Unknown authors · 2000
Researchers measured personal magnetic field exposure, ambient light, and excretion of the melatonin metabolite 6-hydroxymelatonin sulfate over three consecutive workdays in electric utility workers. Men working more than two hours daily in substation and three-phase environments showed a magnetic field-dependent reduction in adjusted mean nocturnal and post-work metabolite levels, while those working two hours or less showed no effect. No changes were observed in men working in single-phase environments.
Unknown authors · 2000
Researchers measured melatonin levels in electric utility workers exposed to 60-Hz magnetic fields from substations and 3-phase power lines. Workers with more than 2 hours daily exposure showed significantly reduced melatonin production, while those with shorter exposures showed no effect. This suggests that power frequency magnetic fields can disrupt the body's natural sleep hormone production.
Unknown authors · 2000
Researchers cultured mouse pre-antral follicles for 5 days and exposed them to pulsed ELF-EMF at 33 Hz or 50 Hz. ELF-EMF did not affect follicular growth over 3 days, but on day 5 the 33 Hz exposure significantly reduced growth compared to controls, while 50 Hz did not. ELF-EMF severely impaired antrum formation at both frequencies, with control follicles forming antral cavities at 79% versus 30% at 33 Hz and 51.6% at 50 Hz. Oocytes from exposed follicles showed a reduced ability to resume meiotic maturation compared to controls.
Unknown authors · 2000
Italian researchers exposed developing mouse egg follicles to extremely low frequency electromagnetic fields at 33 Hz and 50 Hz for 5 days. The EMF exposure severely disrupted normal follicle development, with only 30-52% of exposed follicles forming essential antral cavities compared to 79% of unexposed follicles. This impairment could reduce female fertility by preventing eggs from reaching the developmental stage needed for successful reproduction.
Vijayalaxmi, Leal BZ, Szilagyi M, Prihoda TJ, Meltz ML, · 2000
Researchers exposed human blood cells to 2450 MHz radiofrequency radiation (the same frequency used in microwave ovens and some WiFi) for 2 hours to see if it would damage DNA. They found no evidence of DNA damage - the cells looked identical to unexposed cells, while cells exposed to ionizing radiation showed clear damage. This suggests that RF radiation at these levels doesn't break DNA strands in human immune cells.
Unknown authors · 2000
The researchers studied the effect of extremely low frequency electromagnetic fields combined with mild heat shock on reporter gene expression in two transgenic strains of Caenorhabditis elegans. Reporter gene expression was measured by scoring animals with induced beta-galactosidase activity after staining in toto or by biochemical quantitation of enzyme activity. They defined experimental conditions where electromagnetic fields strongly enhanced the expression of the reporter gene.
Unknown authors · 2000
Researchers used Escherichia coli strain XL-1 Blue as the host and hydroxylamine-mutagenized plasmid pUC8 as the vector for assessment. Bacterial transformants exposed to a 50 Hz magnetic field showed lower percentages of white colonies than unexposed transformants. The lower white colony percentage indicated that DNA repair efficiency had improved. The improvement was mediated by induced overproduction of heat shock proteins DnaK/J (Hsp70/40).
Peinnequin A et al. · 2000
Unknown authors · 2000
Researchers investigated whether exposure to 60-Hz sinusoidal magnetic fields (0.3-1.2 G for 3-72 h) would cause proliferation of human astrocytoma cells. Sixty-Hertz magnetic fields caused a time- and dose-dependent increase in proliferation of astrocytoma cells, measured by (3)H-thymidine incorporation and by flow cytometry, and strongly potentiated the effect of two agonists. However, magnetic fields had no effect on DNA synthesis of rat cortical astrocytes, which are similar nontransformed cells. A protein kinase C inhibitor and down-regulation of protein kinase C inhibited the effect of magnetic fields on basal and agonist-stimulated thymidine incorporation.
Unknown authors · 2000
University of Washington researchers exposed human brain tumor cells (astrocytomas) to 60-Hz magnetic fields at household appliance levels (0.3-1.2 gauss) for up to 72 hours. The magnetic fields caused these cancer cells to multiply faster in a dose-dependent manner, while having no effect on normal brain cells. This provides a potential biological mechanism for epidemiological studies linking magnetic field exposure to increased brain tumor risk.
Unknown authors · 2000
Unknown authors · 2000
Unknown authors · 2000
Researchers used a bacterial conjugation assay with Escherichia coli carrying the transposable element Tn5 as the donor strain. Donor cultures exposed to a 50 Hz, 1.2 mT magnetic field showed stimulated transposition of chromosomal Tn5 to an extrachromosomal episome and subsequent transfer to recipient cells. The transposition increase was mediated by induced synthesis and accumulation of the heat shock proteins DnaK/J. Magnetic field exposure was found to be stimulatory to transposition activity, similar to heat shock and UV irradiation.
Unknown authors · 2000
Researchers examined the effect of 50 mT, 60 Hz ELFMF on heat-induced HSP-70 expression in HL60RG cells. Exposure to 50 mT ELFMF alone did not increase HSP-70 production. Combined exposure to 50 mT ELFMF and mild heat at 40°C and 42°C suppressed heat-induced HSP-70 expression. This suppression required simultaneous exposure for more than 5 hours. Lower magnetic densities of 5 mT and 0.5 mT did not suppress HSP-70.
Unknown authors · 2000
Researchers from Löscher's group in Germany exposed Sprague-Dawley rats to 50-Hz magnetic fields at microtesla flux densities for 13 or 27 weeks using a DMBA breast cancer model. The exposure significantly increased mammary tumor development and growth in those experiments. A similar study by Battelle in the United States did not replicate the effect.
Unknown authors · 2000
German researchers found that 50 Hz magnetic fields at 100 microtesla significantly increased mammary tumor development in rats treated with a cancer-causing chemical. However, when U.S. researchers tried to replicate the study using similar methods, they could not reproduce these findings, highlighting challenges in EMF research reproducibility.
Unknown authors · 2000
Unknown authors · 2000
Scientists exposed human mammary and leukemia cells to 60 Hz magnetic fields (the frequency from power lines) for 24 hours to see if this would change cancer-related gene activity. While some genes showed temporary changes, no consistent pattern emerged across repeated experiments, and the researchers found no reliable evidence that power line frequency magnetic fields alter cancer gene expression.
Unknown authors · 2000
Researchers exposed human breast and leukemia cells to 60 Hz magnetic fields (the same frequency as power lines) for 24 hours to see if it changed cancer-related gene activity. While some genes showed temporary changes, no consistent pattern emerged across repeated experiments, suggesting 60 Hz fields don't systematically alter cancer gene expression in these cell types.
Unknown authors · 2000
Researchers attempted to replicate earlier findings by testing whether a 1.5-G 50-Hz magnetic field alters intracellular free calcium in Jurkat lymphocyte T-cells. Cells were randomly assigned to magnetic field, sham field, or no-field exposures for 8 minutes each in a blinded design. The percentage of cells showing calcium transients was 16.5% for magnetic field, 14.6% for sham, and 14.2% for no field, with no statistically significant differences among them. The authors concluded that their methods did not identify responsive cells, if such cells exist, and that the results do not rule out a magnetic field effect on calcium.
Unknown authors · 2000
Daudi cells were exposed to 60 Hz magnetic fields for 20, 40 or 60 min at flux densities of 12.5, 50, 100 or 500 microT. Exposures included sham/sham, exposed/sham or sham/exposed conditions with blinding, and 12-O-Tetradecanoylphorbol-13-acetate (TPA) treatment was used as a positive control. Human MYC expression was measured by northern blot hybridization as an indicator of the responsiveness of Daudi cells to experimental conditions, and beta-2-microglobulin (B2M) expression was measured simultaneously as an internal control. Exposure to 60 Hz magnetic fields did not significantly alter MYC expression in Daudi cells under any exposure condition.
Grant FH, Schlegel RE, · 2000
Researchers evaluated 20 pacemaker-phone combinations involving 6 pacemakers and 9 phones in vitro under worst-case conditions. The phones represented CDMA, TDMA-11 Hz, TDMA-22 Hz, TDMA-50 Hz, and TDMA-217 Hz digital wireless technologies. Small increases in the perpendicular air gap between the phone and the saline surface resulted in a dramatic reduction in interaction, with approximately half of the 208 test runs showing interaction at 1 cm no longer interacting at 2 cm. At a gap of 7.4 cm the percentage of runs with interaction decreased to 1.4%, and the overall interaction rate was less than 0.07% at a perpendicular distance of 8.6 cm.
Jauchem JR, Ryan KL, Freidagger MR · 2000
Ketamine-anesthetized male Sprague-Dawley rats were exposed to 1 GHz, 10 GHz, or combined 1 and 10 GHz microwaves at a whole-body specific absorption rate of 12 W/kg. Exposures were conducted in E and H orientations under far-field conditions until lethal temperatures were reached. Survival time was shortest at 1 GHz, intermediate for combined frequencies, and longest at 10 GHz, with most differences statistically significant. Temperature values at most sites for combined exposure fell between those of the single-frequency groups. Arterial blood pressure initially increased then decreased until death, heart rate increased throughout, and patterns were similar across all groups.
Gapeev AB, Chemeris NK · 2000
Researchers used a mathematical model to analyze how modulated extremely high frequency electromagnetic radiation affects intracellular calcium concentration in neutrophils. The model showed that the calcium rise depends on both the frequency and phase of the modulating signal relative to chemical stimulation. A rise above 50% of the initial calcium level occurred at about 1 Hz and phase range 0.3-2.5 radians, but only when modulating signal intensity exceeded a threshold and chemical stimulus intensity was high. Added noise changed the phase-frequency characteristics and created multiple response bands with higher Q-factors. The model results matched earlier experimental data showing effects only with extracellular calcium and high calcium ionophore A23187 concentrations.
Nakamura H, Nagase H, Ogino K, Hatta K, Matsuzaki I · 2000
Researchers exposed rats to continuous-wave microwaves at 2 mW/cm² and 2450 MHz for 90 minutes and measured uteroplacental blood flow and hormone levels. Colonic temperature did not change significantly in either virgin or pregnant rats. Microwave exposure decreased uteroplacental blood flow and increased progesterone and PGF2α in pregnant rats but not in virgin rats. Pretreatment with angiotensin II prevented these changes in pregnant rats. Corticosterone increased and estradiol decreased during exposure regardless of pregnancy status or angiotensin II pretreatment.
