370
Electromagnetic Fields in Biological Systems
Direct Effects of Terahertz Radiation on Cellular
Organelles and Biomolecules • Genotoxic
Effects of Terahertz Radiation • Does Terahertz
Radiation Trigger Signature Gene Expression
Profiles in Human Cells?
7.6 Conclusion and Future Prospects ...................... 410
Acknowledgments............................................................ 410
References.......................................................................... 411
7.1 Introduction
Every second the Sun emits a countless number of photons. These photons whirl around
the universe and inundate our everyday lives with electromagnetic (EM) energy. Many
of these photons are visible to us as they scatter throughout the atmosphere, but the vast
majority of them are completely unnoticed. In fact, roughly 98% of the photons released
since the Big Bang have been emitted from a region of the EM spectrum that is not visible to us—the Terahertz (THz) region (Trentham 1999).
Given their natural abundance, one may assume that much is known about the effects
that THz photons elicit when they interact with biological structures. But this is not the
case. In fact, to date, fewer biological studies have been conducted at THz frequencies
than for any other type of EM radiation. Data are scarce at THz frequencies because
high-power sources have historically been unavailable for this region. However, this has
changed over the past decade, where a surge of recent research activity has resulted in
the development of many new types of sources. These sources have bridged the proverbial “THz Gap,” and they have also proven to be incredibly valuable research tools. In
addition, they are increasingly being integrated into a host of practical medical, military, and security applications. For example, THz imaging and sensing techniques are
being tested at airports for security screening (Brijot 2010; Thruvision 2010), at major
hospitals for cancer and burn diagnosis (Woodward et al. 2002; Woodward et al. 2003;
Wallace et al. 2004; Wallace et al. 2004; Wolbarst and Hendee 2006; Bourne et al. 2008;
Oh et al. 2008; Singh et al. 2008; Oh et al. 2009; Suen et al. 2009), and at border patrol
checkpoints for identification of concealed explosives, drugs, and weapons (Federici
et al. 2005; Dobroiu et al. 2006; Bogue 2009).
Widespread use of new THz applications has prompted concerns regarding the
health effects associated with this type of radiation. Such concerns have made it imperative that bioeffects data be available for proper health hazard evaluation, the development of empirically-based safety standards, and safe exploitation of THz technologies.
Fortunately, researchers have recently responded to these concerns by performing
timely investigations to examine the biological effects associated with THz radiation.
(Smye et al. 2001; Clothier and Bourne 2003; Fedorov et al. 2003; Scarfi et al. 2003;
Walker 2003; Ramundo-Orlando et al. 2007; Zeni et al. 2007; Korenstein-Ilan et al. 2008;
Olshevskaya et al. 2008; Cherkasova et al. 2009; Homenko et al. 2009.) These scientific
reports, however, have been performed by researchers from various disciplines, thus,
they are scattered in journals with research foci ranging from engineering to physics to
biology. Unfortunately, a comprehensive chapter has not yet appeared in the literature,
which both collects the information gleaned from these recent works, and also organizes
Electromagnetic Fields in Biological Systems
Direct Effects of Terahertz Radiation on Cellular
Organelles and Biomolecules • Genotoxic
Effects of Terahertz Radiation • Does Terahertz
Radiation Trigger Signature Gene Expression
Profiles in Human Cells?
7.6 Conclusion and Future Prospects ...................... 410
Acknowledgments............................................................ 410
References.......................................................................... 411
7.1 Introduction
Every second the Sun emits a countless number of photons. These photons whirl around
the universe and inundate our everyday lives with electromagnetic (EM) energy. Many
of these photons are visible to us as they scatter throughout the atmosphere, but the vast
majority of them are completely unnoticed. In fact, roughly 98% of the photons released
since the Big Bang have been emitted from a region of the EM spectrum that is not visible to us—the Terahertz (THz) region (Trentham 1999).
Given their natural abundance, one may assume that much is known about the effects
that THz photons elicit when they interact with biological structures. But this is not the
case. In fact, to date, fewer biological studies have been conducted at THz frequencies
than for any other type of EM radiation. Data are scarce at THz frequencies because
high-power sources have historically been unavailable for this region. However, this has
changed over the past decade, where a surge of recent research activity has resulted in
the development of many new types of sources. These sources have bridged the proverbial “THz Gap,” and they have also proven to be incredibly valuable research tools. In
addition, they are increasingly being integrated into a host of practical medical, military, and security applications. For example, THz imaging and sensing techniques are
being tested at airports for security screening (Brijot 2010; Thruvision 2010), at major
hospitals for cancer and burn diagnosis (Woodward et al. 2002; Woodward et al. 2003;
Wallace et al. 2004; Wallace et al. 2004; Wolbarst and Hendee 2006; Bourne et al. 2008;
Oh et al. 2008; Singh et al. 2008; Oh et al. 2009; Suen et al. 2009), and at border patrol
checkpoints for identification of concealed explosives, drugs, and weapons (Federici
et al. 2005; Dobroiu et al. 2006; Bogue 2009).
Widespread use of new THz applications has prompted concerns regarding the
health effects associated with this type of radiation. Such concerns have made it imperative that bioeffects data be available for proper health hazard evaluation, the development of empirically-based safety standards, and safe exploitation of THz technologies.
Fortunately, researchers have recently responded to these concerns by performing
timely investigations to examine the biological effects associated with THz radiation.
(Smye et al. 2001; Clothier and Bourne 2003; Fedorov et al. 2003; Scarfi et al. 2003;
Walker 2003; Ramundo-Orlando et al. 2007; Zeni et al. 2007; Korenstein-Ilan et al. 2008;
Olshevskaya et al. 2008; Cherkasova et al. 2009; Homenko et al. 2009.) These scientific
reports, however, have been performed by researchers from various disciplines, thus,
they are scattered in journals with research foci ranging from engineering to physics to
biology. Unfortunately, a comprehensive chapter has not yet appeared in the literature,
which both collects the information gleaned from these recent works, and also organizes