Worried the TSA Body Scanners Will Give You Cancer? Don't.

So a terrorist snuck by airport security whilst wearing explosive panties, and now your country has completely freaked out, and airports want to install full-body scanners that use radiation to see your naughty bits.

What's a concerned citizen to do?

Let's put aside the potential civil rights violations at play in such searches (there are many). Let's also forget that TSA agents photographing the naked bodies of Muslims might be -- ya' know -- the tiniest bit offensive, or that scanners have the ability to store and transmit these images.

And let's also put aside the fact that the number of deaths by car accident, murder, and the flu vastly outnumber victims of terrorist attacks. Let's even put aside the fact that former Homeland Security secretary Michael Chertoff is advocating the installation of these scanners while his security consulting agency's clientele includes a company that manufactures the machines.

Finally, forget for the moment the plethora of disasters that await the TSA when their bored employees inevitably circulate the scans of their hotter naked passengers, not to mention the child pornography laws these scans potentially violate.

All of these may be good reasons for to oppose the use of these scanners. But this article is about your health. Specifically, it is about this question: Will these full-body scanners give you cancer?

To start, let's look at what, exactly, we're talking about when it comes to these machines.

According to a 2003 National Council on Radiation Protection and Measurements report, there are two types of x-ray scanning systems currently used for security screening of individuals: backscatter systems and millimeter-wave systems.

In backscatter systems, the x-rays do not penetrate depths much beyond the surface of the skin, so they can detect objects hidden beneath clothing, but not objects inserted into any body cavities. These are the systems currently being used in the United States, by U.S. Customs and Border Protection as well as in many prisons. A typical scan lasts about eight seconds and results in an effective dose of approximately 0.03 microsievert (mSv/ºSv) to the individual -- radiation equivalent to that one receives inside an aircraft flying for two minutes at 30,000 feet, according to the American College of Radiology.

That's very little radiation. In fact, a 2003 report from NCRP estimated that 2,500 scans would be needed from full-body scanners in a year to exceed the suggested amount for a single radiation source.

Dr. James M. Hevezi, a member of the American College of Radiology Board of Chancellors and Chair of the ACR Medical Physics Commission, stressed to me via e-mail that backscatter systems have very low emissions:

The energy of the radiation does not penetrate beyond the skin surface, so it's not like a CT scan that has the radiation going completely through the body and producing an image of internal organs.

This energy only images the surface skin of the scanee [sic] and is very low energy. The radiation level is a 1,000 times lower than medical radiation exposures and much lower than the cosmic radiation the traveler would experience in travelling by air cross-country.

Like backscatter systems, millimeter wave systems fall under the classification of full-body imaging, which give security officers a virtual image of a passenger that highlights potentially dangerous items, but also photographs the passenger's naked body.

Millimeter-Wave Technology

In millimeter wave technology, the machines beam millimeter wave radio frequency (RF) energy over the body's surface at high speed from two antennas simultaneously as they rotate around the body. The energy reflected back from the body or other objects on the body is used to construct a three-dimensional image. The face is blurred for privacy, and the image is displayed on a remote monitor so TSA employees are separated from the passenger and can't place a face to the body's image.