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Undernews is the online report of the Progressive Review, edited by Sam Smith, who covered Washington during all or part of ten of America's presidencies and who has edited alternative journals since 1964. The Review, which has been on the web since 1995, is now published from Freeport, Maine. We get over 5 million article visits a year. See for full contents of our site

January 11, 2010


While the use of body scanners at airports are clearly a violation of civil liberties, that may be only part of the story- because we only have it on the word of the notoriously unreliable Homeland Security and its contractors that the use of these scanners are safe. While the scientific facts are sketchy at this point, this fact alone makes the use of the scanners dangerous.

Natural News - Millimeter wave machines represent one of two primary technologies currently being used for the "digital strip searches" being conducted at airports around the world. "The Transportation Security Administration utilizes two technologies to capture naked images of air travelers - backscatter x-ray technology and millimeter wave technology," reports the Electronic Privacy Information Center, a non-profit currently suing the U.S. government to stop these electronic strip searches.

In order to generate the nude image of the human body, these machines emit terahertz photons -- high-frequency energy "particles" that can pass through clothing and body tissue.

The manufacturers of such machines claim they are perfectly safe and present no health risks, but a study conducted by Boian S. Alexandrov and colleagues at the Center for Nonlinear Studies at Los Alamos National Laboratory in New Mexico showed that these terahertz waves could "unzip double-stranded DNA, creating bubbles in the double strand that could significantly interfere with processes such as gene expression and DNA replication."

In layman's terms, any time you're talking about interfering with "gene expression" and "DNA replication," you're essentially talking about something that could be a risk to human health.

"At first glance, it's easy to dismiss any notion that they can be damaging," reports Technology Review. "But a new generation of cameras are set to appear that not only record terahertz waves but also bombard us with them. And if our exposure is set to increase, the question that urgently needs answering is what level of terahertz exposure is safe."

And yet no such long-term safety testing has ever been conducted by a third party. There have been no clinical trials indicating that multiple exposures to such terahertz waves, accumulated over a long period of time, are safe for humans. The FDA, in particular, has never granted its approval for any such devices even though these devices clearly qualify as "medical devices."

(If you try to sell an X-ray imaging device yourself, without FDA approval, you'll be arrested. So why do these TSA suppliers get away with selling human body imaging equipment that has never been adequately safety tested or approved by the FDA?)

Study authors conclude: "Based on our results we argue that a specific terahertz radiation exposure may significantly affect the natural dynamics of DNA, and thereby influence intricate molecular processes involved in gene expression and DNA replication."

In other words, millimeter wave scanning devices may damage your DNA.

Wikipedia - Terahertz radiation is a region of the spectrum between far infrared and microwaves. Until recently, the range was rarely studied and few sources existed for microwave energy at the high end of the band (sub-millimetre waves or so-called terahertz waves), but applications such as imaging and communications are now appearing. Scientists are also looking to apply terahertz technology in the armed forces, where high frequency waves might be directed at enemy troops to incapacitate their electronic equipment.

Diagnostic Imaging - Recent news reports have suggested the new scanners are basically safe. But a more nuanced look at the question suggests the answers are not yet all that clear.

There are two technologies in use in the U.S.: Backscatter technology uses x-rays delivering less than 10 microrem of radiation per scan, equivalent to the radiation one receives inside an aircraft flying for two minutes at 30,000 feet, according to the American College of Radiology. Another approach relies on millimeter-wave technology, which uses radio waves in the millimeter-wave spectrum. Two rotating antennae cover the passenger from head to toe with low-level radiofrequency energy.

The ACR said it was not aware that either of the scanning technologies that the Transportation Security Agency is considering would present a significant biological threat for passengers screened. Indeed, ACR chair Dr. James Thrall was quoted on ABC news as saying, "the individual x-rays themselves are very low energy. And unlike the x-ray spectrum that we use in medicine, the backscatter x-rays don't really penetrate to the organs in the body."

The ABC article also had some useful comparisons: If, after a body scan, a passenger had four hours of flying and a two-and-a-half hour layover in Denver, given the increased proximity to the sun from the high altitudes, the scan would be equal to about one seventieth of the overall radiation exposure.

OK, so far so good for backscatter radiation. It's an ionizing radiation risk, but certainly smaller than the risk from the plane flight that follows. What about the millimeter-wave technology that operates in a different part of the spectrum?

The National Council on Radiation Protection & Measurements, which vouched for the ACR's position on the backscatter radiation scanners, hasn't reached a conclusion on the millimeter-wave technology, its president, Thomas Tenforde, Ph.D., told Diagnostic Imaging. The NCRP, which operates under a Congressional charter, would like to take a look at the new technology, but hasn't had the opportunity so far.

Millimeter-wave scanners are probably within bounds, Tenforde said, but there should be an effort to verify that they are safe for frequent use. According to Tenforde, standards have been established for RF exposures up to 300 gigahertz, but millimeter-wave technology may operate outside those established standards, and potential bioeffects need to be evaluated.

NOTE: As this article suggests, airport scanning may just be the first use of these devices on citizens. Other possibilities include spying into people's homes.

Technology Review - Great things are expected of terahertz waves, the radiation that fills the slot in the electromagnetic spectrum between microwaves and the infrared. Terahertz waves pass through non-conducting materials such as clothes , paper, wood and brick and so cameras sensitive to them can peer inside envelopes, into living rooms and "frisk" people at distance. . .

At first glance, it's easy to dismiss any notion that they can be damaging. Terahertz photons are not energetic enough to break chemical bonds or ionise atoms or molecules, the chief reasons why higher energy photons such as x-rays and UV rays are so bad for us. But could there be another mechanism at work?

The evidence that terahertz radiation damages biological systems is mixed. "Some studies reported significant genetic damage while others, although similar, showed none," say Boian Alexandrov at the Center for Nonlinear Studies at Los Alamos National Laboratory in New Mexico and a few buddies. Now these guys think they know why.

Alexandrov and co have created a model to investigate how THz fields interact with double-stranded DNA and what they've found is remarkable. They say that although the forces generated are tiny, resonant effects allow THz waves to unzip double-stranded DNA, creating bubbles in the double strand that could significantly interfere with processes such as gene expression and DNA replication. That's a jaw dropping conclusion.

. . . Of course, terahertz waves are a natural part of environment, just like visible and infrared light. But a new generation of cameras are set to appear that not only record terahertz waves but also bombard us with them. And if our exposure is set to increase, the question that urgently needs answering is what level of terahertz exposure is safe.

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Blogger Randy Knudson said...

Dr.Daniel Mittleman of Rice University, who has been involved in thz research for many years responds to the DNA damage claim on my blog. In particular read the last paragraph. I believe the claim terahertz damages DNA is very weak, in light of the facts.

I have seen that report about the idea of DNA damage by THz radiation. I remain skeptical. The experimental evidence for any kind of THz-induced damage (other than merely by heating) is so far not repeatable. This recent paper is purely theory, assuming a very specific and detailed model for the dynamics of a DNA chain which may not correspond to reality. The way that they include the solvent damping (i.e., the effects of all those water molecules lying around) is not clear. In fact there doesn’t seem to be any accounting for the fact that the water is going to absorb most of the incident field, which might heat up the water but would have no other effect on the solvated DNA. I can’t say that they’re wrong, but being an experimentalist, I am going to need to see experimental results before I buy this mechanism.

The bottom line here is that the world is awash in THz radiation. Every room-temperature object is emitting THz radiation just by virtue of being at room temperature. In fact, the power (per unit bandwidth) in that ambient THz field is larger than the power in most (though not all) artificial THz sources. This makes it hard to imagine how a typical (weak) THz source could give rise to any biological effects. It could be that this mechanism is relevant to real-world situations, but I think the burden of proof remains in the camp of those who say there is a non-thermal effect.

January 11, 2010 10:05 PM  
Anonymous Anonymous said...

The previous post sounds like the bullshit argument advanced for GMO seed technology; do something untested and likely dangerous and, at any rate, unnecessary and ultimately worthless. Then, push it hard and claim "it's already out there" to squelch criticism...much like a rapist advising the victim to sit back and enjoy it.

I await long-term testing on your children, Randy. I'm sure there's a vendor out there who'll adhere to the highest standards of safety and scientific rigor.

January 12, 2010 4:50 AM  
Blogger Randy Knudson said...

well, it has been tested for almost 20 years, as Lucent began thz research in the early '90s. The reason you haven't heard of terahertz before, is the commercial applications have just been made practical in the last few years.
My kids get more terahertz exposure from the world around them, than they will from a scanner of this type. That's just a fact, you want to ignore. If you want to read more look at the Detroit news article yesterday.

January 12, 2010 9:59 AM  

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