Unknown authors · 2008
Exposure to 3 or 5 tesla static magnetic fields transiently induced genes involved in motor activity, actin binding, cell adhesion, and cuticles in C. elegans. Transient induction of hsp12 family genes was observed after SMF exposure, while the small-heat shock protein gene hsp16 was induced to a much lesser extent. Unlike ionizing radiation, high static magnetic fields did not induce DNA double-strand breaks or germline cell apoptosis during meiosis, and did not upregulate genes encoding apoptotic cell-death activators and secreted surface proteins. Real-time quantitative RT-PCR analyses for 12 of these genes confirmed expression differences between worms exposed to SMFs and IR.
Unknown authors · 2008
Researchers exposed cultured human lens epithelial cells to 0.4 mT 50 Hz magnetic fields for 2, 6, 12, 24, and 48 hours. After exposure, cells were fixed with 4% paraformaldehyde and stained for gamma H2AX immunofluorescence, and foci were counted in at least 200 cells per sample. Cells with more than three foci per cell were classified as positive, and mean foci per cell and percentage of positive cells were used as indexes of DNA double-strand breaks. Exposure for 24 hours significantly increased mean foci per cell to 2.93 and positive cells to 27.88% compared with sham (1.77 and 19.38%, P<0.05), and exposure for 48 hours increased them to 3.14 and 31.00% (P<0.01), while 2, 6, and 12 hour exposures showed no significant difference (P>0.05).
Unknown authors · 2008
Researchers applied continuous-wave 0.1 THz radiation at 0.031 mW/ cm(2) to dividing lymphocytes for 1, 2, and 24 hours and measured chromosome number changes and centromere replication timing using FISH. Chromosomes 11 and 17 showed about a 30% increase in aneuploidy after 2 and 24 hours, while chromosomes 1 and 10 were unaffected. The asynchronous replication mode of centromeres 11, 17, and 1 changed by 40% after 2 hours, and all four centromeres changed by 50% after 24 hours.
Unknown authors · 2008
Researchers exposed the human keratinocyte cell line HaCaT to 1 mT, 50 Hz ELF-EMF for different lengths of time and compared them with unexposed control cells. Cell growth and viability were evaluated by cell count and trypan blue exclusion. Significantly increased growth rates were observed after 48 hours of EMF exposure compared with control cells, while no difference in cell viabilities was detected. Gene expression and release of RANTES, MCP-1, MIP-1 alpha and IL-8 were significantly reduced after 72 hours of exposure. NF-kappaB levels became almost undetectable after only 1 hour of EMF exposure and were inversely correlated with cell density.
Unknown authors · 2008
Researchers exposed Escherichia coli ATCC 700926 to 50 Hz electromagnetic fields at 0.1, 0.5, and 1.0 mT and compared them with sham-exposed controls. Exposed and control samples had similar total and culturable counts. Exposed samples showed increased cell viability after 24 hours of re-incubation outside the solenoid. Exposure for 20–120 minutes caused significant morphological changes including coccoid cells and atypical lengthened forms. DNA fingerprinting showed no changes, while RNA-AFLP analysis revealed some differences at each field intensity.
Unknown authors · 2008
Epidemiological studies reported increased childhood leukemia risk from ELF magnetic field exposure, suggesting possible human carcinogenicity. Animal studies found no carcinogenic effects from ELF magnetic fields alone, and genotoxicity studies generally showed no effects from fields alone. However, ELF magnetic fields were reported to enhance effects of known carcinogens in some animal and several in vitro studies. Most in vitro studies showed positive findings, supporting that fields of 100 microT or higher interact with other chemical and physical agents.
Unknown authors · 2008
The author develops a hypothesis that naturally occurring magnetic nanoparticles could mediate EMF-induced DNA damage, which could increase the risk of childhood leukaemia. Physics calculations estimate that a magnetic nanoparticle within a cell generates a field of about 1-200 millitesla, far exceeding the geomagnetic field. The proposed mechanism suggests that weak alternating magnetic fields of the order of 0.4 muT could increase leukaemia rates via millitesla fields around superparamagnetic nanoparticles in hematopoietic stem cells.
Unknown authors · 2008
Researchers exposed mouse osteoblast-like MC3T3-E1 cells to ELF-EMF at 3 mT and 60 Hz and measured cellular collagen as a marker of differentiation. ELF-EMF exposure significantly increased collagen content in the cells. Inhibiting the p38 MAPK pathway with SB203580 suppressed the ELF-EMF-induced collagen increase, while inhibiting the PI3K pathway with LY294002 accelerated it. The ERK1/2 inhibitor PD98059 reduced collagen in all conditions but did not block the ELF-EMF effect.
Unknown authors · 2008
Researchers evaluated the hormetic effect of non-thermal repetitive electromagnetic field shock (50MHz/0.5W) on primary human T lymphocytes and fibroblast cell lines. REMFS extended the total number of population doublings of mouse fibroblasts and contributed to youthful morphology of cells near their replicative lifespan. REMFS also enhanced cellular defenses of human T cells as reflected in lower cell mortality when compared to non-treated T cells. Mechanistic analysis showed that REMFS increased HSF1 phosphorylation, enhanced HSF1-DNA binding, and improved Hsp70 expression relative to non-REMFS-treated cells.
Vijayalaxmi , Prihoda TJ · 2008
Unknown authors · 2008
Numerical models are used for analysis of Fröhlich's vibration states in cells. The models indicate that reduction of mitochondrial activity and energy production, and disintegration of cytoskeleton structures by phosphorylation during cancer transformation, can diminish excitation of Fröhlich's vibration states and the generated electromagnetic field, resulting in disturbances of the interaction forces between cells. Interaction forces between cancer cells may be smaller than those between healthy cells and cancer cells according to the numerical models.
Unknown authors · 2008
The review examines physical principles for assessing radiofrequency interactions with biological systems at exposures up to endogenous electric field levels. It finds possible demodulation at membrane barriers for frequencies up to 10 MHz but not at higher frequencies. Molecular vibrational modes are too overdamped by water for excitation below the far infrared. Two mechanisms may plausibly affect biology: radical-pair reaction shifts below approximately 150 MHz and dielectric and resistive heating at all frequencies.
Unknown authors · 2008
Fifteen subjectively electrosensitive patients and 15 age- and gender-matched healthy controls were exposed to sham mobile phone radiation and heat as a control condition. During anticipation of and exposure to sham mobile phone radiation, the electrosensitive group showed increased activations in the anterior cingulate and insular cortex as well as fusiform gyrus compared to controls. Heat stimulation led to similar activations in both groups.
Unknown authors · 2008
Researchers exposed groups of 108 DMBA-treated Fischer 344 rats to a 100 muT, 50 Hz magnetic field or sham exposure for 26 weeks. MF exposure significantly facilitated mammary tumorigenesis. The incidence of histologically verified adenocarcinomas was increased by 45% (P = 0.0095). The most pronounced effect on tumor incidence was seen in the cranial inguinal complexes.
Unknown authors · 2008
Unknown authors · 2008
Researchers exposed 48 pregnant rats to two magnetic field patterns across four intensity ranges during prenatal development. Cytometric anomalies were significantly increased in hippocampal regions associated with adult neuronal neogenesis.
Unknown authors · 2008
Researchers measured magnetic fields in 30 buildings in three Finnish cities, comparing apartments above transformer stations with first-floor and upper-floor reference apartments. Spot measurements showed mean magnetic fields of 0.62 µT above transformer stations, 0.21 µT on first floors, and 0.11 µT on upper floors. Twenty-four-hour mean fields were 0.2 µT or higher in 97% of apartments above transformer stations, 25% of first-floor apartments, and 10% of upper-floor apartments. At a 0.4 µT cut-off, 63% of apartments above transformer stations, 14% of first-floor apartments, and 3.3% of upper-floor apartments exceeded the threshold. The authors concluded that transformer station location can reliably classify apartments into high and low magnetic field categories.
Unknown authors · 2008
Recent epidemiological studies report increased leukemia risk near high voltage powerlines at distances beyond direct electric and magnetic fields. Corona ions from powerlines form plumes that generate atmospheric electric field disturbances of tens to a few hundred V/m up to several hundred meters away. The authors hypothesize that these disturbances disrupt nocturnal melatonin synthesis and circadian rhythms, leading to increased risk of adverse health effects including leukemia. A review finds that natural atmospheric electric field variation may act as a weak Zeitgeber, melatonin disruption by electric fields occurs in rats, and human circadian rhythms are disturbed by artificial fields as low as 2.5 V/m.
Unknown authors · 2008
Case-control studies showed a pooled odds ratio of 2.03 and cohort studies a pooled relative risk of 1.62 for Alzheimer disease. Both analyses had moderate to high statistical heterogeneity. Cohort studies found consistently increased risks for exposed men with no heterogeneity. No dose-response relationship was found and publication bias tests suggested small study effects.
Unknown authors · 2008
Researchers conducted a meta-analysis of 13 studies on magnetic field exposure and childhood brain tumors. Summary odds ratios were 0.88 (0.57-1.37) for distance less than 50 meters and 1.14 (0.78-1.67) for calculated or measured magnetic fields above 0.2 microtesla. For exposures above 0.3 or 0.4 microtesla, the summary odds ratio was 1.68 (0.83-3.43) with no differences by exposure assessment method. No single study substantially influenced the summary estimates and there was no indication of publication bias.
Unknown authors · 2008
Researchers exposed 30 adult female Sprague Dawley rats to extremely low frequency magnetic field for 4 hours per day over 7 days, with 15 rats serving as controls. The exposed rats had significantly lower goblet cell density than controls (p = 0.010). They also showed conjunctival edema and inflammation (p < 0.001 and p = 0.003), but no difference in fibroblast proliferation (p = 0.422).
Unknown authors · 2008
Sixteen teachers developed 18 cancers, yielding an observed-to-expected risk ratio of 2.78 for all cancers. Risk ratios were especially high for malignant melanoma (9.8), thyroid cancer (13.3), and uterine cancer (9.2). Sixty Hertz magnetic fields showed no association with cancer, while high frequency voltage transients showed a positive correlation.
Unknown authors · 2008
Researchers measured 50 Hz magnetic fields in 31 apartment buildings with built-in transformer stations. In each building they selected three apartments: one above the transformer room, one on the same floor, and one on a higher floor. The mean magnetic field was 0.98 microT above transformers, 0.13 microT on the same floor, and 0.1 microT on higher floors. At a 0.2 microT threshold, 97% of apartments above transformers exceeded it versus 14% on the same floor and 13% on higher floors. At 0.4 microT, 81% of apartments above transformers exceeded it while none on other floors did.
Unknown authors · 2008
Unknown authors · 2008
The stimulation of protein and DNA by EMF is problematic because the fields do not appear to have sufficient energy to directly affect such large molecules. Studies with electric and magnetic fields in the extremely low-frequency range have shown that weak fields can cause charge movement. Redistribution of charges in large molecules can trigger conformational changes driven by large hydration energies, and such changes play a key role in membrane transport proteins and probably account for DNA stimulation to initiate protein synthesis.
