That is absolutely true. But the same can be said for spinach, potatoes, oranges, granite counter tops, the very air you breathe and even your own body! Radioactivity is all around us and is unavoidable. So what is it? The simple mention of the word “radiation” often evokes fear in people. For others, it’s fun to think a little exposure to radiation could turn you into the next superhero, just like the Hulk.
Everything in the world is composed of elements, (remember the periodic table?) which in turn are made of atoms. Some of these atoms are unstable and decay, or break apart. When this happens, they emit what we call “radiation” that can take the form of subatomic particles such as electrons, alpha particles and neutrons, or electromagnetic waves known as gamma rays. All of these carry energy and are capable of breaking down, or “ionizing,” molecules they encounter. It is damage to important biomolecules such as proteins or DNA that can trigger radiation sickness or cancer. As with chemical toxins, extent of exposure is critical and that is dependent on the nature of the radioactive element in question, the amount of the element, the distance we are from the radioactive material and the presence of shielding substances that may be between us and the source.
What is the actual risk of eating a banana? That can be determined by the dose of the radiation that is absorbed by relevant human tissues as measured in “rem,” a unit that takes into account the amount of radiation absorbed and the medical effects of that radiation. For death to ensue, a million times a thousand, or a billion, bananas would have to be consumed. And that would have to be at one sitting, quite a challenge.
But what about the risk of eating bananas over a lifetime? Cumulative damage?
That doesn’t happen since our bodies contain potassium as a natural component, and the body maintains the amount of potassium at a constant level. Some potassium is always taken in via the diet, and some is always excreted, meaning that there is no build-up of radioactive potassium. So, while bananas are indeed radioactive, the dose of radioactivity they deliver does not pose a risk!
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