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
Zhang D, Zhang Y, Zhu B, Zhang H, Sun Y, Sun C · 2017
Researchers studied 186 power plant workers exposed to high-voltage lines for over 20 years and found elevated DNA damage markers in their blood. When workers took resveratrol supplements, these harmful effects significantly improved, suggesting antioxidants may protect against electromagnetic field damage.
Azanza MJ et al. · 2013
Researchers exposed pairs of snail neurons to weak 50 Hz magnetic fields (similar to power line frequencies) to see if the fields could synchronize their electrical activity. They found that magnetic fields between 0.2 and 150 Gauss could indeed cause the neurons to fire in synchronized patterns, with stronger fields sometimes disrupting this synchronization. This suggests that extremely low frequency magnetic fields can directly influence how nerve cells communicate with each other.
Azanza MJ et al. · 2013
Spanish researchers exposed pairs of snail neurons to weak 50 Hz magnetic fields (the same frequency as household electricity) to study how these fields affect brain cell communication. They found that the magnetic fields could force neurons to fire in sync with each other, creating artificial patterns of brain activity that matched the timing of the field exposure. This suggests that extremely low frequency magnetic fields can directly influence how brain cells communicate with each other.
Cvetkovic D, Cosic I. · 2009
Researchers exposed 33 people to extremely low frequency magnetic fields at different frequencies (4-50 Hz) for 2 minutes each and measured their brain waves using EEG. They found that magnetic fields at specific frequencies could synchronize with and alter corresponding brain wave patterns, particularly in the alpha and beta frequency ranges. This suggests that magnetic fields can directly influence brain activity in measurable ways.
Zmyslony M, Rajkowska E, Mamrot P, Politanski P, Jajte J · 2004
Polish researchers exposed rat immune cells to weak magnetic fields similar to those near power lines. When aligned with Earth's magnetic field, 40 microtesla exposure significantly reduced free radicals - harmful molecules that damage cells. This shows even very weak power-frequency fields can alter basic cellular processes.
Calcabrini C et al. · 2017
Researchers exposed human skin cells to 50 Hz electromagnetic fields for one hour. The fields caused temporary oxidative stress (cellular damage from harmful molecules) at moderate strengths, but cells recovered completely within 24 hours, suggesting no lasting harm occurs.
Mannerling AC, Simkó M, Mild KH, Mattsson MO · 2010
Researchers exposed human blood cells to 50-Hz magnetic fields at household appliance levels for one hour. The exposure doubled stress protein production and increased harmful oxygen radicals by 30-40%, indicating cellular damage at magnetic field strengths commonly found near home electronics.
Naarala J et al. · 2017
Scientists exposed human blood vessel cells and rat brain cells to combinations of Earth's magnetic field and power line magnetic fields. They found that horizontal power line fields caused different cellular effects than vertical ones. This suggests power line magnetic fields may interact with Earth's natural field to influence cell behavior.
Martino CF · 2011
Researchers exposed human blood vessel cells to static magnetic fields and found that very weak fields (30 µT) reduced cell growth while stronger fields increased it. The effects appear linked to free radical production, showing even low-level magnetic fields can measurably affect cardiovascular cells.
Fernie KJ, Bird DM. · 2001
Researchers exposed American kestrels (small falcons) to electromagnetic fields similar to those from power lines for nearly 24 hours daily over 91 days. The EMF-exposed birds showed signs of immune system stress and oxidative damage, including reduced blood proteins, lower red blood cell counts, and decreased protective antioxidants. This suggests that even relatively low-level EMF exposure can trigger biological stress responses in wildlife.
Zmyślony M et al. · 2004
Polish researchers exposed rat immune cells (lymphocytes) to extremely low frequency magnetic fields at 40 microtesla - similar to levels near power lines - while also exposing them to UV radiation. They found that one-hour magnetic field exposure significantly increased DNA damage beyond what UV alone caused, suggesting the magnetic fields interfered with the cells' natural DNA repair processes.
Lee D, Lee J, Lee I. · 2015
Researchers exposed guppies and zebrafish to cell phone radiation (1800 MHz) for 3 minutes and tracked their swimming behavior. They found that fed fish showed significant changes in their movement patterns and swimming speed when exposed to the RF EMF, while hungry fish showed no changes. The study ruled out temperature effects, confirming the behavioral changes were due to the electromagnetic field itself.
Maes A, Anthonissen R, Wambacq S, Simons K, Verschaeve L. · 2016
Scientists exposed cells to 50 Hz magnetic fields from power lines at levels above 50 microtesla and found genetic damage patterns similar to Alzheimer's patients. The exposure caused chromosome instability in cells, suggesting a possible biological link between power line magnetic fields and Alzheimer's disease development.
Manikonda PK et al. · 2014
Researchers exposed young rats to 50 Hz magnetic fields from power lines for 90 days and found significant brain damage from oxidative stress. Higher magnetic field levels caused more harm across multiple brain regions, including areas controlling memory and movement, suggesting potential neurological effects.
Manikonda PK et al. · 2014
Researchers exposed young rats to extremely low frequency magnetic fields (the type emitted by power lines and household appliances) for 90 days and found significant oxidative stress damage throughout their brains. The damage was dose-dependent, meaning higher magnetic field levels caused more harm, and affected different brain regions differently. This suggests that chronic exposure to these common magnetic fields may disrupt normal brain function by overwhelming the brain's natural defense systems.
Calabrò E et al. · 2013
Researchers exposed brain cells to 50 Hz magnetic fields (household electricity frequency) at different strengths. Higher exposures damaged cell membrane proteins and reduced energy production in mitochondria, leading to decreased cell survival and suggesting power-frequency fields harm basic cellular functions.
Manikonda PK et al. · 2013
Researchers exposed young rats to extremely low frequency magnetic fields (the type from power lines and appliances) for 90 days and found significant oxidative stress damage in their brains. The damage was dose-dependent, meaning higher field strengths caused more harm, and affected different brain regions differently. This suggests that chronic exposure to these common magnetic fields may damage brain cells by overwhelming the body's natural antioxidant defenses.
Calabrò E et al. · 2013
Italian researchers exposed human brain cells to 50 Hz magnetic fields (European power frequency) and found exposures above 0.8 milliTesla damaged cellular energy systems and altered protein structures. This demonstrates measurable biological harm from power-frequency magnetic fields at levels found in some occupational environments.
Manikonda PK et al. · 2007
Researchers exposed young rats to magnetic fields from power lines for 90 days, then examined their brain tissue. The exposure disrupted calcium signaling and reduced NMDA receptor function in the hippocampus, suggesting power line magnetic fields could interfere with learning and memory development.
Manikonda PK et al. · 2007
Researchers exposed young rats to 50 Hz magnetic fields (the same frequency used in power lines) for 90 days and found significant changes in brain chemistry, specifically disrupted calcium signaling in the hippocampus, the brain region critical for memory and learning. The magnetic field exposure altered the activity of key enzymes and reduced the function of NMDA receptors, which are essential for memory formation. These findings suggest that chronic exposure to extremely low frequency magnetic fields may interfere with normal brain function and memory processes.
De Nicola M et al. · 2006
Researchers exposed human immune cells to magnetic fields and found that even weak fields (0.09 mT and higher) disrupted the cells' internal chemical balance, increasing harmful molecules called reactive oxygen species while decreasing protective antioxidants. Surprisingly, this cellular stress actually made the cells more resistant to programmed cell death (apoptosis), suggesting magnetic fields might interfere with normal cellular cleanup processes that eliminate damaged cells.
Pooam M, Nakayama M, Nishigaki C, Miyata H · 2017
Scientists exposed immune cells to 50 Hz magnetic fields from power lines at levels found near electrical devices. The magnetic fields damaged cellular energy centers, increased harmful free radicals, and triggered stress responses. This suggests everyday magnetic field exposure may stress our immune systems.
Höytö A, Herrala M, Luukkonen J, Juutilainen J, Naarala J. · 2017
Finnish researchers exposed human brain cells to 50 Hz magnetic fields from power lines for 24 hours. The fields increased harmful superoxide molecules in cells and enhanced DNA damage when combined with blue light, showing magnetic fields can affect cells independently of light exposure.
Samiee F, Samiee K. · 2017
Researchers exposed Caspian Sea carp to extremely low frequency electromagnetic fields (the same 50 Hz frequency used in power lines and household electricity) for 30 minutes to 1 hour. Fish exposed to magnetic field strengths of 3 milliTesla or higher showed severe brain damage, including tissue death. The damage worsened with both stronger fields and longer exposure times.
Martínez MA, Úbeda A, Moreno J, Trillo MÁ · 2016
Researchers exposed human brain tumor cells (neuroblastoma) to 50 Hz magnetic fields at 100 microtesla - similar to levels near power lines - for various time periods. The magnetic field exposure triggered specific cellular pathways that increased cell proliferation, with the effects appearing to be mediated by reactive oxygen species (free radicals). This suggests that power frequency magnetic fields can stimulate abnormal cell growth through oxidative stress mechanisms.