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UNDERNEWS

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 prorev.com for full contents of our site

February 6, 2010

THE UNEXAMINED DANGERS OF TSA BODY SCANNERS

MIT Technology Review - A new model of the way the THz waves interact with DNA explains how the damage is done and why evidence has been so hard to gather

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.

The way terahertz waves are absorbed and emitted can also be used to determine the chemical composition of a material. And even though they don't travel far inside the body, there is great hope that the waves can be used to spot tumours near the surface of the skin.

With all that potential, it's no wonder that research on terahertz waves has exploded in the last ten years or so.

But what of the health effects of terahertz waves? 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 ionize 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.

And it also explains why the evidence has been so hard to garner. Ordinary resonant effects are not powerful enough to do this kind of damage but nonlinear resonances can. These nonlinear instabilities are much less likely to form which explains why the character of THz genotoxic effects are probabilistic rather than deterministic, say the team.

This should set the cat among the pigeons. 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.


1 Comments:

Anonymous Anonymous said...

what about pacemaker/defib combinations? I've always had to be patted down becuase of this. Bottom line, is it safe or will it set off my defibulater? Or eve alter my pacemaker!

March 5, 2010 9:33 PM  

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