8,655 Studies Reviewed. 86.9% Found Biological Effects. The Evidence is Clear.
All Exposure Types

Magnetic Fields (ELF)

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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.

Concern Level Thresholds

Based on Building Biology Institute guidelines (mG (milligauss)):

No Concern
< 0.2 mG
Slight Concern
0.2 – 1 mG
Severe Concern
1 – 5 mG
Extreme Concern
> 5 mG

See where common exposures fall on the scale:

Your RF Exposure in ContextA logarithmic scale showing your reading relative to Building Biology concern thresholds and FCC regulatory limits.Your RF Exposure in ContextNo ConcernSlightSevereExtreme0.215FCC Limit 0.0110,000 mG

Showing 487 studies with measured magnetic fields (elf) exposure

Fifty-Hertz electromagnetic fields facilitate the induction of rat bone mesenchymal stromal cells to differentiate into functional neurons.

Bai WF, Xu WC, Feng Y, Huang H, Li XP, Deng CY, Zhang MS. · 2013

Researchers exposed rat bone marrow stem cells to 50 Hz electromagnetic fields (the same frequency as household electricity) for one hour daily over 12 days. The EMF exposure significantly enhanced the stem cells' ability to transform into functional brain neurons, complete with working synapses and electrical activity. This suggests that power frequency magnetic fields can directly influence cellular development and may have therapeutic applications for treating nervous system diseases.

Effect of exposure to 50 Hz magnetic field with or without insulin on blood-brain barrier permeability in streptozotocin-induced diabetic rats.

Gulturk S et al. · 2010

Researchers exposed diabetic rats to power line frequency magnetic fields for 30 days. The magnetic fields weakened the blood-brain barrier, which normally protects the brain from harmful substances. Diabetic animals with magnetic field exposure showed the worst barrier damage, potentially allowing toxins easier brain access.

Effect of exposure to 50 Hz magnetic field with or without insulin on blood-brain barrier permeability in streptozotocin-induced diabetic rats.

Gulturk S et al. · 2010

Scientists exposed diabetic rats to 50 Hz magnetic fields (from power lines) for three hours daily over 30 days. The magnetic fields increased blood-brain barrier permeability, allowing substances to pass more easily into brain tissue. This matters because a compromised barrier can let toxins reach the brain.

Extremely low frequency (ELF) magnetic fields enhance chemically induced formation of apurinic/apyrimidinic (AP)sites in A172 cells.

Koyama S, Sakurai T, Nakahara T, Miyakoshi J · 2008

Researchers exposed human brain cancer cells to 60 Hz magnetic fields (the same frequency as household electricity) to see if it would increase DNA damage. They found that while the magnetic fields alone didn't damage DNA, they significantly amplified the DNA damage caused by toxic chemicals. This suggests that common power-frequency magnetic fields may make cells more vulnerable to other sources of genetic damage.

ELF electromagnetic fields increase hydrogen peroxide (H2O2)-induced mutations in pTN89 plasmids.

Koyama S et al. · 2004

Japanese researchers exposed DNA-containing plasmids to hydrogen peroxide (a cellular toxin) either alone or combined with 60 Hz magnetic fields at 5 millitesla for 4 hours. When magnetic field exposure was combined with hydrogen peroxide, DNA mutations increased by 155% compared to hydrogen peroxide alone. This suggests that power-frequency magnetic fields can amplify the genetic damage caused by oxidative stress in cells.

Extremely low frequency magnetic fields and the promotion of H2O2-induced cell death in HL-60 cells.

Ding GR et al. · 2004

Researchers exposed human leukemia cells to 60 Hz magnetic fields (the same frequency as household electrical current) while also treating them with hydrogen peroxide, a chemical that damages cells. They found that the magnetic field exposure made the cells die faster and in greater numbers compared to hydrogen peroxide treatment alone. This suggests that power-frequency magnetic fields can amplify cellular damage caused by other harmful substances.

Benign Effect of Extremely Low-Frequency Electromagnetic Field on Brain Plasticity Assessed by Nitric Oxide Metabolism during Poststroke Rehabilitation.

Cichoń N et al. · 2017

Researchers studied 48 stroke patients undergoing rehabilitation, with half receiving additional exposure to extremely low-frequency electromagnetic fields (40 Hz) for 15 minutes daily. The EMF-exposed group showed increased levels of nitric oxide compounds in their blood and demonstrated better functional and mental recovery compared to the control group. This suggests that specific EMF frequencies might help enhance brain healing after stroke.

Benign Effect of Extremely Low-Frequency Electromagnetic Field on Brain Plasticity Assessed by Nitric Oxide Metabolism during Poststroke Rehabilitation

Cichoń N et al. · 2017

Researchers studied whether extremely low-frequency electromagnetic fields could help stroke patients recover by examining brain chemistry changes. They exposed 48 stroke patients to 40 Hz magnetic fields for 15 minutes daily during rehabilitation and found increased levels of nitric oxide (a brain chemical involved in healing) plus improved mental and daily functioning. This suggests that specific EMF exposures might actually support brain recovery after stroke.

Extremely low frequency electromagnetic field (ELF-EMF) reduces oxidative stress and improves functional and psychological status in ischemic stroke patients.

Cichoń N, Bijak M, Miller E, Saluk J. · 2017

Researchers studied 57 stroke patients who received either standard rehabilitation alone or rehabilitation plus daily exposure to extremely low frequency magnetic fields (40 Hz) for four weeks. Patients exposed to the magnetic fields showed improved antioxidant enzyme activity in their blood and better functional recovery, including enhanced daily living skills and reduced depression scores compared to the control group.

Effect of extremely low frequency magnetic field on glutathione in rat muscles.

Ciejka E et al. · 2014

Polish researchers exposed rats to 40 Hz magnetic fields at 7 mT (similar to some therapeutic magnetic devices) for either 30 or 60 minutes daily over two weeks. They found that both exposure durations significantly increased glutathione levels in skeletal muscle tissue compared to unexposed controls. Glutathione is the body's master antioxidant, so this suggests the magnetic fields triggered the muscles' natural defense systems against cellular damage.

Effects of extremely low frequency magnetic field on oxidative balance in brain of rats

Ciejka E, Kleniewska P, Skibska B, Goraca A · 2011

Researchers exposed rats to 40 Hz magnetic fields at 7 mT (milliTesla) for either 30 or 60 minutes daily over 10 days to study brain cell damage. They found that shorter exposures (30 minutes) increased harmful oxidative stress markers in the brain, while longer exposures (60 minutes) triggered protective adaptation responses. This suggests that magnetic field exposure duration significantly affects how the brain responds to electromagnetic stress.

Effects of extremely low frequency magnetic field on oxidative balance in brain of rats.

Ciejka E, Kleniewska P, Skibska B, Goraca A. · 2011

Polish researchers exposed rats to 7 milliTesla magnetic fields at 40 Hz (similar to some therapeutic magnetic devices) for either 30 or 60 minutes daily over 10 days. They found that 30-minute exposures increased oxidative stress markers in brain tissue, indicating cellular damage from free radicals. However, 60-minute exposures triggered adaptive mechanisms that appeared to protect against this damage, suggesting the brain can develop tolerance to longer magnetic field exposures.

Influence of low frequency magnetic field on chosen parameters of oxidative stress in rat's muscles.

Ciejka E, Skibska B, Kleniewska P, Goraca A. · 2010

Polish researchers exposed rats to 40 Hz magnetic fields (the type used in medical magnetotherapy) for either 30 or 60 minutes daily over two weeks. They found significant biochemical changes in muscle tissue, including increased sulfur compounds and altered protein levels, indicating the magnetic fields triggered oxidative stress. This suggests that even therapeutic magnetic field devices can cause measurable cellular damage in muscle tissue.

The influence of low-frequency magnetic field on plasma antioxidant capacity and heart rate.

Ciejka EB, Goraca A · 2009

Researchers exposed rats to 40 Hz magnetic fields (7 mT strength) for different durations and measured heart rate and antioxidant levels in blood. They found that 14 days of exposure slowed heart rate and changed the body's antioxidant defenses, with effects varying based on daily exposure time (30 vs 60 minutes). The study shows that magnetic field exposure duration affects cardiovascular function and cellular protection systems.

Protective effect of melatonin and vitamin E against prooxidative action of iron ions and static magnetic field

Jajte J, Zmyślony M, Rajkowska E. · 2003

Researchers exposed rat blood cells to magnetic fields and iron ions to test for cellular damage. The combination significantly increased harmful oxidation in cells, but pre-treating cells with antioxidants like melatonin or vitamin E prevented most damage, suggesting magnetic fields may amplify iron's harmful effects.

Effect of 7 mT static magnetic field and iron ions on rat lymphocytes: apoptosis, necrosis and free radical processes.

Jajte J, Grzegorczyk J, Zmyślony M, Rajkowska E. · 2002

Polish researchers exposed rat immune cells (lymphocytes) to a 7 milliTesla static magnetic field for 3 hours, both with and without iron particles present. While the magnetic field alone caused no harm, the combination of magnetic field plus iron significantly increased cell death and oxidative damage. This suggests that magnetic fields may become harmful when they interact with metals in our bodies.

Protective effect of melatonin against in vitro iron ions and 7 mT 50 Hz magnetic field-induced DNA damage in rat lymphocytes.

Jajte J, Zmyślony M, Palus J, Dziubałtowska E, Rajkowska E. · 2001

Researchers exposed rat blood cells to power-line magnetic fields plus iron, finding DNA damage only when both were present together. Melatonin (a natural hormone) reduced this damage by 50-100% depending on dose, suggesting magnetic fields may harm DNA through oxidative stress mechanisms.

Influence of extremely low frequency magnetic fields on Ca2+ signaling and double messenger system in mice hippocampus and reversal function of procyanidins extracted from lotus seedpod.

Zhang H et al. · 2017

Researchers exposed mice to power line frequency magnetic fields for 4 hours daily over 28 days. The exposure disrupted brain chemistry in the hippocampus, reducing proteins essential for memory and learning while increasing harmful cellular changes that could affect cognitive function.

Chemoprotective action of lotus seedpod procyanidins on oxidative stress in mice induced by extremely low-frequency electromagnetic field exposure.

Luo X et al. · 2016

Researchers exposed mice to extremely low frequency electromagnetic fields (the type from power lines and appliances) for 4 hours daily for 28 days and found it caused oxidative stress damage in their brains. However, when mice were given lotus seed extract before and during exposure, the natural antioxidants significantly protected against this cellular damage by boosting the body's natural defense systems.

Neuroprotective effects of lotus seedpod procyanidins on extremely low frequency electromagnetic field-induced neurotoxicity in primary cultured hippocampal neurons.

Yin C, Luo X, Duan Y, Duan W, Zhang H, He Y, Sun G, Sun X · 2016

Researchers exposed rat brain cells to 50 Hz magnetic fields and found significant damage including cell death and DNA harm. However, natural compounds from lotus seed pods prevented most of this damage, suggesting magnetic fields can harm brain cells but certain antioxidants may offer protection.