xkcd radiates

By Phil Plait | March 21, 2011 7:09 am

Randall Munroe, who draws the geekerrific xkcd webcomic, has created a really good chart showing relative radiation doses absorbed by humans doing various activities.

I’ve put a piece of it here, the section with the lowest doses. I like this! A lot of folks don’t understand what radiation is — light is radiation, for example — or that just by existing on the surface of our planet you absorb a certain amount all the time: from the ground, from space, from things you eat. Wikipedia actually has an excellent rundown of what radiation is, and the critical distinction between ionizing and non-ionizing radiation (there’s also electromagnetic versus subatomic particle radiation, but that’s less of a concern here).

In the chart, Russel deals with doses from ionizing radiation. This is the kind that can cause damage… but only in sufficiently high doses. For example, bananas are a natural source of gamma rays due to the decay of an isotope of potassium (40K). It’s a pretty weak source — a few years back I had access to a gamma-ray detector and we could barely detect a banana’s emission — and it doesn’t affect you in any real way. Potassium iodide is a common salt that’s also a gamma-ray emitter, but again you’d need a lot of it for it to be dangerous… and if you ate that much you’d have worse issues!

The average amount of radiation you absorb in a year is about 3 – 4 milliSieverts, depending on where you live. At higher elevations — like, say, Boulder, where I live — cosmic radiation puts you on the higher end of that scale. I’ll note that cancer risk is not really higher living up here than at sea level (lung cancer rates are lower than average here, probably due to the healthy lifestyles most people follow in Boulder, but skin cancer rates are slightly higher than average, probably due to a combination of people being outside more than average together with the thinner air blocking less UV).

In general, you can actually absorb a much higher than usual radiation dose (up to a point, of course) without ill effects, since your body can heal some amount of damage (just like it heals from a cut). Too many such doses too close together, or too big a dose all at once, can do too much tissue damage and be fatal (I guess, again, like a cut). For example, I like to point out that the Apollo astronauts got roughly a year’s worth of radiation absorption in their tissue while voyaging to the Moon and back, but didn’t suffer any ill effects.

Obviously, this is a complicated issue, but the xkcd chart looks like a pretty good way to eyeball where things fall on a scale of "nothing to worry about" to "AIEEEEPANICPANICPANIC".

CATEGORIZED UNDER: Cool stuff, Geekery

Comments (102)

  1. Jason

    Made this little chart for a discussion on Facebook to discuss the magnitude of radiation doses involved: http://tinypic.com/view.php?pic=kbx21g&s=7

  2. Rory Kent
  3. Rory: That’s what I came here to say. :p

  4. Brendan

    Amtrak should use this in their advertising.

  5. Chris

    For an undergrad project one of my friends was assigned to measure the radioactivity of a banana. He wound up cooking down a few dozen bananas. It was a mess. Glad I didn’t have that one.

  6. Yotam

    And the Google Ad on the side bar: a $139 reactor meltdown detector.
    Ironic? I would think so.

  7. Juwie

    This chart shows is pretty goot the dimentions of the different sources of radiation, but there is something missing when applying to the situaltion in Japan. All the ‘normal life’ exposures like X-ray scans etc. happen quite seldom. People living in Japan near the Fukushima plant will get the radiation all day.

    And the effect of small dose radition applied over a long time is still not well understood (as far as I know!). We know that here in Germay children living near nuclear power plants have a higher risk of getting leukemia, but the real cause is still unknown – in fact it is still unclear if radiation is the cause here.
    We know that the proposion between boys and girls change at places where there is higher radiation – cause also unknown.

    Compairing the situation near the Fukushima plant with one dental X-ray (or eating one banana) seems a bit too simple to me.

  8. Gary Ansorge

    Back in the old days(when I was studying physics,ie, the stone age), we used rem, which I recall meant roentgen,,,something, something. (hey, it’s been a half century). I guess sievert IS more useful.

    It’s hard to believe, less than 80 years ago, people were using radium enemas for health purposes and nuclear workers didn’t even wear protective clothing. Now if someone mentions radiation(regardless of its energy content), everyone is up in arms. We should never have referred to our short wave electronic ovens as micro wave ovens. I still recall the glazed eyes when I tried to explain how micro waves differ from gamma rays.

    I think my Son is right: higher IQs do not represent a linear progression in intellectual capacity. It’s a measure of quantum leaps in intellect(really have no idea what that means, but it SOUNDS impressive).

    ,,,but we need to keep trying to educate people. How else will they get smart?

    3. Chris

    He should have tried cigarettes.

    Gary 7

  9. davidlpf

    I see the light.

  10. CranialEruption

    Note to Phil: You know when you look back over your blog post before hitting the “Publish” button and have that one niggling doubt about the article, like something isn’t quite right? His name is Randall, not Russel. I suggest more coffee, that’ll clear you up right quick.

    EDIT: On a side note, I’d like to see what the entire continuum between “nothing to worry about” and “AIEEEEPANICPANICPANIC” looks like.

  11. Messier Tidy Upper

    For example, I like to point out that the Apollo astronauts got roughly a year’s worth of radiation absorption in their tissue while voyaging to the Moon and back, but didn’t suffer any ill effects.

    Absolutely true I went through an assessment of this recently here :


    Comment # 140 (& corrected slightly in # 142)

    Upshot : twenty-four men in total travelled to the Earth’s Moon from 1968 to 1973 – only five of them have died in the years since and of those five only two died from cancer. The remaining nineteen are all alive and, from what I can gather, really doing pretty well – both physically and mentally.

    Especially so considering their ages (late 70’s mid-80’s) and predicted average lifespans. Plus past occupations – I suspect the average life expectancy for test pilots & military personnel – which is what almost all those astronauts also were – is rather significantly lower than for civilians. :-)

    Of course, the sample size is probably too small to draw truly significant statistical conclusions but still.

  12. Gary Ansorge

    Hmmm, abrupt environmental change. I expect this will select for some survival traits, like better cellular repair mechanisms. Reminds me of the old Star Trek episode, about the Yangs and the Coms,,,

    Gary 7

  13. CompFedUp

    From my father-in-law, who was in the USAF for 20+ years and regularly worked with their nuclear weapons…

    “In 1960 most bombs had a sphere at least 3′ dia, and overall bomb length of about 10′. After maximum storage period of 18 months, each bomb had to be taken apart, each part inspected/tested. After re assembly and all electrical tests were complete, it was sealed up and returned to storage. The plutonium capsule was stored separate in special pressurized container designed to ensure adequate space between capsules. We would wear medical gloves. Using triclor. And lintfree paper towels, capsule was cleaned to “Minimum count”. The actual reading was of no concern, only that it was as low as you could get. The inside (pit) of the sphere was cleaned likewise with towel taped to toilet brush. All used cleaning towels and gloves were placed in metal can, magenta color,marked radioactive, spring loaded, foot operated. After inspectors left, during cleanup, the cans were emptied into dumpster with regular trash. We did that for years, with no detected problem. We wore a dosimeter which would be read Monthly by Medical personnel. Once a buddy and I wanting to put a little spice in our dull life, put our dosimeters inside the “pit” over night, then when the Medic saw the high reading, he threw the dosimeter into the trash and gave us replacement dosimeters, knowing the meters were defective based on the excessive readings. Not a word was said.
    The pit and capsule would experience “spalding”, equal to rust on iron. Our cleaning would remove the loose oxidation, so when the repeated wipes showed no decrease in radiation reading, bomb was good to return to storage.
    By 1970 most pits were sealed and could not be exposed to ambient air. With sealed pit, we could no longer remove detonators for inspection. The pin to pin resistance/continuity of all internal components are now performed by computer.
    Seeing the ignorance of press and public on the radiation in Japan, I felt compelled to relay this.

  14. Messier Tidy Upper

    @6. CranialEruption : I suggest more coffee, that’ll clear you up right quick.

    I suggest a good cup of tea helps even better, myself! 😉

    I’m not properly awake until I’ve had at least one good cuppa – and often not even then! 😉

    Which is why I have a second cuppa then a third .. 😉

  15. Andy

    What font did they use on that chart?

  16. Nigel Depledge

    Aw! Does that mean I have to stop using my bananaphone?

    Gary Ansorge (4) said:

    we used rem, which I recall meant roentgen,,,something, something.

    Rem = radiation equivalent in man.

  17. Sam H

    Off topic but I need some advice: tomorrow I give a PowerPoint presentation to a class of grade 1s on the solar system, our galaxy and the scale of it all. I want to generally WOW them and instill wonder at a young age that could last for their whole life and possibly lead to careers in science (and I indirectly promised to a thrilled 6 year-old last week that her Tuesday would be “exciting”), so I MUST get this right, no ifs, ands or buts.
    I’ve included things such as the Earth-Moon scale experiment that some guy mentioned in a past comment, a scale model of the solar system I did on Google Earth, the wonders of the Solar System (volcanoes of Io, oceans of Europa, canyons of Mars), the life cycle of a star (with lots of pretty pictures of nebulae and rare space art), VY Canis Majoris, the Hubble Ultra Deep Field, and the Pale Blue Dot (which I’ll compare to Whoville, but that could scare them a bit). I’ve also included a movement break halfway thru feat. one of my best songs, and I’ll be present in my new science blue Trek shirt. Anybody have any more advice? I simply CANNOT fail, so please present any ideas/suggestions/general words of encouragement/advice as soon as you can!!
    Happy day after Vernal Equinox!! :)

  18. The “metric” system uses Sievert, whereas the American system uses rem/roentgen.

    1 Sv = 100 rem. These are measures of absorbed equivalent whole body dose. Actually dose (energy absorbed per unit mass) is Gray in the metric system and rad in the American system. 1 Gy = 100 rad.

    The roentgen is the American unit for exposure in air. It is only defined for gamma radiation, not particulate radiation.

  19. Adam

    @16 Sam H – you’ve probably got it covered under life cycle of a star, but remember to make sure they know that they are made of “stardust”.

  20. George

    @14. Andy Says:
    March 21st, 2011 at 8:30 am
    What font did they use on that chart?

    It’s Mac standard-issue Monaco FTW :)

  21. Messier Tidy Upper

    @ 16. Sam H : Happy equinox for you too mate – although down here in Oz it’s the Autumnal one! 😉

    (Raising my beer to you & wishing you the best for your talk anyhow.)

    PS. @ Nigel Depledge – Regarding a past discussion here :

    http://blogs.discovermagazine.com/badastronomy/2011/01/31/bill-oreilly-tidal-bore/#comment-370057 (Comment # 411.)

    I apologise if you, Nigel Depledge, were offended by my previous understanding of what the word “atheist” actually means. It was, simply, how I have always understood the word / concept of an atheist. No offence intended. It does sometimes take me awhile to get my head around things.

  22. Chief

    This unfortunately is another area where the general public really needs better basics of science in school. Any mention of radiation and most will assume nuke plant and the boogy man therein. Of course we are surrounded by radiation of all types every second of our lives and we have evolved to function in that environment. The graph is a good one above but would like to have seen the representative for microwave ovens (even though the radiation type is quite a different animal).

    I wonder how much schooled information is “untaught” by the misinformation of the media and masses over time to the average adult.*

    * – exception to the Texas board which doesn’t teach anything factual at all….

  23. Messier Tidy Upper

    @ 16. Sam H :

    Not sure where to start frankly.

    I’d recommend :


    for scale just in case you haven’t seen it already.

    Or if you something shorter and quite similar and also superluminous :


    Originally seen via this blog – posted by the BA as Scale posted here June 12th, 2009 2:00 PM

    Try the Shuttle video’s here :


    The one of STS-129 blows me away every time. I guess it may be too long for you tho’?

    Then there’s this :

  24. bill stouffer

    Disappointing to see that the only narrative you have any interest in promulgating is still downplaying the seriousness of the nuclear accident. It is not all about us here in the US or the future of nuclear power generally. The consequences in the vicinity of the reactor are tremendously serious, even under the best case scenario. And things are far from under control yet. Care to acknowledge that? If you need something to be skeptical about then consider the oh so reluctant upgrading of the seriousness of the event to the same as Three Mile Island. Surely we are beyond that.

    All this said, I am only writing this because I like your site so much and really appreciate the astronomy news. Just disappointed on this particular issue.

  25. Messier Tidy Upper

    I know you said you had the Moon size comparison but did you see the quotes and comparisons here :


    in the comments?

    Plus my comment # 133 :

    A scale model : If a galaxy’s central bulge were a hundred miles across, its central supermassive black hole would be roughly the size of a sand grain.

    Source : Page 14, “NewsNotes” in ‘Sky &Telscope ‘ magazine, April 2011, VP Publishing.

    Is another great if rather specific scale comparison that I stumbled on lately.

    Plus there’s what the BA expressed very well here :



    If you want a spectacle with science this :


    with the Solar Dynamics Orbiter launch blasting away a sundog is stunning. :-)

    Are they any help? Hope so! :-)

    What, specifically, are you after?

  26. This piece of the puzzle is misleading, though. The green part of the chart shows background radiation at two sites near Fukushima were 1,000 times higher. It’s still a moderate amount, less than the radiation delivered by a chest CT scan, and far less than the amounts that can conclusively be linked to cancer. However, it’s close to what most people receive in a year. I think in the context of this article, which I suppose is intended to give perspective, it would be better to point this out.

  27. Yojimbo

    So when did the US go metric for radiation units? (I missed it until my wife recently mentioned milliSieverts from a news report).

    And when do we bow to the inevitable and change the rest of our silly system?

    And @24 bill stouffer. Not sure what reports you’re hearing but I have not heard anything either downplaying the seriousness or “upgrading of the seriousness of the event to the same as Three Mile Island”. All credible reports I have heard are along the lines of “second most serious reactor problem in history”. Have I been missing something else? Are you saying that the radiation released is higher than what’s been given here? If so, what are you basing that on?

  28. Messier Tidy Upper

    @ Sam H. Some quotes below on the cosmic scale(s) which may be helpful for you perhaps? I hope! :-)


    “Space isn’t remote at all. Its only an hour away if your car could go straight upwards.”
    – Page 43, Sir Fred Hoyle, ‘The Wonderful World of Space’ , Heather Couper, Octopus Books, 1980.

    (But …)

    “If it were possible to drive straight from the Earth to Neptune, taking the shortest possible route and keeping up a steady 60 m.p.h., the journey would take nearly 5,200 years.”
    – Page 57, ‘The Sky at night’, Patrick Moore, WW. Norton & Co, 1986.

    “If we could transport Phobos and Diemos to our own Moon, they would fit comfortably inside the wide crater Copernicus with room enough for two moons of similar size.”
    – Stephen James O’Meara, page 102 “The Demon Sprites of Mars” in ‘Sky & Telescope’ magazine, June 2001.

    “If our Earth is 1 cm from our Sun – & Pluto is 50 cm from it – then the edge of the Oort Cloud of Comet’s would be 1/2 a kilometer away!”
    – Brian Cox, Wonders of the Solar System documentary. (Paraphrased from memory so hope I’ve got that right but pretty sure I have. Circa March 1st 2011.)

    “To get a sense of the scale of the Jovian system, consider that if the Earth was placed at the centre of Jupiter, our Moon would lie inside the orbit of [Jupiter’s nearest large moon] Io, while distant [outer moon] Sinope would be a third of way to Mars.”
    – P. 186, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

    “Jupiter’s magnetosphere, the wasp-shaped zone within which its magnetic field takes precedence over the charged particles constituting the solar wind, extends more than seven million miles ahead of the planet in the direction of its orbital motion, … and trails so far behind that it sometimes impinges upon Saturn.”
    – P. 186, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

    “If you put three grains of sand inside a vast cathedral, that cathedral will be more densely packed with grains of sand than stars are found apart in space.”
    – British astronomer Sir James Jeans quoted on page 28, ‘Skywatching’, David H. Levy, Ken Fin Books, 1995.

    “Suppose the nearest civilisation on a planet of another star is, say, 200 light years away. Then some 150 years from now they’ll begin to receive our feeble post-world war II television and radio emission.”
    – Carl Sagan, ‘Pale Blue Dot’ page 388, Headline Book Publishing, 1995.

    “Of the 10 million stars within 1,000 light years of earth, Rigel ranks as number 1, radiating more light than any other. Each minute it [Rigel] casts off more light than the Sun generates in a month.”
    – Ken Croswell, “The Blue Witch” p. 22 in ‘Sky &Telescope’ magazine May-June 2007.

    “Around us is a vast galaxy arrayed on scales so gigantic that galactic structure becomes discernible only once the solar system has dwindled to a dot the size of the period of this sentence.”
    – P.211, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

    A scale model : If a galaxy’s central bulge were a hundred miles across, its central supermassive black hole would be roughly the size of a sand grain.
    – Page 14, “NewsNotes” in ’Sky &Telscope’ magazine, April 2011, VP Publishing.

    “Quasars are so luminous that if one was in action in a local group galaxy its brilliance would rival that of the Sun.”
    – P.284, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

    “…about 40 supernovae are exploding somewhere in the universe every second. However, light from most of these events won’t reach Earth for billions of years, if ever.”
    – Page 73, “Ask Astro” column in ‘Astronomy‘ magazine October 2008.

    “Cosmology also tells us that there are perhaps 100 billion galaxies in the universe and that each contains roughly 100 billion stars. By a curious co-incidence, 100 billion is also the approximate number of cells in a human brain.”
    – Page 237, ‘StarGazer’, Dr Fred Watson, Allen & Unwin, 2004.

    “Yet here we are with our eyes and our minds and our curiosity, six+ billion passengers aboard a tiny blue boat, bobbing and wheeling our way around one vast Catherine wheel among many.”
    – P.246, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.
    + Today that figure is apparently seven billion humans – less than a decade later.

  29. The U.S. hasn’t gone metric for radiation units. But I think Japan will be reporting all of their data in terms of metric units, so to compare their data to other things like background dose, bananas, etc. others are also using metric units.

    In the U.S. we frequently use American units and then in parantheses use equivalent metric units. In terms of units of radioactive material, Americans use the Curie (Ci) and the metric system uses the Bequerel (Bq).

    1 Bq = 1 atom disintegrating per second
    1Ci = 3.7 E10 atoms disintegrating per second

    Big difference in fundamental units.

  30. The radiation from living near a nuclear facility does change if it is storing waste and that waste is leaking into the ground and into the ground water and thus into the plants, which are being consumed by local animals such as bunnies and bees – as has been happening at the Hanford storage facility in Eastern WA. I assume those numbers are from a fully functioning nuclear power plant that does not have problems with leakage from its waste.

    Speaking of radiation, my boss came by one day with a geiger counter and put it over my lunch and it started beeping. It didn’t have bananas in it, so could it be because it had been microwaved? He of course had to talk me down that just because a gieger counter beeps it does not mean I’m in danger so I should continue to eat my lunch. It beeped even more over my watch (the battery???)

    Here is a question I’ve been wondering for awhile. We recently moved out of the city and one house we looked at (and decided against for lack of information, the view of the grid was ugly and it wasn’t the best location for us) had one of those huge grids for the high voltage power lines across the street. Some people say those give out huge amounts of EMF which is bad for humans, others say they are harmless. Would be interested to hear your take – which is probably more scientifically educated than any of the people I got feedback from.

  31. XI

    Does the Mammogram dose on this chart seem insane? What am I missing?

  32. bill stouffer

    @25 Yojimbo:

    You say: I have not heard anything either downplaying the seriousness or “upgrading of the seriousness of the event to the same as Three Mile Island”.

    Try here: http://www.nytimes.com/2011/03/19/science/earth/19rating.html?src=mv

  33. Dan I.

    @ 25. Yojimbo

    I see your point but I think that Phil has been most concerned with the panic and fear that is starting to crop up in the U.S.

    There are news stations running stories about “Will Radiation Kill our Food Supply!?” and “Is it safe to eat food from California?”

    Plus scammers running ads for gas masks and iodine etc. So I think it behooves Phil to throw a little cold water on to all that and say “Hey! This is really unlikely to be dangerous to us!”

  34. What you need is a cactus next to your computer! Or not.

  35. Messier Tidy Upper

    @ ^ Dan I. : Seconded by me. :-)

  36. For example, bananas are a natural source of gamma rays due to the decay of an isotope of potassium

    But, since the banana is “proof” of “Intelligent Design”, this must be “proof” that we are “designed” to absorb some radiation!

  37. JP

    @ 17 Sam H:

    I’ve done many aerospace-related outreach presentations and activities in the past. The best advice I can give you is not to overreach! Focus on a subset of things and really polish your presentation so that it is interesting, informative, and engaging. Try to do things with the students, rather than just showing them stuff on slides. For instance, if you want to impress them with scale, I would suggest actually DOING the Earth-Moon distance experiment (e.g. http://www.youtube.com/watch?v=Bz9D6xba9Og). Don’t bombard them with too much information on stellar life cycles, etc, and I suspect that scientific notation would be difficult to explain.

  38. Messier Tidy Upper

    Perhaps the banana ‘s radioactivity explains this :


    superhero recalled from childhood. 😉

  39. JP

    @ 28 Julia:

    Microwaves absolutely do not cause food to become radioactive. Nor do they emit ionizing radiation, which is the kind that can cause damage. People who tell you that microwaves do those things have an incomplete understanding of physics and are missing the difference between ionizing radiation (like gamma rays and x rays, which have enough energy to change the structures of atoms and molecules) and non-ionizing radiation (like microwaves, radio, and light, which do not). In short: the energy content of electromagnetic radiation depends solely on its wavelength or, equivalently, its frequency. Gamma rays have a short wavelength with enough energy for them to occasionally affect the atoms and molecules in chromosomes, which is how they can cause cancer – by screwing up what your DNA codes for. UV light has a longer wavelength and is less energetic, but still has enough energy to be correlated with skin cancer. Visible light, the next type of less-energetic radiation, does *not* have enough energy to do this. Radio and microwave radiation is even less energetic than visible light. So, before you worry about microwaves, worry about incandescent light bulbs!

    Since you have a Geiger counter at your disposal, I will suggest you try an experiment:

    Take a glass of water and point the Geiger counter at it. Then microwave the water for a bit and measure it again. (My hypothesis: you will see no change.)

    You could do the same thing with a cell phone, too, to allay your worries about radio waves! Use the Geiger counter to measure background radiation as well as the radiation from a cell phone that is off, a phone that is on, and a phone that is in a call. (Again, you should see no change.)

  40. Xi – mammogram doses have been coming down in the last 10 years. The 3 mSv or 300 mrem is high for modern machines. Since most women get mammograms of both breasts when getting imaged, it can also be confusing as to whether the dose is per breast or per visit.

  41. MadScientist

    Dang those cosmic rays! They’re always toasting me on those transcontinental flights.

    I wonder if large aircraft still use depleted uranium as ballast. Somehow I don’t think I’ll be given an opportunity to walk around them with a Geiger counter.

  42. The level of ignorance is so bad in the USA that anything “nuclear” or “radiant” brings a panic response. For example, the “nuclear family” and “radiant heat”.

  43. chris j.

    the irony is that bananas don’t contain that much potassium, as compared to other foods.

  44. Joseph G

    Hah! Bananaphone 😀
    Oh no, now I’ve got that damn song in my head.
    Ring ring ring ring ring ring, ba-GODDAMNIT!
    aananaphooooooooo- blah blah blah lalalala woowowoowoowoooo!
    Ring ring ring ring ring blulululululubahbahbah one two three four five six
    Bananaphooooo- *thud thud thud*
    I’ve got my hunches! It grows in bunch-argggggg lalalalalalalalalalala! LALALALA!
    Cellular, modular, interactivodular! Ring ring rin- arggghhhh!
    *gunshot* *thump*

  45. Ross

    Indeed, I thought his name was Randall Munroe as well

  46. Joseph G

    @8 Gary Ansorge: It’s hard to believe, less than 80 years ago, people were using radium enemas for health purposes and nuclear workers didn’t even wear protective clothing. Now if someone mentions radiation(regardless of its energy content), everyone is up in arms. We should never have referred to our short wave electronic ovens as micro wave ovens. I still recall the glazed eyes when I tried to explain how micro waves differ from gamma rays.

    I think it’s just human nature, and to some extent the same thing happened with modern chemistry. At first, everyone’s amazed by the cool new stuff they can do with the technology, and they take very few precautions (PCBs, other dioxins, various pesticides, asbestos, thalidomide, etc). Then when the lack of sufficient caution causes some well-publicized harm, opinions swing to the other extreme, to the point where people are worried about “chemicals” in food (I should hope food has chemicals in it. L-ascorbate, ye scurvy dogs!)
    I would actually put the antivaxx movement (re thimerosal) into this category as well. There was a time when heavy metals like lead and mercury weren’t well regulated, and real harm resulted; so now when people even hear the word mercury, they lose all sense of proportion (literally).

    In some ways, radioactivity was even worse, in the beginning. The Radium Girls cases, those old foot X-rays they had sitting around in shoe stores everywhere, etc (I think someone mentioned radium enemas? WTF? I mean, seriously, WT Fing F?)

    It doesn’t help that now we have the technology to detect things in part-per-trillion concentrations. If your equipment were sensitive enough, you could probably pick up a few molecules of every chemical element in the periodic table* in one normal room. We humans seem to have a knack for being wayyyy too incautious or wayyy too overcautious. We need to find that happy middle somehow.

    *well, the ones with half-lives measured in days or more, at least

  47. gdave

    @Messier Tidy Upper (#11):

    Your example of the Apollo astronauts is well taken, except for two things:

    1) The fact that they were not riddled with cataracts and carcinomas is evidence that they never flew in space in the first place. :)

    2) Seriously, though, your point that “the average life expectancy for test pilots & military personnel…is rather significantly lower than for civilians” makes it all the more remarkable how long many of them have lived is fundamentally flawed. Life expectancy from birth (or, say, from age 20) is probably significantly lower for combat and test pilots in their age cohort* than the general population, but those increased risks stop when the high risk activity does; they don’t magically carry forward throughout the rest of their lives. Considering how many layers of winnowing the Apollo astronauts went through (military service – pilot training – selection for “elite” fighter and test pilot assignments – selection for the astronaut corps – selection to actually fly the Apollo missions) that tested for physical and psychological health and fitness, they were probably some of the fittest and healthiest people on the planet. Add to that the fact that the personality type selected for is probably also likely to maintain a healthy lifestyle (moderate eating, plenty of regular exercise, etc.) throughout life, and I would be shocked if the average combat or test pilot in their cohort did not have a significantly longer life expectancy from, say, age 50 (after ceasing regular combat or test pilot duties) than the general population – and, again, given the layers of winnowing to select the Apollo astronauts, their average life expectancy after retirement would, if anything, probably be even longer than the average combat or test pilot.

    *Combat pilots today are very rarely shot down, but it was a very substantial risk during the Korean and Vietnam Wars.

  48. jfb

    @bill stouffer:

    There’s a difference between downplaying and putting things in perspective. The situation at Fukushima Daiichi is bad, but it’s not Chernobyl bad, at least not yet.

    If the fuel rods in the spent fuel pool at #4 go critical (not likely, but not impossible), then obviously that equation changes.

    The big lesson to take away from this is that you can design and build a BWR to withstand the combined punch of an earthquake followed by a tsunami (after all, the reactor vessels and their containing structures survived that just fine), but if your entire electric grid goes down for more than a day, you are well and truly screwed. It’s the extended loss of power for pumps and monitors that led to the current crisis, not the earthquake itself.

  49. Grizzly

    /rant mode on

    Whatever. Just everybody, please, stop pronouncing it “NUKULAR”.


    /rant mode off

  50. Yojimbo

    @30 Dan I

    And I agree with Phil, and was glad to see the XKCD chart. bill stouffer’s comment seemed to me to be saying that Phil was seriously underestimating the danger, and I wondered where he (bill stouffer) got that idea. Personally I don’t see any conflict between saying this is the second worst reactor mishap and saying there is no reason to panic.

    @34 MadScientist

    I wonder if large aircraft still use depleted uranium as ballast. Somehow I don’t think I’ll be given an opportunity to walk around them with a Geiger counter.

    This is another one I’m a tad confused about. Isn’t depleted uranium what’s left over when you take the U235 out? So, shouldn’t it be less radioactive than unprocessed U? I’ve seen this reference to radiation from depleted U before, and it never made sense to me.

  51. JC

    Out of curiosity, would some number of on-site Stirling engines be able to provide power for cooling in case of loss of outside power? Or would they just not be able to provide enough juice?

  52. Patrick

    I thought potassium-40 was a beta emitter?

  53. K-40 decays by both beta emission (89% of time) and electron capture (11% of time). When K-4o decays by EC the daughter is left in an excited state and emits a gamma. That gamma is usually just associated with the decay of K-40.

    Natural uranium consists primarily of U-238 (99.3%) and U-235 (0.7%). Depleted uranium is uranium which has had the U-235 removed. It is less radioactive than natural uranium (by a tad) because U-238 has a much longer half life than U-235.

  54. NAW

    This is one I like on radioactivity and how much you may receive over time. It may be a little dated, but it is hosted by Mr. Wizard.


  55. Matt Y

    Just want to clarify, are the effects cumulative? Like if I eat a banana and live near a coal plant, do I get 8 of those blue squares?

  56. James Smith João Pessoa (#35):

    The level of ignorance is so bad in the USA that anything “nuclear” or “radiant” brings a panic response. For example, the “nuclear family” and “radiant heat”.

    Not to mention the dropping of “nuclear” from “Nuclear Magnetic Resonance Imaging”, which is now just “MRI”.

  57. samm

    @gdave #40

    “*Combat pilots today are very rarely shot down, but it was a very substantial risk during the Korean and Vietnam Wars.”

    Not to mention that being a fighter/attack/test pilot in the Apollo astronauts era was a very high risk occupation even in peacetime. The accident rates and associated deaths in the 50’s and 60’s, (especially where carrier operations were involved) as experience was gained with new and immature engine and aerodynamic technologies are pretty eye watering compared to today’s standards (and being a combat pilot is still considered relatively high risk).

  58. Bryan Feir

    Indeed, there is no such thing as non-radioactive Uranium; all isotopes are radioactive.

    In fact, there is no such thing as a non-radioactive element with an atomic number greater than or equal to 83 (Bismuth). Uranium is 92. (Although Bismuth 209 might as well be stable, as it has a half-life a billion times greater than the age of the universe.)

  59. Random Armenian

    Depleted uranium still has some radioactivity to it. How safe is the radioactivity of DU? Uranium is also a chemically toxic metal, so there are two issues.

  60. MarcusBailius

    Julia (28): No, a microwave oven will just heat up the food. It certaionly can’t make it radioactive. To do damage, radiation has to be able to ionise: This means light at the UV end of the spectrum (shorter than a few hundred nanometres) and shorter wavelengths. Microwaves have wavelengths of centimetres. Very low energy indeed.
    No, there is no evidence large EM fields cause harm to people. You might choose not to live near power lines from the appearance or the hum in damp weather, but the EM fields themselves don’t cause problems. Consider: a lot of people (including me) have lain in an (N!)MRI machine, and the fields in those are quite strong! But people don’t die in them. Unless it’s of claustrophobia! They also don’t get cancers as a result of lying in them.
    Radioactivity in food: Hell, even you the person are radioactive. You’re loaded with potassium-40, carbon-14, several others. And yet… chances are very much in favour of you not dying of cancer induced by radiation.

  61. samm

    I read a comment somewhere in the last week (maybe here) that most lay-persons knowledge of nuclear radiation comes from watching The Simpsons, with a bit of garbled hearsay from Hiroshima or Chernobyl for flavouring. Frankly, given the general ‘OMG, TEH RADIASHUNS’ reaction I am finding that idea hard to disagree with :)

    @ Bill Stouffer
    I don’t think Phil is downplaying this at all. What is sorely needed, and mostly absent from the mainstream media is context and definition about what the numbers from Fukushima actually mean. If that were present, there might be a smidgen less hysteria about a situation that while very serious, is not perhaps as serious as some are being led to believe, or as it could be.

  62. Slowly but Surly


    You should trademark that 😉

  63. Joe Alvord

    Randall had waived copyright protection so this is going up in my classroom as soon as I can get it printed up!

  64. Astrofiend

    28. Julia Says:
    March 21st, 2011 at 9:52 am

    Hi Julia,

    As far as your food goes, it is not a problem. Radiation occurs naturally everywhere at low levels – in your food, in the air you breathe – even the very atoms that make up your body. Check this out for a bit of an overview: http://en.wikipedia.org/wiki/Background_radiation

    As for your watch – some of the luminescent paint used on watch dials to light them up at night emits radiation from very low activity sources. This is most likely what your boss was detecting. Check this out: http://en.wikipedia.org/wiki/Luminous_paint#Radioluminescent_paint

    None of this is anything to worry about – humans have co-existed with this low background radiation right throughout our evolutionary history. It is only when levels exceed what the body can naturally repair that ionising radiation becomes dangerous.

    As for the non-ionising electromagnetic radiation emitted by powerlines, many studies have been done, and in general these have demonstrated no definitive links between non-ionising emission and adverse health effects. Indeed, many medical physicists would argue that there is no physical mechanism by which the low energy radiation could even theoretically cause cancer etc. However, a number of other researchers have proposed various ’roundabout’ indirect causative mechanisms, though they have never found much in the way of evidence to support their ideas. Anyway, it is still an active area of research, with the current consensus generally being that there is no reason to be overly concerned. This gives a decent overview: http://en.wikipedia.org/wiki/Electromagnetic_radiation_and_health

    Hope that helps a bit, and starts you off on your own research. There is a lot of misinformation, quackery and people with agendas out there spouting nonsense on this stuff, so be careful that if you read a claim somewhere, you can verify that it is coming from a trustworthy source like a medical research journal, a well-respected scientist or a university.

    BTW – ‘healthphysicist’ might be able to elaborate on my post (or even correct parts of it if I have erred!)


  65. jfb

    @Random Armenian:

    Per Wikipedia, DU presents about 60% the radiological hazard of regular uranium. DU is primarily an alpha emitter, so provided you don’t ingest any of it, it won’t be that harmful.

    Also per Wikipedia, its chemical toxicity is about the same as regular uranium, which is nasty; uranium’s far more dangerous as a chemical toxin than as a radiological hazard.

  66. Matt B.

    I’ll have to copy that chart when I get home.

    And Phil, you might want to prepare something about fracking (the oil extraction kind, not the BSG kind). On Real Time with Bill Maher, Richard Belzer claimed that fracking causes earthquakes. I think it might involve explosions, which will register on seismographs, but not actual tectonic activity.

  67. @MarcusBailius

    Thanks for addressing my question on EMF’s. I admit the ugliness of the high voltage towers across the street deterred us more than fear of harm. But it’s been frustrating not being able to find any reliable information on their effects (or lack thereof)

    I’ve had an MRI too (I thought at my clinic they *did* call it an nMRI actually). I was pretty sure I was going to die of claustrophobia. Radiation was the least of my concerns with that awful skinny tube and the heavy wire mask over my face! One of the only things that got me through was looking up how the machines work and imagining pictures in my head of happy little atoms in my head all happily lining up together and then spinning around in unison.

    So, when a Geiger counter clicks over food it is more likely just the natural radiation in the food? I was just guessing about the microwave and my boss is a lawyer, not a scientist so he didn’t know either (the Geiger counter was his scientists friend – not his!). At least he knew enough to say what you did – that there is natural radiation that won’t hurt you. Reminds me of a neighbor who was panicking about flouride added to water and I did a little research and found out that there are lots of place that naturally have flouride in water. It is amazing how many chemicals that freak people out are much more natural than us lay-people know. I think this whole discussion is proof that science education in our schools is hugely lacking!

  68. Jeff

    Of course the alarmists are warning us about rain now due to global circulation of Japan’s nukes fallout. I doubt we have to take any precautions they are calling for, like not bringing your umbrella indoor.

    But maybe leave some kryptonite outside the door, maybe that’ll help. Hey, I’m superstitious, I just donated to a indian school so I could receive their gift of a spirit catcher and hung that in my office.

    And #55, I did teach for many, many years ; I gave it a shot but our society was working against us science teachers. I couldn’t get them too interested, they were too busy with sports, electronics, shopping, too many distractions, I was down the list of priorities. This stuff has to be instilled at ayoung age. When I was 8, I earned Webolos scout and started learning nature back then. They rarely do that these days.

  69. wallace

    Minimizing the problem may in fact be scientifically justified, but it won’t allay fears unless is comes from trusted sources.

    One of the big problems people are having in Japan is not worrying about what low doses can do, it’s distrusting the govt on what doses people are actually getting. No one believes TEPCO or the govt that allowed it to get away with incredible sloppiness for decades.

    Another question no one is answering is exactly what sort of contamination the nearby areas got…was it mostly short-lived stuff and direct radiation that will pose little long-term threat, or is the whole area dusted with iodine and cesium?And will the govt admit it and put 10% of Japanese farmland off-limits if it turns out to be the latter?

    The distrust is the big problem, and will add to the stress that will almost certainly do more health damage than the radiation ever could.

  70. Gonçalo Aguiar

    The funny thing is that the people leaving Japan due to radiation don’t realized they will get a bigger exposure during the airplane flight than if they were in a town near Fukushima for a whole day.

    The irony…

  71. Tim G

    I wonder if hormesis is involved in mammograms. I think recommendations on when to get them assumed a linear model of cancer risk versus exposure.

  72. 2 abdominal CT scans and 2 chest x-rays downrange in 2009 makes me laugh at your nuclear reactor! muahaha!

    Seriously, the magic of internet hysteria is blowing the radiation risk way, way out of proportion. Kudos to xkcd for taking the issue up.

  73. Thameron

    55. Julia Says:

    So, when a Geiger counter clicks over food it is more likely just the natural radiation in the food?

    The radiation is coming either from the food from Terrestrial sources (such as the minerals in the walls/floor etc.) or from space. Foods high in Potassium (like Potassium Chloride salt) will click more.

    I work in a place with Geiger Counters and they click all day long from natural background sources. If you don’t have the context for what an instrument is telling you you probably shouldn’t be using it.

    @57 Wallace – …Another question no one is answering is exactly what sort of contamination the nearby areas got…was it mostly short-lived stuff and direct radiation that will pose little long-term threat, or is the whole area dusted with iodine and cesium?

    It would be great to know the radionuclide breakdown, but I haven’t seen anything like that come out. The Iodine-121 with an 8 day half-life will become a non concern next month. The Cesium-137 with a 30 year half-life will be with them for quite some time.

  74. Rand All

    My name is Randall, and I’ve been mistakenly called Russel many, many times. It’s really annoying.

  75. r0blar

    Well gamma rays bananas made my day.

    Maybe instead of BH, SN, Neutron stars we should look for giant banana’s aggregates in space as ones being responsible for gamma/cosmic rays production hitting our poor planet.

    Or maybe, considering cosmic rays anisotropy, there are some bananas being thrown at us from a direction where another civilization dwells! (Planet of the Apes pun rly not intended).

  76. Tobias

    @29 The mammogram dose is not given as the effective dose (ie whole body equivalent dose) but rather in the equivalent dose, which unfortunately also uses the sievert-unit. The source is this article http://www.nejm.org/doi/full/10.1056/NEJMra072149 which clearly states “organ doses”. That is, it is the breasts that receive 3 mSv, and the effective dose is instead 3 x 0.05 mSv = 0.15 mSv and this should be the value that is used for comparisons. See http://en.wikipedia.org/wiki/Effective_dose and http://en.wikipedia.org/wiki/Sievert.

    Someone should really correct this at Wikipedia… :-)

    (Ps I have a master degree in medical physics)

  77. Nigel Depledge

    Messier Tidy Upper (21) said:

    I apologise if you, Nigel Depledge, were offended by my previous understanding of what the word “atheist” actually means. It was, simply, how I have always understood the word / concept of an atheist. No offence intended. It does sometimes take me awhile to get my head around things.

    ‘Pology accepted. To be honest, I was more exasperated that you didn’t see my point than offended.

    Ultimately, every atheist of whom I am aware acknowledges that it is impossible to prove the non-existence of god (Babelfish argument notwithstanding). Therefore, I do not believe there exist more than a handful of people on the planet who believe absolutely that there is no god. AFAICT, most atheists just consider a god to be unnecessary for … well, anything, and so adopt a working hypothesis that there is none.

    Anyhoo, I’ll stop there, lest I derail the thread.

  78. Nigel Depledge

    Julia (67) said:

    I’ve had an MRI too (I thought at my clinic they *did* call it an nMRI actually).

    I’ve never seen it termed nMRI, but here in the UK it is often called fMRI (functional magnetic resonance imaging). I have no idea why.

  79. Nigel Depledge

    Julia (67) said:

    there is natural radiation that won’t hurt you

    It would be more accurate to say that there is natural radiation that is extremely unlikely to harm you.

    If you are exposed to a single particle of radiation, if that particle just happens to damage your gene for – say – p53 in any of your cells, then it can cause cancer. The likelihood of such a thing happening is very, very tiny. However, if you are exposed to a lot of ionising particles, the likelihood that one of them might damage a crucial gene increases.

    Additionally, at muich higher doses (such as those experienced by the victims of the bombs dropped on Hiroshima and Nagasaki), ionising radiation has a more direct damaging effect on cells. Above a certain threshold, the amount of damage that ionising radiation does to a cell overwhelms the cellular machinery that can repair the damage and the cell dies.

  80. Nigel Depledge

    Thameron (73) said:

    The Iodine-121 with an 8 day half-life will become a non concern next month.

    Did you mean Iodine-131?

  81. Randall beat me to it by a couple hours. I swear that guy’s spying on me.


  82. Rift

    #24 bill stouffer

    I swear there needs to be a reading comprehension test before we let anybody read these blogs.

    Nowhere does Phil even mention what is going on in Japan… Or even nuclear power plants. Let alone down playing anything.

    Radiation is well, duh, an astronomical subject and would be interesting, an relevant, on this blog even without current events.

  83. Rob P.

    N. Depledge 78 — “I’ve never seen it termed nMRI, but here in the UK it is often called fMRI (functional magnetic resonance imaging). I have no idea why.”

    fMRI is a particular variation. While a standard MRI tries to be a static measurement (say of a torn ligament in the knee), fMRI is measuring time-varying activity. It is used in particular to try to understand what portions of the brain are engaged during some type of mental process or another.

  84. Nigel Depledge

    @ Rob P. (82) –

    That’s at least one new thing I learned today.

  85. Messier Tidy Upper

    @77. Nigel Depledge : Thanks. :-)

    @47. gdave : Fair enough. You do make some good points there. I know its also probably too small a sample size to be statistically significant – & I’m no statistician & have limited knowledge in that area – but I still find it interesting as an example with those caveats in mind. :-)

    Incidentally, I’ve just watched David Letterman’s Late Show tonight (ie. last night USA~wise I figure?) & he did a good job of mocking the superMoon silliness – and not so good one of discussing the nuclear issue with Fukushima and a nearby US Indian Point plant. Also had Michio Kaku on – quite interesting interview although Kaku too went in for more radiophobic fear-mongering than I was happy with. :-( :-)

    I’m fairly sure I remember Isaac Asimov, among others, speaking out in favour of nuclear power & against the unreasoning phobia of it in some of his essays.

  86. Quiet Desperation

    less than 80 years ago, people were using radium enemas for health purposes

    They gave you that warm glow inside.

    I’m incredibly sorry.

  87. Naomi

    Well, I’m having some dental work, so apparently all the xrays add up to more radiation than a NY-LA flight… but then, I’ve been on quite a few flights, too (in the space of six and a half months… lemme count that up… sixty-three hours, I think). AAIII CANCER, et cetera et cetera.

  88. CB

    @ bill stoufer:

    You say: I have not heard anything either downplaying the seriousness or “upgrading of the seriousness of the event to the same as Three Mile Island”.

    Try here: http://www.nytimes.com/2011/03/19/science/earth/19rating.html?src=mv

    The article says right off the bat that the event is given the same ranking on a 7-point logarithmic scale as TMI as of last Friday, which is not actually the same as saying it is the same level of seriousness just like having two category 3 hurricanes doesn’t mean they are the same. It then goes right on to say that the consensus outside of Japan is that this definitely is worse than TMI. Maybe (though quite plausibly) the Japanese nuclear agency is sandbagging, or, as the article points out, it means that they think it is worse than TMI, but not ten times worse.

    So while it shows the most basic of existence proof of what the person your were replying to asked for, the article does not support your thesis that there is a “narrative” of downplaying the incident. “Worse than Three Mile Island, not as bad as Chernobyl” is the narrative, and what appears to be the reality, and even for those of us who aren’t scared of the word “radiation” and know what TMI actually entailed, that means “disaster”. It’s not where anyone wants to be.

    That aside, why on earth do you think Phil is “promulgating the narrative” in this post where he rationally — and correctly — discusses the danger of low-dosage and low-energy radiation. He doesn’t even mention any of the nuclear disasters, because this is about preventing irrational fear of the non-nuclear-disaster radiation doses we all get regularly that events like this always kick into overdrive. I mean it’s not like he is claiming no radiation is harmful, as is obvious by his scale from “nothing to worry about” to “AIEEEEPANICPANICPANIC”.

  89. CB

    @ Nigel Depledge

    Above a certain threshold, the amount of damage that ionising radiation does to a cell overwhelms the cellular machinery that can repair the damage and the cell dies.

    Obviously above a certain threshold the damage is simply lethal.

    What’s fascinating though is that there is a range of damage where it is not lethal, but the cell is programmed to commit suicide anyway. It’s a defense mechanism against cancer. This happens all the time, and normally isn’t a problem. The problem is when you receive a large enough dose of radiation where a large number of cells in your organs get damaged and all commit suicide at once.

    So it turns out there’s a wide range of radiation dosages that are lethal to humans, but only because of this suicide response. I learned all this while reading about drugs that can inhibit it and thus save lives. Of course there’s still the actual radiation damage to deal with, but not all damaged cells are cancerous, and apparently many of them can repair themselves just fine.

    Biology is crazy-awesome. :)

  90. Brian Too

    That’s IT! I refuse to sleep next to someone from now on!! Unless, I suppose, they wear lead pajamas. Safety first!

    Make of that what you will!

  91. And on that first part of the image I see coal emitting more than a nuclear plant – yet why are there almost zero news stories (I’ve searched!) on the Chiba Oil refinery that burned for 10 days? I’d like to know the cumulative health effects of that monster!

  92. Bill Woods

    53. healthphysicist: “Natural uranium consists primarily of U-238 (99.3%) and U-235 (0.7%). Depleted uranium is uranium which has had the U-235 removed. It is less radioactive than natural uranium (by a tad) because U-238 has a much longer half life than U-235.”

    Minor correction: Natural uranium also has a trace of U-234, the decay product of U-238. U-234 has a much shorter half-life than either U-235 or U-238, so it contributes almost half the radioactivity of natural uranium. (It’s in equilibrium, decaying at the same rate that U-238 is decaying.) U-234 gets swept out with the U-235 in the enrichment process, leaving depleted uranium substantially less radioactive than natural uranium.

  93. icemith

    @84. Messier Tidy Upper……….Aww dangit! I missed all of that Moon thing on Letterman on here last night too. But I did get to tune in before the Michio Kaku guest spot. He was familiar to us at least in the last couple of weeks, due to the Fukushima Triple Whammy, as our local 24/7 ABC 24 News Service and/or BBC feed had him as an expert. (Must be a cousin of David Suzuki, I wonder.)


  94. Gary Ansorge

    48. jfb

    “If the fuel rods in the spent fuel pool at #4 go critical (not likely, but not impossible),”

    Actually, unless the laws of physics have changed recently, it IS impossible for them to “go critical”. 1) The fuel rods contain way too little rapidly fissioning(U235 or PU239) to do anything but get hot,,,then they may melt.

    2) Even if they did, there is no way to CONTAIN the fissioning fuel long enough for it to go critical(bring two sub critical masses together and they’ll blow themselves apart before going boom). It’s an exponential thing. Criticality is hard to attain. Which is why every mothers son doesn’t have a nuke in the basement.

    60. MarcusBailius

    “and the fields in those are quite strong!”

    I’ll say. When my foot was in an fMRI, it was exposed to a magnetic field intensity of 1.5 Tesla(15,000 gauss), which is about 300,000 times stronger than earths magnetic field.

    As far as radiation causing cancer, don’t forget that old immune system that began its development over the ages earth was a lot more radioactive than it is today(half life decay results in a fraction of the radioactivity today vs 3.5 billion years ago) so life had to develop repair mechanisms for damaged DNA early on. Staphylococcus radiofurans is one life form that has carried that ability to an extreme. They can tolerate and thrive in a radiation environment 5000 times more deadly than what is required to kill a human. Cancer is more a result of the cell failing to die (apoptosis) when it fails its three(known) check points during DNA replication than a failure of the immune system to kill it. We probably kill off a lot of defective cells in our lifetimes. It’s when we get old that cancer can gain a hold (except for those younglings with defective dna control systems) and we have to intervene with medical processes.

    Gary 7

  95. pauls


    I think it is misleading (if done through ignorance) or blatantly dishonest (if done knowingly) to treat the health risks from radioactive fallout (composed of Cs137, I131, etc.) as equivalent to the same increase level increase in the background radiation. ALL of the increase in ‘background’ the Japanese are experiencing is from fallout added to the environment.

    Phil seems to insist on repeatedly making this false comparison. He seems really set on downplaying the risks faced by those living in the fallout zones (a.k.a. Japan). What’s wrong with this is that if his misinformation influences anyone actually living in the fallout areas, they may fail to take the precautions to manage their exposure to the fallout. (E.g. don’t drink dairy and especially don’t give your kids local dairy products right now.)

    What’s your take on this? Are health risks from internal radiation from ingested/inhaled fallout the same as external (background) radiation?

  96. pauls

    @Gary Ansorge

    Uh… mammalian life (and mammalian immune systems) did not evolve in a high radiation environment and therefore have a special tolerance built in to handle ionizing radiation. Instead, the immune system evolved in an enviroment with pre-nuke age background radiation (i.e. lower overall background radiation than we have today).

    Besides, for human individuals the immune system develops from infancy through the childhood years. It’s the fact young children and infants have immature immune systems plus the fact they are still growing (via lots of cell division) that radiation poses a larger risk for children than for adults.

    Also, in your MRI scan, you were exposed to a high magnetic field and radio waves. Neither the magnetic field nor the radio waves posed any biological risk to you. That’s the beauty of an MRI. It’s also why talking about an MRI is irrelevant to a discussion of ionizing radiation (a.k.a. radioactivity).

    Perhaps you are thinking of CT scans which expose the scannee to X-rays. Since X-rays are ionizing radiation, they are similar to but not entirely the same as the radiation this blog post is about.

  97. Adela

    I think some people watch to much Scifi. Someone used the phrase neutron beam to refer to the radiation leakage while others are bitching why isn’t there instant results of sampling as if we have tricorders or something. Right up there with the people saying they should have used the helicopters to remove the reactor cores and dump them in the ocean. The stupid is everywhere on this one.

    Brazil nuts are the most radioactive food. I knew tobacco was bad but hell is it ever radioactive, up to 160mSv/year.

  98. Michael Welford

    Phil, I’ve been looking at demographic information about Boulder County on Wikipedia, and that data shows that the reassuring article that you link to about radiation and cancer rates is simply rubbish. Looking at population growth figures you can only conclude that fewer than half of the people in Boulder County had been living there at for least 20 years during the period of the study cited. Also, it appears that Boulder County has a somewhat younger population than the nation at large, and therefor a lower cancer rate.

    It occured to me that I could look at the cited study ( a county by county breakdown of cancer occurence and mortality ) and find out whether parts of Colorado with less nomadic populations had higher cancer risk. But wouldn’t you know it, I got one of those 404 file not found errors.

    This seems to be a pattern with pro-nuke sites. Lots of links, but no (working) links to the original studies. Not one of the pages Randall Monroe links to is a primary source, and I couldn’t find a working link to a primary source on any of them.

    Phil, since you live in Colorado, you might want to ferret out that study and find out what happens to people that are exposed to Colorados raidation levels for half a century. After all, your own and your families lives are at risk.

  99. Michael Welford

    There are a couple of problems with my previous post.

    First I say ‘radiation’ when I should say ‘ionizing radiation’. As Phil points ‘ionizing radiation’ refers to something apt to give you cancer, while ‘radiation’ without the modifier could just mean what comes out of a flashlight.

    Second. I wasn’t clear about what study I was refering to. Phil links to an article by Richard Hollos and Stephan Hollos. They in turn link to a study about cancer on Colorado. Only that link is broken. Which is unfortunate, since we could probably learn much from that study.

  100. pauls

    From the chart:

    “Extra dose from one day in an average town near Fukushima plant (~3.5 uSv as of March 17, varies quite a bit).”

    From the reference cited in the source page for the chart for March 17:


    “Dose rates to the north-west of the nuclear power plants, were observed in the range 3 to 170 microsievert per hour, with the higher levels observed around 30 km from the plant.

    You know, taking the lowest value from a range where the highest value is larger than the lowest by 50X and calling this ‘the average’ is just dishonest. Calling a dosage ‘daily’ when in fact it is hourly is 24 X dishonest.


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