There’s a lot of discussion of radiation from the Fukushima plants, along with comparisons to Three Mile Island and Chernobyl. Radiation levels are often described as “<X> times the normal level” or “<Y>% over the legal limit,” which can be pretty confusing.
Ellen, a friend of mine who’s a student at Reed and Senior Reactor Operator at the Reed Research Reactor, has been spending the last few days answering questions about radiation dosage virtually nonstop (I’ve actually seen her interrupt them with “brb, reactor”). She suggested a chart might help put different amounts of radiation into perspective, and so with her help, I put one together. She also made one of her own; it has fewer colors, but contains more information about what radiation exposure consists of and how it affects the body.
I’m not an expert in radiation and I’m sure I’ve got a lot of mistakes in here, but there’s so much wild misinformation out there that I figured a broad comparison of different types of dosages might be good anyway. I don’t include too much about the Fukushima reactor because the situation seems to be changing by the hour, but I hope the chart provides some helpful context.
(Click to view full)
Note that there are different types of ionizing radiation; the “sievert” unit quantifies the degree to which each type (gamma rays, alpha particles, etc) affects the body. You can learn more from my sources list. If you’re looking for expert updates on the nuclear situation, try the MIT NSE Hub. Ellen’s page on radiation is here.
Lastly, remember that while there’s a lot of focus on possible worst-case scenarios involving the nuclear plants, the tsunami was an actual disaster that’s already killed thousands. Hundreds of thousands more, including my best friend from college, are in shelters with limited access to basic supplies and almost no ability to contact the outside world. If you’re not sure how to help, Google’s Japan Crisis Resource page is a good place to start.
Edit: For people who asked about Japanese translations or other types of reprinting: you may republish this image anywhere without any sort of restriction; I place it in the public domain. I just suggest that you make sure to include a clear translation of the disclaimer that the author is not an expert, and that anyone potentially affected by Fukushima should always defer to the directives of regional health authorities.
xkcd 
Nick – Imaging doses *are* whole body equivalent doses, in order to properly compare them with each other for rad protection uses, so it’s entirely right to have them here. The units Sv are used to indicate effective dose or the older eff dose equivalent, which indicates the radiation dose that would give the same risk as it it were a whole body irradiation.
Thanks, good graphic, too much silliness, confusion and panic around nuclear versus thousands of people suffering right now.
How many die from fossil fuel processes, miners in NZ, cars, chemicals…but it seems getting a few Bq of I131 in your body is far worse according to the media.
It’s essential to put risk into perspective, else patients stop going to hospital for essential radiological procedures that can save their lives because of the fear associated with radiation. To say that anyone trying to bring a balance to the hysteria is somehow in collusion with nuc industry is pointless, self-referencing, evidence-ignoring & fear-driven.
Glad Ellen is helping reduce the fear-factor. Radiation professionals get more radiation than the public every year, we work with this stuff, we’re not made of special radiation resistant material, we just have an idea of risk & balance.
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Please consider adding a value for the slab granite counter tops. People happily take the “risk” from granite counter tops but freak out at a much lower risk of airborne radiation reaching California from Japan.
The dose makes the poison!
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Randall, could you publish the SVG source, so I can translate it easier? Sentences in portuguese are usually bigger than in english, and squeezing them into your chart is not looking good.
I’m no wiz on editing images, but really would like to spread the word and reduce misinformation.
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It would be interesting to see the limits in comparison to the maximum exposures permitted for astronauts.
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Outstanding. You have performed a critically needed service for all. I would love to see both of these charts and descriptions printed and posted everywhere. Especially in schools, universities, malls, libraries. Numbers, exposure periods, implications.
Suggestion/Question: Can you also make an equally accessable, understandable chart regarding the levels of danger and specific biological effects from the various specific radionuclides ….. i.e., iodine 131, cesium 137, strontium 90, plutonium 239 and the many other toxic materials in fallout/nuclear pollution? Or, can you recommend such a chart, [already in print] or text, or booklet, etc with clear and graphic depictions and explanations?
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So, theoretically, if I eat 8 million bananas, then I’ll die. Hmm… I like this chart.
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It would be interesting to make another version of the chart, arranged right to left (blue green red yellow), with the bottom row normalized to the same size, and the exploded views above them. It might be easier to grok the relative amounts.
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Let’s talk about INTERNAL doses.
55,000 Bequerels – the amount of 131I found in 1Kg of Spinach.
That’s 1.48 µCi
8.2 rads (aka 82mSv) – the thyroid dose to 1-4 year child from ingesting a single µCi of 131I
16 rads (ala 160mSv) the maximum estimated per capita thyroid dose in the most heavily contaminated areas from all combined domestic nuclear tests.
(Last two paragraphs per NCI Thyroid dose study regarding downwinders)
So, effectively – 2 µCi of 131I (or 1.35Kg of Spinach) puts a 1-4 year old child at a higher risk of cancer than all of the St. George Utah downwinders.
If you don’t know – entire families were wiped out – multiple generations killed by all sorts of cancers.
Funny how we talk EXTERNAL dose vs. INTERNAL where the TRUE dangers are.
To the authors – I’ll carry 10µCi of 131I in a vial in my breast pocket for a month – you feed same to your child. (I doubt I’d have any takers)
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Here is the scary part about this nuclear disaster. The earthquake didn’t shake the building down. The tsunami didn’t sweep the plant away, it just flooded the backup generators. So lack of power, and some water in the generators, brought three reactors to the brink of meltdown. Doesn’t sound like much of a margin for error considering the enormity of the possible consequence.
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Thank you for the chart. Obviously lots of work to put it together but great info!
Its funny (and so sad) how everyone is missing the point – even the best laid engineering plans can go awry….no such thing as 100%. HUGE Difference between 100% guaranteed and 99%.
At the end of the day what has brought us all to this incident is the failure of backup generators and water!!
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@Jim Conforti:
Where did you get the committed effective thyroid dose in children per unit activity for iodine-131? Is that from the NCI study? Is that available online? And the 55 kBq/kg in spinach? That probably doesn’t come from the NCI study—it sounds specific to Fukushima. (It also sounds like quite a lot.)
In any case, assuming your numbers are correct and that 1 kg of spinach really has 55 kBq of iodine 131 and that if a child ingests that, they get a committed dose of 82 mSv dose, then that probably still implies more or less the amount of risk shown on the chart, which is to say a committed dose at about the same level as the dose allowed yearly to radiation workers. Perhaps for the specific case of the thyroid, and for children, the comparison is not exact. But the general picture offered by the chart is still quite reasonable. Carrying 10 uCi of a beta or gamma emitter in your pocket (even assuming no shielding from the container) would never give you anything near the committed dose from eating same, but comparing the dose in sieverts from external exposure to the committed dose from internal exposure is at least approximately correct.
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The absurdity in this chart is that NO ONE knows the total dose received by the public at Three Mile Island. During critical periods of time during that event, radiation monitors were not functioning or their detection limits were being exceeded by an unknown amount.
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@sci-fi
Those are indeed effective dose values. Mea culpa, and thanks for the correction.
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Love the graphic!
I think it’d be great if you could update it with information about the backscatter X-ray machines that are being used by the TSA at US airports.
I found a link:
http://www.justchromatography.com/general/backscatter-x-ray-p2
that lists it between 0.1 and 0.8 or 0.9 uSv, but I think you’d want to double-check that with another source.
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lame.
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I posted this for friends and family! Thank you, as always your charts and graphs bring sense to confusion. 😉
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so what i think i understand is that sleeping next to 80,000,000 people in one sitting can kill you…
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I think you are taking this a little too easy. According to the news agency Kyodo they just measured 0.5 sievert per hour at block 2 in Fukushima. Source: German newspaper: http://www.taz.de/1/zukunft/umwelt/artikel/1/liveticker-japan-3/
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All of which goes to prove it is better to sleep next to someone than eat a banana.
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This is SO WELL DONE! Will circulate this as widely as I can. I should create an award for selfless efforts to educate the public about scientific matters so I can give it to you.
Thank you for your extraordinary efforts.
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How do these numbers translate into Fallout’s ‘Rads’?
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They do not translate to fallout rads…
When you breathe in radioactive particles, it stays in your lungs, radiating you from inside until you die.
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What’s the dose from sleeping next to a banana? The real lesson is that EVERYTHING is more or less radioactive– including the meat you’re made of. And don’t forget the research that suggests that the dose-response curve may start out with negative slope. This is called “hormesis”.
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Great Chart!
I’m going to print it today and place it on the wall, for everyone to see.
Very informtive, very nice.
Thnks
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Nice looking chart, this is. I know, it is really much work to create such a detailed chart to visualize that much confusing data.
However, from pure statistical point of view, this chart may confuse readers in a way they may not get aware of at first. The worst problem with that chart is, that you are mixing up different time bases. How can you seriously compare e.g. “ONE-DAY dose […] at two sites 50 km NW of Fukushima” with “normal YEARLY background dose” by graphics which are nearly equal in size?? This may lead people to underestimate the real harm of the dose near Fukushima. Yes, 3.6 mSv PER YEAR may not be harmful as your immune system may get to manage this easly. But getting the same dose EACH DAY is definitely a very other level of risk.
I am not a nuclear nor a biological expert. I just see it from a statistical point of view and come to the conclusion that this chart has to be taken with care.
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I have translated your chart into Japanese.
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The chart is misleading because you are comparing a *daily* dose 50km from Fukushima with the maximum permissible *yearly* dose for a US radiation worker (50mSv). You need to compare over equal time periods for the chart to make sense, and if you do so you will find that the annual dose 50km from Fukushima is 1314mSv; more than 26 x that permissible for a US radiation worker, and over 10 x the lowest one year dose that is clearly linked to increased cancer risk (100mSv).
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@Lin
That’s completely irrelevant since the radiation level you write about was just a brief moment, not a year. The other thing is noone would live in the area with this level of radiation for this long.
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@Lin
if you do so you will find that the annual dose 50km from Fukushima is 1314mSv;
That would imply however that the radiation levels will not decrease at all for a full year and THAT would be criminally misleading. Granted, it would have been more accurate if he had waited after the crisis is over and put up an overall number as in the Three Mile Island Incident, but by then there would be little need for the table (I believe we can all agree on the goldfish-like attention span of the average Mass Media consumer).
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I am trained as a Nuclear Diver and as a first responder for Nuclear Emergencies. Let me make this clear to everyone.
DON’T PANIC!
That being said, there are people out there that are gobbling potassium Iodide like Skittles and afraid to send their kids outside to play. I found a webcam in california that was aimed at a Geiger counter that was showing 68 cph, I can’t say for sure what that translates to on their meter, but I’m getting 720 cph on my front steps and that converts to something like 122 usv a year. The host of that site called it elevated but did not elaborate.
This shit has to stop. There are people dying in Japan. They are buried under rubble. They are exposed to rotting bodies, and they have real issues. Here, on the other side of the world we are freaking out about radiation levels that are hard to detect 10 miles from ground zero. To put it in perspective, if you have granite counter tops in your kitchen, you are probably taking as big a dose of radiation as the people at that plant.
Deal with real life folks, please.
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Thanks for the great work! One question: i’m a chemistry teacher and would love a printed version, but the png is a bit low in print quality if printed in adequate size… could you send me a pdf of the graph? that would be lovely! i guess you’re able to see my email adress as editor 🙂
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Fantastic! About time someone put this in perspective. xkcd to the rescue again. 🙂
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bananas should be the new standard radiation measure.
for example, one-day dose near Fukushima on 3/16 is almost like 36.000 bananas
and mammogram is almost like 30.000 bananas
and so on..
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