3 ms·

Bananas throw out beta radiation. It's not as penetrating as alpha - attenuation depth in water on the order of centimeters rather than millimeters? - but I thi

by saulrh 11y ago

Bananas throw out beta radiation. It's not as penetrating as alpha - attenuation depth in water on the order of centimeters rather than millimeters? - but I think a banana-equivalent dose will be pretty solidly concentrated in your digestive tract.

VLM 11y ago
Its mostly the fault of one isotope of potassium and many hiker types eat bananas specifically to boost their blood K levels because otherwise they get really annoying muscle cramps. Its a moderately strong beta emitter and the range in water (close to human body) is about 2 cm or so. There are probably no parts of your innards more than 2 cm from the nearest bodily fluid (blood or whatever). Humans are surprisingly radioactive BTW. We each have about a hundred grams of potassium happily radiating away. An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. For security sensing or something. Maybe in a 100 years automatic supermarket style doors will sense humans radioactively rather than current microwave doppler and infrared systems. Maybe.
- Florin_Andrei 11y ago
  > An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. Beta is super-easily stopped. A piece of cardboard or tinfoil reduces it dramatically, or stops it completely, depending on energy per particle, total flux, etc. I've a Luminox watch, the dial is visible in darkness all the time, you don't have to "recharge" it. It works by having small amounts of tritium decay within luminescent tubes. The radiation produced is beta - but the levels of radiation outside the watch are essentially zero. The body of the watch is enough to contain it.
  - onnoonno 11y ago
    Again, and as others pointed out in other contexts here, it depends on the energy. Tritium has 20keV betas AFAIR. Some elements produce multi-MeV beta decay. That is not stopped by thin cardboard.
Retric 11y ago
No, the banana is radioactive from potassium-40, which your absorbing and spreading throughout your body. However, you also excrete potassium making the Banana equivalent meaningless as it's calculated by assuming you kept that potassium for 50 years which simply does not happen. AKA you would end up with less than 365 Banana equivalent doses by eating 1 banana a day for 1 year. (https://en.wikipedia.org/wiki/Banana_equivalent_dose https://en.wikipedia.org/wiki/Banana_equivalent_dose)
- Retric 11y ago
  PS: Due to homeostasis you generally get less than 1/500th Banana equivelent dose from eating a Banana.
- saulrh 11y ago
  Right, forgot about that part. Thanks.
IanCal 11y ago
> beta radiation. It's not as penetrating as alpha That's the wrong way around. Alpha radiation barely penetrates at all.
- saulrh 11y ago
  Ah, yeah, meant gamma there.

by saulrh 11y ago

VLM 11y ago

Its mostly the fault of one isotope of potassium and many hiker types eat bananas specifically to boost their blood K levels because otherwise they get really annoying muscle cramps. Its a moderately strong beta emitter and the range in water (close to human body) is about 2 cm or so. There are probably no parts of your innards more than 2 cm from the nearest bodily fluid (blood or whatever). Humans are surprisingly radioactive BTW. We each have about a hundred grams of potassium happily radiating away. An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. For security sensing or something. Maybe in a 100 years automatic supermarket style doors will sense humans radioactively rather than current microwave doppler and infrared systems. Maybe.

Florin_Andrei 11y ago
> An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. Beta is super-easily stopped. A piece of cardboard or tinfoil reduces it dramatically, or stops it completely, depending on energy per particle, total flux, etc. I've a Luminox watch, the dial is visible in darkness all the time, you don't have to "recharge" it. It works by having small amounts of tritium decay within luminescent tubes. The radiation produced is beta - but the levels of radiation outside the watch are essentially zero. The body of the watch is enough to contain it.
- onnoonno 11y ago
  Again, and as others pointed out in other contexts here, it depends on the energy. Tritium has 20keV betas AFAIR. Some elements produce multi-MeV beta decay. That is not stopped by thin cardboard.

Retric 11y ago

No, the banana is radioactive from potassium-40, which your absorbing and spreading throughout your body. However, you also excrete potassium making the Banana equivalent meaningless as it's calculated by assuming you kept that potassium for 50 years which simply does not happen. AKA you would end up with less than 365 Banana equivalent doses by eating 1 banana a day for 1 year. (https://en.wikipedia.org/wiki/Banana_equivalent_dose https://en.wikipedia.org/wiki/Banana_equivalent_dose)

Retric 11y ago
PS: Due to homeostasis you generally get less than 1/500th Banana equivelent dose from eating a Banana.
saulrh 11y ago
Right, forgot about that part. Thanks.

IanCal 11y ago

> beta radiation. It's not as penetrating as alpha That's the wrong way around. Alpha radiation barely penetrates at all.

saulrh 11y ago
Ah, yeah, meant gamma there.