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Electromagnetic Fields in Biological Systems
the amount of absorbed EM energy is capable of heating the tissues, the temperature of
the tissues does not increase because of the body thermoregulation mechanisms. Finally,
nonthermal effects comprise complicated interactions between live cells and ions (calcium, potassium, etc.) and are related to the behavior of big molecules (proteins and DNA).
So far, all recommendations and regulations set by national and international organizations regarding the limits on allowable absorbed power in the body are based on quantitative short-term evaluation of the thermal effects caused by the EM fields (Lin 2000). The
two major standards relating to RF radiation have been set up by the Institute of Electrical
and Electronic Engineers (IEEE) (IEEE 2005) and the International Commission on
Non-Ionizing Radiation Protection (ICNIRP) (ICNIRP 1998). In these standards, basic
restrictions are defined, in terms of specific absorption rate (SAR) and induced current
density, to limit human exposure to time-varying EM fields. Furthermore, more-readilymeasurable reference levels are provided, in terms of the external electric and magnetic
field strength and power density incident on the human body, to practically estimate the
exposure and check compliance with the basic restrictions (Lin 2007).
Considerable dosimetric research efforts have been devoted to assess the interactions
between the EM radiation emitted by mobile communication devices and the human
body (Lin 2009). Dosimetry is necessary to “evaluate the dose,” or equivalently, to identify the dose metric that is closely related to the effect of concern. These efforts have
been motivated by three factors: (1) the need to evaluate potential health effects and
compliance with standards (compliance testing), (2) the need to verify if existing protection standards are still adequate, and (3) the need to assess antenna performance and
improve antenna design to minimize the energy absorbed in the human body while
maximizing the radiated energy.
The calculation of the SAR prevails in most of the studies (Beard et al. 2006; Christ
and Kuster 2005; Virtanen, Keshvari, and Lappalainen 2007). The SAR may be spatially
averaged over the total mass of the exposed body or its parts and may be time-averaged
over a given time of exposure or even a single pulse or modulation period of the radiation. However, the values of other dosimetric quantities are also calculated in a number
of works. For example, the resonance frequencies of biological bodies are examined in
the studies of Massoudi et al. (1979), and the currents induced inside the human head
are presented in the works of Chen and Wang (1994), while the thermal effects of electromagnetic field exposure are considered in studies by Kriticos and Schwan (1979).
Compliance can also be demonstrated by showing that the incident field is below the
derived exposure limits defined in terms of the electric and magnetic field strengths.
This is a suitable approach for base stations, and tabletop and computer-mounted devices
(Bernardi et al. 2000a; Cortel-Carrasco et al. 2006; Lacroux et al. 2008).
Priority was initially given to epidemiological studies related to the possible connection between cellular phone use and brain tumors, parotid and salivary gland tumors,
other kinds of head and neck tumors, leukemia, and lymphoma (Christensen et al. 2004,
2005; Hepworth et al. 2006; Kan et al. 2007; Klaeboe, Blaasaas, and Tynes 2007; Lahkola
et al. 2007; Lonn et al. 2006; Schoemaker et al. 2005; Schuz et al. 2006; Takebayashi et al.
2006). These studies have not provided any sign that exposure to RF EM fields emitted
by cellular phones increases the chance of carcinogenesis. Apart from the epidemiological studies, whose main characteristics are long duration, application to a wide swath.
Electromagnetic Fields in Biological Systems
the amount of absorbed EM energy is capable of heating the tissues, the temperature of
the tissues does not increase because of the body thermoregulation mechanisms. Finally,
nonthermal effects comprise complicated interactions between live cells and ions (calcium, potassium, etc.) and are related to the behavior of big molecules (proteins and DNA).
So far, all recommendations and regulations set by national and international organizations regarding the limits on allowable absorbed power in the body are based on quantitative short-term evaluation of the thermal effects caused by the EM fields (Lin 2000). The
two major standards relating to RF radiation have been set up by the Institute of Electrical
and Electronic Engineers (IEEE) (IEEE 2005) and the International Commission on
Non-Ionizing Radiation Protection (ICNIRP) (ICNIRP 1998). In these standards, basic
restrictions are defined, in terms of specific absorption rate (SAR) and induced current
density, to limit human exposure to time-varying EM fields. Furthermore, more-readilymeasurable reference levels are provided, in terms of the external electric and magnetic
field strength and power density incident on the human body, to practically estimate the
exposure and check compliance with the basic restrictions (Lin 2007).
Considerable dosimetric research efforts have been devoted to assess the interactions
between the EM radiation emitted by mobile communication devices and the human
body (Lin 2009). Dosimetry is necessary to “evaluate the dose,” or equivalently, to identify the dose metric that is closely related to the effect of concern. These efforts have
been motivated by three factors: (1) the need to evaluate potential health effects and
compliance with standards (compliance testing), (2) the need to verify if existing protection standards are still adequate, and (3) the need to assess antenna performance and
improve antenna design to minimize the energy absorbed in the human body while
maximizing the radiated energy.
The calculation of the SAR prevails in most of the studies (Beard et al. 2006; Christ
and Kuster 2005; Virtanen, Keshvari, and Lappalainen 2007). The SAR may be spatially
averaged over the total mass of the exposed body or its parts and may be time-averaged
over a given time of exposure or even a single pulse or modulation period of the radiation. However, the values of other dosimetric quantities are also calculated in a number
of works. For example, the resonance frequencies of biological bodies are examined in
the studies of Massoudi et al. (1979), and the currents induced inside the human head
are presented in the works of Chen and Wang (1994), while the thermal effects of electromagnetic field exposure are considered in studies by Kriticos and Schwan (1979).
Compliance can also be demonstrated by showing that the incident field is below the
derived exposure limits defined in terms of the electric and magnetic field strengths.
This is a suitable approach for base stations, and tabletop and computer-mounted devices
(Bernardi et al. 2000a; Cortel-Carrasco et al. 2006; Lacroux et al. 2008).
Priority was initially given to epidemiological studies related to the possible connection between cellular phone use and brain tumors, parotid and salivary gland tumors,
other kinds of head and neck tumors, leukemia, and lymphoma (Christensen et al. 2004,
2005; Hepworth et al. 2006; Kan et al. 2007; Klaeboe, Blaasaas, and Tynes 2007; Lahkola
et al. 2007; Lonn et al. 2006; Schoemaker et al. 2005; Schuz et al. 2006; Takebayashi et al.
2006). These studies have not provided any sign that exposure to RF EM fields emitted
by cellular phones increases the chance of carcinogenesis. Apart from the epidemiological studies, whose main characteristics are long duration, application to a wide swath.