Pakhomova ON, Belt ML, Mathur SP, Lee JC, Akyel Y · 1998
Researchers exposed yeast cells to UV radiation followed by ultra-wide band electromagnetic pulses. The UWB pulses had intensities of 101-104 kV/m, 1.0 ns width, 165 ps rise time, and repetition rates of 0 Hz (sham), 16 Hz, or 600 Hz. The effect was evaluated by colony-forming ability on complete and selective media and the number of aberrant colonies. The experiments found no effect of UWB exposure on UV-induced reciprocal and non-reciprocal recombination, mutagenesis, or cell survival.
Unknown authors · 1998
Researchers exposed cultured human osteosarcoma Saos-LP-12 cells to a 400 mT, 50 Hz extremely low frequency magnetic field. The exposure induced mutations in the HPRT gene. The Saos-LP-12 cells have a deletion in the p53 coding region. Introducing a wild-type p53 expression plasmid into these cells suppressed the ELFMF-induced mutations. No marked difference in the mutation spectrum was observed among ELFMF exposure with or without p53 and sham exposures.
Unknown authors · 1998
Researchers screened 1,920 randomly selected cDNAs in HL60 cells exposed to 60 Hz magnetic fields (2 mT) or X rays (5 Gy) compared to unexposed cells. Eighteen cDNAs were differentially expressed in X-irradiated cells, and 15 matched known genes related to cell growth, protein synthesis, energy metabolism, oxidative stress, or apoptosis. BIGEL analysis revealed no differences greater than 1.5-fold in expression levels in magnetic-field-exposed cells compared to sham-exposed cells.
Nakamura et al. · 1998
Researchers exposed pregnant rats to microwaves at 2 mW/cm2, 2450 MHz for 90 minutes and measured natural killer cell activity and beta-endorphin levels. Microwave exposure raised colonic temperature and increased beta-endorphin in blood and anterior pituitary but did not change corticosterone. Naloxone administered before exposure increased natural killer cell activity and beta-endorphin in blood and placenta of pregnant rats.
Phillips et al. · 1998
Researchers exposed Molt-4 T-lymphoblastoid cells in vitro to pulsed radiofrequency signals at cellular telephone frequencies of 813.5625 MHz (iDEN® signal) and 836.55 MHz (TDMA signal) to detect DNA damage. The alkaline comet assay was used to measure DNA single-strand breaks in exposed cell cultures compared to sham-exposed cultures. At an SAR of 24 μW g−1, exposure to the iDEN® signal for 2 h and 21 h significantly increased DNA damage, while at 2.4 μW g−1 the same signal significantly decreased DNA damage. The researchers concluded that the data indicate a need to study the effects of exposure to RF signals on direct DNA damage and on the rate at which DNA damage is repaired.
Kavaliers M, Choleris E, Prato FS, Ossenkopp K · 1998
Researchers studied how nitric oxide (NO) and nitric oxide synthase (NOS) influence opioid-induced antinociception in the land snail Cepaea nemoralis, and whether these chemicals play a role in the effects of extremely low frequency (ELF) magnetic field exposure. Pain relief was measured by how long snails took to withdraw their foot from a thermal stimulus of 40°C. Exposure to a 60-Hz magnetic field at 141 μT peak for 15 minutes reduced the enkephalinase-induced antinociception in the snails. The inhibitory effects of the magnetic field were significantly reduced by a nitric oxide synthase inhibitor and significantly enhanced by a nitric oxide releasing agent.
Phillips et al. · 1998
Researchers exposed immune system cells to radiofrequency radiation from cell phone signals at extremely low power levels for 2 to 21 hours. They found that very low exposures actually reduced DNA damage, while slightly higher exposures increased DNA breaks in the cellular genetic material. This suggests that even minimal RF radiation can alter DNA integrity in immune cells, though the effects varied depending on the specific exposure level.
Behari J, Kunjilwar KK, and Pyne S · 1998
Researchers studied the effect of low-level amplitude-modulated radiofrequency radiation on Na+–K+-ATPase activity in the brains of developing male Wistar rats aged 23 days. Rats were exposed to carrier wave frequencies of 147 MHz and its sub-harmonic frequencies 73.5 and 36.75 MHz, amplitude modulated at 16 and 76 Hz, for 30–35 days at 3 hours per day. Na+–K+-ATPase activity increased by around 19–20% in rats exposed with amplitude modulation at 16 Hz, and by around 15–16% in rats exposed with amplitude modulation at 76 Hz, compared to controls. The researchers concluded that the effect on Na+–K+-ATPase activity was insensitive to the carrier wave frequencies under investigation.
Braune, S, Wrocklage, C, Raczek, J, Gailus, T, Lucking, CH · 1998
The study enrolled seven healthy men and three women volunteers aged 26 to 36 years in a single-blind placebo-controlled design. Participants were exposed to a GSM 900 MHz signal at 2 Watt with a 217 Hz frame repetition rate for 35 min per session. Blood pressure and heart rate were recorded continuously with a Finapres device, while capillary perfusion was measured with an infrared plethysmograph on the right hand.
Kwee S, Raskmark P · 1998
Researchers exposed transformed human epithelial amnion cells to 960 MHz microwave fields at three power levels and three exposure times using a TEM cell. Cell growth was reduced in exposed cells compared to control and sham-exposed cells. The proliferation response varied with SAR level and exposure duration, showing a linear correlation between power level and growth change. At lower power levels, a longer exposure time was needed to reach the maximum effect, and repeated exposures did not alter the outcome.
Malyapa RS et al. · 1998
Researchers exposed male Sprague-Dawley rats to 2450 MHz continuous-wave microwaves for two hours at 1.2 W/kg specific absorption rate. No significant differences in DNA damage were found between sham-exposed and irradiated rats in either the cerebral cortex or hippocampus, regardless of euthanasia method. Rats euthanized by CO2 asphyxia showed more intrinsic DNA damage and greater experiment-to-experiment variation than those euthanized by guillotine. The authors concluded that guillotine euthanasia is the most appropriate method for DNA damage studies. The study did not confirm previous reports of DNA damage from 2450 MHz microwave exposure.
Mann et al. · 1998
Researchers exposed healthy humans to a 900 MHz pulsed electromagnetic field (217 Hz, 0.02 mW/cm²) and measured nocturnal hormone profiles of growth hormone, cortisol, luteinizing hormone, and melatonin under polysomnographic control. Cortisol showed a slight, transient elevation that persisted for one hour after exposure onset. No significant changes were found for growth hormone, luteinizing hormone, or melatonin, and sleep EEG showed no significant alterations, though there was a trend toward REM suppression.
Repacholi et al. · 1997
Researchers exposed female E mu-Pim1 transgenic mice to pulsed 900 MHz fields for two 30-minute periods per day for up to 18 months. Lymphoma risk was significantly higher in exposed mice than in controls (OR = 2.4, P = 0.006). Follicular lymphomas were the major contributor to the increased tumor incidence.
Lai, H, Singh, NP, · 1997
Researchers investigated the effects of microwave exposure on DNA strand breaks in rat brain cells. They found that treating rats with either melatonin or the spin-trap compound PBN immediately before and after radiofrequency electromagnetic radiation exposure blocked the DNA strand breaks. Because both substances are free radical scavengers, the researchers hypothesized that free radicals are involved in the radiofrequency electromagnetic radiation-induced DNA damage.
Unknown authors · 1997
Rats were exposed for 2 h to a 60 Hz magnetic field at flux densities of 0.1, 0.25, and 0.5 mT. DNA strand breaks in brain cells were assayed by microgel electrophoresis 4 h postexposure. Single-strand DNA breaks increased after exposure to 0.1, 0.25, and 0.5 mT, while double-strand DNA breaks increased at 0.25 and 0.5 mT.
Unknown authors · 1997
Unknown authors · 1997
They note that EMF energies are far below those typical of biomolecules, induced electric forces are considerably smaller than biological forces, and magnetic-moment sensory cells have not been found in humans. Resonant interaction mechanisms conflict with accepted physics and many experimental tests have not found the predicted effects. The review states that biological effects at residential levels [< or = 2 microT (< or = 20 mG)] are implausible, while effects at higher fields [> 10 microT (> 100 mG)] might reach plausibility but lack demonstrated transduction structures.
Penafiel LM, Litovitz T, Krause D, Desta A, Mullins JM · 1997
Persson BRR, Salford LG, Brun A · 1997
Researchers studied blood-brain barrier permeability in Fischer 344 rats of both sexes exposed to radio frequency electromagnetic fields. The exposure used 915 MHz microwaves delivered as either pulse-modulated or continuous wave signals. The rate of pathological leakage rose from 0.17 in controls to 0.39 across all exposed rats, a highly significant difference. Continuous wave exposure produced a higher rate of pathological rats (0.50 ± 0.07) than pulse-modulated exposure (0.35 ± 0.03), and that difference was also statistically significant.
Lai H, Singh NP · 1997
Researchers investigated whether melatonin and the spin-trap compound N-tert-butyl-alpha-phenylnitrone (PBN) could block the effect of magnetic fields on brain cell DNA. Rats were injected with melatonin or PBN immediately before and after two hours of exposure to a 60-Hz magnetic field at an intensity of 0.5 mT. Both drug treatments blocked the magnetic field-induced DNA single- and double-strand breaks in brain cells, as measured by a microgel electrophoresis method.
Malyapa RS et al. · 1997
Researchers exposed mouse and human cells to cell phone frequencies (835-847 MHz) for up to 24 hours at power levels similar to phone use to see if the radiation damaged DNA. Using a sensitive test called the comet assay, they found no DNA damage in the exposed cells compared to unexposed control cells. This suggests that cell phone radiation at typical exposure levels may not directly break DNA strands in laboratory conditions.
Roschke, J, Mann, K · 1997
Researchers tested 34 healthy men in a single-blind cross-over study with a 900 MHz GSM field at 0.05 mW/cm² for nearly 3.5 minutes. They measured spontaneous EEG from C3 and C4 under closed eyes and found no difference in spectral power density between active and inactive phone conditions.
Malyapa RS et al. · 1997
Researchers used the alkaline comet assay to test whether 2450 MHz radiation causes DNA damage in cultured mammalian cells. Exponentially growing U87MG and C3H 10T1/2 cells were exposed to 2450 MHz CW radiation at SARs of 0.7 and 1.9 W/kg for durations of 2 h, 2 h followed by 4-h incubation, 4 h, and 24 h. No significant differences were observed between the test group and the controls after exposure.
Ivaschuk OI et al. · 1997
Researchers exposed nerve growth factor-treated PC12 rat pheochromocytoma cells to a packet-modulated 836.55 MHz radiofrequency field at power densities of 0.09, 0.9, and 9 mW/cm2 for 20, 40, or 60 minutes, with an intermittent 20-minute on/off regimen. Sham-exposed cells served as controls, and c-fos and c-jun expression was measured by Northern blot analysis of total RNA. C-fos transcript levels did not change after 20 minutes at any intensity, while c-jun transcripts decreased by 38% only after 20 minutes at 9 mW/cm2.
Stagg RB, Thomas WJ, Jones RA, Adey WR · 1997
Researchers exposed transformed and normal rat glial cells to an 836.55 MHz packet-modulated RF field at power densities of 0.09, 0.9, and 9 mW/cm2, with SARs from 0.15 to 59 muW/g. Primary rat glial cells showed no significant differences in DNA synthesis between sham and RF-exposed conditions for either log-phase or serum-starved cultures. C6 glioma cells exposed at 5.9 muW/g SAR showed small but significant increases in thymidine incorporation in 38% of experiments. Growth curves showed no differences between sham and RF-exposed cultures for either cell type, and doubling times of C6 glioma cells did not differ significantly.
