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Scientists Question Safety of New Airport Scanners 357

Posted by Soulskill
from the don't-bombard-your-customers-with-radiation dept.
An anonymous reader sends this quote from a story at NPR about the accelerated deployment of new scanning machines at airports: "Fifty-two of these state-of-the-art machines are already scanning passengers at 23 US airports. By the end of 2011, there will be 1,000 machines and two out of every three passengers will be asked to step into one of the new machines for a six-second head-to-toe scan before boarding. About half of these machines will be so-called X-ray back-scatter scanners. They use low-energy X-rays to peer beneath passengers' clothing. That has some scientists worried. ... The San Francisco group thinks both the machine's manufacturer, Rapiscan, and government officials have miscalculated the dose that the X-ray scanners deliver to the skin — where nearly all the radiation is concentrated. The stated dose — about .02 microsieverts, a medical unit of radiation — is averaged over the whole body, members of the UCSF group said in interviews. But they maintain that if the dose is calculated as what gets deposited in the skin, the number would be higher, though how much higher is unclear."
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Scientists Question Safety of New Airport Scanners

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  • by ThreeGigs (239452) on Monday May 17, 2010 @01:59PM (#32242040)

    Cosmic rays at 30,000 feet, plus other ionizing radiation is significantly higher than at ground level. 4 hours on a plane is something like a month's worth of ground-level exposure. Yet people still fly. I don't think this will have any impact on air travel.

  • itis not the same (Score:4, Informative)

    by aepervius (535155) on Monday May 17, 2010 @02:00PM (#32242074)
    Backscatter x ray is *not* the same as millimeter wave. Millimeter wave is about of the order of magnitude of milli-electron volt and not an ionizing radiation energy. OTOH x ray is at least on the order of magnitude from 100 electron volt and is definitively an ionizing radiation. There is a reason they were measuring the amount of radiation absorbed in millisievert, whereas for millimeter wave scanner there is no concern (around near infrared).
  • Re:i could be wrong (Score:5, Informative)

    by Ultimate Heretic (1058480) on Monday May 17, 2010 @02:04PM (#32242176)
    You are correct. One of the highest radiation dose jobs in the world is pilot, followed by co-pilot and flight attendant. This is drilled into those taking radiation safety courses. Of course, one must be aware of the different affects the specific energy particles/rays have on DNA to give a complete picture of the long term hazards. Interestingly enough, the NPR piece, which had an expert stating that they were not worried about excessive x-ray dosages from equipment malfunction, was immediately followed by one on the accidental excessive x-ray doses from medical scanners. Whoops!
  • by pizzach (1011925) <pizzachNO@SPAMgmail.com> on Monday May 17, 2010 @02:08PM (#32242260) Homepage
    Every time your 5-year-old child steps through, it's just like you made them smoke a cigarette. Would you make your 5-year-old child smoke a cigarette?
  • by Shakrai (717556) * on Monday May 17, 2010 @02:10PM (#32242280) Journal

    The passengers are checked to ridiculous measures, but if you work at an airport your protocols are entirely different

    That's an understatement. I have a friend who used to work at the local airport. I've been on behind the scenes tours with him and the security folks (ranging from TSA, to law enforcement to rent-a-cops) never even batted an eyelash when he took me past the checkpoint. They didn't ask me to go through the metal/explosives detectors or to wear a guest badge of some sort. We just walked right past them and my friend says "He's with me." Granted, this is a small town airport with not a lot of activity (three flights per day) but the ease with which it was possible to get into the secured areas seemed to make a mockery of all the FUD we've been fed about airport security. It occurs to me that if somebody wanted to do bad things he could just buy off the right person(s) at the airport to gain access.

  • Re:hang on slashdot (Score:5, Informative)

    by MoonBuggy (611105) on Monday May 17, 2010 @02:11PM (#32242292) Journal

    Looks like it's mandatory [timesonline.co.uk].

  • Re:Nobody cares (Score:5, Informative)

    by phantomfive (622387) on Monday May 17, 2010 @02:13PM (#32242348) Journal
    On thing the article points out is that the level of x-ray radiation you receive during your flight (because of the high altitude) is going to be higher than the amount of radiation you're going to get from the scanner. Essentially spending 4 minutes at cruising altitude will expose you to the same level as the machine.

    Also, the average person in the average year receives 3,000 microsieverts of radiation just from the environment (cosmic radiation, etc). So the .02 received from the machine is probably negligible, unless it really is significantly concentrated in certain places on the skin.
  • Re:hang on slashdot (Score:5, Informative)

    by dgatwood (11270) on Monday May 17, 2010 @02:32PM (#32242716) Journal

    In the U.K.

    Everywhere else but the U.K., you have a fundamental right to be hand searched. That's why I've decided that instead of going through Heathrow like I usually do, for future trips to Europe, I'll be flying through Charles de Gaulle instead.

    For everyone who thinks U.S. air travel policies are absurd, the U.S. allows you to request a manual search. Only the U.K. is so fascist that they will not allow hand searches.

  • by mbone (558574) on Monday May 17, 2010 @02:49PM (#32243050)

    The stated dose — about .02 microsieverts, a medical unit of radiation — is averaged over the whole body, members of the UCSF group said in interviews. But they maintain that if the dose is calculated as what gets deposited in the skin, the number would be higher, though how much higher is unclear."

    Well, a quick back-of-the-envelope calculation says it could be a lot. Suppose you model a person as a cylinder 2 meters high by 1/2 meter across. The volume is 0.4 meters^3, the surface area is 3 meters^2. If the skin is 0.1 mm thick, then the volume of the skin is only 0.0003 meters^3, a factor of > 1000 smaller. So a dose of 0.02 microsieverts for the whole body would be 25 microsieverts for the skin.

    If you read the original article, a chest X ray is about 100 microsieverts, but of course that is absorbed in the body, not the skin. Radiation therapy causes skin "burns", but I couldn't find in a quick search the level of radiation absorbed by the skin to make that happen. However, if this is a problem as indicated, then flying one round trip per week (100 flights/year) would mean an exposure of order 2500 microsieverts, or 25 chest X rays, a level I don't think Doctors would be comfortable with.

  • by Intron (870560) on Monday May 17, 2010 @02:54PM (#32243142)
    Umm. Because the people screening the passengers as they got on were in England maybe?
  • Re:Nobody cares (Score:3, Informative)

    by phantomfive (622387) on Monday May 17, 2010 @03:05PM (#32243376) Journal

    Saying that it doesn't matter because you're exposed to more of it in your daily life is like saying that picking up a possibly-loaded revolver, putting it up to your head, spinning the cylinder, and pulling the trigger on Cinco de Mayo is not dangerous because people are shooting guns up in the air anyway and one of those bullets might hit you.

    If you look at the levels of radiation involved, it is more like walking across the street an extra time today, even though that does add a small degree of extra risk to your day. We're talking about less than .0007% of your total annual radiation. It's good to be aware, but you need to learn to keep things in perspective.

    I don't think these devices will stop terrorists, but they are more likely to catch a terrorist than you are to die from radiation from them.

  • by kaiser423 (828989) on Monday May 17, 2010 @04:47PM (#32245258)
    Have you ever been through one? They're slower than a metal detector. You still have to put your bags through the conventional scanner. Then rather walk through and wait for your bags on the other side, you have a 30 second procedure to get yourself scanned also.

    And everyone stands in there wrong, or is used to carrying their wallet (which you can't do into these), and so on and so forth. Based upon standing in line and counting numbers at Albuquerque, NM the millimeter wave system is anywhere from 2x-5x slower than traditional systems largely based upon the ability of the people going through it to understand advanced instruction....

    All of this to see if you have a conformal bomb strapped to you. Something that, obviously, a bomb-sniffing dog would be very good at doing......But you can't build a job program around bomb sniffing dogs.
  • by Anonymous Coward on Monday May 17, 2010 @09:14PM (#32248116)

    This is not an alternative to existing security, this is an addition. It won't detect anything in your bag, so you'll still need to have your bag scanned. It won't detect anything in your shoes, so you'll still have to remove and x-ray your shoes. They're wickedly more expensive than the magnet/sniffer you walk through now, so there will be fewer. They're slower than existing scanners. They won't detect explosive residue, so you'll still need to go through a sniffer. These scanners offer the potential to detect devices which are less threatening than things you can buy on the concourse at great expense.

    You, personally, may not have a nudity taboo, but that places you in the minority. May even make you the creepy guy parents tell their kids to avoid.

  • by HopefulIntern (1759406) on Tuesday May 18, 2010 @03:41AM (#32250134)
    When I was in Zurich waiting to fly out from Switzerland I had a gander in their Swiss Army shop. You know, pen knives, folding knives etc. I wondered why they would bother selling this stuff at the airport, if you cant take this stuff on board. So I asked the lady. She asked me where I was flying to. England, I said. She said thats fine then, you can take any knives you want on board in your hand luggage....(?)
  • Re:Nobody cares (Score:3, Informative)

    by TheTurtlesMoves (1442727) on Tuesday May 18, 2010 @05:04AM (#32250504)
    The point however is what tissue received the dosage. In the backscatter cases its a thin layer of skin. While in the normal Xray or at high altitude (not xrays by the way) its the whole body.

    The problem is that they quote the scanner dose as if the whole body is absorbing the xray energy. Thus the does level measured in this misleading way for a increased chance of cancer is much much lower.

    For example if the whole dose is absorbed by just a 1 millimeter of skin, thats probably less than 100th total body mass. So the "true" does for exposed tissues is about 100 times higher than the quoted value.

"If that makes any sense to you, you have a big problem." -- C. Durance, Computer Science 234

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