There has been growing concern about the possibility of adverse health effects resulting from exposure to radiofrequency radiations (RFR), such as those emitted by wireless communication devices. ...Since the introduction of mobile phones many studies have been conducted regarding alleged health effects but there is still some uncertainty and no definitive conclusions have been reached so far. Although thermal effects are well understood they are not of great concern as they are unlikely to result from the typical low-level RFR exposures. Concern rests essentially with the possibility that RFR-exposure may induce non-thermal and/or long-term health effects such as an increased cancer risk. Consequently, possible genetic effects have often been studied but with mixed results. In this paper we review the data on alleged RFR-induced genetic effects from
in vitro and
in vivo investigations as well as from human cytogenetic biomonitoring surveys. Attention is also paid to combined exposures of RFR with chemical or physical agents. Again, however, no entirely consistent picture emerges. Many of the positive studies may well be due to thermal exposures, but a few studies suggest that biological effects can be seen at low levels of exposure. Overall, however, the evidence for low-level genotoxic effects is very weak.
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Hook, G. J., Zhang, P., Lagroye, I., Li, L., Higashikubo, R., Moros, E. G., Straube, W. L., Pickard, W. F., Baty, J. D. and Roti Roti, J. L. Measurement of DNA Damage and Apoptosis in Molt-4 Cells ...after In Vitro Exposure to Radiofrequency Radiation. Radiat. Res. 161, 193–200 (2004). To determine whether exposure to radiofrequency (RF) radiation can induce DNA damage or apoptosis, Molt-4 T lymphoblastoid cells were exposed with RF fields at frequencies and modulations of the type used by wireless communication devices. Four types of frequency/modulation forms were studied: 847.74 MHz code-division multiple-access (CDMA), 835.62 MHz frequency-division multiple-access (FDMA), 813.56 MHz iDEN® (iDEN), and 836.55 MHz time-division multiple-access (TDMA). Exponentially growing cells were exposed to RF radiation for periods up to 24 h using a radial transmission line (RTL) exposure system. The specific absorption rates used were 3.2 W/kg for CDMA and FDMA, 2.4 or 24 mW/kg for iDEN, and 2.6 or 26 mW/kg for TDMA. The temperature in the RTLs was maintained at 37°C ± 0.3°C. DNA damage was measured using the single-cell gel electrophoresis assay. The annexin V affinity assay was used to detect apoptosis. No statistically significant difference in the level of DNA damage or apoptosis was observed between sham-treated cells and cells exposed to RF radiation for any frequency, modulation or exposure time. Our results show that exposure of Molt-4 cells to CDMA, FDMA, iDEN or TDMA modulated RF radiation does not induce alterations in level of DNA damage or induce apoptosis.
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In this study we investigated the effect of the Enhanced Data rate for GSM Evolution (EDGE) signal on cells of three human brain cell lines, SH-SY5Y, U87 and CHME5, used as models of neurons, ...astrocytes and microglia, respectively, as well as on primary cortical neuron cultures. SXC-1800 waveguides (IT'IS-Foundation, Zürich, Switzerland) were modified for in vitro exposure to the EDGE signal radiofrequency (RF) radiation at 1800 MHz. Four exposure conditions were tested: 2 and 10 W/kg for 1 and 24 h. The production of reactive oxygen species (ROS) was measured by flow cytometry using the dichlorofluorescein diacetate (DCFH-DA) probe at the end of the 24-h exposure or 24 h after the 1-h exposure. Rotenone treatment was used as a positive control. All cells tested responded to rotenone treatment by increasing ROS production. These findings indicate that exposure to the EDGE signal does not induce oxidative stress under these test conditions, including 10 W/kg. Our results are in agreement with earlier findings that RF radiation alone does not increase ROS production.
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Abstract Objective The objectives of this work were: (i) to evaluate the relevance for clinical studies of repetitive transcranial magnetic stimulation (rTMS) investigations on rats, (ii) to ...investigate the occurrence of DNA damage in rat brain cells following rTMS under conditions similar to those used in clinical treatment of depression. Methods Rats were exposed to 2000 magnetic pulses at 100% of motor threshold (MT). Software, written to take detailed anatomical and conductivity data into account, was used to map current density in the rat brain. A method was developed for standardizing magnetic pulse efficacy to facilitate comparison with other rTMS studies. Genotoxicity was explored using the alkaline comet assay on rat brain cells, measuring Olive moment and %DNA in the tail. Results The current density was ca. 6.6 A/m2 in the motor cortex at MT (Motor Cortex Threshold Densities: MCTDs), 5.2 A/m2 in the brain (range 0–17 A/m2 ), and 2.0 A/m2 at prefrontal cortex. Similar standard MCTDs were found in rats and humans. Concerning the comet assay, both Olive moment and %DNA in the tail, there was no statistically-significant difference between rTMS-exposed and sham-exposed brain cell samples. In contrast, significant increases in both parameters were detected in positive controls. Conclusions Under the assumptions developed in the discussion, these data showed no evidence that the standard current density at motor threshold in human motor cortex would differ from that in rats. Furthermore, there was no evidence of DNA damage in rat brain cells following a single scheme of rTMS, under conditions similar to the clinical treatment of depression. Significance This study supports the use of rats as a model for studying the bioeffects of rTMS (molecular targets, action mechanisms, toxicology, etc.) and suggests that a single rTMS scheme, similar to that used daily in the treatment of depression, is not genotoxic.
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In a series of Russian and Ukrainian papers published from 1974–1986, it was reported that 30-day whole-body exposures to continuous-wave (CW) radiofrequency (RF) radiation at 2375 MHz and 5 W/m2 ...disrupted the antigenic structure of rat brain tissue. The authors suggested that this action caused an autoimmune response in exposed animals. Moreover, these studies reported that blood serum from exposed rats injected into intact nonexposed female rats on the 10th day of pregnancy led to increased postimplantation embryo mortality and decreased fetus size and body weight. Because the results of these studies served in part as the basis for setting exposure limits in the former USSR, it was deemed necessary to perform confirmation studies, using modern dosimetric and biological methods. In our study, a new system was constructed to expose free-moving rats under far-field conditions. Whole-body and brain-averaged specific absorption rates (SARs) were calculated. All results, using ELISA and classic teratology end points, were negative in our laboratory. On the basis of this investigation, we conclude that, under these exposure conditions (2450 MHz, CW, 7 h/day, 30 days, 0.16 W/kg whole-body SAR), RF-radiation exposure had no influence on several immune and degenerative parameters or on prenatal development.
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Sanchez, S., Haro, E., Ruffié, G., Veyret, B. and Lagroye, I. In Vitro Study of the Stress Response of Human Skin Cells to GSM-1800 Mobile Phone Signals Compared to UVB Radiation and Heat Shock. ...Radiat. Res. 167, 572–580 (2007). The evolution of mobile phone technology is toward an increase of the carrier frequency up to 2.45 GHz. Absorption of radiofrequency (RF) radiation becomes more superficial as the frequency increases. This increasingly superficial absorption of RF radiation by the skin, which is the first organ exposed to RF radiation, may lead to stress responses in skin cells. We thus investigated the expression of three heat-shock proteins (HSP70, HSC70, HSP27) using immunohistochemistry and induction of apoptosis by flow cytometry on human primary keratinocytes and fibroblasts. A well-characterized exposure system, SXC 1800, built by the IT'IS foundation was used at 1800 MHz, with a 217 Hz modulation. We tested a 48-h exposure at an SAR of 2 W/kg (ICNIRP local exposure limit). Skin cells were also irradiated with a 600 mJ/cm2 single dose of UVB radiation and subjected to heat shock (45°C, 20 min) as positive controls for apoptosis and HSP expression, respectively. The results showed no effect of a 48-h GSM-1800 exposure at 2 W/kg on either keratinocytes or fibroblasts, in contrast to UVB-radiation or heat-shock treatments, which injured cells. We thus conclude that the GSM-1800 signal does not act as a stress factor on human primary skin cells in vitro.
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Purpose: To investigate the effect of 2450 MHz pulsed-wave microwaves on the induction of DNA damage in brain cells of exposed rats and to discover whether proteinase K is needed to detect DNA damage ...in the brain cells of rats exposed to 2450 MHz microwaves.
Materials and methods: Sprague-Dawley rats were exposed to 2450 MHz pulsed-wave microwaves and sacrificed 4 h after a 2-h exposure. Rats irradiated whole-body with 1 Gy 137Cs were included as positive controls. DNA damage was assayed by two variants of the alkaline comet assay on separate aliquots of the same cell preparation.
Results: Significant DNA damage was observed in the rat brain cells of rats exposed to γ-rays using both versions of the alkaline comet assay independent of the presence or absence of proteinase K. However, neither version of the assay could detect any difference in comet length and or normalized comet moment between sham- and 2450 MHz pulsed-wave microwave-exposed rats, regardless of the inclusion or omission of proteinase K in the comet assay.
Conclusions: No DNA damage in brain cells was detected following exposure of rats to 2450 MHz microwaves pulsed-wave at a specific absorption rate of 1.2 W kg−1 regardless of whether or not proteinase K was included in the assay. Thus, the results support the conclusion that low-level 2450 MHz pulsed-wave microwave exposures do not induce DNA damage detectable by the alkaline comet assay.
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Li, L., Bisht, K. S., LaGroye, I., Zhang, P., Straube, W. L., Moros, E. G. and Roti Roti, J. L. Measurement of DNA Damage in Mammalian Cells Exposed In Vitro to Radiofrequency Fields at SARs of 3–5 ...W/kg. Radiat. Res. 156, 328–332 (2001). In the present study, we determined whether exposure of mammalian cells to 3.2–5.1 W/kg specific absorption rate (SAR) radiofrequency fields could induce DNA damage in murine C3H 10T½ fibroblasts. Cell cultures were exposed to 847.74 MHz code-division multiple access (CDMA) and 835.62 frequency-division multiple access (FDMA) modulated radiations in radial transmission line (RTL) irradiators in which the temperature was regulated to 37.0 ± 0.3°C. Using the alkaline comet assay to measure DNA damage, we found no statistically significant differences in either comet moment or comet length between sham-exposed cells and those exposed for 2, 4 or 24 h to CDMA or FDMA radiations in either exponentially growing or plateau-phase cells. Further, a 4-h incubation after the 2-h exposure resulted in no significant changes in comet moment or comet length. Our results show that exposure of cultured C3H 10T½ cells at 37°C CDMA or FDMA at SAR values of up to 5.1 W/kg did not induce measurable DNA damage.
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Purpose: The purpose of this work was to determine whether the cellular components of Hairless-rat skin are affected by a chronic local exposure to non-ionizing radiations of Global Mobile Phone ...System: GSM-900 or -1800 radiations at specific absorption rate (SAR) 2.5 and 5 W kg.
Materials and methods: A selected part of the right back of five-week old female hairless rats was exposed or sham exposed (n = 8) for 2 h per day, 5 days a week, for 12 weeks to GSM-900 or -1800 signals using a loop-antenna. At the end of the experiment, skin biopsies were taken.
Results: Analyses of skin sections using hematoxylin eosin saffron (HES) coloration showed no significant difference in skin thickness among the groups. Immunohistochemical analysis of basal lamella cells in radiofrequency radiation (RFR)-exposed epidermis showed that the ratio of the antigen Ki-67 (cellular proliferation marker) positive cells to total lamella cells remained within the range of the normal proliferation ratio. No significant differences in the level of filaggrin, collagen, and elastin were observed among the different groups.
Conclusions: The results of this 12-week chronic study do not demonstrate major histological variations in the skin of hairless rats exposed to RFR used in mobile telephony (GSM-900 or -1800).
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Lagroye, I., Hook, G. J., Wettring, B. A., Baty, J. D., Moros, E. G., Straube, W. L. and Roti Roti, J. L. Measurements of Alkali-Labile DNA Damage and Protein–DNA Crosslinks after 2450 MHz Microwave ...and Low-Dose Gamma Irradiation In Vitro. Radiat. Res. 161, 201–214 (2004). In vitro experiments were performed to determine whether 2450 MHz microwave radiation induces alkali-labile DNA damage and/or DNA–protein or DNA–DNA crosslinks in C3H 10T½ cells. After a 2-h exposure to either 2450 MHz continuous-wave (CW) microwaves at an SAR of 1.9 W/kg or 1 mM cisplatinum (CDDP, a positive control for DNA crosslinks), C3H 10T½ cells were irradiated with 4 Gy of γ rays (137Cs). Immediately after γ irradiation, the single-cell gel electrophoresis assay was performed to detect DNA damage. For each exposure condition, one set of samples was treated with proteinase K (1 mg/ml) to remove any possible DNA–protein crosslinks. To measure DNA–protein crosslinks independent of DNA–DNA crosslinks, we quantified the proteins that were recovered with DNA after microwave exposure, using CDDP and γ irradiation, positive controls for DNA–protein crosslinks. Ionizing radiation (4 Gy) induced significant DNA damage. However, no DNA damage could be detected after exposure to 2450 MHz CW microwaves alone. The crosslinking agent CDDP significantly reduced both the comet length and the normalized comet moment in C3H 10T½ cells irradiated with 4 Gy γ rays. In contrast, 2450 MHz microwaves did not impede the DNA migration induced by γ rays. When control cells were treated with proteinase K, both parameters increased in the absence of any DNA damage. However, no additional effect of proteinase K was seen in samples exposed to 2450 MHz microwaves or in samples treated with the combination of microwaves and radiation. On the other hand, proteinase K treatment was ineffective in restoring any migration of the DNA in cells pretreated with CDDP and irradiated with γ rays. When DNA–protein crosslinks were specifically measured, we found no evidence for the induction of DNA–protein crosslinks or changes in amount of the protein associated with DNA by 2450 MHz CW microwave exposure. Thus 2-h exposures to 1.9 W/ kg of 2450 MHz CW microwaves did not induce measurable alkali-labile DNA damage or DNA–DNA or DNA–protein crosslinks.
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