Evaluation of the Potential Biological Effects of the 60-GHz Millimeter Waves Upon Human Cells
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Abstract
We investigate potential biological effects of low-power millimeter-wave radiation on human cell viability and intracellular protein homeostasis. A specific exposure system allowing to perform far-field exposures with power densities close to those expected from the future wireless communications in the 60-GHz band has been developed and characterized. Specific absorption rate (SAR) values were determined for the biosamples under test using the FDTD method. It was shown that millimeter-wave radiation at 60.42 GHz and with a maximum incident power density of 1 mW/cm<sup>2</sup> does not alter cell viability, gene expression, and protein conformation.
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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 10, OCTOBER 2009 2949
Evaluation of the Potential Biological Effects of the
60-GHz Millimeter Waves Upon Human Cells
Maxim Zhadobov, Member, IEEE, Christophe Nicolas Nicolaz, Ronan Sauleau, Senior Member, IEEE,
Fabienne Desmots, Daniel Thouroude, Denis Michel, and Yves Le Dréan
Abstract—We investigate potential biological effects of
low-power millimeter-wave radiation on human cell viability
and intracellular protein homeostasis. A specific exposure system
allowing to perform far-field exposures with power densities
close to those expected from the future wireless communications
in the 60-GHz band has been developed and characterized.
Specific absorption rate (SAR) values were determined for the
biosamples under test using the FDTD method. It was shown that
millimeter-wave radiation at 60.42 GHz and with a maximum
incident power density of mW/cm does not alter cell viability,
gene expression, and protein conformation.
Index Terms—Bioelectromagnetics, biological effects, millimeter
waves, numerical dosimetry, wireless communications.
I. INTRODUCTION
IN THE LAST decade, progress in computational and exper-
imental millimeter-wave electronics has allowed to iden-
tify the millimeter-wave frequency band as highly promising
for a number of high-resolution and high-speed wireless sys-
tems [1]–[6]. If we restrict our attention to the interactions with
biological tissues, current and near-future applications of mil-
limeter waves can be divided into two subgroups depending on
the radiated power: 1) high-power systems inducing a signifi-
cant heating of the human body surface, like nonlethal weapons
(e.g., active denial systems at 94–95 GHz) and therapeutic appli-
cations at 42.25, 53.57, and 61.22 GHz [7]; 2) low-power com-
munications, imaging, and radar systems in V- and W-bands
that do not induce any substantial temperature increase (typi-
cally less than C) of human tissues, but may possibly pro-
duce biological and health effects due to prolonged exposure of
the users.
In particular, the unlicensed 57–64 GHz subband is of
strong interest today for high data rate Gb/s short-range
point-to-point and point-to-multipoint communications (e.g.,
wireless USB2.0, wireless video, streaming data, telecom back-
hauls) [8]–[12]. From the bioelectromagnetic point of view, the
Manuscript received August 29, 2008; revised January 29, 2009. First
published August 04, 2009; current version published October 07, 2009. This
work was supported in part by the Agence Nationale de la Recherche (ANR),
France, under Grant 2006 SEST 19 02 (HIMWR project), by the Health and
Radiofrequencies Foundation, France (StressOM project), and in part by the
NIH NCCAM, USA, under Grant P01-AT002025.
M. Zhadobov, R. Sauleau, and D. Thouroude are with the Institute of Elec-
tronics and Telecommunications of Rennes, UMR CNRS 6164, University of
Rennes 1, 35042 Rennes, France (e-mail: maxim.zhadobov@univ-rennes1.fr).
C. Nicolas Nicolaz, F. Desmots, D. Michel, and Y. Le Dréan are with the
Intracellular Protein Homeostasis Laboratory, UMR CNRS 6026, University of
Rennes 1, 35042 Rennes, France (e-mail: yves.le-drean@univ-rennes1.fr).
Digital Object Identifier 10.1109/TAP.2009.2029308
human body has never been exposed in natural conditions to
radiations in the 60-GHz band since these frequencies, which
correspond to the peak of molecular oxygen absorption, are
strongly attenuated in the atmosphere [13]. Furthermore, a large
number of spectral lines of molecular groups containing carbon
or oxygen molecules are located around 60 GHz. Moreover,
these frequencies have also been used in several countries for
biomedical purposes [14], thereby suggesting that molecular
interactions between the millimeter waves and the human body
are possible.
A few theories were proposed to explain potential biological
effects of millimeter waves [15]. A number of experimental
efforts have been also undertaken and have shown that mil-
limeter-wave radiations may interfere with several cellular
processes under certain exposure conditions. For instance, it
was demonstrated that these radiations can induce changes
in gene expression [16]. Additionally, millimeter waves were
found to reduce tumor metastasis [17] and protect cells from
toxicity of anticancer medicines [18]. It was also reported that
cellular metabolism and cell proliferation can be affected by
exposure to low-power millimeter waves [19]. Furthermore, it
was recently demonstrated that these radiations can modify the
structural state of phospholipids within biomembranes [20],
[21]. However, there remains a crucial lack in identification of
exact cellular targets of millimeter waves, and today there is
no well-established scientific interpretation for the observed
effects. Within this context, from the general public safety
viewpoint, it is important to investigate the possible biological
effects of low-power communication systems in the 60-GHz
band before their wide, near-future deployment within domestic
and professional environments.
Various environmental factors can cause significant changes
in the organization and conformation of biological macro-
molecules. DNA and proteins are the cellular components most
affected by variations of physical and chemical conditions.
DNA damages are induced by high-energy treatments (e.g.,
ionizing radiations), whereas proteins are particularly fragile
and affected by relatively weak disruptive treatments, such
as heat. Millimeter waves are nonionizing radiations and, as
expected, it was shown that they are not genotoxic [22]. Never-
theless, physical principles do not exclude that these radiations
might alter the protein conformations or cause a proteotoxic
stress. Denaturation of proteins due to environmental insults
may have many biological consequences. It may lead to various
cellular dysregulations, such as defects in enzymatic activities,
signal transduction, cellular organization, or cell growth. Fi-
nally, prolonged stress conditions may also affect the cellular
0018-926X/$26.00 © 2009 IEEE
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2950 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 10, OCTOBER 2009
Fig. 1. Methodology implemented to investigate potential in vitro biological
effects of millimeter waves. Assay 1: Cell growth measurement. Assay 2: Lu-
ciferase assay on purified proteins. This reflects the possibility of direct protein
denaturation after exposure to millimeter waves. Assay 3: Quantitative reverse
transcription polymerase chain reaction (RT-PCR). This technique enables one
to measure gene expression of stress-inducible factors in order to verify if mil-
limeter waves could trigger cellular adaptive response.
viability and trigger apoptosis, a form of programmed cell death
that can lead to severe diseases when deregulated. Consistently,
cells have developed sophisticated molecular systems to sense
and respond rapidly to changes in their environment [23]. In the
presence of stress conditions, cells express specific chaperones
and stress factors to cope with the accumulation of misfolded
proteins. These factors also have protective functions that allow
cells to survive.
Consequently, a relevant and accurate way for the investi-
gation of biological effects of millimeter waves at the cellular
level consists of studying and quantifying the most sensitive
cellular responses to stress as indicators (biomarkers) of cel-
lular homeostasis. As cellular stress is a multistep process,
we developed and applied several assay systems to assess
potential stress induction after exposure. Our methodology is
summarized in Fig. 1. Several complementary aspects of the
cell physiology have been considered in this work, starting with
relatively general characterization of cellular viability (assay
1) and then investigating potential subcellular modifications at
the level of protein conformation (assay 2) and gene expression
(assay 3).
As human skin is the primary target for the millimeter waves,
we used the immortalized keratinocytes HaCaT cells derived
from human epidermis [24]. Additionally, to validate and com-
pare the results obtained using keratinocyte cells, the human
astrocytoma glial cell line U-251 MG was used as a relevant
and well-characterized biological model to investigate cellular
stress.
This paper is organized as follows. We describe in Section II
the structure and characteristics of our exposure system and
provide numerical dosimetry data for the exposed biosamples.
Some details about the biological protocols are also provided at
the end of this section. The experimental results of the biological
tests after exposure of human cells at 60.42 GHz are described
in Section III. Finally, discussions and conclusions are given in
Section IV.
Fig. 2. Experimental setup and exposure system. Signal generation subunit
(QuinStar Technology Inc., CA): 1—60.42 GHz Gunn oscillator. 2— dB
power divider (58–62 GHz). 3—V-band power amplifiers (25-dB gain).
4—Power combiner (58–62 GHz). 5—Isolator (20-dB isolation). Frequency
control subunit:6— -dB directional coupler HP V752D. 7—Isolator HP
V365A (30-dB isolation). 8—Mixer M15HWD. 9—Spectrum analyzer R3182.
Exposure chamber: 10—17-dB-gain pyramidal horn antenna. 11—Absorbing
materials. 12—Incubator MEMMERT UE400. 13—6-well or 96-well tissue
culture plate. 14—Thermocouple.
II. EXPERIMENTAL SYSTEMS AND NUMERICAL DOSIMETRY
In our experiments, the biological samples were placed
in standard 6-well or 96-well tissue culture dishes and were
exposed or sham-exposed to low-power millimeter waves.
In this section, the exposure system and experimental setup
are described. Then, numerical dosimetry data on the specific
absorption rate (SAR) within the exposed biological samples
are provided. Finally, some specific characteristics of the con-
sidered cells and bioassays used to quantify potential bioeffects
are given.
A. Experimental Setup
A narrowband exposure system for in vitro studies has been
specifically developed for human cells exposure under far-field
conditions. Fig. 2 schematically represents the three main sub-
units of this system, namely the signal generation subunit, the
frequency control subunit, and the exposure chamber.
A low-power CW signal is generated by a Gunn oscillator at
the center frequency GHz. This frequency value
coincides with the maximal oxygen-induced absorption peak in
V-band. A mechanical tuning system enables one to shift the
resonant frequency by MHz around . This signal is am-
plified and transmitted toward a 17-dB-gain pyramidal horn an-
tenna with aperture dimensions mm mm through
a set of WR-15 rectangular waveguides and a directional cou-
pler. In this work, the output power equals 180 mW; this
corresponds to a maximum incident power density (IPD) of
mW/cm at the center of the tissue culture plate. This value
coincides with the general public exposure limit established by
international guidelines and recommendations [25].
The radiated power was carefully checked before and after
each exposure. The use of a Gunn oscillator guarantees a
very satisfactory frequency stability of the output signal as
highlighted in Fig. 3, GHz . This also ensures
its location within the peak region of oxygen absorption.
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ZHADOBOV et al.: EVALUATION OF THE POTENTIAL BIOLOGICAL EFFECTS OF 60-GHZ MILLIMETER WAVES 2951
Fig. 3. Frequency stability of the output signal versus exposure duration. The
center frequency is equal to 60.42 GHz.
The tissue culture plates cm cm with cells were
exposed or sham-exposed under far-field conditions in two dif-
ferent moments in the incubator at C and then compared
later. Sham-exposures were performed under the same experi-
mental conditions as exposures, but with the generator switched
off.
B. Numerical Dosimetry
The exposure levels of biological samples at millimeter waves
are typically characterized by two parameters, namely the IPD
and the SAR values. IPD data have been previously reported for
6-well and 24-well tissue culture plates illuminated by a pyra-
midal horn antenna [26]. Here, we mainly focus on determina-
tion of the average SAR for the two exposure scenarios corre-
sponding to the three assays defined in Fig. 1: 1) exposure of cell
monolayers located in 6-well or 96-well culture plates (assays 1
and 3); 2) exposure of purified protein solutions in a 96-well
tissue culture plate (assay 2).
1) Average SAR in Cell Monolayers: The analysis of
gene expression modifications after exposure at 60.42 GHz
(Section III-C) was performed using standard 6-well culture
plates made of polystyrene. In the experiments, each plate
was illuminated under far-field conditions by a pyramidal horn
antenna 27 cm apart, as illustrated in Fig. 2. The cell monolayer
is located at the bottom of each well and is covered by a culture
medium whose height is equal to 1 cm. In the modeling, the
thickness of the monolayer was assumed to be m. Previ-
ously, it was shown that the SAR within the cell layers in the
tissue culture plates is not critical to the thickness variations of
the monolayer ranging from 10 to 30 m [27]. The wells and
culture plates are schematically represented in Fig. 4.
The dielectric properties of the cell monolayer and culture
medium were determined applying Maxwell’s mixture equa-
tion to the free-water permittivity data. The corresponding data
are available in [27] from 30 to 100 GHz. They are given at
60.42 GHz in Table I.
The distribution of the electromagnetic field within each of
the six wells was computed using the FDTD method (XFDTD
software from REMCOM Inc.) that proved to be very well
adapted for biomedical electromagnetic dosimetry [28]–[30].
Fig. 4. Dimensions of 6-well and 96-well tissue culture plates, and schematic
representation of individual wells. (a) 6-well tissue culture plate. (b) 96-well
tissue culture plate.
TABLE I
PROPERTIES OF THE MATERIALS USED IN THE MODELING AT 60.42 GHz
All simulations were performed using adaptive rectangular
mesh with a cell size ranging from m up to
( m in free space), where and are the wavelength in
the considered substructure and the smallest dimension of this
substructure, respectively. We assumed the incident field to be
a normally incident, linearly-polarized plane wave. Each com-
putation was performed for single-well applying boundary con-
ditions as defined in Fig. 5.
The average SAR over the cell monolayer volume was deter-
mined from the electric field values, electric conductivity, and
average mass density of the cells g/cm (Fig. 5).
This modeling strategy has already been validated experimen-
tally using infrared thermometry for 24-well plates [27]. As the
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2952 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 10, OCTOBER 2009
Fig. 5. IPD distribution (grayscale), average IPD, and average SAR in each
well of the 6-well tissue culture plate. PML, PEC, and PMC denote the per-
fectly matched layer, the perfect electric conductor, and the perfect magnetic
conductor boundary conditions, respectively.
four corner wells and two central wells are symmetrical from the
electromagnetic point of view, their average SAR is the same.
The SAR was also computed for monolayers located in
96-well tissue culture plates. Such plates have been employed
to study cell viability (Section III-A). Here, taking into ac-
count the large number of wells, periodic boundary conditions
were applied at four lateral sides of a well. For a peak IPD of
mW/cm , the average SAR ranges from 26.2 (center well)
down to 13.7 W/kg (corner wells).
2) Average SAR in Purified Protein Solutions: The direct ef-
fect on possible protein conformation changes after exposure to
the millimeter waves was studied using a purified protein so-
lution located in a 96-well tissue culture plate (Section III-B).
Each well was filled with L of protein solution forming a
cylinder whose height and diameter equal 1.8 and 6 mm, respec-
tively. The volume of the solution was carefully chosen to get
enough material for the biological tests and, at the same time,
to ensure a maximum variation of the average SAR at different
heights of the solution smaller than dB with respect to the
averaged SAR over the total volume of the solution.
The relative permittivity and electric conductivity of our so-
lution were determined as explained in Section II-B1; they are
given in Table I. It is important to note that due to the diffraction,
multiple reflections, and mutual coupling between neighboring
wells, the protein solution was also partly exposed from the lat-
eral sides and from the top that increases the averaged over the
solution volume SAR. It is also worthwhile to mention that due
to the Brownian motion and convection, the protein solution is
constantly mixed, which ensures more homogeneous exposure
conditions.
The electromagnetic problem was solved using the FDTD
method by applying periodic boundary conditions on opposite
lateral sides of a single well. Depending on the well location in
the culture plate, the averaged SAR over the solution volume
was found to be in the range W/kg. The resulting
averaged SAR values are much smaller than for cell mono-
layers (Fig. 5) since the penetration depth of millimeter waves
is smaller than the protein solution height [27].
C. Cell Culture and Bioassays
1) Cell Culture: Immortalized HaCaT cells [24], derived
from human epidermis, were kindly provided by Dr. M-D.
Galibert-Anne (University of Rennes 1, Rennes, France),
and they were grown in Dubelcco’s modified Eagle medium
(Gibco/Life Technologies), supplemented with 10% of Fœtal
Calf Serum, 100 units/mL penicillin, g/mL streptomycin,
and g/ml amphotericin (Gibco/Life Technologies).
We also used human astrocytoma cell line U-251 MG [31],
as they are highly sensitive and respond with great efficiency
to environmental perturbations. Cell culture of U-251 MG was
performed as described previously [32], using the same culture
medium as for the HaCaT cells.
Both cell lines were maintained at C under 5% in
the air. The cell cycle durations for HaCaT and U-251 MG cells
are 20 and 24 h, respectively. Cells were spread in order to
have around 60%–70% of confluence at the end of the expo-
sure experiments.
2) Bioassays: As summarized in Fig. 1, three series of bi-
ological assays were carried out after exposure to millimeter
waves: 1) study of cell growth and viability; 2) analysis of direct
protein denaturation; 3) determination of possible modifications
of gene expression. In each case, multiple exposures were per-
formed to ensure appropriate statistics. The corresponding ex-
perimental results are given in Section III.
Cell growth and viability (assay 1 in Fig. 1) were measured
using the “cell growth determination kit” from Sigma-Aldrich.
Cell viability was determined by measurements of cellular
metabolic activity, which is proportional to the number of
viable cells in the culture dish. This method is based on the
cleavage of the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetra-
zolium bromide (also known as MTT) by the mitochondrial
dehydrogenases of viable cells. Cells spread in a 96-well plate
were sham-exposed or exposed to 60.42 GHz radiation for 24 h.
The cells were incubated with the MTT reagent for the last
3 h of the culture. Cleavage by metabolically active cells leads
to the formation of purple formazan crystals. The latter were
solubilized and measured by a spectrophotometric method,
according to the manufacturer’s recommendations.
The direct protein denaturation was studied using in vitro
luciferase (Luc) assay (assay 2 in Fig. 1). The cDNA encoding
the luciferase enzyme from firefly (Photinus pyralis)was
inserted into the pGEX-3X plasmid (GE Heathcare Bio-Sci-
ences, Uppsala, Sweden), which corresponds to a Glutathione
S-Transferase (GST) expression vector. The presence and
the orientation of the insert within the recombinant plasmid
were verified by restriction enzyme analysis. E. coli BL21
bacteria cells were transformed with the resulting pGEX-Luc
expression vector and selected colonies were tested for pro-
tein production. Recombinant GST-Luc fusion protein was
expressed and purified as described in GE Healthcare Life
Sciences protocols [33]. Briefly, whole cell lysates were ob-
tained from transformed bacteria grown at C and induced
with 0.5 mM IPTG for 5 h. Soluble proteins were separated
from insoluble materials by centrifugation. Then, the GST-Luc
fusion protein was purified by affinity chromatography using
glutathione-agarose beads. The purified GST-Luc ( ng L,
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ZHADOBOV et al.: EVALUATION OF THE POTENTIAL BIOLOGICAL EFFECTS OF 60-GHZ MILLIMETER WAVES 2953
Fig. 6. Cell viability test results. (a) Positive control in presence of cell death
inductors. (b) Cell viability for cells exposed or sham-exposed to millimeter
waves. Data is shown for 12 samples as mean value and standard deviation.
580 nM) was incubated in L of phosphate buffered saline
(PBS) in a 96-well plate. The purified GST-Luc was exposed
or sham-exposed to millimeter waves for 15 min at C.
Its enzymatic activity was then determined in a luminometer
using a luciferase assay system kit (Promega). As a positive
control, thermal denaturation of luciferase (10 min at C)
was performed under the same conditions.
Finally, to assess potential modifications of gene expression
(assay 3 in Fig. 1), we used reverse transcription polymerase
chain reaction (RT-PCR) analysis. Total RNA from U-251
MG or HaCaT cells, exposed or sham-exposed for 24 h, were
prepared and reverse-transcribed as previously described [32].
The mRNA expression levels of stress-induced survival factors
(HSP70, BiP) were measured by real-time PCR and normalized
as explained in [34].
Statistical significance of the performed essays was evaluated
by using Student’s test within the Minitab 15.1.1 software.
was considered as a criterion of nonsignificance.
III. RESULTS
In this section, we present the experimental results on the po-
tential modifications induced at cellular (viability of cells) and
subcellular (protein conformation and gene expression) levels
after cell exposure to low-power millimeter-waves.
A. Viability of Cells
To address the potential cytotoxicity of millimeter-wave ra-
diation, the MTT assay was performed after 24 h of exposure to
60.42 GHz (Fig. 6).
As a positive control demonstrating the decrease of cell vi-
ability as a reaction to stress, the MTT test was performed for
U-251 MG cells in the presence of cell death inductors, namely
M staurosporine (Stauro: a potential anticancer drug that
provokes apoptosis) or M cadmium (Cd: a highly toxic heavy
metal). Under these conditions, the cell viability was decreased
by a factor larger than 6 [Fig. 6(a)].
Then, the cell viability was compared for the exposed (
mW, mW/cm , W/kg)
or sham-exposed cells mW . Our results are given in
Fig. 6(b). They clearly show that, in contrast to the positive con-
trols, millimeter-wave radiation does not decrease cell viability
or cellular proliferation for the cell lines used in our study.
Fig. 7. Protein luciferase activity after exposure or sham-exposure to
60.42-GHz radiation. (a) To demonstrate how sensitive the luciferase enzyme
to denaturing conditions is, a heat shock treatment ( C, 10 min) was
performed and compared to control ( C, 10 min). (b) Activity of exposed at
60.42 GHz and sham-exposed samples ( C, 15 min). Data provided for four
samples.
B. Effects on Protein Conformation
Purified protein luciferase dissolved in saline solution was ex-
posed to 60.42 GHz or sham-exposed. The choice of the bio-
logical system under test was determined by its extremely high
sensitivity to various physical and chemical conditions.
As a positive control, an in vitro denaturation experiment was
performed, demonstrating that a short incubation at C is suf-
ficient to entirely denature the luciferase [Fig. 7(a)].
The protein solution was exposed or sham-exposed for 15
min at C( mW, mW/cm ,
W/kg). This experiment was restricted to very short-term
exposure time as purified luciferase is extremely fragile and its
prolonged incubation may rapidly abolish its enzymatic activity.
Our experimental results [Fig. 7(b)] show that millimeter waves
do not significantly change luciferase activity under the consid-
ered exposure conditions. Taking into account relatively non-
homogeneous distribution of the SAR in the protein solution,
further complementary investigations in this direction might be
useful.
C. Effects on Gene Expression
Finally, we studied whether prolonged exposure to mil-
limeter-wave radiation has a proteotoxic effect strong enough
to trigger cellular adaptive response and overexpression of stress
factors. To address this issue, we selected two stress-biomarker
genes, namely the heat shock protein 70 (HSP70) and the
immunoglobulin heavy-chain binding protein (BiP). These two
genes are highly inducible by cellular stresses and can be used
as perfect indicators of cellular aggression [35], [36]. To mon-
itor the cellular stress level, cells were exposed to 60.42 GHz
(mW, mW/cm , W/kg
for central well, W/kg for corner well) or
sham-exposed for 24 h. Then, total RNA was purified for quan-
titative real-time PCR analysis. This technique is considered
nowadays as the most sensitive and accurate one for gene
expression measurement.
For the positive control, cells were incubated for 3 h 30 min
at C. The expression of HSP70 and BiP increased 2.2- and
9.2-fold, respectively, after heat shock treatment [Fig. 8(a)].
Our experimental results have shown that the mRNA levels
of HSP70 and BiP do not increase after exposure of the cells to
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2954 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 10, OCTOBER 2009
Fig. 8. Gene expression of stress-related proteins after exposure to 60.42 GHz
or sham-exposure. (a) Human astrocytoma glial cell line U-251 MG. (b) Human
epidermis cells HaCaT. Each test was performed at least in triplicate.
millimeter waves for two human cell lines, namely the glial cells
U-251 MG [Fig. 8(a)] and the keratinocytes HaCaT [Fig. 8(b)].
IV. DISCUSSIONS AND CONCLUSION
In this study, we investigated potential biological effects of
millimeter waves at 60.42 GHz upon human cells (skin cells and
glial cells). A specific exposure system for in vitro studies was
developed and characterized. The output power level was se-
lected to achieve superficial power densities on biological sam-
ples close to those typically expected from the future wireless
communication systems in the 60-GHz band.
First, the average SAR values within cell monolayers or
protein solutions used in our bioelectromagnetic experiments
were computed with the FDTD method. The numerical results
demonstrated that, for the maximum IPD of mW/cm (expo-
sure limit for general population), the average SAR values range
between 17 and 21.4 W/kg and between 13.7 and 26.2 W/kg
for 6-well and 96-well tissue culture plates, respectively. The
average SAR W/kg for purified protein solutions in
96-well plates is 4.7 times lower than for cell monolayers due
to the shallow penetration of millimeter waves in the solution.
Then, various biological assays were defined and imple-
mented to assess the effects of low-power millimeter wave at
the cellular, subcellular, and molecular levels. Our experimental
results demonstrated that, for the IPD lower than mW/cm ,
exposure to millimeter waves does not modify cell growth
and viability. Furthermore, the experiments did not show any
statistically significant effect on protein conformation and
adaptive gene expression. These data confirm recent studies
showing that, if care is taken to avoid thermal effects, exposures
to low-power millimeter-wave have no proteotoxic effects and
do not induce protein chaperones expression [26], [34], [37].
In conclusion, our results indicate that exposure to low-power
radiations around 60 GHz does not cause any significant effect.
However, they do not exclude a possibility of existence of local
subcellular effects or effects potentially induced by prolonged
exposures. Moreover, we cannot neglect possible synergistic ef-
fects and eliminate the possibility that other exposure param-
eters, like frequency, exposure time, or field polarization may
have effects on biosystems. Therefore, additional gene markers
and radiation parameters should be further analyzed for an ex-
tensive investigation of the potential biological effects of mil-
limeter waves.
ACKNOWLEDGMENT
The authors acknowledge Dr. M.-D. Galibert-Anne, Uni-
versity of Rennes 1, Rennes, France, for providing HaCaT
cells, and Dr. M. C. Ziskin and Dr. S. I. Alekseev, Center for
Biomedical Physics, Temple University, Philadelphia, PA, for
their useful suggestions regarding dosimetry.
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Maxim Zhadobov (S’05–M’07) was born in Gorky,
Russia, in 1980. He received the M.S. degree in ra-
diophysics from Nizhni Novgorod State University,
Nizhni Novgorod, Russia, in 2003, and the Ph.D.
degree in bioelectromagnetics from the Institute
of Electronics and Telecommunications of Rennes
(IETR), University of Rennes 1, Rennes, France, in
2006.
He accomplished postdoctoral training at the
Center of Biomedical Physics, Temple University,
Philadelphia, PA, in 2008 and recently rejoined IETR
as an Associate Scientist CNRS (Centre National de la Recherch Scientifique).
He has authored or coauthored more than 40 scientific contributions. His main
scientific interests are in the field of biological effects of EM waves, including
interactions of low-power millimeter waves and pulsed radiations at the cellular
level, therapeutic applications of EM fields, and experimental and numerical
EM dosimetry.
Dr. Zhadobov was the recipient of the 2006 Best Scientific Paper Award from
the Bioelectromegnetics Society (BEMS) and the 2005 Best Poster Presentation
Award from the International School of Bioelectromagnetics.
Christophe Nicolas Nicolaz was born in Brest,
France, in 1982. He received the M.S. degree in
“Génomique fonctionnelle et santé” from the Uni-
versity of Rennes 1, Rennes, France, in 2006.
He is currently a Ph.D. student at the Institute
of Electronics and Telecommunications of Rennes
(IETR), University of Rennes 1, and his main scien-
tific interest consists in studying biological effects
of millimeter waves at the cellular level.
Ronan Sauleau (M’04–SM’06) received the
Electronic Engineering and Radiocommunications
degree and the French DEA degree in electronics
from the Institut National des Sciences Appliquées
(INSA), Rennes, France, in 1995, the Aggregation
degree from Ecole Normale Supérieure (ENS) de
Cachan, France, in 1996, and the Ph.D. degree
in signal processing and telecommunications and
“Habilitation à Diriger des Recherche” degree from
the University of Rennes 1, Rennes, France, in 1999
and 2005, respectively.
He was an Assistant Professor at the University of Rennes 1 from 2000 to
2005 and has been an Associate Professor since 2005. He has received three
patents and is the author or coauthor of 53 journal papers and more than 110 con-
tributions to conferences and workshops. His current fields of interest are numer-
ical modeling, millimeter-wave printed and reconfigurable (MEMS) antennas,
lens-based focusing devices, periodic structures (electromagnetic bandgap ma-
terials and metamaterials), and biological effects of millimeter waves.
Dr. Sauleau received the 2004 ISAP Conference Young Researcher Scientist
Fellowship (Japan) and the first Young Researcher Prize in Britany, France, in
2001 for his research work on gain-enhanced Fabry–Perot antennas. In 2007,
he was elevated as a Junior Member of the Institut Universitaire de France. He
was also awarded the CNRS Bronze Medal in 2008.
Fabienne Desmots was born in Saint-Nazaire,
France, in 1971. She received the Ph.D. degree in
cellular and molecular biology from the University
of Rennes 1, Rennes, France, in 2000.
She obtained a one-year teaching position in Bio-
chemistry and Molecular Biology at the University of
Rennes 1 in 2001. Then, in 2002, she joined the De-
partment of Genetics at St. Jude Children’s Research
Hospital, Memphis, TN, as a Postdoctoral Fellow for
three years. Since 2005, she has been a Postdoctoral
Fellow with Prof. Michel’s team (“Homéostasie In-
tracellulaire des Protéines (HIP)”) in the UMR CNRS 6026 Laboratory, Univer-
sity of Rennes 1. Her main subject of interest was the understanding of cellular
responses to alteration of protein homeostasis and the biological roles of chap-
erones and co-chaperones proteins. She is now a Supervisor of a core facility
named “Molecular Genetics of Cancer” at the Pontchaillou Hospital, Rennes,
France. She is the author and coauthor of two articles in research news journals,
11 scientific publications, and 14 communications in national and international
conferences.
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2956 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 10, OCTOBER 2009
Daniel Thouroude received the Ph.D. degree from
the University of Rennes 1, Rennes, France, in 1987.
Before 1989, his work was primarily focused
on beam dynamics in particle accelerators. Since
1989, his research interests include the analysis and
synthesis of microstrip antenna, the modeling of
ferrite substrate antenna and Fabry-Perot cavities
using the FDTD method. He is currently Professor
at the University of Rennes 1 and Director of the
Institute of Electronics and Telecommunications of
Rennes (IETR), Rennes, France. With around 230
people, the unit is linked to the French National Center for Scientific Research
(CNRS) and places the emphasis on developing the skills needed to explore a
wide range of emerging applications, including smart antennas, radiomobile
communications, system on chip (SoC), UWB technology, radar polarimetry,
silicon-based microsystems, etc.
Denis Michel was born in Saint Lô, France, in 1957.
He received the Aggregation degree in biology from
the Ecole Normale Supérieure (ENS) de Saint-Cloud,
Saint-Cloud, France, in 1981, and the Ph.D. degree
in cellular biology from the University Paris 6, Paris,
France, in 1984.
He was a Postdoctoral Fellow the University Laval,
Quebec, Canada, from 1982 to 1983. Then, he was an
Assistant Professor at the ENS de Saint-Cloud from
1984 to 1987 and at the ENS de Lyon, Lyon, France,
from 1987 to 1996. Since 1997, he has been a Pro-
fessor in molecular biology at the University of Rennes 1. His main research
activities are in the fields of neuro-endocrinology, genetic expression in cancers,
and responses of eukaryotic cells to stresses, including exposures to electromag-
netic radiations.
Yves Le Dréan was born in 1964. He received
the Ph.D. degree and “Habilitation à Diriger des
Recherches” in biology from the University of
Rennes 1, Rennes, France in 1993 and 2007,
respectively.
He joined the Hospital for Sick Children, Toronto,
ON, Canada, as a Post-Doctoral Fellow in 1994.
Since 1997, he has been an Associate Professor at
the University of Rennes 1, where he teaches molec-
ular biology and biochemistry. His main subject
of interest is the control of genetic expression. His
current research activities are related to the investigations of cell responses to
proteotoxic stress. Since 2004, he has been also actively involved in the field of
biological effects of electromagnetic waves.
Dr. Le Dréan is the author or coauthor of two book chapters, 21 journal pub-
lications, and 25 communications in national and international conferences.
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Citations (41)
References (41)
... However, the authors were able to replicate their own findings on pain relief whereas other laboratories have not replicated this work. In the in vitro studies, various biological endpoints were examined [28,[32][33][34]42,45,50,59,60,66,83,88,94,95,108]. ...
... In a series of investigations with nerve cell-relevant cell lines, the dopamine transmission properties, stress, pain and membrane protein expression were investigated (60.4 GHz, 10 mW/cm 2 , 24 h) and no responses were detected [32][33][34]59,60,108]. ...
... Other studies also examined human keratinocytes and astrocytoma glial cells after exposure to 60 GHz (0.54, 1 and 5.4 mW/cm 2 ) [60,108]. Various parameters such as cell survival, intracellular protein homeostasis, and stress-sensitive gene expression were investigated. Also, in these studies, no e↵ects were observed. ...
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