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 443 studies with measured magnetic fields (elf) exposure
Goraca A, Ciejka E, Piechota A. · 2010
Researchers exposed rats to magnetic fields used in medical therapy to test heart effects. Thirty minutes daily caused no harm, but sixty minutes significantly increased cellular damage and reduced natural antioxidants. This shows exposure duration matters more than field strength for heart health.
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.
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.
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.
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.
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.
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.
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.
Duan Y, Wang Z, Zhang H, He Y, Fan R, Cheng Y, Sun G, Sun X. · 2014
Researchers exposed mice to 50 Hz magnetic fields (the same frequency as power lines) for 28 days and found significant brain changes in the hippocampus, a region critical for memory and learning. The exposure disrupted brain chemistry by increasing glutamate levels and damaging cellular signaling pathways that are essential for proper brain function. Importantly, the study also showed that these harmful effects could be reversed with a natural antioxidant treatment.
Duan Y, Wang Z, Zhang H, He Y, Fan R, Cheng Y, Sun G, Sun X. · 2014
Researchers exposed mice to 50 Hz electromagnetic fields (the same frequency used in power lines) for 4 hours daily over 28 days and found significant cognitive impairment and brain chemistry changes. The EMF exposure disrupted critical brain chemicals like glutamate and damaged important cellular pathways involved in memory formation. However, treatment with natural antioxidants from lotus seeds reversed these harmful effects, suggesting the brain damage was preventable.
Duan Y, Wang Z, Zhang H, He Y, Lu R, Zhang R, Sun G, Sun X. · 2013
Researchers exposed mice to 50 Hz magnetic fields (8 mT) for 28 days and found significant damage to learning and memory abilities, plus harmful oxidative stress in brain tissue. When mice were also given lotus seedpod extract, these negative effects were largely prevented. This suggests that extremely low frequency electromagnetic fields can damage brain function through oxidative stress mechanisms.
Duan Y, Wang Z, Zhang H, He Y, Lu R, Zhang R, Sun G, Sun X. · 2013
Researchers exposed mice to 50 Hz magnetic fields (the type from power lines) for 28 days and found it damaged their learning, memory, and brain cells through oxidative stress. When mice were given lotus seedpod antioxidants during exposure, these harmful effects were largely prevented. This suggests that extremely low frequency EMF exposure can cause measurable brain damage, but antioxidants may offer some protection.
Li Y, Zhang Y, Wang W, Zhang Y, Yu Y, Cheing GL, Pan W. · 2019
Researchers exposed rats with chemically-induced dementia to pulsed magnetic fields (10 mT at 20 Hz) and found dramatic improvements in learning and memory abilities. The treated rats showed 66% faster escape times in maze tests and 55% shorter swimming distances compared to untreated dementia rats. The magnetic field exposure also increased expression of genes linked to brain growth and repair, suggesting the fields may help protect against cognitive decline.
Hong I et al. · 2018
Researchers exposed rat brain cells to weak magnetic fields at 1 Hz and 10 Hz frequencies, finding both altered cellular energy processes, with 1 Hz having stronger effects. This demonstrates that magnetic fields can change how brain cells function biochemically, providing insights into magnetic stimulation's neural effects.
Akbarnejad Z et al. · 2018
Researchers injected rats with Alzheimer's-causing proteins and then exposed them to magnetic fields (50 Hz at 10 milliTesla) for 14 days. The magnetic field exposure significantly improved memory and learning abilities in the Alzheimer's rats, as measured by maze tests. This suggests that certain electromagnetic fields might help protect brain function in neurodegenerative diseases.
Djordjevic NZ, Paunović MG, Peulić AS · 2017
Researchers exposed rats to 50 Hz electromagnetic fields (the type from power lines and household wiring) for one week and found the animals developed anxiety-like behaviors. Brain analysis revealed increased oxidative stress and nitric oxide in the hypothalamus, the brain region that regulates emotions and stress responses. This suggests that even short-term exposure to extremely low frequency EMFs can alter brain chemistry in ways that affect mood and behavior.
Gao X, Wang X, Chen F, Qi H, Wang X, Ming D, Zhou P. · 2014
Chinese researchers exposed 10 people to extremely low frequency magnetic fields (1 Hz pulses at 10 milliTesla) for 20 minutes and measured their brain activity using EEG. They found significant changes in brainwave patterns and slower cognitive processing compared to a sham exposure group. This demonstrates that even brief exposure to pulsed magnetic fields can measurably alter brain function.
Glinka M, Sieroń A, Birkner E, Cieślar G · 2013
Researchers exposed rats with skin wounds to 40 Hz magnetic fields at 10 mT (millitesla) to see if it would help healing. They found the magnetic field exposure increased antioxidant enzyme activity and reduced cellular damage markers, suggesting the treatment helped protect cells from harmful oxidative stress during the wound healing process.
Korpinar MA, Kalkan MT, Tuncel H. · 2012
Researchers exposed rats to 50 Hz magnetic fields (the same frequency as power lines) at 10 milliTesla for 21 days and measured their behavior using standard anxiety tests. The exposed rats showed significantly more anxiety and stress-related behaviors, spending much less time in open, exposed areas compared to unexposed rats. This suggests that prolonged exposure to power-frequency magnetic fields may increase anxiety levels.
Korpinar MA, Kalkan MT, Tuncel H. · 2012
Researchers exposed rats to 50 Hz magnetic fields (the same frequency as household electrical wiring) for 21 days and measured their anxiety levels using standard behavioral tests. The exposed rats showed significantly higher anxiety and stress-related behaviors compared to unexposed rats, spending much less time in open, exposed areas of test mazes. This suggests that prolonged exposure to power-frequency magnetic fields may increase stress responses in the brain.
Henrykowska G et al. · 2009
Researchers exposed human blood platelets to power line frequency magnetic fields for 15 minutes. The exposure increased cellular damage markers and free radicals while reducing natural antioxidant defenses, suggesting that brief magnetic field exposure can disrupt normal cell function and potentially harm health.
Sahebjamei H, Abdolmaleki P, Ghanati F · 2007
Researchers exposed tobacco plant cells to static magnetic fields of 10 and 30 millitesla for 5 hours daily over 5 days to study effects on cellular defense systems. The magnetic field exposure disrupted the cells' antioxidant enzyme balance, decreasing some protective enzymes while increasing cellular damage markers. This suggests that magnetic fields can weaken biological cells' ability to defend against harmful oxidative stress.
Wang X et al. · 2008
Researchers exposed rats to extremely low-frequency electromagnetic fields (20 Hz) during morphine treatment to study brain changes after drug withdrawal. They found that EMF exposure made the reduction of dopamine D2 receptors in the hippocampus (a brain region crucial for memory and learning) even more severe during withdrawal. This suggests that EMF exposure may worsen brain chemistry changes associated with drug addiction and withdrawal.
Jouni FJ, Abdolmaleki P, Ghanati F. · 2012
Researchers exposed broad bean plants to static magnetic fields for eight days, finding reduced antioxidant defenses and DNA damage. Effects worsened when combined with naturally radioactive soil, demonstrating that magnetic fields can overwhelm biological protection systems and cause genetic harm in living organisms.
Ahmed Z, Wieraszko A. · 2008
Researchers exposed brain tissue from the hippocampus (memory center) to pulsed magnetic fields for 30 minutes. The neurons became significantly more electrically active, firing more signals and changing how they communicate. This shows magnetic fields can directly alter brain cell function.