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 
Nice graphic. Just want to let you know that the mammogram dose is an order of magnitude high. A complete exam is about 0.4 mSv rather than 3 mSv. Yearly mammogram are very important and don’t want misinformation regarding cancer risk discouraging people from this exam.
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Coal should be mentioned on the chart, as it’s the largest source of man-made radiation and the largest source of electricity.
http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste
Over all, each coal plant puts out about a hundred times the radiation of each nuclear power plant.
I know it’s much harder to source things like ‘lives in a house of bricks’ because each brick was made in a different region, and therefore has a different radiological signature. But those are known, common sources, and should be mentioned. Especially when comparing to nuclear sources!
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I just earned my PhD in health physics not too long ago, and this chart is close to one I’d make myself. It quantifies different radiation doses in a pretty easy-to-follow, understandable way.
The only thing I might add is that when you get into extremely high doses, like anything over 1 Sv, they’re not necessarily fatal unless the dose is applied to the whole body. You can survive doses in the tens of Sv to individual organs, and radiation therapy typically involves doses that high to tumors.
That’s nitpicking though. I’ll point this out to my non-nuclear friends when they want to have an idea of what all those dose numbers on TV mean.
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Hello Randall! I’m the author of the blog post that was mentioned as one of the sources for this. A long time xkcd fan, happy to be of help.
Also, if you check the fourth photo of the blog post, the one where I’m standing at the checkpoint, you might spot a familiar looking t-shirt 🙂
http://blog.vornaskotti.com/2010/07/15/into-the-zone-chernobyl-pripyat/
Thank you for a brilliant webcomic!
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One important thing to note is that the major danger from the Fukoshima plants, as from Chernobyl, isn’t direct exposure to radiation, but exposure to radioactive bioaccumulants like iodine and cesium. It is possible to have an area showing only modest elevations in radiation levels, compared to background, but which is still unsafe due to the risk of absorbing radioisotopes that will either concentrate in particular tissues (as iodine does in the thyroid gland) or which will remain in the body, emitting radiation, for a long period of time due to long biological half-life.
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Why not also include places that have among the highest natural background radiation on earth. places that have been extensivly studdied and where the result only shows limied effect on healt if any
Karunagapally in india where the background radiation is 3mSv/y
and Yangjiang in china had an internal dose of 6.4mSv/y
Click to access 01325.pdf
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7581-4FJT8MK-11&_user=10&_coverDate=02%2F28%2F2005&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1686188364&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b1dde18bae24b9bd5c0da528a648efae&searchtype=a
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I should mention, too, that the radiation argument is often used as a red herring by those who wish to take the wind out of the sails of those arguing against nuclear power. It is true that the radiation emitted from a nuclear plant (when things are working properly) is negligible. The much better arguments against nuclear energy are (1) it is not a zero emissions technology, for the mining and refining of uranium results in CO2 emissions per kWh of electricity produced that are comparable to those of natural gas, (2) it is the most expensive means of generating electricity that anyone has ever come up with, and (3) we don’t know what to do with the tonnes of nuclear waste that are accumulating in storage facilities, and which will remain dangerously radioactive for millennia.
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Note that the numbers for the nuclear plant assume that nothing goes wrong and everything critical behaves according to spec, which in surprisingly many cases is not true.
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Thanks Randall: I’ll never buy a bananaphone again!
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@Vikram
1) No nuclear is not a zero emissions technology, but it produces less CO2 than any power source except hydro-electric. It has lower CO2 emissions than both wind (due to the amount of concrete used building the thousands of foundations to produce the same amount of power as a single nuclear plant) and solar (due to the chemical processes needed to produce photo-voltaic cells).
http://www.world-nuclear.org/education/comparativeco2.html
2) Nuclear power is not the most expensive means of generating electricity. It’s not even close to being the most expensive. You just made that up. It literally could not be more wrong. The up front construction costs are the most expensive, but the fuel cost is extremely low. The fuel is actually much cheaper than coal and natural gas because fuel rods last for 5 years. Overall, the cost per kW-hr for nuclear is comparable to fossil fuels and several times cheaper than solar and wind. The relative costs depend on where you are of course, but hydro-electric power is the only source that is consistantly cheaper and unfortunately we have already tapped most of our hydro power sources, so we really can’t make any more electricity this way than we already do.
http://en.wikipedia.org/wiki/Relative_cost_of_electricity_generated_by_different_sources
3) We do know what to do with the fuel, but we don’t do it yet because it does increase the cost of the fuel cycle. The fuel can be recycled, as it still has 95% of its energy after 5 years in a reactor. The long lived isotopes in the waste can be extracted and transmuted into short lived waste by placing it in a special type of reactor. Hopefully these processes will become economically competitive in the near future, but if not, we are capable of building waste repositories. We already have one in New Mexico that has been operating for 12 years, but it is only being used for military nuclear waste. They’re also building a geological repository in Finland as we speak.
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Thank you for putting up the comparison between Nuclear and Coal Power plants, I am no Nuclear advocate, however we deal with radiation poisoning on a daily basis due to coal power and nobody mentions it. However they get all funny about Nuclear power. Baffles me.
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Thanks for this chart. It really helps put things into perspective.
Is there a high-res version available, a .pdf for example? I would love to print this out on a large sheet at 300dpi quality.
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I really liked the assonance in Ellen’s version:
Sleeping with a partner
eating a banana
Somebody should write a radiation dosage song incorporating this. People could sing it to remind themselves how worried they should(n’t) be in various situations. I would sing it at all sorts of inappropriate times, as I do with most scientific or humorous songs.
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@Jamie
I’m surprised to hear actual cases of radiation poisoning occurring, my understanding was that coal ash was pretty radioactive but only as much as granite.
I’m pretty baffled actually. I take it this exposure to radiation occurs during mining because I can’t see it happening at the plant?
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This chart mixes up a whole bunch of different kinds of radiation, that have completely different effects on the human body. Regarding Bananas – the potassium is safe for humans, and thus bananas are not comparable to things like Cesium 137 or Plutonium. The banana and sleeping next to another person are not the same as other forms of radiation, and should be taken out due to being misleading information.
“The problem is that this system implies that all radioisotopes are created equal—That there’s no difference between 520 picocuries of Potassium-40 and a similar intake of, say, radioactive iodine. And that simply isn’t true. I contacted Geoff Meggitt—a retired health physicist, and former editor of the Journal of Radiological Protection—to find out more.
Meggitt worked for the United Kingdom Atomic Energy Authority and its later commercial offshoots for 25 years. He says there’s an enormous variation in the risks associated with swallowing the same amount of different radioactive materials—and even some difference between the same dose, of the same material, but in different chemical forms.” http://boingboing.net/2010/08/27/bananas-are-radioact.html
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Hi there.
Awesome post. Very well done. I saw it mentioned on io9.com this morning.
On “Radiophobia”: http://edition.cnn.com/2011/WORLD/asiapcf/03/19/nuclear.radiophobia/index.html?hpt=T2
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Am I the only one who thinks this would have made a great comic?
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This is a great chart! Being an engineer, I am always trying to explain to the non-scientific / technical people what is a real risk compared to perceived. As usual you great work is inspiring and effective in getting to the point. Thanks for the great chart.
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As a foreigner living in Japan, I am constantly swamped with emails and phone calls from loved ones overseas insisting I return to my home country because “it’s not safe”. It’s not just me – many other expats are getting the same messages from back home.
I appreciate the concern but I’m thoroughly sick of all the misinformation and sensationalist headlines from the foreign media. I’m not starving from lack of food from supermarkets (I can live without cup noodles), I’m not living without electricity or gas or water (although occasionally I am), I’m not being bombarded with high levels of nuclear particles.
Unfortunately the same can’t be said for the people affected by the quake and tsunami, but the rest of Japan is getting on with our lives as normally as possible, and we all are fighting on for the sake of those who are left with nothing.
I am very grateful for this chart you have posted and will pass this on to my friends and family overseas. I just hope the foreign media would publish something similar so everyone can have some peace of mind, and help them focus their money on the real victims in this triple tragedy, rather than buying a plane ticket to get me home (which would give me more radiation than if I just sat here..)
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I was aware of the dose amounts for the different radiation scenarios presented, but your chart really gives a powerful visual comparison! Thanks!
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Heidi Hanson:
This chart mixes up a whole bunch of different kinds of radiation, that have completely different effects on the human body. Regarding Bananas – the potassium is safe for humans, and thus bananas are not comparable to things like Cesium 137 or Plutonium.
The dose unit used in the chart is the Sievert, which corrects for biological effects of different types of radiation. Thus, your quote from boingboing, which talks about curies (simple radiation dose without reference to biological activity), is irrelevant to this chart.
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Very cool chart! It definitely puts everything into perspective.
One source of radiation I’m curious about is the amount people get through radiation therapy as treatment for certain types of cancer. Where would that figure in the chart?
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Damn you for getting that infernal Raffi song in my head again.
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Sarah, typical prescription doses of radiation for cancer are in the range of 50-70 Gy, (and in this case, 1 Sv is the same as 1 Gy) depending on the disease, it’s location, and extent. It also depends on the radiation technique being used (external beam versus low dose rate or high dose rate brachytherapy) However, as previously explained, organ (or tumor) doses cannot be compared with whole body doses.
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Heidi, while it is correct that different radioisotopes behave different in a human body due to their chemical composition, a dose (as given in Sv) delivered from any of them to a specific organ is, in fact, the same.
As Mike pointed out, your quote is about Curies ingested. The Curie is not a radiation dose unit, it is a unit of activity. Specifically, it’s 3.7×10^10 disintegrations per second. In addition, the Curie gives no information about the type of radiation produced in a disintegration, or its average energy. Both of these are very important in determining radiation dose. A 1 Curie source that emits a low energy neutron delivers different dose than a 1 Curie source that emits a low energy electron, delivers a different dose than a 1 Curie source that emits a high energy electron.
Add to this the fact that, due to chemical properties, different radioisotopes localize in different parts of the body and stay for different amounts of time, dose deposition from the same activity of a different isotope is, in fact, different. However, radiation doses to the same organ from different sources can be compared, because it is not looking at the number of disintegrations that occurred, but the energy deposited in that organ by those disintegration processes (divided by the mass of organ that received that energy deposition).
However, for an explanation of why one may compare doses to the same organ type, but not organ doses to whole body doses, please see my previous posts.
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I want to second Radiologist Pat that the radiation dose of a mammogram is too high. According to my sources (including the “Mammography” article on Wikipedia) the dose of a traditional mammogram is about 0.7 mSv, whereas the dose of a digital mammogram is about 0.4 mSv.
By the way, these are still high compared to the dose of other x-ray procedures, hence there is a legitimate debate about who should get mammograms and how often.
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Why does a hand x-ray require more radiation than an arm x-ray? Could there be a typo on the eighth entry, where it should read: Dental or head x-ray?
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How much radiation did Spock receive in The Wrath of Khan?
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I think this chart is a bit misleading.
For one thing, most researchers believe that the effect of ionizing radiation is non-linear, and that small doses are disproportionally damaging.
For another thing, this chart is all about doses, rather than contamination. A picogram of plutonium in your lung is probably going to give you cancer, but this chart tends to downplay that by making ridiculous comparisons with bananas and stone buildings. This chart is about relatively short periods of time, whereas contamination is about ongoing, relatively permanent exposure. I-131 isn’t the only thing produced — caesium-137, a calcium mimic, has a half-life of some 30 years!
Most researchers agree that there is no “threshold effect,” under which harm does not occur. Yet this chart clearly states 100 millisieverts as the minimum amount that increases cancer risk. This flies in the face of statistical studies that show that 430 “excess infant deaths” occurred during the Three Mile Island accident.
Finally, the “sources” seem to be limited to nuclear fan-boys, such as the NRC (who, despite “Regulatory” in their name, NEVER turned down an operating permit) and Brookhaven.
There’s a lot of “alternative” research out there. Google for papers by Gofman, Tamplin, Sternglass, Steward, et. al. and realize that all is not what the government tells you!
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Any chance you’ll produce poster prints of this one? I would buy one in a heartbeat!
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So what you’re telling me is, I shouldn’t eat bananas.
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Actually, Jan, most researchers do not believe that low doses are disproportionately damaging. The data for low doses cannot show, statistically speaking, if very low doses cause an increase in a person’s risk for cancer or not. I would argue that most researchers recognize this. However, to be conservative in a regulatory approach, a no-threshold model is used. This no-threshold is not backed up by data, it’s just a reasonable approach for safety purposes. In fact, you can google for radiation hormesis and find arguments that chronic low doses can actually be protective rather than harmful. Regardless, the chart just states a dose that can be *statistically shown* to increase cancer risk.
While Cs-131 does have a long half life, its levels are being monitored in the region about the reactor in milk and in plants. When levels above regulatory limits are found (and if I recall correctly, there have been a few cases), the food being grown in that area will be disposed of, not sold and eaten. I-131 has a much shorter half life, and can be “blocked” with stable iodine. Supplements for this purpose are being administered at evacuation stations.
As for the NRC, having dealt with their inspections, I can assure you they uphold regulations. They even revoke licenses, and do not even hand out amendments lightly. They certainly do not hand out materials licenses like candy.
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Sleeping next to someone per what? “one night” or “one year”?
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Gizmodo even did a blog post on this. And put xkcd in all caps, not lowercase.
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I measured the output from my dentists new xray machine at the same distance which an xray would be taken. The skin dosage read exactly 1 Rad of exposure for 100 mil seconds (one hundredth of a second).
0.1RAD = 1MSV (milli servert) I hope this is of use to somebody dentist found it Interesting.
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I suppose I’ll get cancer if I inhale 2,740 bananas every day for a year.
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