Ever since 2009, when that guy smuggled plastic explosives in his Jockey shorts and tried to blow up a plane on its way to Detroit, the Transportation Security Administration (TSA) has been pushing for full-body scanners at all airports.
Having recently been groped (sorry, “patted down”) before flying out of Chicago and then full-body scanned before flying home, I was curious about the risks of this additional radiation. A recent article in Archives of Internal Medicine helped put it into (mildly guarded) perspective. I say “guarded” because even experts in the field ultimately can only make educated guesses.
Using a technique called backscatter radiation, the scanners offer the person viewing the images extremely detailed information. On screen you appear in your birthday suit, so if like me you’ve got a knapsack full of body-image neuroses, you might prefer being patted down. (Really, if you want to know my circumcision status, I’d prefer you just ask.)
To reassure me that some yahoo isn’t chuckling about my love handles, they’ve installed a software-based face scrambler (which could probably be disabled by any 14-year-old) and allegedly there’s also no way to store or transmit the images. Allegedly, of course, because the feds admitted they actually were storing the images (though apparently not posting them on Facebook). Now they promise no more of this, saying they’re keeping tabs on it.
The security person viewing the image is offsite, so you’re spared the smirk, guffaw, or, for the fortunate few, thumbs up.
How the scanner works and the risks of going through one
The scanning device you’ve been passing through, arms in the air, thumbs pointing at each other, uses backscatter technology, which works in a kind of two-step process.
First, you receive a very tiny dose of the same x-ray radiation you’d get in any medical imaging procedure, but the dose is so low that it’s absorbed only by your skin (rather than passing through your body and onto a piece of film like a regular x ray). Next, the scanning device collects an image of the radiation reflected off your body–the “backscatter.”
Before you start fretting about your precious skin being deep-fried, you need to have a sense of how small the radiation exposure really is:
- During most flights themselves, because you’re up there at 35,000 feet and much closer to the sun, you receive radiation from the sun that passes right through the plane. The amount is still quite small and harmless (frequent flyers have no increased cancer risk).
- The radiation from the scanner equals what you’d receive in about two minutes of flying.
- 50 airport scans gets you radiation equal to that of one dental x-ray.
- 1000 airport scans equal a chest x-ray.
- 4000 airport scans equal a mammogram.
- 200,000 airport scans equal a CT scan of your abdomen.
Because radiation from an airport scanner concentrates in the skin, never reaching internal organs, the only cancer that could theoretically occur if you literally lived in a scanner would be skin cancer.
A team of statisticians came up with the following:
- We know there are 750 million plane boardings every year, taken by 100 million passengers. During the entire lifetime of these 100 million people, 40 million of them will develop cancer. Only six out of these 40 million cancers might theoretically be attributed to airport scanners, and these would be skin cancers rather than internal ones.
- Among the one million frequent flyers who take ten or more flights per year, 400,000 will develop cancer sometime in their lives. Of these 400,000, just four cancers (again, skin) might be attributable to backscatter radiation.
In medicine, we often use the phrase “risk-benefit” in regard to medical decisions involving everything from diagnostic tests to prescription drugs and surgical procedures. For example, there’s a greater risk in prescribing an antibiotic for a common cold than any benefit you could ever receive from it (antibiotics have no affect on cold viruses or any other viruses).
Given the extraordinarily tiny radiation exposure from an airport scanning device, the risk-benefit ratio of going through one is good, provided it actually does improve national security and safety.
Of course you can always opt for the pat-down, and I notice quite a few people prefer it. However, if you’re getting a pat-down to avoid radiation from the scanner, don’t bother. After liftoff you’ll be five miles closer to the sun and out from under any protective cloud cover, receiving a dose of radiation 150 times that of the scanner you chose to avoid.
All in all, you could also consider the train.
David Edelberg, MD