Extremely Low Frequency (ELF) magnetic fields are produced by the flow of electrical current. They are measured in milligauss (mG) or microtesla (µT). Unlike electric fields, magnetic fields easily penetrate walls and most materials.
Based on Building Biology Institute guidelines (mG (milligauss)):
See where common exposures fall on the scale:
Showing 486 studies with measured magnetic fields (elf) exposure
Esmekaya MA et al. · 2013
Scientists exposed E. coli bacteria to 50 Hz magnetic fields for 24 hours. While the bacteria survived normally, the magnetic field exposure damaged their cell surfaces, creating holes and destroying membranes. This shows EMF can harm cells even when they appear healthy overall.
Wang X et al. · 2013
Researchers exposed early adolescent male mice to a 50 Hz magnetic field at 2 mT for 60 minutes per day from postnatal day 23 to 35. Spatial memory was then tested using the Y-maze and Morris water maze tasks. The magnetic field exposure did not affect Y-maze performance but improved spatial learning acquisition and memory retention in the water maze.
Esmekaya MA et al. · 2013
Researchers investigated the effects of a 50 Hz, 2 mT magnetic field, with or without iron(III) chloride, on the growth and morphology of Escherichia coli. No significant differences in cell viability were found between exposed and sham-exposed bacteria, and FeCl3 treatment also did not change cell viability. However, pore formations and membrane destruction were observed on the surface of cells exposed to the ELF field for 24 hours.
Deng Y, Zhang Y, Jia S, Liu J, Liu Y, Xu W, Liu L. · 2013
Researchers divided sixty male SPF Kunming mice into four groups: a control group, an ELF-MF group exposed at 2 mT for 4 hours per day, a group given aluminum at 200 mg per kg, and a combined ELF-MF plus aluminum group. After 8 weeks of treatment, all three exposure groups showed learning memory impairment, with prolonged escaping latency to the platform and a reduced percentage of time in the platform quadrant in the Morris water maze task. All three exposed groups showed a statistically significant decrease in superoxide dismutase activity and an increase in malondialdehyde levels. The combined ELF-MF plus aluminum treatment induced no more damage than ELF-MF and aluminum did separately.
Cho SI et al. · 2012
Researchers exposed rats to 60 Hz magnetic fields (like those from power lines) for five days and found increased nitric oxide production in key brain regions. While brain structure remained normal, the biochemical changes suggest power-frequency magnetic fields can alter brain chemistry and potentially affect neurological function.
Cho SI et al. · 2012
Researchers designed the study to confirm that extremely low-frequency magnetic fields affect neuronal NOS in several brain regions and to investigate the correlation between nitric oxide and nNOS activation. Exposure of rats to a 2 mT, 60 Hz ELF-MF for 5 days resulted in increases of nitric oxide levels in parallel with cGMP elevations in the cerebral cortex, striatum, and hippocampus. The numbers of nNOS-immunoreactive neurons were significantly increased in those cerebral areas in ELF-MF-exposed rats. Staining and electron microscopy showed no significant differences in the morphology or number of neurons in the cerebral cortex, striatum, and hippocampus.
He LH, Shi HM, Liu TT, Xu YC, Ye KP, Wang S. · 2011
Researchers exposed adult rats daily to a 50-Hz extremely low frequency magnetic field set to 2 mT, dividing them into a control group, a 1-hour exposure group, and a 4-hour exposure group. After 4 weeks of daily exposure, anxiety-related behaviors were assessed in the open field test and the elevated plus maze, and spatial learning and memory were assessed in the Morris water maze. Rats in the 4-hour group showed increased anxiety-like behaviors, reduced latency to find a hidden platform, and improved long-term memory of the platform's former location, without changes in short-term memory or locomotor activity.
Osera C et al. · 2011
Researchers investigated the effects of an electromagnetic wave at 2 mT and 75 Hz on human neuroblastoma cells overexpressing amyloid precursor protein (APP). After prolonged electromagnetic treatment, lower mitochondrial activity and proliferation rate were observed, resulting in higher cellular quiescence. The treatment was also associated with an overall increase of HSP70 and superoxide dismutase-1 (SOD-1), and with increased expression of the enzyme ADAM10 and enhanced release of the neurotrophic factor sAPPα. The researchers suggested a possible use of this physical stimulation to improve the functional capability of cells to face noxae.
He LH, Shi HM, Liu TT, Xu YC, Ye KP, Wang S. · 2011
Researchers exposed adult rats to 50-Hz magnetic fields (the same frequency as power lines) for either 1 or 4 hours daily over 4 weeks. They found that rats exposed for 4 hours showed increased anxiety-like behaviors but also improved spatial learning and long-term memory. This suggests that extremely low frequency magnetic fields can affect both emotional and cognitive brain functions, even at relatively short daily exposure periods.
Sun H, Che Y, Liu X, Zhou D, Miao Y, Ma Y. · 2010
Researchers investigated memory impairment in newly hatched chicks following in ovo exposure to a 50-Hz magnetic field of 2 mT for 60 minutes per day on embryonic days 12 through 18. Memory retention was tested at 10, 30, and 120 minutes after exposure to a bitter-tasting bead.
Aldinucci C et al. · 2009
Researchers exposed synaptosomes to a peak magnetic field of 2 mT for 2 hours. They evaluated mitochondrial respiration rate, ATP production, membrane potential, intrasynaptosomal calcium concentration, and release of free iron and F2-isoprostanes. Oxygen consumption and ATP production remained unchanged in exposed synaptosomes. Intrasynaptosomal calcium concentration decreased slowly with no membrane depolarization detected, and free iron and F2-isoprostane release remained unchanged.
Aldinucci C et al. · 2009
Italian researchers exposed rat brain nerve terminals (synaptosomes) to 50 Hz magnetic fields at 2 milliTesla for 2 hours and measured multiple indicators of cellular function including energy production, calcium levels, and oxidative stress markers. They found no changes in any of the measured parameters, indicating that this level of extremely low frequency magnetic field exposure did not affect normal nerve terminal function. This suggests that moderate-strength power frequency magnetic fields may not directly disrupt basic brain cell operations at the cellular level.
Strasák L, Bártová E, Krejci J, Fojt L, Vetterl V. · 2009
Researchers exposed female and male laboratory mice for 4 days to a 50 Hz magnetic field at 2 mT inside a cylindrical coil. After exposure, levels of the proteins c-Jun and c-Fos in different parts of the brain were measured using Western-blot techniques. The expression of c-Jun decreased after magnetic field exposure, while c-Fos expression was not affected, and neither result depended on the sex of the mice.
Strasák L, Bártová E, Krejci J, Fojt L, Vetterl V. · 2009
Researchers exposed laboratory mice to extremely low frequency magnetic fields (50 Hz at 2 milliTesla) for four days and measured changes in brain proteins. They found that exposure decreased levels of c-Jun, a protein involved in cellular stress responses and gene regulation, while another protein (c-Fos) remained unchanged. This suggests that even short-term exposure to magnetic fields can alter brain biochemistry at the cellular level.
Liu T, Wang S, He L, Ye K. · 2008
Researchers tested spatial learning and memory in rats using the Morris water maze after four weeks of daily exposure to a 50-Hz magnetic field of 2 mT for either one or four hours. Chronic exposure reduced the time rats took to find a hidden platform and improved long-term memory of the platform's former location. Short-term memory and motor activity were not affected.
Liu T, Wang S, He L, Ye K. · 2008
The study investigated whether anxiety levels could be affected by repeated extremely low frequency magnetic field (ELF MF) exposure of different daily durations. Rats exposed for 4 h/day showed increased anxiety-like behaviors in the open field test and the elevated plus maze test, without changes in locomotor activity, but showed no effect in the light/dark box test. Rats exposed for 1 h/day showed no effect in any of the tests.
Jadidi M et al. · 2007
Researchers exposed rats to 50 Hz magnetic fields (household electricity frequency) immediately after learning a maze. An 8 milliTesla field for 20 minutes disrupted memory formation when applied right after learning, suggesting magnetic fields can interfere with how brains consolidate new memories.
Jadidi M et al. · 2007
Researchers used a water maze to evaluate how magnetic field exposure affects consolidation and retrieval of spatial memory in rats. Exposure to a 50 Hz, 8 mT magnetic field for 20 minutes immediately after training impaired retention performance, but exposure at 2 mT did not. Exposure given shortly before retention testing had no effect on performance.
Todorović D, Kalauzi A, Prolić Z, Jović M, Mutavdzić D. · 2007
Researchers measured the influence of a static magnetic field at 2 mT on neuronal population activity in eight individuals of the endangered insect species Morimus funereus. Five minutes of exposure produced excitatory effects in 5 of 8 individuals and inhibitory effects in 3 of 8 individuals in the antennal lobe. When reversibility was analyzed, the induced effects were prevailingly irreversible: 7 of 8 for the neuronal population and 6 of 8 for the nearest neuron.
Nikolova T et al. · 2005
ELF-EMF significantly affected transcript levels of bcl-2, bax, and GADD45 genes but did not affect neural-specific gene mRNA levels. RF-EMF down-regulated neural-specific Nurr1 and up-regulated bax and GADD45 mRNA levels. Short-term RF-EMF exposure for 6 hours caused a transient increase in DNA double-strand breaks, while 48-hour exposure did not. No effects were observed on mitochondrial function, nuclear apoptosis, cell proliferation, or chromosomal alterations.
De Mattei M et al. · 2003
Researchers exposed bovine articular cartilage explants to a 75 Hz, 2,3 mT electromagnetic field in vitro, with and without interleukin-1. EMF exposure significantly increased proteoglycan synthesis and residual tissue proteoglycan content compared with controls, without affecting proteoglycan release or nitric oxide production. In interleukin-1-treated explants, EMF increased proteoglycan synthesis and kept tissue proteoglycan content at control levels while not changing proteoglycan release. Lactate production increased in both experimental conditions with EMF exposure.
Unknown authors · 1978
Evoked potentials measured inside and outside the magnet were essentially the same, and the latency of fast and slow waves from limb to brain was not changed by the magnetic field. Heart rate was lower inside the magnet, while blood pressure results showed opposite directions in the two monkeys. Noticeable changes in blood hematology and chemistry can be attributed to the trauma caused by the implantation of the cortical electrodes. From the tests which were performed, as described above, we conclude that there were no observable effects in the two monkeys.
J. D. CLEMENT-METRAL · 1975
Calabrò E et al. · 2013
Researchers investigated the effects of exposing human SH-SY5Y neuronal-like cells to a uniform static magnetic field at an intensity of 2.2 mT. Fourier transform infrared spectroscopy analysis showed that exposure changed the secondary structure of cellular proteins and lipid components. A decrease of membrane mitochondrial potential up to 30% was measured after 24 h of exposure, and this effect was associated with reactive oxygen species production increase.
Chu LY et al. · 2011
Researchers investigated whether extremely low frequency magnetic field (ELF-MF) induces lipid peroxidation and reactive oxygen species in mouse cerebellum. After exposure to 60 Hz ELF-MF at 2.3 mT intensity for 3 hours, malondialdehyde and hydroxyl radical levels increased significantly. The researchers concluded that ELF-MF may induce oxidative stress in mouse cerebellum, though the mechanism remains to be characterized.