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.
Vijayalaxmi et al. · 1997
C3H/HeJ mice prone to mammary tumors were exposed to 2450 MHz RF radiation at 1.0 W/kg for 20 hours per day, 7 days a week, over 18 months, with sham-exposed controls and positive controls treated with mitomycin C. The incidence of micronuclei in peripheral blood and bone marrow did not differ significantly between RF-exposed and sham-exposed groups. Positive controls treated with mitomycin C showed significantly elevated micronuclei frequencies. A separate analysis of mice that developed mammary tumors also found no significant differences in micronuclei frequency between exposure groups.
Gos, P, Eicher, B, Kohli, J, Heyer, WD · 1997
Researchers exposed exponentially growing Saccharomyces cerevisiae cells to electromagnetic fields from 41.682 GHz to 41.710 GHz in 2 MHz increments at power densities of 0.5 and 50 microW/cm2. Cell division was assessed by time-lapse photography using two identical chambers that allowed concurrent control and exposure experiments. Control experiments showed the cells were dividing at submaximal rates, ensuring that any increase or decrease in division rate could be observed. No consistently significant differences were found between exposed and unexposed cells across multiple independent experiment series.
Cleary, SF, Cao, G, Liu, LM, Egle, PM, Shelton, KR · 1997
Researchers investigated stress protein induction in HeLa and CHO cells following a 2-hour exposure to radiofrequency or microwave radiation. Cells were exposed under isothermal conditions maintained at 37 ± 0.2 °C. Neither microwave nor RF radiation had a detectable effect on stress protein induction.
Donnellan M, McKenzie DR, French PW · 1997
Researchers exposed a mast cell line, RBL-2H3, to 835 MHz radiation for 20 minutes, three times per day for 7 days at a power density of 8.1 +/- 3 mW/cm2. From day 4 onward, DNA synthesis and cell replication increased, cell morphology changed, and beta-hexosaminidase release was significantly enhanced compared to unexposed cultures. No effects were seen on cytoskeletal protein synthesis or beta-actin mRNA levels. Morphological changes persisted following subculture for at least 7 days in the absence of further exposure.
Donnellan M, McKenzie DR, French PW. · 1997
Researchers exposed immune cells called mast cells to cell phone radiation at 835 MHz for 20 minutes, three times daily for a week. They found that starting on day four, the cells began growing faster, changed shape, and became more reactive to chemical triggers. What's particularly concerning is that these changes persisted for at least a week after the radiation exposure ended, suggesting the effects may be long-lasting.
Jensh RP · 1997
This review examined whether chronic prenatal microwave exposure in rats caused adverse effects at birth or alterations in offspring development and growth. Pregnant rats were exposed throughout pregnancy to continuous wave 915 MHz, 2450 MHz, or 6000 MHz radiation at power density levels of 10, 20, or 35 mW/cm2, respectively. Animals exposed to 915 MHz did not exhibit any consistent significant alterations in any of the parameters measured. Offspring exposed to 6000 MHz showed an initial slight but significant retardation in term weight, delayed eye opening, lower weekly weights that recovered by the fifth week, and changes in water T-maze and open field performance.
Vijayalaxmi, Mohan, N, Meltz, ML, Wittler, MA, · 1997
Vollrath L, Spessert R, Kratzsch T, Keiner M, Hollmann H · 1997
Researchers exposed male and female Sprague-Dawley rats and Djungarian hamsters to 900 MHz electromagnetic fields at 0.1 to 0.6 mW/cm2, continuous or pulsed at 217 Hz, for 15 min to 6 h. At day or night had no notable short-term effect on pineal melatonin synthesis in male and female Sprague-Dawley rats and Djungarian hamsters. Pineal synaptic ribbon profile numbers (studied in rats only) were likewise not affected The 900 MHz electromagnetic fields, unpulsed or pulsed at 217 Hz, as applied in the present study, have no short-term effect on the mammalian pineal gland.
Vijayalaxmi, Mohan N, Meltz ML, Wittler MA · 1997
Researchers exposed human blood cells to 2450 MHz radiofrequency radiation (microwave oven frequency) for 90 minutes and found no genetic damage or changes in cell division. The study tested both continuous and intermittent exposure patterns at power levels similar to some industrial microwave applications.
Vorobyov VV, Galchenko AA, Kukushkin NI, Akoev IG · 1997
Researchers studied averaged EEG frequency spectra in eight unanesthetized adult male rats with chronically implanted electrodes in symmetrical somesthetic areas during intermittent exposure to a weak 945 MHz microwave field amplitude-modulated at 4 Hz. Hemispheric asymmetry showed power decreases in the 1.5-3 Hz range on the left and in the 10-14 and 20-30 Hz ranges on the right hemisphere. No differences between control and exposure were found in averaged spectra over 10 or 1 minute periods. However, significant elevations of EEG asymmetry in the 10-14 Hz range occurred during the first 20 seconds after most microwave field onsets when spectra were averaged every 10 seconds.
Salford LG, Brun A, Persson BRR · 1997
Researchers used Fischer 344 rats of both sexes with implanted glioma cells (RG2 and N32) in a matched-pair design. Starting on day 5 after inoculation, rats were exposed for 7 hours a day, 5 days a week for 2–3 weeks to 915 MHz continuous or pulse-modulated microwaves. The study found no significant difference in tumour size between exposed and control animals. Tumour size was estimated as the volume of an ellipsoid after histopathological examination of all brains.
Nakamura H, Seto T, Nagase H, Yoshida M, Dan S, Ogino K. · 1997
Pregnant rats exposed to microwaves showed a significant reduction in splenic natural killer cell activity, while no such reduction was seen in exposed virgin rats. Corticosterone and ACTH increased, and oestradiol decreased, in both exposed virgin and pregnant rats, while beta-endorphin and progesterone increased significantly only in pregnant rats.
Cain CD, Thomas DL, Adey WR · 1997
The study tested whether a TDMA-modulated RF field and the tumor promoter TPA together increase focus formation of transformed cells cocultured with parental C3H/10T1/2 murine fibroblasts. Cell cultures were exposed to an 836.55 MHz TDMA-modulated field at specific absorption rates of 0.15, 1.5, and 15 μW/g in a repeating cycle of 20 minutes on and 20 minutes off continuously for 28 days. RF exposure did not significantly alter TPA-induced focus formation at any of the tested exposure levels across multiple independent experiments.
Lai H, Carino MA, Singh NP · 1997
Researchers exposed rats to 2450 MHz pulsed radiofrequency radiation at a power density of 2 mW/cm2 for 2 hours and then measured DNA double strand breaks in brain cells. The RFR exposure significantly increased DNA double strand breaks in rat brain cells, and the effect was partially blocked by naltrexone treatment. The researchers concluded that endogenous opioids play a mediating role in RFR-induced DNA strand breaks in brain cells of the rat.
Lai, H, Carino, MA, Singh, NP, · 1997
Researchers exposed rats to 2.45 GHz microwave radiation (the same frequency used in WiFi and microwave ovens) for 2 hours and found it caused DNA double strand breaks in brain cells. When they gave the rats naltrexone, a drug that blocks the body's natural opioids, it partially prevented this DNA damage. This suggests the body's own opioid system plays a role in how microwave radiation damages DNA in brain cells.
