- Health & Wellness
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In this world full of controversies, opinions, rumors, and conspiracies, I do my best to stick to the facts. Some issues, however, are works in progress and do not (yet) have clear answers. As new studies come along, the picture changes.
Most of us travel by air and have already experienced the new body scanners. You have heard that the scanners are safe, and you have heard that the scanners are unsafe. Well, which is it?
Body scanning technology, which is better able to detect weapons, tools, liquids, narcotics, and currency, is rapidly replacing simple metal detectors at airports.
Two types of body scanners are being used:
•Backscatter technology produces an image that resembles a chalk etching. This is more sophisticated then the typical X-ray we see in a doctor’s office or lab. The subject stands between two large boxes and is scanned with a narrow X-ray beam that rapidly moves left to right and up and down the body, using ionizing radiation to create a 2D image.
•The millimeter wave scanner creates a 3D image. The subject enters a chamber that resembles a round phone booth and is scanned using radio-frequency waves (not ionizing radiation).
There’s been much debate over whether these devices violate our privacy. Backscatter x-rays do have the potential to produce photo-quality images of what lies beneath our clothes. For this reason, in some locations the scan has been designed to distort private areas. But could this blurring obscure a weapon as well? In an attempt to respect privacy, in many airports the person viewing the images doesn’t actually come into contact with the person being scanned. Note that the images from the millimeter wave scanner do not show details of human anatomy, and have not raised these privacy issues.
The real crux of the controversy is not the realism of the image, but the level of exposure to radiation and potential harm to our body. Because the backscatter scanner x-ray beams are concentrated on the skin and not distributed throughout the body, the dose to the skin may be dangerously high. There are no conclusive studies of what happens when they are not working correctly, or, for that matter, long-term studies on the safety of either type of scanner. Most information on backscatter machines comes either from the government or the manufacturer of the machines, but there have been a number of academic studies:
•The journal Radiology published two articles, one advocating for the backscatter scanners, and the other advising that they not be used. The argument in their favor concluded that subjects get more radiation from routine medical x-rays. However, frequent flyers go through security far more often than they get medical x-rays. Research shows that each round-trip using a backscatter scanner has a one-in-ten million risk of causing cancer. While this seems like a small number, consider that a billion yearly scans would result in 100 extra cancers per year. Controversy continues regarding the actual amount of radiation emitted. (A University of California 2011 study published in the Archives of Internal Medicine found similar results.)
•Scientists at Columbia University Medical Center state if you were scanned every day of your life, you would still only receive a tenth of the dose of a typical CT scan, or the equivalent of about ten minutes of natural background radiation outdoors.
•Another study found that the radiation from a single backscatter scan equals that received from two minutes of flying. On the ground, we are exposed to, very roughly, .0065 mSv per day of natural background radiation. A single long-distance flight exposes us to the equivalent of about a week’s worth of background radiation, or .046 mSv, because at those altitudes the earth’s atmosphere no longer shields us from radiation.
Millimeter wave scanners, on the other hand, use radio waves instead of radiation, cost roughly the same, and are considered about as effective as backscatter scanners. In November of 2011, backscatter scanners were banned from airports in the European Union’s 27 member nations “in order to not risk jeopardizing citizens’ health and safety.” Here in the United States, there are currently about 250 backscatter machines and about 260 millimeter-wave scanners in use.
So, where do we go from here? We can certainly opt out of the backscatter body scanner and request a pat down instead. Indeed, if enough people show concern and reject their use, labor costs will rise and make backscatter scanner use too expensive. My own infrequent flying doesn’t make me very concerned about being occasionally subjected to these scans, but for those more often aloft, avoiding the cumulative radiation may be a wise move.
I wish you safe travels!
Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 8301 E. Florence Ave., Suite 100, Downey, CA 90240.
Published: February 23, 2012 – Volume 10 – Issue 45