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.
Advertisement
With all that potential, it’s no wonder that research on terahertz
waves has exploded in the last ten years or so.
This story is only available to subscribers.
Don’t settle for half the story.
Get paywall-free access to technology news for the here and now.
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 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 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.