12 April 2011

Do I Trust the New Airport Scanners? No.

I recently decided that I will refuse to step into the new backscatter and millimeter wave scanners that the TSA has deployed at US airports. So far, this hasn't cost me much. Despite flying six times in the last two weeks I haven't yet provoked the infamous pat-down. So far, I've been able to survey the scene and pick the line that uses the old-school metal detector. That won't work forever, they still pick people randomly from the alternative lines and send them through the megadetector. But it should work for a while because the new scanners are too slow to handle full passenger volume.

According to the TSA, one scan by a backscatter x-ray machine exposes an indivdual to a radiation dose of 0.005 millirem which is equivalent to 0.05 microsievert (µSv). Meanwhile, this extremely helpful chart indicates that the dose is equivalent sleeping one night next to someone, it's 1/20 the dose of eating a banana and it's 1/800 the cosmic ray dose of a cross-country airline flight. Millimeter wave scanners, which are also being deployed, use non-ionizing radiation and should pose even less of a threat.

I'm a fairly scientifically-minded individual. So, why am I taking this seemingly unscientific position? The main answer is because I don't trust the information we've been given. I even have some indicators for this lack of trust. For example, in this blog post, the TSA states, "Backscatter X-ray technology uses X-rays that penetrate clothing, but not skin, to create an image." This is language they've used in other places and it's technically true but it's also misleading. The X-rays that make the image penetrate clothing and bounce off the skin and other materials to reach the detector. But the rest of the X-rays, those that didn't make the image, are absorbed by the body. So, my spontaneous lack of trust is reinforced by the TSA's use of misleading language.

I'm not alone in distrusting government assurances. A recent survey conducted by Xavier University indicates that 78% of Americans have less trust in government than they had 10 years ago. A CNN poll shows that only one in four Americans trusts government to do the right thing most of the time.

But for me to distrust the TSA's explanations, I have to either distrust their intentions or their judgement. The fact is, I distrust both. It turns out that the benefits of the scanners weren't sufficiently convincing until the manufacturers spent millions of dollars lobbying congress and federal agencies for their adoption. And security expert Bruce Schneier says it's all just security theater with no real benefit.

So, I guess my opt out represents a concern that the scientific tests are incomplete combined with a relatively inexpensive form of civil disobedience. But my real hope is that someday government officials will quit trying to convince us they're right and start earning back our trust.

Added 2011-04-13:
My son just sent me a link to a letter written by concerned UCSF scientists. After a little more research I found this response from the FDA. Both parties agree that the absorption by the skin of low-intensity X-Rays results in a disproportionally high dose compared to medical X-Ray systems. In fact, the FDA estimates the effective dose to be 0.56 µSv which is more than 10 times the number reported by the TSA that I used above. That's still a small dose. Where they disagree is on whether sufficient research has been done to establish the safety of these scanners. So, it remains an issue of trust and with all of the misinformation in the TSA statements they just aren't behaving in a trustworthy way.

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