Radioactive bananas - should we stop eating them?!
Yeah, you heard right. Stop eating that banana! Nah, just kidding, keep eating. But as matter of fact bananas are radioactive. How is that possible?! Well bananas are rich in potassium and some of that potassium (isotope potassium-40) is naturally radioactive. What does that actually mean for us – banana consumers?
Banana for scale
Radioactivity is usually measured in sieverts (Sv) and this unit is used to indicate the health effects of small doses of ionizing radiation on human body. 1 Sv basically corresponds to 5,5% chance of developing cancer and is as well the maximum allowed radiation exposure for NASA astronauts over their career. One normally sized banana corresponds to ca. 0,1 µSv – sooo that is really low. As a matter of fact, you would need more than 10 million bananas in order to achieve radiation equivalent of 1 Sv. But the fact, that bananas are indeed radioactive gave birth to the idea to use them as informal unit of radiation dose. BED – Banana Equivalent Dose – meaning the dose of radiation person is exposed to by eating one average-sized banana (ca. 150 g). This kind of graphic representation is great for education and public- Coz you know, everyone can imagine a banana. See the chart bellow showing radiation equivalent of certain activities in bananas.
Should I stop eating bananas?
No.
But they are radioactive and will give me cancer!
Indeed, bananas do contain radioactive potassium isotopes, but the dose of radiation of one banana (0,1 µSv) is in contrast much less significant than the background dose received by average person over one normal day (ca. 10 µSv). The radioactivity gain due to your lust for bananas is also not cumulative – meaning that even though you ate like 5 bananas today the radioactive component is excreted from your body to maintain metabolic equilibrium. And really, stop and think about it a bit. Do you know someone who died because of banana radiation?! I think not.
Concluding remarks & interesting links
Hopefully you all learned something new today. If you are interested in this topic I recommend watching THIS video, that basically explains levels of radioactivity using bananas for scale. And the whole “banana chart” I used is in fact much longer and if you are interested go check THIS site. :)
Thank you and stay BANANAsome! :)
References:
https://en.wikipedia.org/wiki/Banana_equivalent_dose
https://en.wikipedia.org/wiki/Sievert
https://www.helmholtz-berlin.de/pubbin/nutzernews_seite?nid=153&typoid=39337;sprache=en
https://www.universityofcalifornia.edu/longform/what-know-you-go-bananas-about-radiation
How does living in a granite area compare to that? I heard that granite is naturally radioactive too ... and I'm surrounded by it.
It is always nice when someone asks questions! :) Well, as I am no expert in the topic I can not really evaluate whether living near granite could somehow impact health of humans in terms of exposure to radioactivity. As I found out, granite is indeed radioactive (as most of the natural stones), but some granites are reportedly more radioactive. So in a way yes, there might be some health risk. On the other hand x-ray, flight or smoking cigarretes represent much higher doses of radiation.
Thanks for looking into this. Good job I don't fly too often. ;)