Scan or scandal?
May 24th 2017, 13:36
You're running late for a flight and when you get to security, you hope to get diverted to the manual security channel. But it's not your day—and you can't face the stress of trying to explain to the security officers why you want a manual pat-down—you're going to be bombarded with the new-fangled millimeter (mm)-wave technology. The US Transportation Security Administration (TSA), the presumed global experts in airport security, considers the devices safe. But are they?
These machines—which emit terahertz radiation waves somewhere between microwaves and infrared on the radiation spectrum—are presumed safer than the backscatter X-ray machines that preceded them and were banned by the European Commission in 2011.
The reality is that neither mm-wave nor X-ray machines are safe—it's just that there are fewer data to prove this for these devices.
With the Rapiscan backscatter machines that reflect X-rays off the target, the safety issue is clear. The X-ray dose is proportional to DNA damage and cancer risk. But only a handful of studies were used to justify the roll-out of these machines from jails into airports. Prompted by 9/11 and cemented by the incident where a Nigerian tried to blow up a plane with explosives in his underpants, not one study used to inform the decision was peer-reviewed.
The machines escaped scrutiny by the US Food and Drug Administration (FDA) because they weren't medical devices being used for medical purposes. Instead, full-body scanners are like TV sets—electronics equipment requiring only rudimentary data from the manufacturer before being used by millions of people.
Much of Rapiscan's rapid rollout in airports around the world was linked to the company's intense lobbying in Washington, DC, and the subsequent TSA agreement to use them instead of the less controversial mm-wave machines—all this while prominent radiation experts were claiming the backscatter machines were not safe, as there is no safe threshold for X-rays.
Various estimates suggested the scanners would induce one cancer for every million people scanned—or 100 additional cases of cancer in the US alone. Security officers using the machines would be at even greater risk, as the machines radiate variable levels of X-rays that sometimes significantly exceed the established thresholds.
But safety concerns were then obscured by a parallel issue: privacy. Public outcry and a lawsuit meant that special software (automatic target recognition, or ATR) must now be used to prevent people's naked bodies being revealed to the operator who now, since the FAA Modernization and Reform Act of 2012, only sees a generic outline of the human body. In fact, it was Rapiscan's inability to adopt ATR quickly enough that shifted the US towards using mm-wave machines.
The take-home message is that X-ray scanning technology found its way into mass usage through crony capitalism. Analyses of risks and benefits, and proper comparisons with other technologies like mm waves—already commercially available when backscatter machines became entrenched in airports around the world in the new millennium—never entered the equation. Determining the risks with either device by objective scientific methods for, say, pregnant women, their foetuses, cancer survivors or the growing number of 'electrohypersensitive' people never figured in any decisions taken.
Worse, it turns out the machines are pretty hopeless at spotting plastic explosives and guns placed at certain angles to foil the devices. There are testimonials from ex-TSA officers across the Internet exposing what a sham the whole thing is, while scientists like radiation oncologist John Moulder, at Medical College of Wisconsin, have been outspoken about the incompetent way decisions have been handled.1
Even more disturbing is the provisional evidence suggesting that mm-wave body scanners don't actually have more evidence of safety—it's simply presumed because they don't use ionizing radiation. Terahertz radiation has well-documented thermal effects, although their manufacturers have data suggesting that no passenger would ever get a dose resulting in such effects.
But it's the non-thermal effects that are the real concern. There is compelling research on the non-thermal effects of radiofrequency radiation, such as from mobile phones, but funding was mostly stopped when the big phone companies realized it might not be in their best interests.
There's less data on the non-thermal effects of terahertz radiation from body scanners, but studies using mouse cells by Boian Alexandrov and colleagues at the Los Alamos National Laboratory—a world leader in radiation research—suggest that mm-wave technology can alter DNA expression.2,3
Our history shows that we trust what governments tell us—about body scanners and a lot of other things too, like vaccines and low-fat diets.
Next time you're at the airport, though, make an effort to get the manual pat-down. Then you'll only need to factor in the ionizing radiation you'll be bombarded with in a metal tube at 35,000 feet.
Radiat Res, 2012; 177: 723-6
Biomed Opt Express, 2011; 2: 2679-89
Sci Rep, 2013; 3: 1184