A correction was made to this article on Dec. 15.
Any would-be terrorist can easily outsmart the ubiquitous backscatter scanners found in major airports around the world, two scientists say.
The Transportation Security Administration's X-ray backscatter scanners have been the center of a widespread controversy, following concerns from privacy advocates that they take nearly naked photos of people. The trade-off is improved security, of course. Yet Leon Kaufman and Joseph W. Carlson, two physics professors at the University of California, San Francisco offer a stark conclusion: They can be easily duped, according to a recent paper published in the Journal of Transportation Security.
"It is very likely that a large (15–20 cm in diameter), irregularly-shaped, cm-thick pancake with beveled edges, taped to the abdomen, would be invisible to this technology -- ironically because of its large volume, since it is easily confused with normal anatomy," the researchers said in the paper. Kaufman and Carlson conclude that some types of foreign objects can be reliable detected only if they are packed outside the sides of the body, and some well hidden items would be impossible to see even with the scanner.
"It is also easy to see that an object such as a wire or a box-cutter blade, taped to the side of the body, or even a small gun in the same location, will be invisible," the paper notes.
Experts have already highlighted that such machines are unable to detect hidden plastic explosives. The authors of the new paper expand on these limitations -- and it couldn’t come at a worse time, as families prepare for holiday travel plans.
Because of the inherent detection methods, raising the level of X-ray exposure and thus the picture clarity wouldn’t help. “Even if exposure were to be increased significantly, normal anatomy would make a dangerous amount of plastic explosive with tapered edges difficult if not impossible to detect.”
The TSA maintains that the machines remain an integral part of their security arsenal, telling FoxNews.com that it trusts the controversial machines. “Advanced imaging technology is a proven, highly-effective tool that safely detects both metallic and non-metallic items concealed on the body that could be used to threaten the security of airplanes,” a TSA spokesman told FoxNews.com.
The report will nevertheless leave many critics wondering if the machines are worth the hassle with many already opposed to their use because of privacy and safety concerns. The ACLU has dubbed the scan a “virtual strip search” as it gives clear view of the person’s genitalia.
These privacy considerations came to the forefront of the conversation last month when online tech site Gizmodo published 100 scans from a similar type of scanner at a federal courthouse in Florida, images that are also not supposed to be saved. [See editor's note below]
The TSA stresses that backscatter scanners are merely one tool in the arsenal, however, and just one front in the war on terror.
“TSA employs many layers of security that work collaboratively to form a system that gives us the best chance to detect and disrupt the evolving threats we face,” the spokesman said.
Editor's Note: An earlier version of this article incorrectly described images published on tech site Gizmodo as coming from a TSA scanner. Those images came from a scanner at a federal courthouse.