The Bioinitiative Report- Chapter 6

DNA Damage and Genotoxicity

Dr. Lai





SECTION 6


EVIDENCE FOR GENOTOXIC EFFECTS
(RFR AND ELF Genotoxicity)



Henry Lai, PhD
Department of Bioengineering
University of Washington
Seattle, Washington
USA










Prepared for the BioInitiative Working Group
July 2007

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TABLE OF CONTENTS


I.
Introduction

II.
Radiofrequency radiation (RFR) and DNA damage
A. Studies that reported effects
B. Studies that reported no significant effect


III. Micronucleus studies
A. Studies that reported effects
B. Studies that reported no significant effect


IV. Chromosome and genome effects
A. Studies that reported effects
B. Studies that reported no significant effect


V. Conclusions


VI. References


Appendix 6-A - Abstracts on Effects of Extremely Low Frequency (ELF) on DNA
showing Effect (E) and No Significant Effect (NE)



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I. Introduction

Toxicity to the genome can lead to a change in cellular functions, cancer, and cell death.
A large number of studies have been carried out to investigate the effects of
electromagnetic field (EMF) exposure on DNA and chromosomal structures. The single-
cell gel electrophoresis (comet assay) has been widely used to determine DNA damages:
single and double strand breaks and cross-links. Studies have also been carried out to
investigate chromosomal conformation and micronucleus formation in cells after
exposure to EMF.


II. Radiofrequency radiation (RFR) and DNA damage (28 total studies – 14 reported
effects (50%) and 14 reported no significant effect (50%))


II A. DNA studies that reported effects:


The following is a summary of the research data reported in the literature.


Aitken et al. [2005] exposed mice to 900-MHz RFR at a specific absorption rate (SAR)
of 0.09 W/kg for 7 days at 12 h per day. DNA damage in caudal epididymal
spermatozoa was assessed by quantitative PCR (QPCR) as well as alkaline and
pulsed-field gel electrophoresis postexposure. Gel electrophoresis revealed no
significant change in single- or double-DNA strand breakage in spermatozoa.
However, QPCR revealed statistically significant damage to both the mitochondrial
genome (p < 0.05) and the nuclear -globin locus (p < 0.01).
Diem et al [2005] exposed human fibroblasts and rat granulosa cells to mobile phone
signal (1800 MHz; SAR 1.2 or 2 W/kg; different modulations; during 4, 16 and 24 h;
intermittent 5 min on/10min off or continuous). RFR exposure induced DNA single-
and double-strand breaks as measured by the comet assay. Effects occurred after 16 h
exposure in both cell types and after different mobile-phone modulations. The
intermittent exposure showed a stronger effect in the than continuous exposure.
Gandhi and Anita [2005] reported increases in DNA strand breaks and micronucleation in
lymphocytes obtained from cell phone users.
Garaj-Vrhovac et al [1990] reported changes in DNA synthesis and structure in Chinese
hamster cells after various durations of exposure to 7.7 GHz field at 30 mW/cm2.
Lai and Singh [1995; 1996; 1997a; 2005] and Lai et al. [1997] reported increases in
single and double strand DNA breaks in brain cells of rats exposed for 2 hrs to 2450-
MHz field at 0.6-1.2 W/kg.
Lixia et al. [2006] reported an increase in DNA damage in human lens epithelial cells at 0
and 30 min after 2 hrs of exposure to 1.8 GHz field at 3 W/kg.

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Markova et al. [2005] reported that GSM signals affected chromatin conformation and
gama-H2AX foci that colocalized in distinct foci with DNA double strand breaks in
human lymphocytes.
Narasimhan and Huh [1991] reported changes in lambdaphage DNA suggesting single
strand breaks and strand separation.
Nikolova et al. [2005] reported a low and transient increase in DNA double strand break
in mouse embryonic stem cells after acute exposure to 1.7- GHz field.
Paulraj and Behari [2006] reported an increased in single strand breaks in brain cells of
rats after 35 days of exposure to 2.45 and 16.5 GHz fields at 1 and 2.01 W/kg.
Phillips et al. [1998] found increase and decrease in DNA strand breaks in cells exposure
to various forms of cell phone radiation.
Sun et al. [2006] reported an increase in DNA single strand breaks in human lens
epithelial cells after 2 hrs of exposure to 1.8 GHz field at 3 and 4 W/kg. The DNA
damages caused by 4 W/kg field were irreversible.
Zhang et al. [2002] reported that 2450-MHz field at 5 mW/cm2 did not induce DNA and
chromosome damage in human blood cells after 2 hrs of exposure, but could increase
DNA damage effect induced by mitomycin-C.
Zhang et al. [2006] reported that 1800-MHz field at 3.0 W/kg induced DNA damage in
Chinese hamster lung cells after 24 hrs of exposure.


II B. DNA studies that reported no significant effect:

Chang et al. [2005] using the Ames assay found no significant change in mutation
frequency in bacteria exposed for 48 hrs at 4W/kg to an 835-MHz CDMA signal.
Hook et al. [2004] showed that 24-hr exposure of Molt-4 cells to CDMA, FDMA, iDEN
or TDMA modulated RF radiation did not significantly alter the level of DNA
damage.
Lagroye et al. [2004a] reported no significant change in DNA strand breaks in brain cells
of rats exposed for 2 hrs to 2450-MHz field at 1.2 W/kg.
Lagroye et al. [2004b] found no significant increases in DNA-DNA and DNA-protein
cross-link in C3H10T(1/2) cells after a 2-hr exposure to CW 2450 MHz field at 1.9
W/kg.
Li et al. [2001] reported no significant change in DNA strand breaks in murine
C3H10T(1/2) fibroblasts after 2 hrs of exposure to 847.74 and 835.02 MHz fields at
3-5 W/kg.
Maes et al. [1993, 1996, 1997, 2000, 2001, 2006] published a series of papers on in vitro
genotoxic effects of radiofrequency radiation and interaction with chemicals. Their
mostly found no significant effect.
Malyapa et al. [1997a,b, 1998] reported no significant change in DNA strand-breaks in
cells exposed to 2450-Hz and various forms of cell phone radiation. Both in vitro and
in vivo experiments were carried out.
McNamee et al. [2002a,b, 2003] found no significant increase in DNA breaks and
micronucleus formation in human leukocytes exposed for 2 hrs to 1.9 GHz field at
SAR up to 10 W/kg.

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Sakuma et al. [2006] exposed human glioblastoma A172 cells and normal human IMR-
90 fibroblasts from fetal lungs to mobile communication radiation for 2 and 24 hrs.
No significant change in DNA strand breaks were observed up to 800 mW/kg.
Stronati et al. [2006] showed that 24 hrs of exposure to 935-MHz GSM basic signal at 1
or 2 W/Kg did not cause DNA strand breaks in human blood cells.
Tice et al. [2002] measured DNA single strand breaks in human leukocytes using the comet
assay after exposure to various forms of cell phone signals. Cells were exposed at 37±1°C,
for 3 or 24 h at average specific absorption rates (SARs) of 1.0-10.0 W/kg. Exposure for
either 3 or 24 h did not induce a significant increase in DNA damage in leukocytes.
Vershaeve et al. [2006] long-term exposure (2 hrs/day, 5 days/week for 2 years) of rats to
900 MHz GSM signal at 0.3 and 0.9 W/kg did not significantly affect levels of DNA
strand breaks in cells.
Vijayalaximi et al [2000] reported no significant increase in single strand breaks in
human lymphocytes after 2 hrs of exposure to 2450-MHz field at 2 W/kg.
Zeni et al. [2005] reported that a 2-hr exposure to 900-MHz GSM signal at 0.3 and 1
W/kg did not significantly affect levels of DNA strand breaks in human leukocytes.


III. Micronucleus studies (29 Total studies: 16 reported effects (55%) and 13
reported no significant effect (45%))

III A. Micronucleus studies that reported effects:

Balode [1996] obtained blood samples from female Latvian Brown cows from a farm
close to and in front of the Skrunda Radar and from cows in a control area.
Micronuclei in peripheral erythrocytes were significantly higher in the exposed cows.
Busljeta et al. [2004] exposed male rats to 2.45 GHz RFR fields for 2 hours daily, 7 days
a week, at 5-10 mW/cm2 for up to 30 days. Erythrocyte count, haemoglobin and
haematocrit were increased in peripheral blood on irradiation days 8 and 15. Anuclear
cells and erythropoietic precursor cells were significantly decreased in the bone
marrow on day 15, but micronucleated cells were increased.
D’Ambrosio et al. [2002] exposed human peripheral blood to 1.748 GHz continuous
wave (CW) or phase-modulated wave (GMSK) for 15 min at a maximum specific
absorption rate of 5 W/kg. No changes were found in cell proliferation kinetics after
exposure to either CW or GMSK fields. Micronucleus frequency result was not
affected by CW exposure but a statistically significant increase in micronucleus was
found following GMSK exposure.
Ferreira et al. [2006] found that rat offspring exposed to radiation from a cellular phone
during their embryogenesis showed a significant increase in micronucleus frequency.
Fucic et al. [1992] reported increase in frequencies of micronuclei in the lymphocytes of
humans exposed to microwaves.
Gandhi and Singh [2005] analyzed short term peripheral lymphocyte cultures for
chromosomal aberrations and the buccal mucosal cells for micronuclei. They reported
an increase in the number of micronucleated buccal cells and cytological
abnormalities in cultured lymphocytes.

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Garaj-Vrhovac et al [1992] exposed human whole-blood samples to continuous-wave 7.7
GHz radiation at power density of 0.5, 10 and 30 mW/cm2 for 10, 30 and 60 min. In
all experimental conditions, the frequencies of all types of chromosomal aberrations
(dicentric and ring chromosomes) and micronucleus were significantly higher than in
the control samples.
Garaj-Vrhovac et al. [1999] investigated peripheral blood lymphocytes of 12 subjects
occupationally exposed to microwave radiation. Results showed an increase in
frequency of micronuclei as well as disturbances in the distribution of cells over the
first, second and third mitotic division in exposed subjects compared to controls.
Haider et al. [1994] exposed plant cuttings bearing young flower buds for 30 h on both
sides of a slewable curtain antenna (300/500 kW, 40-170 V/m) and 15 m (90 V/m)
and 30 m (70 V/m) distant from a vertical cage antenna (100 kW) as well as at the
neighbors living near the broadcasting station (200 m, 1-3 V/m). Laboratory controls
were maintained for comparison. Higher micronucleus frequencies than in laboratory
controls were found for all exposure sites in the immediate vicinity of the antennae,
Tice et al. [2002] measured micronucleus frequency in human leukocytes using the comet
assay after exposure to various forms of cell phone signals. Cells were exposed at 37±1°C,
for 3 or 24 h at average specific absorption rates (SARs) of 1.0-10.0 W/kg. Exposure for 3
h did not induce a significant increase in micronucleated lymphocytes. However, exposure
to each of the signals for 24 h at an average SAR of 5.0 or 10.0 W/kg resulted in a
significant and reproducible increase in the frequency of micronucleated lymphocytes.
The magnitude of the response (approximately four fold) was independent of the
technology, the presence or absence of voice modulation, and the frequency.
Trosic et al. [2001] investigated the effect of a 2450-MHz microwave irradiation on
alveolar macrophage kinetics and formation of multinucleated giant cells after whole
body irradiation of rats at 5-15 mW/cm2. A group of experimental animals was
divided in four subgroups that received 2, 8, 13 and 22 irradiation treatments of two
hours each. The animals were killed on experimental days 1, 8, 16, and 30.
Multinucleated cells were significantly increased in treated animals. The increase in
number of nuclei per cell was time- and dose-dependent. Macrophages with two
nucleoli were more common in animals treated twice or eight times. Polynucleation
was frequently observed after 13 or 22 treatments.
Trosic et al. [2002] exposed adult male Wistar for 2 h a day, 7 days a week for up to 30
days to continuous 2450-MHz microwaves at a power density of 5-10mW/cm2.
Frequency of micronuclei in polychromatic erythrocytes showed a significant
increase in the exposed animals after 2, 8 and 15 days of exposure compared to sham-
exposed control.
Trosic et al. [2004] investigated micronucleus frequency in bone marrow red cells of rats
exposed to a 2450-MHz continuous–wave microwaves for 2 h daily, 7 days a week, at
a power density of 5-10 mW/cm2 (whole body SAR 1.25 +/- 0.36 (SE) W/kg). The
frequency of micronucleated polychromatic erythrocytes was significantly increased
on experimental day 15.
Trosic et al. [2006] exposed rats 2 h/day, 7 days/week to 2450-MHz microwaves at a
whole-body SAR of 1.25 +/- 0.36W/kg. Control animals were included in the study.
Bone marrow micronucleus frequency was increased on experimental day 15, and

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polychromatic erythrocytes micronucleus frequency in the peripheral blood was
increased on day 8.
Zotti-Martelli et al. [2000] exposed human peripheral blood lymphocytes in G(0) phase
to electromagnetic fields at different frequencies (2.45 and 7.7 GHz) and power
densities (10, 20 and 30 mW/cm2) for 15, 30 or 60min. The results showed for both
radiation frequencies an induction of micronuclei as compared to control cultures at a
power density of 30mW/cm2 and after an exposure of 30 and 60 min.
Zotti-Martelli et al. [2005] exposed whole blood samples from nine different healthy
donors for 60, 120 and 180 min to continuous-wave 1800-MHz microwaves at power
densities of 5, 10 and 20 mW/cm2. A statistically significant increase of micronucleus
in lymphocytes was observed dependent on exposure time and power density. A
considerable decrease in spontaneous and induced MN frequencies was measured in a
second experiment.

III B. Micronucleus studies that reported no significant effects:

Bisht et al. [2002] exposed C3H 10T½ cells to 847.74 MHz CDMA (3.2 or 4.8 W/kg) or
835.62 MHz FDMA (3.2 or 5.1 W/kg) RFR for 3, 8, 16 or 24 h. No exposure
condition was found to result in a significant increase relative to sham-exposed cells
either in the percentage of binucleated cells with micronuclei or in the number of
micronuclei per 100 binucleated cells.
Juutilainen et al. [2007] found no significant change in micronucleus frequency in
erythrocytes of mice after long-term exposure to various mobile phone frequencies.
Koyama et al. [2004] exposed Chinese hamster ovary (CHO)-K1 cells to 2450-MHz
microwaves for 2 h at average specific absorption rates (SARs) of 5, 10, 20, 50, 100,
and 200 W/kg. Micronucleus frequency in cells exposed at SARs of 100 and 200
W/kg were significantly higher when compared with sham-exposed controls. They
speculated that the effect observed was a thermal effect.
Port et al. [2003] reported that exposure of HL-60 cells to EMFs 25 times higher than the
ICNIRP reference levels for occupational exposure did not induce any significant
changes in apoptosis, micronucleation, abnormal morphologies and gene expression.
Scarfi et al [2006] exposed human peripheral blood lymphocytes to 900 MHz GSM
signal at specific absorption rates of 0, 1, 5 and 10 W/kg peak values. No significant
change in micronucleus frequency was observed.
Vijayalaximi et al. [1997a] exposed human blood to continuous-wave 2450- MHz
microwaves, either continuously for a period of 90 min or intermittently for a total
exposure period of 90 min (30 min on and 30 min off, repeated three times). The
mean power density at the position of the cells was 5.0 mW/cm2 and mean specific
absorption rate was 12.46 W/kg. There were no significant differences between RFR-
exposed and sham-exposed lymphocytes with respect to; (a) mitotic indices; (b)
incidence of cells showing chromosome damage; (c) exchange aberrations; (d)
acentric fragments; (e) binucleate lymphocytes, and (f) micronuclei.
Vijayalaximi et al. [1997b] exposed C3H/HeJ mice for 20 h/day, 7 days/week, over 18
months to continuous-wave 2450 MHz microwaves at a whole-body average specific
absorption rate of 1.0 W/kg. At the end of the 18 months, peripheral blood and bone
marrow smears were examined for the extent of genotoxicity as indicated by the

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presence of micronuclei in polychromatic erythrocytes. The results indicate that the
incidence of micronuclei/1,000 polychromatic erythrocytes was not significantly
different between groups exposed to RF radiation and sham-exposed groups.
Vijayalaximi et al. [1999] exposed CF-1 male mice to ultra-wideband electromagnetic
radiation (UWBR) for 15 min at an estimated whole-body average specific absorption
rate of 37 mW/kg. Peripheral blood and bone marrow smears were examined to
determine the extent of genotoxicity, as assessed by the presence of micronuclei
(MN) in polychromatic erythrocytes (PCE). There was no evidence for excess
genotoxicity in peripheral blood or bone marrow cells of mice exposed to UWBR.
Vijayalaximi et al. [2001a] reported that there was no evidence for the induction of
micronuclei in peripheral blood and bone marrow cells of rats exposed for 24h to
2450-MHz continuous-wave microwaves at a whole body average SAR of 12 W/kg.
Vijayalaximi et al. [2001b] reported that there is no evidence for the induction of
chromosomal aberrations and micronuclei in human blood lymphocytes exposed in
vitro for 24 h to 835.62 MHz RF radiation at SARs of 4.4 or 5.0 W/kg.
Vijayalaximi et al. [2001c] reported no evidence for induction of chromosome
aberrations and micronuclei in human blood lymphocytes exposed in vitro for 24 h to
847.74 MHz RF radiation (CDMA) at SARs of 4.9 or 5.5 W/kg.
Vijayalaximi et al. [2003] exposed timed-pregnant Fischer 344 rats (from nineteenth day
of gestation) and their nursing offspring (until weaning) to a far-field 1.6 GHz Iridium
wireless communication signal for 2 h/day, 7 days/week at power density of 0.43
mW/cm2 and whole-body average specific absorption rate of 0.036 to 0.077 W/kg
(0.10 to 0.22 W/kg in the brain). This was followed by chronic, head-only exposures
of male and female offspring to a near-field 1.6 GHz signal for 2 h/day, 5 days/week,
over 2 years. Near-field exposures were conducted at an SAR of 0.16 or 1.6 W/kg in
the brain. At the end of 2 years, all rats were necropsied. Bone marrow smears were
examined for the extent of genotoxicity, assessed from the presence of micronuclei in
polychromatic erythrocytes. There was no evidence for excess genotoxicity in rats
that were chronically exposed to 1.6 GHz microwaves compared to sham-exposed
and cage controls.
Zeni et al. [2003] investigated the induction of micronucleus in human peripheral blood
lymphocytes after exposure to electromagnetic fields at various duration of exposure,
specific absorption rate (SAR), and signal [continuous-wave (CW) or GSM (Global
System of Mobile Communication)-modulated signal]. No statistically significant
difference was detected in any case.

IV. Chromosome and genome effects (21 studies total: 13 reported effects (62%)
and 8 reported no significant effect (38%))

IV A. Chromosome and genome studies that reported effects:

Belyaev et al. [I992] studied the effect of low intensity microwaves on the
conformational state of the genome of X-irradiated E. coli cells by the method of
viscosity anomalous time dependencies. A power density of 1 microW/cm2 is
sufficient to suppress radiation-induced repair of the genome conformational state.

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Belyaev et al. [1996] studied the effect of millimeter waves on the genome
conformational state of E. coli AB1157 by the method of anomalous viscosity time
dependencies in the frequency range of 51.64-51.85 GHz. Results indicate an
electron-conformational interactions.
Belyaev et al. [2005] investigated response of lymphocytes from healthy subjects and
from persons reporting hypersensitivity to microwaves from GSM mobile phone (915
MHz, specific absorption rate 37 mW/kg), and power frequency magnetic field (50
Hz, 15 microT peak value). Changes in chromatin conformation were measured with
the method of anomalous viscosity time dependencies (AVTD). Exposure at room
temperature to either 915 MHz or 50 Hz resulted in significant condensation of
chromatin, shown as AVTD changes, which was similar to the effect of heat shock at
41 degrees C. No significant differences in responses between normal and
hypersensitive subjects were detected.
Belyaev et al. [2006] investigated whether exposure of rat brain to microwaves of global
system for mobile communication (GSM) induces DNA breaks, changes in chromatin
conformation and in gene expression at a specific absorption rate (SAR) of 0.4 mW/g
for 2 h. Data showed that GSM MWs at 915 MHz did not induce DNA double
stranded breaks detectable by pulsed-field gel electrophoresis or changes in chromatin
conformation, but affected expression of genes in rat brain cells.
Gadhia et al. [2003] reported a significant increase in dicentric chromosomes in blood
cells among mobile users who were smoker–alcoholic as compared to nonsmoker–
nonalcoholic; the same held true for controls of both types.
Garaj-Vrhovac et al. [1990] exposed V79 Chinese hamster cells to continuous-wave 7.7
GHz RFR at power density of 30 mW/cm2 for 15, 30, and 60 min. Results suggest
that the radiation causes changes in the synthesis as well as in the structure of DNA
molecules.
Garaj-Vrhovac et al. [1991] exposed V79 Chinese hamster fibroblast cells to continuous
wave 7.7 GHz radiation at power density of 0.5 mW/cm2 for 15, 30 and 60 min.
There was a significantly higher frequency of specific chromosome aberrations such
as dicentric and ring chromosomes in irradiated cells.
Mashevich et al. [2003] found that human peripheral blood lymphocytes exposed to
continuous 830-MHz electromagnetic fields (1.6-8.8 W/kg for 72 hr) showed a SAR-
dependent chromosome aneuploidy, a major “somatic mutation leading to genomic
instability and thereby to cancer. The aneuploidy was accompanied by an abnormal
mode of replication of the chromosome 17 region engaged in segregation (repetitive
DNA arrays associated with the centromere), suggesting that epigenetic alterations
are involved in the SAR dependent genetic toxicity. The effects were non-thermal.
Ono et al. (2004) exposed pregnant mice intermittently at a whole-body averaged specific
absorption rate of 0.71 W/kg (10 seconds on, 50 seconds off which is 4.3 W/kg
during the 10 seconds exposure) for 16 hours a day, from the embryonic age of 0 to
15 days. At 10 weeks of age, mutation frequencies at the lacZ gene in spleen, liver,
brain, and testis were examined. Quality of mutation assessed by sequencing the
nucleotides of mutant DNAs revealed no appreciable difference between exposed and
non-exposed samples.
Sarimov et al. [2004] reported that exposure to microwaves of 895-915 MHz at 5.4
mW/kg resulted in statistically significant changes in condensation of chromatin in

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human lymphocytes. Effects are similar to stress response, differ at various
frequencies, and vary among donors.
Sarkar et al. [1994] exposed mice to 2450-MHz microwaves at a power density of 1
mW/cm2 for 2 h/day over a period of 120, 150 and 200 days. Rearrangement of DNA
segments were observed in testis and brain of exposed animals.
Semin et al. [1995] exposed DNA samples at 18oC at 10 different microwave frequencies
(4- to 8 GHz, 25 ms pulses, 0.4 to 0.7 mW/cm2 peak power, 1- to 6-Hz repetition rate,
no heating). Irradiation at 3 or 4 Hz and 0.6 mW/cm2 peak power clearly increased
the accumulated damage to the DNA secondary structure (P< .00001). However,
changing the pulse repetition rate to 1, 5, 6 Hz, as well as changing the peak power to
0.4 or 0.7 mW/cm2 did not induce significant effect. Thus, the effect occurred only
within narrow ‘windows’ of the peak intensities and modulation frequencies.
Sykes et al. [2001] exposed mice daily for 30 min to plane-wave fields of 900 MHz with
a pulse repetition frequency of 217 Hz and a pulse width of 0.6 ms for 1, 5 or 25 days.
Three days after the last exposure, spleen sections were screened for DNA inversion
events. There was no significant difference between the control and treated groups in
the 1- and 5-day exposure groups, but there was a significant reduction in inversions
below the spontaneous frequency in the 25-day exposure group. This observation
suggests that exposure to RF radiation can lead to a perturbation in recombination
frequency which may have implications for recombination repair of DNA.

IV. B. Chromosome and genome studies that reported no significant effects:

Antonopoulos et al. [1997] found no significant change in cell cycle progression and the
frequencies of sister-chromatid exchanges in human lymphocytes exposed to
electromagnetic fields of 380, 900 and 1800 MHz.
Ciaravino et al. [1991] reported that RFR did not affect changes in cell progression
caused by adriamycin, and the RFR did not change the number of sister chromatid
exchanges that were induced by the adriamycin.
Garson et al. [1991] analyzed lymphocytes from Telecom Australia radio-linemen who
had all worked with RFR in the range 400 kHz-20 GHz with exposures at or below
the Australian occupational limits. There was no significant increase in chromosomal
damage in circulating lymphocytes.
Gos et al. [2000] exposed actively growing and resting cells of the yeast Saccharomyces
cerevisiae to 900-MHz Global System for Mobile Communication (GSM) pulsed
modulation format signals at specific absorption rates (SAR) of 0.13 and 1.3 W/kg.
They reported no significant effect of the fields on forward mutation rates on the
frequency of petite formation, on rates of intrachromosomal deletion formation, or on
rates of intragenic recombination in the absence or presence of the genotoxic agent
methyl methansulfonate.
Kerbacher et al (1990) reported that exposure to pulsed 2450-MHz microwaves for 2 h at
an SAR of 33.8 W/kg did not significantly cause chromosome aberrations in CHO
cells. The radiation also did not interact with Mitomycin C and Adriamycin.
Komatsubara et al. [2005] reported that exposure to 2.45-GHz microwaves for 2 h with
up to 100 W/kg SAR CW and an average 100 W/kg PW (a maximum SAR of 900
W/kg) did not induce chromosomal aberrations in mouse m5S cells.

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