Adey WR et al. · 1999
Researchers tested an 836.55 MHz NADC-modulated field in a 2-year bioassay with fetal exposure in Fischer 344 rats. Of 236 original rats, 182 (77%) survived to termination at age 709-712 days. There was no evidence of tumorigenic effects in the CNS from TDMA field exposure. Exposed animals showed trends toward reduced incidence of spontaneous CNS tumors (P < 0.16) and ENU-induced CNS tumors (P < 0.16). In preterm rats where neural tumors caused death, fields decreased ENU-induced tumor incidence (P < 0.03).
Schonborn F, Burkhardt M, Kuster N · 1998
In order to investigate the differences in absorption between adults and children due to their differing anatomies, simulations were performed using head phantoms based on MRI scans of an adult and two children aged 3 and 7 years. Ten different tissue types were distinguished and all simulations were performed using a commercial code based on the finite integration technique. The differences in absorption were investigated for the frequencies of 900 MHz and 1,800 MHz using 0.45 lambda dipoles instead of actual mobile phones. The results revealed no significant differences in the absorption of electromagnetic radiation in the near field of sources between adults and children.
Wagner, P, Roschke, J, Mann, K, Hiller, W, Frank, C · 1998
Researchers recorded all-night polysomnographies of 24 healthy male subjects with and without exposure to a circularly polarized 900 MHz pulsed electromagnetic field at 0.2 W/m². Suppression of REM sleep and a sleep-inducing effect under field exposure did not reach statistical significance, so previous results indicating alterations of these sleep parameters could not be replicated. Spectral power analysis also did not reveal any alterations of the EEG rhythms during EMF exposure.
Malyapa RS et al. · 1998
Researchers exposed rats to 2450 MHz microwave radiation (the same frequency used in microwave ovens and some WiFi devices) for 2 hours to see if it would damage DNA in brain cells, as a previous study had suggested. They found no DNA damage in either the brain's cortex or hippocampus regions, contradicting the earlier research. This study suggests that short-term exposure to this type of radiation at moderate levels may not cause immediate genetic damage to brain cells.
Imaida K et al. · 1998
Researchers exposed male F344 rats to a 929.2 MHz electromagnetic near-field for 90 minutes a day, five days a week, over six weeks. The exposed rats showed no significant difference in GST-P positive foci numbers or areas compared to sham-exposed rats. Maximum local specific absorption rates were 7.2 to 6.6 W/kg in the whole body and 2.0 to 1.7 W/kg in the liver.
Imaida et al. · 1998
Researchers exposed male F344 rats to a 1.439 GHz TDMA electromagnetic near-field for 90 minutes a day, 5 days a week, over 6 weeks. The rats were initiated with diethylnitrosamine and underwent partial hepatectomy at week 3. Peak liver SARs ranged from 1.91 to 0.937 W/kg and whole-body average SARs from 0.680 to 0.453 W/kg at 0.33 W antenna power. Exposure did not significantly alter the numbers or areas of GST-P-positive foci in the liver compared to sham-exposed rats. Serum levels of corticosterone, ACTH, and melatonin were increased in exposed rats.
Frei et al. · 1998
Researchers exposed 100 C3H/HeJ mice to continuous-wave 2450 MHz RF radiation at 1.0 W/kg for 78 weeks, 20 hours per day, 7 days per week, while 100 mice were sham-exposed. There was no significant difference in mammary tumor incidence between exposed mice (38%) and sham-exposed mice (30%). Latency to tumor onset was similar: 62.5 weeks for exposed mice and 62.0 weeks for sham-exposed mice. Histopathological evaluation found no significant difference in malignant, metastatic, or benign neoplasms between groups.
Walters TJ et al. · 1998
Researchers measured hypothalamic, cortical, tympanic, and rectal temperatures in rats exposed to 2.06 GHz microwave radiation at two power densities. The high-power density was 1700 mW/cm² with specific absorption rates of 1224 W/kg in hypothalamus and 493 W/kg in cortex, while the low-power density was 170 mW/cm² with SARs of 122.4 W/kg and 49.3 W/kg. During high-power exposure, the hypothalamic temperature rose significantly faster than cortical or rectal temperatures, whereas low-power exposure produced more uniform heating. For comparison, warm-water immersion produced uniform heating, while warm ambient exposure and exercise maintained the pre-existing temperature gradient between hypothalamus and cortex.
Novoselova ET, Fesenko EE. · 1998
Researchers studied whether weak electromagnetic waves in the centimeter range could affect tumor necrosis factor production in macrophages from mice. Whole-body microwave irradiation of male NMRI mice, exposure of macrophages in vitro, and irradiation of culture medium with 8.15-18 GHz at a power density of 1 microW/cm2 each caused a significant enhancement of tumor necrosis factor production in peritoneal macrophages.
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.
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.
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.
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.
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.
