body retains almost none of the radiation consumed while eating Brazil nuts. Paradoxically, these radioactive nuts are thought to help prevent breast and prostate cancer thanks to their high levels of selenium.