The Daily Need

How much radiation is too much? A handy guide

Japan’s nuclear crisis has understandably induced a panic over leaking radiation and the potential danger it poses to human health. The Japanese government has interrupted food shipments of tainted milk and spinach, and radiation has been found in the seawater near the Fukushima plant. Although health authorities have stressed that much of this radiation poses minimal danger to human health, the idea of any radiation emanating from a nuclear accident is worrying. Some Americans have been requesting potassium iodide pills, and Geiger counters have sold out in Paris.

People safely absorb small levels of radiation every day. Plants, rocks and even human bodies give off radiation. But how much radiation is normal? Randall Munroe, the mind behind the brilliantly nerdy stick figures in the web comic XKCD, has tried to answer that question. He recently drew an extremely helpful graphic comparing the radiation levels of common activities like getting a medical scan or taking a transcontinental flight with large-scale nuclear accidents like those at Three Mile Island or Chernobyl. Although Munroe, a former NASA roboticist, takes care to mention that he is no radiation expert, he provides an open list of his sources, which includes the United States Nuclear Regulatory Commission and MIT’s Nuclear Science and Engineering department.

One sievert, the unit measurement for a dose of radiation, will cause illness if absorbed all at once, and 8 sieverts will result in death, even with treatment. According to the chart, the average person safely absorbs about 3.65 millisieverts (or 0.00365 sieverts) of radiation annually, through simple activities like living in a brick or concrete building (70 microsieverts a year) or sleeping next to another person (0.05 microsieverts). A person living within 50 miles of a nuclear power plant absorbs 0.09 microsieverts of radiation per year, which is less than the amount absorbed by eating a banana.

Although the chart does not contain extensive information about the radiation leaking from the Fukushima power plant, it does note that spending a day in a town near the Fukushima plant will expose a person to an extra 3.5 microsieverts of radiation – slightly less than that of a dental X-ray. To make a few more comparisons, a mammogram will give off about 3 millisieverts (0.003 sieverts) – three times more than the maximum dose of radiation absorbed from Three Mile Island’s 1979 nuclear accident.

While some of these revelations are reassuring, the chart also shows that when things get bad, they get very bad. Spending just 10 minutes next to the post-meltdown nuclear reactor core of the Chernobyl power plant – the site of the worst nuclear catastrophe in history – a person would have taken in 50 sieverts of radiation, nearly seven times more than a fatal dose.

Of course, although a person can absorb many nonlethal doses of radiation without a noticeable effect, overall long-term absorption definitely contributes to the risk of cancer. For that reason, many of the health concerns for those living near the site of nuclear accidents are entirely valid. But a quick reality check on the safe levels of radiation we absorb every day might at least help some people save a few dollars on a Geiger counter.

 
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Comments

  • http://www.facebook.com/people/Robert-Wm-Ruedisueli/1449220449 Robert Wm Ruedisueli

    Yes, the media, as usual, exaggerates the immediate danger and misses the whole point that the halt of shipment and to evacuate areas was to prevent poisonous levels, not to address them.

    Likewise, the media has been regularly downplaying the risk of the plant’s condition worsening. However, the ones that have acknowledged that meltdown is possible, keep exaggerating what would happen should that occur.

  • http://www.borneoholidays.net Borneo Boy

    One issue of note though is that over the last 50 years or so government specified levels of ‘safe’ have repeatedly been revised and lowered. Sometimes by thousands of times, only to be lowered again later, then lowered yet again… and 10 years later lowered yet again!

  • bob

    This radiation chart measures electromagnetic radiation waves. This measure is disingenuous with respect to the problem of the Fukashima radiation release. The reactors are releasing particles of Plutonium, Cesium-137 and Strontium-90. If one should inhale or ingest a particle into the body, the immediate tissue surrounding the particle is irradiated at one trillion times the safe dosage. The MSM article is damage control.

  • Anonymous

    I thought to myself “this is why PBS should not receive government moneys” then I thought ” this is why PBS receives government money”.

  • http://krishan.info/id/ Clare Krishan

    ditto Bob,

    The intransitive risk is as described, but once water or air transports the radiation source, its transative until it comes to rest again – iodine vapor condensing or dissolving on any exposed surface or water course (or ground water in the case of the new contaminated seepage in the transmission plants adjacent to the reactor housings) it comes into contact with and then its intransitive ON YOU for as long as it takes to excrete it naturally (unless it reaches somatic cells such as gametes (testicular sperm cells and ovary egg cells) in which case genetic mutations are irreversible ie CAN NEVER BE ELIMINATED)
    Here’s the common fallacy data added to the chart “for comparison”
    http://www.nytimes.com/interactive/2011/03/16/world/asia/20110316-japan-quake-radiation.html?hp

    EGREGIOUSLY misleads visually (one could speak of deception or fraud) in that the tick mark are scaled 8760.(YES EIGHT THOUSAND SEVEN HUNDRED AND SIXTY FOLD) larger than that of the data measured on site, In other words the 400 mSv release mentioned as far back a ten days ago is THREE AND A HALF MILLION TIMES the normal dose of exposure prior to the crisis,

    http://www.counterpunch.org/takashi03222011.html

    “Say there is a nuclear particle one meter away from you. You breathe it in, it sticks inside your body; the distance between you and it is now at the micron level. One meter is 1000 millimeters, one micron is one thousandth of a millimeter. That’s a thousand times a thousand: a thousand squared. That’s the real meaning of “inverse ratio of the square of the distance.” Radiation exposure is increased by a factor of a trillion. Inhaling even the tiniest particle, that’s the danger. ” from translated Japanese TV transcript (see URL above)

  • http://krishan.info/id/ Clare Krishan

    ditto Bob,

    The intransitive risk is as described, but once water or air transports the radiation source, its transative until it comes to rest again – iodine vapor condensing or dissolving on any exposed surface or water course (or ground water in the case of the new contaminated seepage in the transmission plants adjacent to the reactor housings) it comes into contact with and then its intransitive ON YOU for as long as it takes to excrete it naturally (unless it reaches somatic cells such as gametes (testicular sperm cells and ovary egg cells) in which case genetic mutations are irreversible ie CAN NEVER BE ELIMINATED)
    Here’s the common fallacy data added to the chart “for comparison”
    http://www.nytimes.com/interactive/2011/03/16/world/asia/20110316-japan-quake-radiation.html?hp

    EGREGIOUSLY misleads visually (one could speak of deception or fraud) in that the tick mark are scaled 8760.(YES EIGHT THOUSAND SEVEN HUNDRED AND SIXTY FOLD) larger than that of the data measured on site, In other words the 400 mSv release mentioned as far back a ten days ago is THREE AND A HALF MILLION TIMES the normal dose of exposure prior to the crisis,

    http://www.counterpunch.org/takashi03222011.html

    “Say there is a nuclear particle one meter away from you. You breathe it in, it sticks inside your body; the distance between you and it is now at the micron level. One meter is 1000 millimeters, one micron is one thousandth of a millimeter. That’s a thousand times a thousand: a thousand squared. That’s the real meaning of “inverse ratio of the square of the distance.” Radiation exposure is increased by a factor of a trillion. Inhaling even the tiniest particle, that’s the danger. ” from translated Japanese TV transcript (see URL above)

  • Chrrywelch

    you got it right clare. this PBS article is bulls*** just like other MSM articles.

  • http://pulse.yahoo.com/_YC7NFJQVWTJQDI42ADASD4FE44 George Washington

    Shouldn’t int’l community order Japan to seal off that plant asap, instead of letting it to try to regain control of its cooling system. What are they trying to do? Become the 1st to generate power from a fallout site? IMO, they should just have to face the fact Fukushima is a nuclear waste dump site now.

  • http://profile.yahoo.com/6TMSLQWM3OKHRARXOR52UJ3KVY Jordan

    “What are they trying to do? Become the 1st to generate power from a fallout site?”

    Actually they wouldn’t be the first, the Chernobyl Nuclear Power Plant was still in use and producing power right up until December 2000.

  • Angel_ungas08

    I’m working now in japan we are now cleaning
    All the play ground that affected in the radiation
    My question is this I have now 1.110 radiation
    On my body what harm can it do to me?

  • Jessa

    This chart isn’t recent at all…. This is three or four years old and not even relevant to what people are specifically worrying about????

  • http://www.facebook.com/TeeYongTeng.Hacker Tee Yong Teng

    Okay,lets stop eating banana and use more of the cell phone

  • Mark McDonough

    I think the chart is correct. I was exposed to acute radiation 8 hours on the ground in Chernobyl with up to 800 mSv in some parts the buildings/reactors and the clean up claw was reading 860 mSv alone. About 5 minutes exposure to the claw. when I returned to Kiev about 4 hours later after the exposure I started to feel light headed with a headache and began sweating profuse with a high temp without vomiting. The symptoms lasted about 8 hours and I then felt perfectly normal after the symptoms were gone and bought a bottle of Red Wine and took it easy the following day. There’s my 2 bits to this.