Even as the U.S. Department of Homeland Security races to deploy full body scanners at airports across the U.S., significant concerns have been raised.  The scanners have been shown to be ineffective at detecting dangerous low density materials like liquids, powders, or plastic weapons.  In addition, some studies have linked them to potentially cancer-causing DNA damage.  Perhaps most importantly, major privacy concerns remain unresolved around the scanners, which digitally disrobe passengers. 

Despite those problems, the DHS appears to believe that the perception of security is too important to wait for further study.  It is instead beginning a mass deployment, rolling out new scanners in 11 cities including Boston, Chicago, Los Angeles, and San Diego.

The advanced imaging technology (AIT) units were installed at the Boston Logan International airport on Friday and will be installed at Chicago O'Hare International in the next week – all installations will be completed by the summer's end.  

Currently, forty AIT units are in limited use at 19 U.S. airports.  The new units will mark the first mass deployment of the technology to the U.S. airports.  More units are expected to be deployed later this year.

The scanners will come at a relatively high expense to taxpayers.  They are funded by a $1B USD appropriation from the American Recovery and Reinvestment Act (ARRA).  The spending plan -- crafted by Congress, President Obama, and the Department of Homeland Security -- calls for $700 million in new screening for checked baggage and $300 million in checkpoint explosives-detection technologies.

The nine other airports receiving scanners will be: Fort Lauderdale-Hollywood International (FFL), Cincinnati/Northern Kentucky International (CVG), Mineta San Jos International (SJC), Los Angeles International (LAX), Port Columbus International (CMH), Oakland International (OAK), San Diego International (SAN), Kansas City International (MCI), and Charlotte Douglas International (CLT).  Of the airports, only LAX previously had full-body scanners.

The DHS is defending its pricey plan, arguing that there's no privacy risk.  It says that images of passengers unclothed won't be stored, despite the recent revelation that the scanners had the built in capability to do so.  They also admit that the scanners are only efficient at detecting metal objects, but say that could be very helpful in detecting knives or metal-based guns.  

They also claim there's no health risk with the non-ionizing radio frequency energy in the millimeter wave spectrum used by the scanners to generate their images.  They say the system's energy is 100,000 times less than a cell phone transmission.  (Recent studies, however, have suggested that DNA damage may certainly be possible).

For better or worse, though, the 450 new scanner units will soon be a common sight in the 11 airports on the mass deployment's front.  The U.S. appears to be marching in Britain's footsteps, moving towards a "no scan, no fly" policy.