Banana Equivalent Dose | Hacker News Reader

Banana Equivalent Dose

en.wikipedia.org

84 pointssph62 comments

I appreciate this is supposed to be educational, but I have to wonder something regarding this point:

> The radiation exposure from consuming a banana is approximately 1% of the average daily exposure to radiation, which is 100 banana equivalent doses (BED).

If your scale starts at 100, maybe it’s not such a great educational example.

If the Average Daily Exposure (ADE) is 100 BED, the number inflates in a way that make the values seem unnecessarily high.

It’s implicitly a kind of “appeal to nature” argument, but already eating 100 bananas is completely unrealistic, and that’s just background radiation.

The article goes on to say:

> The maximum permitted radiation leakage for a nuclear power plant is equivalent to 2,500 BED (250 μSv) per year

I really don’t think this is helpful, because first of all nobody eats 2,500 bananas and it doesn’t say anything about safety, and secondly we now know that this is the same thing as 25 ADE, which both sounds less and gives a better relative comparison to how small the amount is.

Before jumping straight to high BED scenarios, are there any banana standards? BED would appear to dependant on banana size and type, which isn’t defined as far as I can see.

Is the EU standard banana a worthy banana for BED calculation?

https://en.m.wikipedia.org/wiki/Commission_Regulation_(EC)_N....

The intent here is not to show how harmful eating a banana is but instead showing how harmless living nearby a nuclear powerplant.

If eating one banana only is comparable to living 50km from a nuclear powerplant for one entire year, then clearly the radiation you get from the powerplant is ridiculously small.

That fact that all this is only 1% of the radiation dose you'd otherwise get due to background radiation should only help bringing the point home.

Mostly it is an example of failing at science communication, as highlighting the radioactivity of a banana basically just serves to make bananas seem more scary. Because radioactivity is scary: it can lethally damage without you feeling anything before your start puking.

Saying living next to a reactor is safe because even bananas contains a bit of radioactivity is somewhat like saying living next to a Ebola lab is safe because there are viruses in bananas... it's not really speaking to the fear of getting caught up in the fallout when bad things happen at the reactor.

yeah, as always it really depends who are you communicating something to

Fruit are scary! The brits used to give lessons (1970's) on defending yourself against a variety of fruit attacks, here is a clip (https://youtu.be/MlroOdP8p2Y)

> speaking to the fear of getting caught up in the fallout when bad things happen at the reactor.

The comparison focuses on the normal amount of background radiation from living near a nuclear plant, so fear of fallout "when bad things happen" is a separate issue and irrelevant to the banana example. The Ebola lab comparison is a good one though.

In the exact example you provide I agree that “bananas for scale” can make sense, but I still claim that it scales very badly when talking about larger amounts of radiation.

But the whole point is to discuss small amounts of radiation.

So you’re saying “The maximum permitted radiation leakage for a nuclear power plant” in my example is not a small amount?

It's pretty small, but it's not bananas small. The maximum plausible exposure a person could expect to encounter from a nuclear plant leaking that maximum amount of radiation is.

Unfortunately this 'explanation' turned meme has had unintended consequences. I've seen this used by the uninformed online as a counter argument to dismiss legitimately dangerous sources of radiation on more than one occasion, likening radiation exposure to just being around a large amount of bananas. Sometimes only partially understanding something can be worse than not understanding it at all, especially when someone confidently misunderstands it.

Half of the probability mass is below the average in a normal distribution so, yeah, it makes sense for the average to sit at a nonzero and nonunit number. The fact that it's a nice and neat number like 100 is interesting. That's about one box of bananas.

Maybe someday the banana industry will address your concerns by making the fruit more radioactive.

i think it makes sense as a way to show the safety of nuclear power plants, considering measures of amounts of radiation can sound scary to someone who's unfamiliar with them

The human body itself is more radioactive than a banana. Again just looking at the potassium content (that is, the source of the banana radiation). From TFA:

"These amounts may be compared to the exposure due to the normal potassium content of the human body of 2.5 grams per kilogram,[15] or 175 grams in a 70 kg adult. This potassium will naturally generate 175 g × 31 Bq/g ≈ 5400 Bq of radioactive decays, constantly through the person's adult lifetime"

That is, you constantly contain about 400 bananas worth of potassium. Without this potassium, of course, you wouldn't be too healthy.

So, are you suggesting we measure nuclear radiation exposure in amounts based on cannibalism? AJED, Average Joe Equivalent Dose? How many trucks of refugees do you have to eat, to get exposed to as much radiation as say, being 100 km away from the blast of Little Boy?

This reminds me of the Micromort - which I thought was supposed ch great idea, but never seemed to go anywhere…

https://en.m.wikipedia.org/wiki/Micromort

I actually use it with friends now and then and find it useful.

A challenge I have with understanding and communicating risk is that some risk is an instant and some is across distance/time/some quantity.

If you skydive your chance of death is X.

If you drive your chance of death is Y per hour (or km).

Any advice from anyone on the best way to reconcile this? We could add a unit time or distance to the first kind, but I feel that betrays the fact that it’s mostly about “does your parachute deploy?” and is disconnected from how long or far you skydove that day.

(these examples are easy to debate but I hope you get what I’m trying to communicate)

Aren’t they already the same? You’re just not applying the same metric in both cases.

The chance of dying in a car accident isn’t the number of miles driven, it’s the chance of a failure happening and killing you — the distance driven is simply more rolls of the dice.

The same with parachute-failure — the number of chutes opened is the number of dice rolls. You should be saying skydiving death rate is X per chute

What is the driving equivalent to one skydive?

I think that question genuinely illustrates their point that some risk is best considered as a rate whereas some is as a discrete event but I am very interested if you can elaborate a perspective that reconciles that

The link gives both of those, actually. Skydiving is 8 micromorts per jump, car travel is one micromort per ~250 miles. So the equivalent chance of death for one skydive is driving 2000 miles.

But how to combine them, i.e., micromorts per skydiving jump via a car that travels 250 miles in the air before driving it out of the back of a cargo plane?

I think we should just add them together and call it 9 micromorts, assuming the car has an appropriately sized parachute.

That seems to further solidify the original observation.

I do appreciate you finding their break even point though!

I think the answer is that it’s always a rate; it’s just that the skydiving is such a rare event we can implicitly drop the “per chute” because we’re assuming it’s always going to be “1 chute”.

If you took the skydiver instructor, doing hundreds of rounds, then suddenly skydiving should no longer be considered a “discrete event” — your determination of how to treat it isn’t based on the event-type itself, but the object undergoing the event.

There is also the microlife which denotes reduction in life expectancy that is more applicable for lifestyle and environmental factors (everyday you live in Mexico City vs London takes 30min off your life) vs acute risks (sky diving)

https://en.m.wikipedia.org/wiki/Microlife

I dunno, I use it all the time. Putting the danger of Covid-19 into micromort terms was a useful exercise for instance.

Useful for what? Peace of mind? Or as a comparison, where you calculate the micromorts for taking a vaccine, or social distancing, etc?

In terms of deciding how careful to be about it. An interesting property of Covid is that getting it for the first time without vaccination is about the equivalent of a typical person's full actuarial Micromort budget for a year regardless of their age. That's a serious level of danger but not a terrifying one and worth some a good number of lifestyle changes until I got vaccinated but not every potential change.

Wonderful, yeah, great way to put it into perspective. I hope everyone knows by now, but the media feeds off unbounded, hysterical-style risk. Putting a cap on the worst case (or average worst case) frees you from the fear of the unknown.

> A micromort (from micro- and mortality) is a unit of risk defined as a one-in-a-million chance of death.

Ah... so it happens nine times out of ten.

> The micromort concept was introduced by Ronald A. Howard

I was genuinely surprised that not by Terry Pratchett.

When I was growing up hearing about "fallout" was always in terms of some power plant accident and exposure meant some imperceptible increase in lifetime cancer risk. Much later in life I learned that the "fallout" from a thermonuclear bomb exploding a hundred kilometers upwind could easily mean death, not of cancer in a decade but in hours or days from acute radiation sickness. It seems strange that we use the same word in both cases where in other cases our words clearly distinguish amounts by levels of danger, "falling pebble" versus "falling boulder", "raindrop" versus "flood", etc. It would be good if we could have that with radiation dangers as well.

It rained, watch out for puddles.

It rained, watch out for flooding.

The word used is "rain" in both cases. Degrees of danger is communicated elsewhere. Same with "fallout".

This comparison is misleading because it confuses irradiation and contamination. While the dose rate recorded by a Geiger counter at a nuclear site may be low, that radiation is being generated by particles as small as dust. Ingesting a particle by breathing or swallowing it can lead to long term internal exposure.

It is also worth remembering that radioactive particles generate a static electricity charge so they are sticky. Think: sticky, invisible, dangerous.

Not all radiation is created equal, and the delivery mechanism is very important.

Breathing in material emitting an otherwise harmless amount of alpha particles (essentially a helium isotope particle stripped of electrons) is very harmful. Those ionizing particles get into lung tissues and since they’re charged and have a lot of mass they can do a lot of damage in a local area. Internal doses are orders of magnitude more harmful.

Radiation is generally safe, but there are types of radiation doses that are very harmful. It’s less about the radiation level and more about what kind, how it’s delivered, and over how long a time span.

You're conflating two things, so just to be clear about both bad things, for everyone else:

Alpha radiation is massively damaging, but is blocked entirely by the outer, dead layers of skin. Once it gets inside your body where it can access vulnerable tissue, it's a different story.

Contamination (think "source of radiation") that gets inhaled or ingested (committed) is bad because you fractionally take it with you, getting continually irradiated. Even worse, some committed contamination eagerly accumulates or replaces in processes where it won't be exchanged out. This is the case with iodine, and that is why iodine pills can be helpful in large releases of radioactivity.

The Banana Equivalent Dose is a misleading and incorrect because it has an implicit "over a lifetime" in its definition where instead it should be "until potassium level returns to normal". It is the lifetime dose one would be exposed to if the body didn't replace old material with new and instead stored the banana forever.

talked about here too https://www.youtube.com/watch?v=TRL7o2kPqw0

My favorite video of Veritasium, I knew it'd get posted as a comment when I saw the title!

It’s weird how bananas got the rap for having a lot of potassium. Kind of a meme I guess. It’s like the first thing you think about bananas and nutrition. A lot of stuff has a lot more though. I guess Swiss Chard equivalent dose didn’t have the same ring to it.

Swiss chard, 1 cup cooked (960 mg)

Spinach, 1 cup cooked (840 mg)

Avocado, 1 cup (708 mg)

Sweet potato, medium (700 mg)

Bok choy, 1 cup cooked (630 mg)

Potato, medium (610 mg)

White beans, 1/2 cup (600 mg)

Beets, 1 cup (520 mg)

Brussels sprouts, 1 cup cooked (500 mg)

Broccoli, 1 cup cooked (460 mg)

Cantaloupe, 1 cup (430 mg)

Banana, 1 medium (420 mg)

That is some weird and unhelpful mixing of units. There is no way to look at that data and work out which food has the most potassium pr. gram. At a guess a "medium" banana is possibly 1/3 - 1/2 cup raw, maybe less if cooked down? If that's the case it jumps to the top of your list again. And the "1 cup" of cooked chard, is that 1 cup pre or post cooking, packed or loose or perhaps pureed. The difference in weight between 1 cup loose raw chard and 1 cup cooked pureed chard is probably a factor of 10 if not more.

https://www.dietaryguidelines.gov/food-sources-potassium

This is a better list and everything is per serving. Spinach and potato are rocking banana's world at about double the potassium per serving.

I wonder if focusing on this section in anti-smoking propaganda would be effective:

Tobacco contains traces of thorium, polonium and uranium. The process of drying and then smoking the solid matter concentrates those radionuclides further, creating in essence technologically enhanced naturally occurring radioactive material.

It's not like people are addicted because they think it's harmless. And people routinely do things that are many times more harmful than smoking your first cigarette ever. Telling addicts they are harming their health is a terrible tactic to curb the problem.

It's taken me 12 years to successfully quit smoking, and I knew about the lung cancer, the cardiovascular issues and the radioactive tobacco trivia all along.

Oh sure, I generally agree with you, and have also smoked on/off for the last couple decades. I just wonder if people’s general phobia of all things radioactive would further move the needle here.

Edit: I have to say though, that health concerns are what ultimately made me quit for good, so maybe all that propaganda isn’t entirely useless.

The other banana test.

https://m.youtube.com/watch?v=Y4yBvvGi_2A

In resume, if we imagine than Plutonium is Potasium instead then nuclear plants are safe. This is bananas.

I quite like the XKCD visualisation of this - eating one banana == 2 small blue squares.

https://xkcd.com/radiation/

So, eating a banana == sleeping next to 2 people.

Later, virgins.

I have no clue how safe bananas are to eat so this metric is meaningless to me.

Sample size of one: I have eaten bananas, and I'm not dead.

Just think of all the lunatics living next to banana plantations! Or having banana trees in their back yard.

And their children playing under those trees!!

Monsters!

Ah for the old days where you only had to worry about the wafts of DDT floating over the fence!

Everyone who ate bananas in this video are dead...

New York City 1900

https://youtu.be/QlBinV6pFM8

> the "banana equivalent dose" [is] "very useful in attempting to explain infinitesimal doses (and corresponding infinitesimal risks) to members of the public"

It's not though, unless you have a strong a priori belief that eating a banana is safe with respect to radiation.

Who doesn't have a strong a priori belief that bananas are safe to eat?

You clearly fell for BigBanana's propaganda.

More seriously -- challenging "US standard" dietary norms often leads to fruitful discussions of nutrition and how off-optimal most "common sense" tends to be.

Eating bananas is very safe. Unless there is a poisonous spider inside it.

It seems banana for scale didn't come around for another 10 years

The "banana equivalent dose" is an error that refuses to die. Based on tables that estimate the effect of various radioactive isotopes acting for 50 years, people ignoring physiology decided that the average K40 in a banana will produce 0.078 microsievert of damage (rounded to 0.1 because it's close enough for jazz and comics).

The reality is that, due to homoeostasis, the excess potassium you ingest is eliminated the next time you piss, so there's no accumulation inside the organism. Those 50 years become something like 12 hours and the radiation exposure is more in the ballpark of 0.00000213 microsievert.

But that value is now too small to use it in science fanboyism, isn't it?

https://www.epa.gov/sites/default/files/2015-05/documents/52... - page 156. That's where these people took the effective dose equivalent for K^40 from, but those values are for 50 years of exposure.

"For radioisotopes of elements that are under tight homeostatic control by the human body, the inhalation or ingestion risk coefficients given in this document may not be appropriate for application to some exposure scenarios. For example, the ingestion risk coefficient for ^(40)K would not be appropriate for application to ingestion of ^(40)K in conjunction with an elevated intake of natural potassium. This is because the biokinetic model for potassium used in this document represents the relatively slow removal of potassium (biological half-time of 30 d) that is estimated to occur for typical intakes of potassium, whereas an elevated intake of potassium would result in excretion of a nearly equal mass of natural potassium, and hence of ^(40)K, over a short period." - ["Federal Guidance Report No. 13: Cancer Risk Coefficients for Environmental Exposure to Radionuclides"](https://www.epa.gov/sites/default/files/2015-05/documents/40...) - page 16

So, if you accept that the duration of exposure from eating a banana is 12 hours instead of 50 years, a dental x-ray is the equivalent of eating 2,347,417 bananas.

Boo! Get your facts away from my cute little factoids!

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