If you have been feeling uneasy about having to be X-rayed by a Transportation Security Administration goon who can look under your clothes every time you fly, consider this: at least you can say no, and agree to be subjected to an old-fashioned full-body search.

No opt-out for the latest in anti-terror technology though, with reports just out in Forbes Magazine and the Christian Science Monitor that the Homeland Security Department has purchased 500 mobil X-ray vans called ZBVs that can scan cars, trucks and homes without the drivers or residents in a building even knowing that they’re being zapped.

These vans, made by a Massachusetts company called American Science & Engineering, are fitted out with what are called Z Backscatter X-ray devices, which aim a powrful X-ray beam that reportedly has the capability of penetrating 14 inches of steel.

In theory, the device is supposed to be safe for human targets, because it is operated at a distance, and because the beam is weakened by penetrating the metal of a vehicle before it reaches a person. But the flaws in this kind of reassuring safety calculus are readily apparent in a photo of a small truck carrying contraband that accompanies the Christian Science Monitor story. The X-ray image, after penetrating the truck cab’s metal body, clearly shows the contraband behind the driver’s seat, but it also just as clearly shows the shadowy outline of the driver of the pickup. Worse yet, even his window is half-way down, so there is no shielding at all of the X-rays hitting his head. Houses meanwhile, are most often built of wood, which offers little or no shielding protection.

We can expect these mobil X-ray vans to be proliferating around the country soon, if they’re not out there already, but they may be hard to spot. As American Science & Engineering says in a note to investors on the company website:

A breakthrough in X-ray detection technology, AS&E’s Z Backscatter Van is the number one selling non-intrusive mobile inspection system on the market. The ZBV system is a low-cost, highly mobile screening system built into a commercially available delivery van.

Prof. Peter Rez, a physicist a Arizona State University who specializes in X-ray technology, and who has been doing research on backscatter X-ray dosages, says that if used properly, the radiation doses received by targeted persons would be very minute, but then he notes that if the government begins a major campaign of surreptitious X-raying on highways and at locations of security concern (the machines are already being used at major sporting events like the Superbowl), there have to be concerns about whether the machines are being maintained in proper working condition (driving them around on America’s run-down highways is subjecting the machines to quite a beating), and about whether the operators are using them properly.

This is even the case with airport X-ray machines, he says, where the doses are very low, but the actual beam is quite powerful. Since X-ray beams cannot be focussed, two moving mechanical parts are used, including a spinning wheel with a small series of holes in it, so that what reaches the targeted individual is just short bursts of X-rays. If either of those moving mechanical parts broke down while a person was being zapped, though, Rez says the person would be “fried” by a major X-ray exposure. “I was assured by the government that the machines have a fail-safe system so they shut down instantly if the moving parts fail,” he says, “but BP had a fail-safe system too, and we saw how well that worked. For my part, I wouldn’t go through an X-ray scanner unless they could show me a very low documented failure rate!”

Arjun Makhijani, an engineer and physicist with the Institute of Energy and Environmental Research in Maryland, also points out that any safety studies for the backscatter machines are referring to their effect on average adults. But if the government is scanning moving vehicles on a highway, or looking inside trailers, for example to spot smuggled immigrants (the metal-piercing backscatter machines are being installed at border crossings on the Mexican border), there is no way to know when they are exposing children or the fetuses of pregnant women, both of which populations are far more vulnerable to damage from ionizing radiation than an average adult.

Americans in Atlanta got a taste of this latest government intrusion into their lives when Homeland Security last Tuesday ran what it called a “counterterrorism operation” not prompted by any specific threat. The agency set up one of its ZBV vans on I-20 and snarled traffic for hours while all trailer trucks were stopped and scanned by Homeland Security personnel.

ThisCantBeHappening! has also learned that the US military has been operating backscanner X-ray machines on the streets of New York, where it has been aiming the devices even at pedestrians. One location where this was done was outside the United Nations building on 1st Avenue in Manhattan.

If you want to see how outrageous this is getting, check out this promotional video produced by AS&E, which shows their vans cruising the streets of New York, X-raying parked cars and trucks along the curb. Imagine what happens as this mobil X-ray device inadvertently zaps pedestrians walking on the sidewalk. In fact, in the video, you can actually see people walking on the pavement as the vehicle goes by scanning the parked cars. (Since the operator is busy monitoring the screen, there’s no way he is turning it off to spare the pedestrians.)

The mobil X-ray vans are only the latest step in a steady march by the American government towards a total national security state, where citizens can expect to be monitored in everything they do. Cities are installing video cameras all over the place, allegedly to fight crime and catch drivers who speed or run red lights. And just last week, the Obama administration announced that it was seeking to expand monitoring of communications to include non-phone systems like Skype and Google Phone, and that it would require internet communications providers to provide it with customer messages, even encrypted ones.

What makes the new mobile X-ray campaign even worse is that, like the airport X-ray machines, they are unlikely to work as advertized. For example, as Prof. Rez notes, the one thing that the airport X-ray devices cannot detect is liquid or semi-liquid explosives–the very thing they were installed to try and keep off of planes! He notes for example, that plastic explosive, like C-4, can easily be molded to look like a roll of fat on the body in an X-ray. Similarly, once criminals or would-be terrorists know that the government has mobile X-ray vans on the highways, they can just stay to secondary roads, or disguise their bomb materials to look like something ordinary, like a bag of groceries.

In other words, we all get zapped for nothing.

Says IEER’s Makhijani, “I know there can be a legitimate concern about security, but all this is happening in secret. We really need to open things up, so we know how these things work, what the dosages are, how they are being used and maintained, and we especially need to have a thoughtful public discussion about whether we really want this kind of thing to be done.”