- 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
- 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
- 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 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
- 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 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 affects
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.
- Ref: <http://arxiv.org/abs/0910.5294>arxiv.org/abs/0910.5294:
DNA Breathing Dynamics in the Presence of a Terahertz Field