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Interaction of Extremely Low–Frequency Electromagnetic Fields
experimental animals (Nakasono et al. 2008; Shigemitsu et al. 2009). In cellular experiments, microorganisms and cells were used to study the mutagenic effect of IF magnetic
fields, using newly built in vitro exposure facilities (Fujita et al. 2007, 2010; Miyakoshi
et al. 2007).
As biological studies on animals and cells progressed, dosimetric studies on ELF EMF
in Japan excelled (partly including IF magnetic fields) (Kato 2006; Takuma et al. 2006;
Suzuki and Taki 2005). Dosimetry can be divided into two categories: experimental and
numerical. In experimental dosimetry studies, researchers conducted measurements
of induced currents inside inhomogeneous saline models (Yamazaki, Kawamoto, and
Shigemitsu 1996; Yamazaki et al. 2000b,c). Here, dosimetry is defined as the evaluation
of induced electric fields and current densities in phantom models representing human
and animal bodies. In Section 4.2, we review dosimetric intricacies about induced
electric fields and current densities inside phantom models exposed to ELF EMF. This
comprehensive review provides useful information for understanding the historical
development of and recent trends in numerical dosimetry.
In addition to the experimental studies involving animals and dosimetry, this chapter will discuss examples of the state-of-the-art calculations illustrating the induced
electric fields and current densities inside biological systems and the assessment of
exposure to ELF EMF. This chapter introduces readers to numerical dosimetry and
computational bioelectromagnetics through a discussion of dosimetric methods
involving macro- and microinteractions with human and animal models. In Section 2,
we discuss the electrical properties of tissues in relation to electromagnetic dosimetry and the general properties of coupling between EMF and biological systems. In
Section 3, a short summary contains several methods of calculation for estimating the
induced electric field inside the model. Before reviewing the results, in Section 4, we
present technological advancements using human and animal models. In Section 5,
the discussion branches into three subsections: (1) the interactions between biological tissues and ELF electric fields, ELF electric field dosimetry; (2) the interactions
between biological tissues and ELF magnetic fields, ELF magnetic field dosimetry;
and (3) the interactions between biological tissues and ELF EMF, ELF EMF dosimetry. Within these frameworks, literature citations are discussed, along with valuable
examples of the state-of-the-art calculations applying numerical dosimetry in the field
of ELF EMF.
4.2 EMF and Biological Systems
4.2.1 Electrical Properties of Biological Tissues
In order to understand the effects of EMF on biological tissues, it is necessary to determine the magnitude of induced electric fields and induced current densities in the
various parts of the object. The method used for determining the magnitude is called
dosimetry. Numerical and experimental dosimetries require information pertaining to
the electrical properties of the objects.
The electrical properties of body tissues are usually described in terms of electrical conductivity and the relative dielectric constant called permittivity. These two