Unknown authors · 1999
Researchers exposed HL-60 cells to a sinusoidal 0.1 or 1 mT magnetic field at 60 Hz for 2 hours and then pulse-labeled them with radioactive isotopes. In control cultures without magnetic field exposure, the cognate form of stress protein 72c was faintly observed, and 0.1 mT exposure did not alter stress protein metabolism compared to controls. At 1 mT, the inducible form of stress protein 70i was synthesized, stress protein 90 was phosphorylated but not synthesized, and stress protein 27 isoforms a and b were induced. Statistical analysis of Western blot data confirmed a significant increase in stress proteins 90 and 27a after 1 mT exposure.
Unknown authors · 1999
Researchers exposed groups of 100 female Sprague-Dawley rats to 50 Hz magnetic fields at 1 or 5 G, or 60 Hz at 1 G, for 18.5 hours a day, 7 days a week, for 13 weeks after initiating mammary tumors with DMBA. A second study used a lower DMBA dose of 2 mg and exposed rats to 50 Hz fields at 1 or 5 G for the same duration. Magnetic field exposure did not affect body weight, tumor latency, or tumor size in either study, and the authors concluded there was no evidence that 50 or 60 Hz fields promoted breast cancer.
Unknown authors · 1999
Groups of 100 female Sprague–Dawley rats were initiated with a single 10 mg gavage dose of DMBA at 50 days of age and then exposed to ambient fields, 50 Hz magnetic fields at 1 or 5 Gauss, or 60 Hz fields at 1 Gauss for 18.5 hours per day, 7 days per week for 26 weeks. There was no effect of magnetic field exposure on body weight gains or the time of appearance of mammary tumors. Carcinoma incidence was 96%, 90%, 95%, and 85% for the DMBA controls, 1 G 50 Hz, 5 G 50 Hz, and 1 G 60 Hz groups respectively, total carcinoma numbers were 649, 494, 547, and 433 with significant decreases in the 1 G 50 Hz and 1 G 60 Hz groups, and the authors concluded there was no evidence that 50 or 60 Hz magnetic fields promoted breast cancer under the conditions of this assay.
Unknown authors · 1999
Researchers conducted a double-blind laboratory study of 24 healthy young men to examine effects of intermittent versus continuous exposure to a 60 Hz, 28.3 microT magnetic field on EEG measures of night sleep. Intermittent exposure was associated with less total sleep time, reduced sleep efficiency, increased Stage II sleep, and decreased REM sleep, while continuous and sham exposure showed no such effects. Subjects exposed intermittently reported sleeping less well and feeling less rested in the morning compared to the other groups. All observed effects were significant at P < or = .04 or less.
Miyakoshi J, Koji Y, Wakasa T, Takebe H · 1999
Researchers exposed Chinese hamster ovary K1 cells to 5 mT ELFMF at 60 Hz for up to 6 weeks with or without X-irradiation. Long-term exposure to 5 mT ELFMF alone did not increase mutant frequency of the HPRT gene. However, exposure to 5 mT ELFMF after X-irradiation enhanced the X-ray-induced mutation rate. As little as 1 week of ELFMF exposure after X-irradiation increased the mutation rate.
Lu ST, Mathur SP, Akyel Y, Lee JC · 1999
Researchers exposed male Wistar-Kyoto rats to ultrawide-band electromagnetic pulses at 0.5-kHz and 1-kHz for 6 minutes. They measured cardiovascular functions including heart rate, systolic, mean, and diastolic pressures using a noninvasive tail-cuff sphygmomanometer. Exposure caused a significant decrease in arterial blood pressure that was robust, consistent, and persistent, while heart rate did not change. Cardiovascular functions were evaluated from 45 minutes to 4 weeks after exposure.
Unknown authors · 1999
Researchers investigated the effect of 50 Hz magnetic fields on the cytosolic calcium oscillator in Jurkat E6.1 cells at field strengths from 0 to 0.40 mT root mean square. The total spectral power of the cytosolic Ca2+ oscillator was reduced by magnetic field exposure and the effect increased in a dose-response manner. This reduction was also observed in the 0-10 mHz subinterval of the oscillation spectrum, while higher frequency subintervals showed no significant change.
Unknown authors · 1999
Researchers exposed human leukemia T-cells to 50 Hz magnetic fields (the same frequency as electrical power lines) and measured calcium oscillations inside the cells. They found that magnetic field exposure reduced these calcium signals in a dose-dependent manner - the stronger the field, the greater the reduction. This matters because calcium signaling is crucial for immune cell function and communication.
Unknown authors · 1999
Researchers exposed HBL-100 cells and normal human mammary epithelial cells to 60 Hz EMF at flux densities of 0.1, 1.0, and 10.0 Gauss for periods ranging from 20 min to 24 h. Gene expression was quantitated using ribonuclease protection assays. EMF exposure had no statistically significant effect on basal levels of c-myc transcripts in either human breast cell model, and had no effect on alterations in c-myc expression induced by 12-O-tetradecanoylphorbol-13-acetate. Transcript levels of c-erbB-2, p53, p21, GADD45, bax, bcl-x, mcl-1, and c-fos were also unaffected by EMF exposure.
Unknown authors · 1999
Researchers exposed human breast cells to 60 Hz magnetic fields (the same frequency as household electricity) at various strengths for up to 24 hours to see if EMF exposure would alter cancer-related genes. The study found no significant changes in gene expression for key cancer markers like c-myc, p53, and others, suggesting 60 Hz magnetic fields don't promote breast cancer through genetic mechanisms.
Unknown authors · 1999
Researchers exposed human breast cells to 60 Hz magnetic fields at various strengths (0.1 to 10 Gauss) for up to 24 hours to test whether power line frequencies could trigger cancer-related gene changes. The study found no significant effects on cancer-associated genes including c-myc, p53, and others, suggesting 60 Hz EMF is unlikely to promote breast cancer through direct gene expression changes.
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.
Jauchem JR, Frei MR, Ryan KL, Merritt JH, Murphy MR · 1999
The study investigated the lack of effects on heart rate and blood pressure in ketamine-anesthetized rats briefly exposed to ultra-wideband electromagnetic pulses. Exposures at a repetition frequency of 1 kHz for 0.5 s or to repetitive pulse trains for a total of 2 min resulted in no significant changes in heart rate or mean arterial blood pressure. These results suggest that acute whole-body exposure to UWB pulses does not have a detrimental effect on the cardiovascular system.
Unknown authors · 1999
Researchers conducted a population-based case-control study across England, Wales, and Scotland. They measured household and school magnetic fields for 2226 matched case-control pairs and estimated average exposure in the year before diagnosis. For children with mean exposures above 0.2 microT compared to below 0-1 microT, the adjusted odds ratio for all malignant disease combined was 0.87 (95% CI 0.56-1.35).
Unknown authors · 1999
Unknown authors · 1999
Unknown authors · 1999
Researchers evaluated the effect of a 60 Hz electromagnetic field on NF-kappaB or AP-1-dependent reporter gene expression in human U937 leukemia cells. Reporter genes were electroporated into the cells and pathway activation was measured by CAT protein using CAT ELISA. Magnetic field intensities of 0.08, 0.1, 1.0, and 1.3 mT had no effect on either signaling pathway.
Unknown authors · 1999
Researchers studied DNA migration using the comet assay in brain cells of CBA mice exposed continuously to 50 Hz, 0.5 mT magnetic fields for 2 hours, 5 days, or 14 days. No differences were observed in mice exposed for 2 hours or 5 days compared with controls. Mice exposed for 14 days showed significantly extended DNA migration (0.02 < p < 0.05).
Unknown authors · 1998
The authors reviewed 23 studies published since their 1993 review of 55 studies plus six additional earlier studies. Three attempts to replicate previously reported positive results were unsuccessful. Negative studies in several exposure categories met the quality criteria.
Unknown authors · 1998
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.
Unknown authors · 1998
Researchers measured magnetic field exposure and melatonin levels in electric utility workers over three consecutive days. They found that temporally stable 60 Hz magnetic fields (the kind from power lines) were associated with reduced nighttime melatonin production. This matters because melatonin is crucial for sleep, immune function, and protecting against cancer.
Unknown authors · 1998
Researchers conducted a nationwide mortality study of 21,236 men employed in Danish utility companies between 1900 and 1993. Causes of death from 1974 through 1993 were analyzed by latency and estimated 50-Hz electromagnetic field exposure. Overall mortality was slightly lower than expected with a standardized mortality ratio of 0.96 (95% confidence interval 0.93-0.99). A twofold increase in ALS mortality was observed based on 14 deaths and increased with time since first employment, while a tenfold increase in electrical accident mortality was based on 10 deaths.
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 rats to 60 Hz magnetic fields (the same frequency as household power lines) for one hour before maze training sessions. While the rats could still learn to find a hidden platform, they swam slower and showed impaired spatial memory when tested later. This suggests power frequency magnetic fields may affect brain function and memory formation.
