The banana-equivalent dose

This travel season, opt for the full-body scanner

Terrorists are stubborn creatures. Even as we leave soft targets across the U.S. unguarded, they continue to target airplanes. It’s an obsession, and appropriately, we’ve dedicated considerable resources to detecting and defeating just these types of attacks.

One such defense we’ve created is full body scans. These scans use either high frequency radio waves (the waves pass through clothing and other such soft materials at certain wavelengths), or x-rays (which pass through the clothes and scatter off the target).

It’s easy to object to these scans. Just as Americans want to reduce the deficit but not cut spending or raise taxes in the process, airline travelers want to travel securely, but not bear any of the burden of providing that security. Unfortunately, we have little choice — either we scan, and thus obtain some chance of stopping a dedicated enemy who has shown shockingly little variety in his modus operandi, or we live our lives at the whims of lunatics.

Whether you object or not, it’s moot in the short term. Your choice for air travel this holiday season is this: either you submit to the scan, or you submit to a “enhanced pat down” which is just a few steps removed from a full body groping.

There are two main objections to body scans. The first is privacy. Although body scan images are black and white, too blurry to reveal anatomical detail or facial features, and destroyed after use (the machines physically do not have the capability to store or send images), they are, however abstractly, pictures of naked bodies. Though I personally would feel much more comfortable letting someone take a blurry photo of my body than letting them grope me, perhaps you feel the opposite way. De gustibus non est disputandum — have fun being felt up.

The second objection is health concerns. There are some out there who believe the backscatter x-ray type of machine (but not the radio wave type) represents an undue risk to passengers because they use ionizing radiation, which has the potential to cause cancer. Let’s put to rest this worry right now.

A backscatter x-ray machine will give you approximately 0.01 millirem of radioactive dose. Let’s put that in perspective.

You receive, on average, around 360 millirem of dose per year, just living and breathing on this earth (you might receive twice that if you live in a high altitude place such as Colorado, or spend a lot of time around granite). If you receive a 1000 millirem of dose in a year, the Nuclear Regulatory Commission estimates it will lower your expected lifespan by about 51 days due to increased risk of cancer. A transcontinental flight will increase your annual dose by about 4 millirem — like living in Colorado, being up high reduces the amount of shielding between you and cosmic rays.

So what is your 0.01 millirem dose equivalent to? Roughly speaking, it is equal to a banana.

Bananas are naturally radioactive, owing to their high levels of potassium. When you eat one, it temporarily raises the amount of potassium in your body, and you get a little bit of dose. In fact, you can get some radiation just sitting next to a crate of bananas. The amount of dose you get from a backscatter x-ray scan is about the same as eating a banana. The risk of death is on par with smoking 1/700th of a cigarette, or spending a third of a second in a canoe.

So if you prefer being groped to having a blurry, black and white photograph of your naked body exist for a few seconds on this earth, then by all means, tell airport security you want the full treatment. Otherwise, save the employees of the TSA, your fellow travelers, and yourself a great deal of time and just go through the damn scanner already.