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Electromagnetic Fields in Biological Systems
hope to confirm the reliability of numerical modeling. The comparisons of induced
electric fields for all the organs show differences of 1% or less for the majority of tissues
(e.g., liver, stomach, and muscle). In a few cases, the difference reaches 2%–3% (e.g., skin,
spinal cord, and breast). The effects of body model size and shape including anatomy and
resolution on the average (E h ), voxel maximum (E max ), and 99th percentile (E 99 ) of the
induced electric fields are also investigated.
Hirata et al. (2009) studied the in situ electric fields and induced current densities
in anatomically based Japanese adult male and female models, TARO and HANAKO,
exposed to 50 Hz, 0.1-mT magnetic fields. Using a quasistatic FDTD method, they computed two electrical quantities. As an exposure scenario, three orientations of magnetic
fields to the human model standing in free space were considered: AP, LAT, and TOP.
The computational results showed that the 99th percentile values of the in situ electric
fields and the current densities averaged over an area of 1 cm 2 of the nerve tissues in
HANAKO were 35% and 25% lower, respectively, than those in TARO. They pointed
out that the two quantities induced in the Japanese models are smaller than those for
European models due to the difference in anatomical modeling. Hirata et al. (2010a)
published an interesting paper on the comparison of induced quantities in a human
model for ELF magnetic fields. They provided an intercomparison of the in situ electric
fields and current densities in an anatomically based Japanese adult male model named
TARO for uniform magnetic field exposure at 50 Hz. A total of six Japanese research
groups, CRIEPI, NICT, Utsunomiya University (UU), Takamatsu National College of
Technology (TNCT), Kyoto University (KU), and Nagoya Institute of Technology (NIT),
participated in this research. They used four different computational methods: IM
(CRIEPI and NICT), SPFD method (TNCT and UU), fast-multipole surface-difference
time-domain method (KU), and quasistatic FDTD method (NIT). The phantom model
was standing in free space and was exposed to three orientations of magnetic fields with
0.1 mT: AP, LAT, and TOP. Differences in the maximum and 99th percentile value of
the in situ electric fields were less than 30% and 10% except for the result of one group.
The current density averaged over 1 cm 2 for the central nervous system (CNS) tissue
is 10% or less except for the result of one group. It is suggested that the computational
uncertainty in the induced current densities and in situ electric fields due to different
calculation methods and coding is smaller than that caused by different models and
conductivities of tissues. This result is similar to that of Stuchly and Gandhi (2000).
It is very important to calculate the induced current densities and electric fields inside
human bodies exposed to ELF magnetic fields generated from electric appliances, transmission lines, and electric power facilities. These sources generate highly nonuniform
magnetic fields. For example, workers on the transmission line are exposed to highly
nonuniform magnetic fields. Several investigations on nonuniform magnetic fields
from domestic and industrial devices have been done (Cheng et al. 1995; Gandhi et al.
2001; Iivonen et al. 2005; Iivonen and Sarvas 2007; Iivonen and Laakso 2009; Nishizawa
et  al.  2004; Nishizawa, Landstorfer, and Kamimura 2007; Park and Min 2008; Ruoss
et al. 2001; Scorretti et al. 2005; Tarao, Hayashi, and Isaka 1997, 1998, 2003; Tofani et al.
1995a,b; Yamazaki and Kawamoto 2001b, 2005, 2007). Tofani et al. (1995b) measured
and analyzed the magnetic fields from domestic appliances such as a razor, hair dryer,
and drill. Each appliance has high-frequency components. For example, the harmonic