Fesenko EE et al. · 1999
Researchers investigated how weak electromagnetic waves in the centimeter range affected the cytotoxic activity of natural killer cells in mice. Irradiation at 8.15 to 18 GHz at 1 microwatt per square centimeter increased the cytotoxic activity of natural killer cells of rat spleen. In mice exposed for 24 to 72 hours, natural killer cell activity increased by 130 to 150%, and this elevated activity persisted for 24 hours after exposure ended. Microwave irradiation of animals in vivo for 3.5 and 5 hours, and a short exposure of splenic cells in vitro, did not affect natural killer cell activity.
Gandhi OP, Lazzi G, Tinniswood A, Yu QS, · 1999
Researchers compared numerical and experimental methods for determining SAR and radiation patterns of handheld wireless telephones at 835 and 1900 MHz. Peak 1-g SARs ranged from 0.13 to 5.41 W/kg, yet agreement between calculated and measured data was generally within plus or minus 20%. The study noted that for a maximum radiated power of 600 mW at 800/900 MHz, peak 1-g SARs can be higher than 1.6 W/kg unless antennas are carefully designed and placed further away from the head.
Galat VV et al. · 1999
Researchers investigated the effects of nonthermal millimeter-range electromagnetic radiation on early development of mouse and sea urchin embryos. An MRTA-01E-03 generator with a frequency of 54-78 GHz and radiation intensity of 0.06 mWt/cm2 was used, and embryos were irradiated for 30 minutes at the two-blastomere stage. More mouse embryos reached the blastocyst stage (97.3%) compared with controls (87.5%), and the total cultivation time to reach that stage was shorter (72 h) than in controls (96 h). For sea urchin embryos, the radiation had an effect only when embryos with weakened viability were tested.
Fink JM, Wagner JP, Congleton JJ, Rock JC · 1999
This study evaluated police officers' exposures to microwaves emitted by traffic radar units, with measurements taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Fifty-four radar units covering 17 different models, 4 frequency bands, and 3 antenna configurations were provided by four speed-enforcement agencies and one transportation research institute. The researchers concluded that police officer exposure to microwave radiation is apparently minimal.
Fesenko, EE, Makar, VR, Novoselova, EG, Sadovnikov, VB, · 1999
Researchers exposed male NMRI mice to whole body microwave irradiation at 8.15-18 GHz and a power density of 1 microW/cm2 and measured tumor necrosis factor (TNF) production in immune cells. Shorter exposures ranging from 5 hours to 3 days significantly enhanced TNF production in peritoneal macrophages and splenic T lymphocytes. Chronic irradiation for 7 days decreased TNF production in peritoneal macrophages. Microwave treatment increased endogenously produced TNF more effectively than lipopolysaccharide, described as one of the most potent stimuli of this cytokine.
Dasdag et al. · 1999
Borbely et al. · 1999
Researchers exposed healthy young subjects during an entire night-time sleep episode to a 900 MHz electromagnetic field at a maximum specific absorption rate of 1 W/kg. The exposure schedule consisted of alternating 15-min on-15-min off intervals. Compared with a control night with sham exposure, the amount of waking after sleep onset was reduced from 18 to 12 min, and EEG spectral power in non-rapid eye movement sleep was increased. The researchers concluded that pulsed high-frequency EMF in the range of radiotelephones may promote sleep and modify the sleep EEG.
Adair ER, Cobb BL, Mylacraine KS, Kelleher SA, · 1999
Researchers measured thermoregulatory responses in two groups of seven adult volunteers exposed for 45 minutes to whole-body radio-frequency fields at either 450 or 2450 MHz. At each frequency, two power densities were tested at each of three ambient temperatures (24, 28, and 31 degrees C), along with no-RF control conditions. No change in metabolic heat production occurred under any exposure conditions at either frequency. At both frequencies, normalized peak SARs in excess of ANSI/IEEE C95.1 guidelines were easily counteracted by normal thermophysiological mechanisms.
Khadir R, Morgan JL, Murray JJ. · 1999
Researchers investigated the effects of a sinusoidal 60 Hz magnetic field on free radical production, degranulation, and viability in human neutrophils. Exposure of unstimulated human neutrophils to the magnetic field did not affect the functions examined. When cells were also stimulated with PMA, exposure to a 22 mT, 60 Hz magnetic field induced significant increases in superoxide anion production of 26.5% and in β-glucuronidase release of 53%. Release of lysozyme and lactate dehydrogenase was unchanged by the magnetic field, whether the cells were stimulated or not.
Unknown authors · 1998
Researchers exposed HL60 cells to 6-microT 60 Hz magnetic fields and measured MYC expression. The assay methods and exposure conditions were as close as practical to those of the investigators that originally reported a positive effect. A chemical agent demonstrated the cells responded to a known stimulus and the system had low basal variability to detect effects of the previously reported magnitude. Using cells from a commercial source and from the original investigators, no evidence was found that EMF exposure induces MYC expression.
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
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.
Unknown authors · 1998
Unknown authors · 1998
Researchers exposed DT40 lymphoma B cells to low energy electromagnetic fields and measured inositol phospholipid turnover. PLC-gamma2-deficient cells and cells with SH2 domain mutant PLC-gamma2 did not show increased IP3 levels after EMF exposure. SYK-deficient cells lacked PLC-gamma2 activation, and the C-terminal SH2 domain of SYK was essential. LYN-deficient cells did not show enhanced inositol phospholipid turnover, but introduction of wild-type fyn restored responsiveness. The results indicate EMF-induced PLC-gamma2 activation is mediated by LYN-regulated stimulation of SYK downstream of LYN and upstream of PLC-gamma2.
Unknown authors · 1998
Researchers exposed DT40 lymphoma B-cells to low energy electromagnetic fields and observed activation of PLC-γ2 and increased inositol phospholipid turnover. PLC-γ2 activation was mediated by stimulation of Bruton's tyrosine kinase (BTK), which acts downstream of LYN kinase and upstream of PLC-γ2. BTK-deficient B-cells did not show enhanced PLC-γ2 activation in response to EMF, but introducing the wild-type human btk gene restored EMF responsiveness. The authors conclude that BTK exerts a pivotal and mandatory function in initiation of EMF-induced signaling cascades in B-cells.
Unknown authors · 1998
Researchers used BTK-deficient DT40 B cells reconstituted with the human btk gene to test whether a 1-gauss 60-Hz electromagnetic field alters inositol 1,4,5-trisphosphate production. Blinded exposures with anti-IgM treatment as a positive control showed no significant effect of the field on inositol 1,4,5-trisphosphate production. The researchers also evaluated BTK activation in wild-type DT40 cells and found that while pervanadate activated BTK in a dose- and time-dependent manner, detection of BTK activation depended on the kinase buffer. Using cells from the original investigators, no evidence supported the hypothesis that the magnetic field had a causal effect on protein-tyrosine kinase activities affecting inositol 1,4,5-trisphosphate production.
Unknown authors · 1998
Researchers conducted two population-based case-control studies on childhood leukemia in northwestern Germany and Berlin from 1992 to 1996. They obtained 24-hour measurements for 176 cases and 414 controls. Multivariate regression analysis comparing exposures of 0.2 microT or more to lower exposures yielded an odds ratio of 2.3 with a 95% confidence interval of 0.8 to 6.7.
Unknown authors · 1998
Researchers investigated the effect of a single electric charge on the deposition efficiency of ultrafine particles in human airways. They measured and compared deposition of singly charged, charge-neutralized, and zero-charge 20-nm and 125-nm particles in hollow-cast models of human airways. Singly charged 20-nm particles deposited 3.4 times more than charge-neutralized aerosols and 5.3 times more than zero-charged particles, while 125-nm particles showed ratios of 2.3 and 6.2 respectively. The authors concluded that because most ambient particles are charged, this effect must be considered when models predict dose from inhaled ultrafine particles.
Unknown authors · 1998
Unknown authors · 1998
Researchers examined the separate and combined effects of 60 Hz magnetic fields and a phorbol ester on PKC activity in HL60 cells. Exposure to a 1.1 mT magnetic field alone or combined with 2 microM PMA for 1 h did not enhance PKC activity. In a second experiment, cells preexposed to 50 nM PMA for 45 min then exposed to both PMA and magnetic field for 15 min showed a greater decrease in cytosolic PKC activity and a larger increase in membrane activity than PMA treatment alone or PMA with sham exposure. The authors concluded that magnetic fields may act synergistically on an already activated pathway.
Unknown authors · 1998
Public concern about EMF and cancer stems from epidemiological studies that appear to show an association between cancer and residence near power lines. The epidemiological evidence falls far short of establishing a causal relationship, and biophysics suggests biological effects are implausible at environmental field strengths. Approximately 100 published reports looked for evidence that power-frequency fields have genotoxic or epigenetic activity. These studies found no replicated evidence that power-frequency fields have the potential to cause or contribute to cancer.
Unknown authors · 1998
Rats were trained in six sessions to locate a submerged platform in a water maze and exposed to a 1 mT, 60 Hz magnetic field for one hour before each session. There was no significant difference in learning to locate the platform between exposed and control rats. Exposed rats had significantly slower swim speed and spent less time in the target quadrant during a probe trial, with different swim patterns.
Unknown authors · 1998
Researchers exposed primary rat tracheal epithelial cells and two immortalized cell lines to a 50-Hz magnetic field at 100 microT[rms] combined with a 55 microT geomagnetic-like field and to gamma rays from cobalt-60. Both exposures produced similar patterns and amplitudes of c-jun and c-fos protein induction. Combining magnetic field and radiation exposure did not produce a synergistic effect on protein expression.
Unknown authors · 1998
Researchers studied the effects of 60-Hz magnetic field and ambient light exposures on the pineal hormone melatonin among electric utility workers. Personal exposure was measured at 15-second intervals over 3 consecutive 24-hour periods. Magnetic field intensity, intermittence, or cumulative exposure had little influence on nocturnal 6-OHMS excretion. Residential RCMS magnetic field exposures were associated with lower nocturnal 6-OHMS/cr concentrations. The greatest reductions occurred when RCMS exposures both at work and at home were combined.
