Unknown authors · 2009
The review states that electromagnetic fields in both extremely low frequency and radio frequency ranges activate the cellular stress response, inducing stress response genes such as HSP70 and increasing stress proteins like hsp70. The 20 stress protein families are evolutionarily conserved and act as chaperones that help repair and refold damaged proteins and transport them across cell membranes. Induction of the stress response involves DNA activation, and the same cellular pathways respond to both frequency ranges despite their large energy difference. Specific DNA sequences on the HSP70 promoter are responsive to EMF, and model systems suggest EMF could interact directly with electrons in DNA. Increasing EMF energy in the radio frequency range can lead to breaks in DNA strands.
Unknown authors · 2009
The review examined 101 publications that studied genotoxicity of radiofrequency electromagnetic fields in vivo and in vitro. Of these studies, 49 reported a genotoxic effect and 42 did not. Eight studies found that RF-EMF enhanced the genotoxic action of other chemical or physical agents without directly affecting genetic material. The author concluded there is ample evidence that RF-EMF can alter the genetic material of exposed cells in vivo and in vitro in more than one way.
Unknown authors · 2009
Unknown authors · 2009
They analyzed 53BP1 foci marking DNA repair sites using laser confocal microscopy. Microwaves inhibited 53BP1 focus formation in both human primary fibroblasts and mesenchymal stem cells, with the same GSM (915 MHz) and UMTS (1947.4 MHz) frequencies effective across all cell types. Exposure at 905 MHz did not inhibit foci in differentiated cells but showed some effects in stem cells, and stem cells did not adapt to chronic exposure over 2 weeks unlike fibroblasts.
Ziemann C et al. · 2009
Researchers exposed male and female B6C3F1 mice to GSM 902 MHz and DCS 1747 MHz signals for two years. The exposure regimen was 2 hours per day, 5 days per week, at whole-body averaged SARs of 0.4, 1.3, and 4.0 W/kg. Micronuclei were counted in peripheral blood erythrocytes stained with May-Grunwald-Giemsa or acridine orange. No significant differences in micronuclei frequency were observed between RF-exposed, sham-exposed, and cage control mice. Positive control mice injected with mitomycin C had significantly increased micronuclei, and the authors concluded that the data did not indicate RF-induced genotoxicity after two years.
Hansteen IL et al. · 2009
The aim was to test if exposure used in mobile phones and wireless network technologies would induce DNA damage in cultured human lymphocytes with and without a known clastogen. Lymphocytes from six donors were exposed to 2.3 GHz, 10 W/m(2) continuous waves, or 2.3 GHz, 10 W/m(2) pulsed waves (200 Hz pulse frequency, 50% duty cycle). Mitomycin C was added to half of the cultures. No statistically significant differences were observed between control and exposed cultures. A weak trend for more chromosomal damage with the interaction of pulsed fields with mitomycin C compared to a constant field was observed.
Hansteen IL et al. · 2009
Researchers exposed lymphocytes from two smoking and four non-smoking donors for 53 hours to 1.0 W/m(2) continuous-wave at 18.0 GHz or 10 W/m(2) pulsed-wave at 16.5 GHz, alone or with MMC. DNA synthesis and repair were inhibited in some cultures. No synergistic effect was observed with MMC or with cells pre-exposed to tobacco smoke. A non-significant trend toward increased aberration frequencies appeared for 16.5 GHz pulsed exposure in DNA synthesis and repair inhibited cultures. Neither exposure induced statistically significant increases in chromosomal aberration frequencies.
Sannino A et al. · 2009
Researchers exposed human dermal fibroblasts from a healthy donor and a Turner's syndrome donor to 900 MHz RF radiation for 24 hours using a GSM-like signal at 1 W/kg, and Turner's syndrome fibroblasts were also exposed for 1 hour. For RF exposure alone, DNA damage was assessed with the alkaline comet assay and the cytokinesis-block micronucleus assay. RF radiation alone caused no genotoxic or cytotoxic effects in either cell line. MX increased DNA migration in the comet assay, but RF exposure did not enhance this MX-induced DNA damage.
Belyaev IY, Markovà E, Hillert L, Malmgren LO, Persson BR. · 2009
The study investigated microwaves from UMTS and GSM mobile phones on human lymphocytes. UMTS microwaves inhibited the formation of DNA repair foci in lymphocytes from both hypersensitive and healthy individuals. The inhibition persisted for up to 72 h after exposure, longer than the stress response to heat shock. Effects of GSM microwaves depended on carrier frequency. No significant differences were found between hypersensitive and healthy groups, except for specific responses to UMTS and GSM-915 MHz microwaves.
Zhijian C et al. · 2009
Researchers used the in vitro comet assay to determine whether 1.8-GHz radiofrequency radiation can influence DNA repair in human leukocytes exposed to X-rays. Leukocytes from four young healthy donors were intermittently exposed to RFR at a SAR of 2 W/kg for 24 hours with fields on for 5 minutes and off for 10 minutes, then irradiated with X-rays at doses of 0.25, 0.5, 1.0 and 2.0 Gy. DNA damage was measured at 0, 15, 45, 90, 150 and 240 minutes after X-rays using percent tail DNA, and repair speed was assessed via DNA repair percentage. The results showed individual differences in DNA repair speeds among the four donors. Intermittent RFR exposure did not directly induce DNA damage or show synergistic effects with X-rays.
Tkalec M et al. · 2009
Researchers exposed Allium cepa seeds for two hours to 400 and 900MHz fields at strengths of 10, 23, 41 and 120Vm(-1), and also tested a four-hour exposure and modulation at 23Vm(-1). Germination rate and root length did not change significantly under any exposure condition. At 900MHz, higher field strengths (41 and 120Vm(-1)) and modulated fields significantly increased the mitotic index, while all 900MHz exposures increased the percentage of mitotic abnormalities. At 400MHz, the mitotic index increased only after modulated exposure, and higher numbers of mitotic abnormalities were found after modulated exposure and after higher field strengths (41 and 120Vm(-1)). The chromosomal aberrations were mainly lagging chromosomes, vagrants, disturbed anaphases and chromosome stickiness.
Sannino A et al. · 2009
Lymphocytes were collected at 72 hours to measure micronuclei frequency in cytokinesis-blocked binucleated cells. Four donors exhibited a significant reduction in micronuclei after RF pre-exposure, indicating an adaptive response. One donor showed no significant difference in micronuclei between pre-exposed and unexposed cells, indicating a non-responder. The data indicated heterogeneity in the induction of an adaptive response between individuals exposed to RF radiation.
Luukkonen J et al. · 2009
Researchers exposed human SH-SY5Y neuroblastoma cells to 872 MHz radiofrequency radiation at 5 W/kg for 1 hour, combined with menadione, a chemical that induces intracellular ROS production and DNA damage. Continuous-wave RF radiation increased DNA breakage compared to cells exposed only to menadione, and ROS levels were higher at 30 and 60 minutes after exposure ended. No effects of the GSM signal were seen on either ROS production or DNA damage.
Kesari KK, Behari J. · 2009
Researchers investigated the effects of 50-GHz microwave radiation on the brain of Wistar rats. The animals were exposed for 2 hours a day for 45 days continuously at a power level of 0.86 μW/cm2. Exposed rats showed DNA double-strand breaks and a significant decrease in GPx and SOD activity in brain cells, while catalase activity showed a significant increase compared with control. PKC decreased significantly in the whole brain and hippocampus of the exposed group.
Gajski G, Garaj-Vrhovac V. · 2009
Researchers investigated whether bee venom could protect against DNA damage caused by 915-MHz microwave radiation in Wistar rat lymphocytes. Whole blood lymphocytes were treated with 1 μg/mL bee venom before irradiation, and comet assays were used to assess basal and oxidative DNA damage. Bee venom showed a decrease in DNA damage compared with irradiated samples, and was found to have a radioprotective effect against both basal and oxidative DNA damage.
De Iuliis GN, Newey RJ, King BV, Aitken RJ. · 2009
Researchers exposed purified human spermatozoa in vitro to radio-frequency electromagnetic radiation tuned to 1.8 GHz across a range of specific absorption rates from 0.4 W/kg to 27.5 W/kg. As the SAR increased, sperm motility and vitality were significantly reduced, while mitochondrial reactive oxygen species generation and DNA fragmentation were significantly elevated (P<0.001). The researchers also observed highly significant relationships between SAR, the oxidative DNA damage biomarker 8-OH-dG, and DNA fragmentation after exposure.
Unknown authors · 2008
Researchers investigated the effects of 50 Hz magnetic fields on DNA damage response in murine L929 cells. Cells were exposed to magnetic fields at 100 or 300 microT combined with menadione or UVB radiation using various exposure schedules. Pre-exposure to 100 microT magnetic fields for 24 hours before menadione treatment decreased the proportion of sub G1 cells and increased the proportion of cells in G2/M phase. Exposure to 300 microT magnetic fields also decreased the proportion of cells in G1 phase. Magnetic field exposure after menadione treatment did not alter the response, and no effects were seen from magnetic fields alone or combined with UVB radiation.
Unknown authors · 2008
Exposure to 3 or 5 tesla static magnetic fields transiently induced genes involved in motor activity, actin binding, cell adhesion, and cuticles in C. elegans. Transient induction of hsp12 family genes was observed after SMF exposure, while the small-heat shock protein gene hsp16 was induced to a much lesser extent. Unlike ionizing radiation, high static magnetic fields did not induce DNA double-strand breaks or germline cell apoptosis during meiosis, and did not upregulate genes encoding apoptotic cell-death activators and secreted surface proteins. Real-time quantitative RT-PCR analyses for 12 of these genes confirmed expression differences between worms exposed to SMFs and IR.
Unknown authors · 2008
Researchers exposed cultured human lens epithelial cells to 0.4 mT 50 Hz magnetic fields for 2, 6, 12, 24, and 48 hours. After exposure, cells were fixed with 4% paraformaldehyde and stained for gamma H2AX immunofluorescence, and foci were counted in at least 200 cells per sample. Cells with more than three foci per cell were classified as positive, and mean foci per cell and percentage of positive cells were used as indexes of DNA double-strand breaks. Exposure for 24 hours significantly increased mean foci per cell to 2.93 and positive cells to 27.88% compared with sham (1.77 and 19.38%, P<0.05), and exposure for 48 hours increased them to 3.14 and 31.00% (P<0.01), while 2, 6, and 12 hour exposures showed no significant difference (P>0.05).
Unknown authors · 2008
Researchers applied continuous-wave 0.1 THz radiation at 0.031 mW/ cm(2) to dividing lymphocytes for 1, 2, and 24 hours and measured chromosome number changes and centromere replication timing using FISH. Chromosomes 11 and 17 showed about a 30% increase in aneuploidy after 2 and 24 hours, while chromosomes 1 and 10 were unaffected. The asynchronous replication mode of centromeres 11, 17, and 1 changed by 40% after 2 hours, and all four centromeres changed by 50% after 24 hours.
Vijayalaxmi , Prihoda TJ · 2008
Unknown authors · 2008
The stimulation of protein and DNA by EMF is problematic because the fields do not appear to have sufficient energy to directly affect such large molecules. Studies with electric and magnetic fields in the extremely low-frequency range have shown that weak fields can cause charge movement. Redistribution of charges in large molecules can trigger conformational changes driven by large hydration energies, and such changes play a key role in membrane transport proteins and probably account for DNA stimulation to initiate protein synthesis.
Unknown authors · 2008
Researchers tested whether alternating magnetic fields could induce DNA and chromosomal damage in primary human fibroblasts using comet and gammaH2AX assays. Cells were exposed to switching fields of 5 minutes on and 10 minutes off for 15 hours at intensities from 50 to 1000 microtesla using two different exposure systems. No DNA damage or chromosomal damage was detected with either exposure system. The study could not confirm previous reports of significant genotoxic effects from similar magnetic field parameters.
Unknown authors · 2008
Researchers investigated DNA sensitivity in peripheral blood leukocytes of radar-facility workers daily exposed to microwave radiation and unexposed controls. The study used alkaline comet assay and chromatid breakage assay to evaluate DNA damage and sensitivity. Exposed workers showed increased DNA damage by comet assay and almost three times more bleomycin-induced chromatid breaks than controls. The difference in break per cell values between smokers and non-smokers was statistically significant in the exposed group. Regression analyses revealed a significant positive correlation between the two assay results, with the best correlation between tail moment and number of chromatid breaks.
Unknown authors · 2008
Researchers exposed human lens epithelial cells intermittently for 24 hours to radiofrequency fields at specific absorption rates of 1, 2, 3, and 4 W/kg. DNA damage measured by alkaline comet assay increased significantly at 3 and 4 W/kg, while double-strand breaks increased only at 4 W/kg. Intracellular reactive oxygen species levels rose significantly at 3 and 4 W/kg, and cells exposed to 4 W/kg showed G0/G1 cell cycle arrest. Apoptosis did not differ between exposed and sham groups, and all observed effects were blocked when the radiofrequency field was superposed with 2 muT electromagnetic noise.
