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 
let’s do a comparison on the deaths directly related to burning coal for electricity over deaths directly related to nuclear power. keep in mind that nuclear powered deaths are usually acute and coal burning powered deaths are typically chronic (except when a mine caves in). my guess would be that because coal powered deaths are chronic no one pays much attention. when a relative few people die suddenly in a nuclear accident most ignorant people go a little coo-coo from the propaganda they’re inundated with.
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One thing omitted was cigarette smoke. It contains polonium that is in the tobacco leaves.
Smokers’ lungs are thought to absorb as much as 160 to 200 mSv/yr
Compare this with the ~3 mSv/yr from natural sources!
http://www.nap.edu/openbook.php?isbn=0309051908&page=106
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Your friend Ellen lives in Portland. I would like to know her.
And not just because it’d be handy to know someone in town with access to a nuclear reactor.
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To be informative the dose limits to the public (and radiation workers) exclude radiation for medical purposes, as medical problems that are being scanned for are much more dangerous than the small probability of cancer.
I do agree that contamination with radioactive isotopes should be quantised separately from external exposure, while the a Sv from each will do the same damage, the logistics of calculating dose from unsealed radiation sources in prohibitive, so treatment using radioactive isotopes is prescribed in terms of activity (Bq), therefore accidental exposure should be measured the same way. In saying that, contamination should be kept in perspective, like this info-gram does for external radiation.
@ DCX2 @Deb Cee
For clarity I assume Deb was talking about nuclear imaging like SPECT or PET (positron immersion tomography) where they inject you with a radioactive martial and detect the radiation leaving the body.
@ Tiago Freire
Mobile phones and wifi use non-ionising radiation, to be ionising radiation it needs enough energy to ionise an atom in air, which infers to having enough energy to break the chemical bonds in DNA. If DNA is broken (in just the right way as some else described earlier) the cell can become cancerous. Mobile phones and wifi do not have short enough wavelength to cause cancer in this way (and in no other way known)
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I forgot to ask, does anyone know what reference the “100mSv lowest 1 year dose clearly linked to cancer” is from
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I object to that chart for being insufficiently scary.
It shows the maximum radiation exposure for Fukushima as being ~3.6mSv,
But in fact the highest recorded level was 400mSv an hour.
http://www.iaea.org/press/?p=1248
And that was only the highest recorded level…
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You must have already seen this, but nevertheless…
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You really should have used “sunshine units” for better nuclear industry propaganda. That’s an idea that the Atomic Energy Commission promoted while they were irradiating the whole country with nuclear fallout from bomb tests.
Oh … and you also need to talk about “hormesis” because radiation is good for you!!
http://www.prwatch.org/tsigfy.html
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THANK YOU for providing a realistic chart of radiation. In general, people don’t know the difference between radiation and radioactive contamination. This chart explains the radiation perfectly, as for the contamination there will be little to none from Japan. Even with the worst possible scenario from fukushima the total exposure to radiation would be far less than just living within a hundred miles of a coal plant.
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ChrisB: You are fearmongering. You are presenting absolute values without any mention of distance.
Randall explicitly stated that the ~3.5mSv/day dose was for sites 50km NW of Fukushima. Your report said that the 400 mSv/hr was at the site of the explosion itself.
As Ellen’s article very clearly explains, distance has a tremendous impact on dose. If the dose is 400 mSv/hr at the site (let’s say 10m away, just to make the math easier), then at 1km (100x that distance) the dose is 1/10,000, or 0.04 mSv/hr (or 0.96 mSv/day). At 50km away (another 50x distance), divide that by another 2500.
Randall’s 3.5 mSv/day at a 50km distance is actually worse than the 40 mSv/hr recorded on-site.
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I liked how Mr. Munroe implied a Banana Phone is more likely to cause cancer than a cell-phone. With some of the hystaria over electromagnetic radiation, this is probably a good think. Most people get the bulk of their radiation exposure from that big fusion reactor 8 light minutes away.
That said, the comparison is not fair because it only considers *ionizing* radiation: basicly anything with more energy than visible light. A cell phone will expose the user to a lot more energy than the banana phone. It is known this can measurably raise the temperature in the brain. Such small heating effects are assumed to be benign (you get more heating walking out in the sun). However, it is still prudent to avoid excessive exposure to radio-frequency waves.
That said, I prefer CRTs, even with the leaking X-rays 🙂
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Lots of people have made the very good point that transient exposure to ionizing radiation from an external source should not be confused with internal exposure, because in the latter case, the dose may continue to accumulate, depending on the half-life and decay chain of the isotope under consideration, and its biochemical activity.
The chart shows “equivalent radiation doses” in sieverts. The “equivalent radiation dose” is how much energy is absorbed in a unit amount of tissue, adjusted for the local distribution of absorbed energy. (An alpha particle, which deposits all of its energy in a tiny spot, does more damage than a gamma ray, even for equal energy deoposition.) The concept of “equivalent radiation dose” is independent of whether the source is internal or external.
But what is not easy (and is in fact very hard!) to do is to calculate how much *dose* you get (in sieverts) from how much radioactive material you ingest or inhale (for example, in grams, or more likely, in becquerel—number of decays per second in the quantity of material under consideration).
This is called the “committed effective dose per unit intake” and is difficult to calculate because it depends on:
1. The half-life of the material. Longer half life = slower dose rate, if expressed in Sv/Bq.
2. The half-life for biological elimination of the element. Some elements, like strontium, can be fixed in the body and remain a long time. Others are quickly eliminated.
3. The tissues affected (lungs, bone) and the intake route (ingestion, inhalation)
Basically, you have to calculate how long the material will stay inside of you, how long it will remain active, and then calculate the cumulative dose that you will receive.
To know how much dose you get from, for example, eating a package of spinach contaminated of cesium 137, you could try to multiply the
quantity of radiation in the spinach (say, 1000 Bq) by the committed effective dose per unit activity for cesium 137 (1.3e-8 Sv/Bq, according to the NIH), to get 1.3e-5 Sv, or 13 microsieverts. Then you can compare that to Randall’s chart.
This is how the dose from contamination is calculated, in principle. That said, I’m not positive if the Fukushima-related exposures in the chart take this into consideration. You would need a complete inventory of the radioisotopes released and a model for the exposure of the population, including the routes of exposure (inhalation, ingestion).
Note that expressing the dose in sievert will *not* automatically guarantee that internal exposure is correctly accounted for, as some commentators have mentioned. Using sieverts, as opposed to grays, adjusts for the difference between alpha, beta, and gamma emmitters, and in the end, it’s the dose in sieverts that matters. But that does still has to be correctly accounted for, over all time.
Some numbers on committed effective dose per unit activity intake are available at:
http://webwiser.nlm.nih.gov/
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Its not a big deal and doesn’t detract from the point of the chart, but I want to point out that as Sv are a unit of dose per unit mass, I don’t think it’s wholly correct to put the imaging doses alongside the whole-body doses which are generally assumed for the other scenarios. Otherwise, a non-technical person might assume that one common treatment for prostate cancer, which delivers more than *40 times* the 4 Sv value at the upper end of your chart, would be invariably fatal.
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I mean energy per unit mass. Bedtime, clearly.
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Two videos that everyone should watch, explaining why the theat model for radiation shown in the XKCD chart is wrong.
The speakers are Professor Chris Busby (European Committee on Radiation Risk) and Doctor Jack Valentin (former Scientific Secretary of the International Commission on Radiological Protection).
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Thanks for compiling this awesome chart! I haven’t been keeping track of the various random units-of-measure quoted in different news sources, and this context helps a lot.
btw, you’ve been cited in The Guardian. Nice work 🙂
ref. http://m.guardian.co.uk/ms/p/gnm/op/sgvhghaSx_kB_ev4Q2pP53Q/view.m?id=15&gid=commentisfree/2011/mar/21/pro-nuclear-japan-fukushima
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Damn! XKCD… What if you just caused a self fulfilling prophecy for a Y 2017 apocalypse..
However maybe this gag is worth it! Following XKCD for a while and really want to thank Randall Munroe for loads of fun…and shifted angles of view.
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While I don’t dispute any of the information in the chart, I really wish you hadn’t put yearly cumulative doses side-by-side with large single doses, as if they were equivalent. That will only lend ammunition to the duplicitous assholes who deliberately conflate the two to make the latter seem harmless.
There’s a difference between being slowly pushed along by a car going 80 miles per year and being hit by an identical car going 80 miles per hour – especially if the first car will keep on pushing, no matter how many other impacts you suffer.
Oh, and somewhere along the route of the slow car lies Cancer City. You probably won’t reach it this year, but you never know how close it is until your doctor tells you you’re already a resident (though usually not for very long).
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it’s a nice chart but as far as information about the risk from radation it’s a bit useless.
For instance will 1Sv over a life time do put me at any damage?
What is 0.5 Sv over a day equivelnt to for a years exposure?
That sort of thing. It’s good your trying to clarify an unclear and importent topic but for me atleast this chart isn’t very helpfull to learn more about the dangers of radiation, but sure is pretty.
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hi
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“This impressive chart assembled by the web-based science “comic” XKCD shows how doses scale up in sieverts, the units by which absorption of radiation into living tissue is measured.” – New Scientist.
Ref: http://www.newscientist.com/article/dn20268-nuclear-crisis-how-safe-is-japans-food-and-water.html
Go xkcd!
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Most smoke detectors contain a little bit of Americium-241, which cannot be encapsulated for the device to work. A minor hazard to be sure, but it is part of our background exposure.
Of course one of the biggest human exposures to ionizing radiation in many parts of the US is radon.
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So, did anyone else realize that based on this: eating 10 Million Bananas “all at once” will probably make you sick?
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I like this chart 🙂
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I wonder how many Sieverts were absorbed by Spock at the end of Star Trek II?
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I’m kind of surprised you didn’t include eating a Brazil nut, the naturally most radioactive food in the world.
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I’m wondering if all those people who rushed out to buy potassium iodide pills realize that they purchased radioactive material?
I’m guesstimating around 0.1 banana-equivalent-dose per 130 mg pill… (which is likely more dose than one would get in the U.S. from the Japanese reactor site)
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