March 28th, 2011
06:47 PM ET

Cancer risk is low, but possible in airport scanners

If you’ve traveled through an airport lately, you’ve probably seen one of the new full body X-ray machines called a backscatter, a type of imaging technology used by the Transportation Security Administration  to identify concealed items.

A special article published Monday in the  Archives of Internal Medicine says “passengers should not fear.”  The device, which raised concerns among some because it uses small doses of ionizing radiation, a known carcinogen, poses “no significant threat” even to  frequent fliers, the authors say.

Researchers at the University of California San Francisco estimated the cancer risks associated with exposure to the backscatter and found that the scan, which takes only a few seconds, contributes less than 1% of the radiation dose a flier would receive from cosmic rays during the actual flight.

They also estimated that for every 100 million passengers who flew on seven one-way flights (just over three round trips) per year, six extra cancers were detected over the course of a lifetime.  For every 1 million frequent fliers – defined in this study as those who took 10 trips per week for a year where each trip lasted at least six hours – four additional cancers were detected.

“A lot of people are fearful of radiation, and I think they need to be conscious that all radiation is not the same,” says study author Dr. Rebecca Smith-Bindman, a California radiologist. “I don't think the risk is worth us worrying about because it is so low.”

According to the TSA, 486 advanced imaging technology machines are being used at 78 airports nationwide. The agency says  the devices are safe and meet national health and safety standards for all passengers, including children, pregnant women, and individuals with medical implants.

Still there are some who are cautious. “I think one of the main issues with this paper is that it took doses direct from the manufacturers data, but in other recent publications doses were estimated based on the actual x-ray backscatter images that the machine produces and were higher,” says David Brenner, director of the Center for Radiological Research at the Columbia University Medical Center.

He published an article in April in the journal Radiology, and also found the radiation exposure to be small, but says even though the cancer risk is low, it is possible.  “The bottom line is that both my paper and this suggest that there will be some cancers produced in the long run from mass screening with X-rays,” he says. "The analogy I usually give is with someone buying a lottery ticket. Your individual chance of winning is extremely small, but we do know that some people will indeed win."

“There is considerable uncertainty about just how many cancers that will be.”

Passengers should keep in mind they don’t have to face the risk if they don’t want to. TSA press officer, Kristin Lee, notes that the technology is optional for all passengers, and that those who do not wish to go through the backscatter screening will receive an alternative screening, including a pat-down. Find out what experts do when they go to the airport later this week in the Empowered Patient column.

soundoff (119 Responses)
  1. James

    We are exposed to small amounts of ionizing radiation everywhere in life. Even bananas are slightly radioactive due to the potassium they contain. I hate these scanners, but it's not because of the radiation. People hear that word and freak out irrationally. Interesting chart for a bit of perspective http://xkcd.com/radiation/

    March 29, 2011 at 14:36 | Report abuse | Reply
    • Jackie DuBois

      What if you were told that the one person getting cancer from the airport scanner was you? Would you go through the machine?
      A perspecitve....

      March 29, 2011 at 15:48 | Report abuse |
    • Kevin

      I have to go with Jackie on this one.

      March 30, 2011 at 08:29 | Report abuse |
    • bacos

      Then I would say don't fly at all Jackie.

      The scan "contributes less than 1% of the radiation dose a flier would receive from cosmic rays during the actual flight." If you get cancer, it's not going to be from the scanner.

      So, if the scanner still frightens you... you should probably just drive anyway and NEVER visit Denver.

      March 30, 2011 at 16:14 | Report abuse |
  2. Meh

    omg – ban airplanes

    March 29, 2011 at 14:48 | Report abuse | Reply
  3. Really?

    I'm not supposed to have my teeth xrayed while pregnant but I can go through the x-ray scanner at the airport if I'm pregnant?

    March 29, 2011 at 16:01 | Report abuse | Reply
    • MrGneissGuy

      You're not being X-ray'd at the airport... thats an entirely different form of radiation. If you are genuinely concerned about radiation, read any entry-level physics textbook (i.e. not an internet blog by joe schmo) and put you're irrational fears to rest.

      March 30, 2011 at 00:20 | Report abuse |
    • bacos

      Exactly, MrGneissGuy.

      This isn't penetrating radiation like a dental x-ray. It is low enough energy that very little will penetrate enough layers to reach the fetus (and if it DOES, then there is a miniscule chance that it will have enough energy to deposit to cause any problems for the fetus).

      I would imagine that the most sensitive body part being exposed is the eyes.

      March 30, 2011 at 16:17 | Report abuse |
    • Jeff Buske

      Really, dental and x-ray mammography use about same energy x-ray about 50,000V. Penetrating teeth, soft tissue and your body to about 2" (5cm) this is why lower leg bone shadows are visible in backscatter images. Skin, testicles, breast receives a small but significant does of about 1/20 to 1/50th of a chest x-ray. As far as x-rays being "safe" for expecting mothers is bunk your dentist knows that. Hope this helps. Jeff Learn more about radiation and protection:


      August 24, 2011 at 13:50 | Report abuse |
  4. tx

    Is that why TSA ordered 're-tests' of radiation levels on airport body scanners

    March 29, 2011 at 16:16 | Report abuse | Reply
  5. jo l

    Were we not told the air at the site of the World Trade Center Bombing was ok. Remember that? And why should we take the word of the TSA or those who sold the machines to the airports. They will tell us whatever it takes, even lie so they can keep selling those scanners.

    March 29, 2011 at 16:34 | Report abuse | Reply
  6. Ajnabee

    Today they are saying its okay.
    Tommorow they will come back and say oh its not safe.
    Remember same thing with Lead.

    March 29, 2011 at 16:47 | Report abuse | Reply
    • marc

      What's wrong with lead? It actually protects us from radiation. Just don"t eat it.

      March 29, 2011 at 23:32 | Report abuse |
  7. No Thanks

    I'll do without the radiation. Thank you. Did anybody consider frequent flyers?

    March 29, 2011 at 18:35 | Report abuse | Reply
    • FirstResponder

      The device, which raised concerns among some because it uses small doses of ionizing radiation, a known carcinogen, poses “no significant threat” even to frequent fliers, the authors say

      March 29, 2011 at 20:58 | Report abuse |
    • bacos

      Plus, since the scan contributes less than 1% of the dose recieved on the flight... frequent fliers that DON'T use the scanners have more to worry about than infrequent fliers that DO use 'em.

      March 30, 2011 at 16:18 | Report abuse |
  8. Worried

    How about land border crossings? I heard they are using x-ray there too to scan all passing cars. Is it true?

    March 29, 2011 at 19:22 | Report abuse | Reply
    • Jeff Buske

      Regarding border crossing only selected cars. However, portable versions mounted on x-ray vans are being used worldwide and US. See as-e.com
      New powerful "total recall" walk through scanners are being installed in airports and soon may be used for borders, sport venues and public buildings. Hope this Helps. To learn more about radiation protection:


      August 24, 2011 at 13:59 | Report abuse |
  9. Cio

    No amount of radiation is safe, and just because we are exposed to daily background radiation does not mean that we need to get more exposure to more scatter radiation. What worries me is the workers who are limited trainned to handle such equipment, and with so many new equipment out there, I can't help but wonder: who is calibrating them and keeping up with the monthly (etc)checks? There is a reason we have safety regulations for radiation equipment and people who handle them.

    March 29, 2011 at 19:47 | Report abuse | Reply
  10. max

    whats really interesting is how many TSA officials were saying that there was NO risk. I forget her name but one female senator was speaking on the floor and said "she was told they (the machines) produces no radiation", which would of course be impossible.

    i would like to see the full details, including the real risk to frequent travellers (60+ flights). The TSA has no credibility and doesnt deserve to be taken at their word...

    also, isnt ionizing radiation the type that stays in your body forever? if so, how about seeing how a frequent traveller over a number of years s affected.

    March 29, 2011 at 22:05 | Report abuse | Reply
    • bacos

      "isnt ionizing radiation the type that stays in your body forever?"

      There's no such thing.

      Ionizing radiation means that it has enough energy to displace an electron from an atom (such as UV light, x-rays, gamma rays, beta particles, etc.).

      Non-ionizing radiation means that the radiation doesn't have enough energy to displace that electron (most visible light, radio waves, etc.).

      March 30, 2011 at 16:21 | Report abuse |
  11. Paperwork

    And when the TSA employees who run the scanners start showing up with thyroid cancer, leukemias, and increased birth defects, will anyone put 2 and 2 together? If it gives you 1% of what you'd get on a flight, then they should be able to say, "you get 2 milliseieverts" or whatever. Now, how much is spilling out of the machine when it's fired? Are the TSA agents taking thousands of "trips" a day? I can just see it now. "If you or a loved one worked with the scanners at an airport and later developed cancer or died, we can help you get money for your pain and suffering...." And who's going to write the check for that? We are.

    March 30, 2011 at 02:08 | Report abuse | Reply
    • Jeff Buske

      Scatter dose to operators according to existing FDA/OSHA limits would classify security staff as radiation workers. The scattered and direct beam dose is significant to people in the security area. Protective clothing and dosimeter should be standard equipment.

      June 4, 2011 at 02:13 | Report abuse |
  12. SAM

    But Passive SMoke is ? Oh wow

    March 30, 2011 at 09:06 | Report abuse | Reply
  13. Steven

    What about the TSA workers who stand right outside those things? They work 2000 hours a year just feet away from them. How many of them will end up with cancer? This is an important question.

    April 4, 2011 at 02:01 | Report abuse | Reply
  14. Dgood

    I find it very interesting that we even suggest "Protective clothing and dosimeter should be standard equipment." for the workers. We know these machines use radiation. We know radiation causes cancer. Then WE choose to put these machines in place, then WE mandate that workers are protected, then WE will pay for lawsuits for harmed workers. WE are creating our own problem.

    It's not like we are all going to die WITHOUT these machines. So why don't WE just NOT put the damned machines in service?

    September 15, 2011 at 17:50 | Report abuse | Reply
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