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
Janać B et al. · 2012
Researchers exposed young and older gerbils to power-line frequency magnetic fields for seven days. Both age groups showed significant behavioral changes, with younger animals becoming more active. The effects persisted three days after exposure ended, indicating potential lasting impacts on brain function.
Markkanen A, Naarala J, Juutilainen J · 2010
Finnish researchers tested whether 50 Hz magnetic fields (the type from power lines) could amplify DNA damage from UV radiation in mouse cells. They exposed cells to magnetic fields of 100-300 microTesla during or before UV exposure and measured cellular oxidative stress. The study found no evidence that magnetic fields increased UV-induced damage, contradicting their hypothesis about how magnetic fields might affect cellular chemistry.
Morabito C et al. · 2010
Researchers exposed muscle cells to extremely low frequency electromagnetic fields (the type from power lines and household wiring) for short periods and measured cellular stress responses. The EMFs triggered increased production of harmful reactive oxygen species, disrupted the cells' energy-producing mitochondria, and altered calcium levels that control muscle function. These changes suggest that even brief EMF exposure can disrupt fundamental cellular processes in muscle tissue.
Morabito C, Guarnieri S, Fanò G, Mariggiò MA · 2010
Researchers exposed nerve cells to electromagnetic fields for 30 minutes or 7 days. Brief exposures increased harmful molecules and disrupted calcium signaling essential for nerve function, while longer exposures showed different effects. These findings suggest EMF exposure can interfere with healthy nerve cell development.
Akdag MZ, Dasdag S, Ulukaya E, Uzunlar AK, Kurt MA, Taşkin A · 2010
Researchers exposed rats to magnetic fields at safety-approved levels for 10 months. Even these "safe" exposures caused brain cell damage and reduced natural antioxidant defenses. This suggests current safety standards may not adequately protect against long-term biological harm.
Akdag MZ et al. · 2010
Researchers exposed rats to extremely low-frequency magnetic fields at levels matching current safety standards for 2 hours daily over 10 months. They found that these exposures significantly increased oxidative stress (cellular damage from free radicals) and weakened the brain's natural antioxidant defenses, though they didn't trigger cell death. This suggests that even magnetic field exposures within current safety limits may cause harmful biochemical changes in brain tissue over time.
Akdag MZ et al. · 2010
Researchers exposed rats to low-frequency magnetic fields at safety-approved levels for 10 months. The fields increased harmful oxidative stress and weakened brain antioxidant defenses without killing cells. This suggests current safety standards may not prevent cellular damage from long-term exposure.
Di Loreto S et al. · 2009
Researchers exposed rat brain cells to 50 Hz magnetic fields and found the exposure improved cell survival and reduced cell death. The magnetic fields also triggered protective antioxidant responses and increased production of proteins that support brain health, suggesting potential protective effects.
Falone S et al. · 2008
Scientists exposed young and old rats to power-line magnetic fields for 10 days. Young rats strengthened their brain's protective systems, but older rats experienced weakened defenses against cellular damage. This suggests aging makes brains more vulnerable to magnetic field exposure from electrical devices.
Yokus B, Akdag MZ, Dasdag S, Cakir DU, Kizil M · 2008
Researchers exposed rats to power line frequency magnetic fields for 10 months and found DNA damage in their blood cells. The exposure caused oxidative damage that creates genetic mutations potentially leading to cancer, providing first direct evidence of cellular harm.
Falone S et al. · 2008
Researchers exposed young and old rats to power line magnetic fields for 10 days. Young rats strengthened their brain's antioxidant defenses, but older rats experienced weakened protection against cellular damage, suggesting aging increases vulnerability to electromagnetic field effects.
Falone S et al. · 2008
Italian researchers exposed young and older rats to 50 Hz magnetic fields from power lines for 10 days. Young rats strengthened their brain's antioxidant defenses, but older rats experienced significant weakening of these protective systems, suggesting aging brains are more vulnerable to EMF damage.
Carrubba S, Frilot C, Chesson AL, Marino AA. · 2007
Researchers exposed eight people to weak 60 Hz magnetic fields from power lines for two seconds and measured brain activity. The brain consistently responded to these brief exposures in complex ways that standard tests couldn't detect, suggesting humans may be more sensitive to electromagnetic fields than previously recognized.
Akdag MZ, Bilgin MH, Dasdag S, Tumer C · 2007
Researchers exposed rats to extremely low-frequency magnetic fields (the type produced by power lines and household wiring) for 2 hours daily over 10 months. They found that this exposure significantly reduced nitric oxide levels in the blood, a molecule essential for healthy blood vessel function and immune response. The magnetic field strengths tested were within current safety limits set by international guidelines.
Carrubba S, Frilot C, Chesson AL, Marino AA. · 2007
Researchers exposed eight people to weak 60 Hz magnetic fields (1 gauss) for 2 seconds and measured their brain activity using specialized electrodes. They discovered that human brains can detect these low-level magnetic fields and respond in complex, nonlinear ways that standard testing methods miss. This suggests humans may have an evolutionary magnetic sensing ability that makes us vulnerable to artificial electromagnetic fields in our environment.
Noda Y, Mori A, Liburdy RP, Packer L · 2000
Researchers exposed rat brain tissue to weak pulsed magnetic fields at 0.1 mT and found an 11% increase in nitric oxide production specifically in the cerebellum. This shows extremely weak magnetic fields can alter brain chemistry in targeted regions, potentially affecting neurological function.
Yoshikawa T et al. · 2000
Researchers exposed mice to 60 Hz magnetic fields (the same frequency as power lines) at 0.1 mT to see how it affected nitric oxide production in the liver. They found that magnetic field exposure alone didn't generate nitric oxide, but when combined with an immune system trigger, it significantly enhanced nitric oxide production compared to the trigger alone. This suggests that power frequency magnetic fields may amplify certain biological responses even when they don't cause direct effects.
Roy S et al. · 1995
Researchers exposed rat immune cells called neutrophils to a weak 60 Hz magnetic field (0.1 mT) and found it increased their production of free radicals by 12.4% when the cells were stimulated. Free radicals are reactive molecules that can damage cells and contribute to inflammation and disease. This was the first study to show that magnetic fields can directly influence free radical production in living immune cells.
Kavaliers M, Choleris E, Prato FS, Ossenkopp K · 1998
Researchers exposed land snails to 60-Hz magnetic fields from power lines and found the fields disrupted the animals' natural pain relief systems by altering brain chemistry. This shows that common household electrical frequencies can interfere with basic biological processes controlling pain in living organisms.
Mohammadi F, Ghanati F, Sharifi M, Chashmi NA · 2018
Researchers exposed tobacco plant cells to weak static magnetic fields (0.2 millitesla) for 24 hours and found the magnetic field disrupted the cells' normal cycle of growth and division. The exposure triggered a cascade of cellular stress responses, including increased production of reactive molecules and changes in key proteins that control when cells divide. This demonstrates that even relatively weak magnetic fields can interfere with fundamental cellular processes.
Ayoobi F, Shamsizadeh A, Shafiei SA. · 2017
Researchers exposed 65 young adults to magnetic fields similar to power lines for three minutes. Participants showed slower reaction times after exposure compared to fake treatment, while sleepiness levels remained unchanged. This demonstrates that brief magnetic field exposure can impair cognitive performance and brain function.
Alcaraz M, Olmos E, Alcaraz-Saura M, Achel DG, Castillo J. · 2014
Researchers exposed mice to 50 Hz magnetic fields (the same frequency as power lines) for up to 28 days and found evidence of genetic damage in bone marrow cells. The magnetic field exposure caused an increase in micronucleated cells, which are markers of DNA damage, though the effect was less than X-ray radiation. Importantly, antioxidants that protect against radiation damage did not protect against the magnetic field damage, suggesting different biological mechanisms.
El Gohary MI, Salama AA, El Saeid AA, El Sayed TM, Kotb HS. · 2013
Researchers exposed rats to magnetic fields from power lines for 15 days and monitored brain activity. The magnetic fields altered brainwave patterns, particularly in the brain's right side. Caffeine appeared to modify these effects, suggesting everyday exposures may interact in unexpected ways.
El Gohary MI, Salama AA, El Saeid AA, El Sayed TM, Kotb HS. · 2013
Researchers exposed rats to extremely low frequency magnetic fields (the type emitted by power lines and appliances) for 15 days and found these fields significantly altered brain wave patterns, particularly enhancing activity in the right hemisphere. When caffeine was given alongside the magnetic field exposure, it appeared to partially counteract some of the brain changes, especially in areas controlling movement.
Amirifalah Z, Firoozabadi SM, Shafiei SA. · 2013
Researchers exposed 10 women to weak magnetic fields targeting brain regions for 9 minutes. The exposure reduced specific brainwave activity by 12-27% after treatment ended. This suggests targeted magnetic fields could potentially help treat conditions like anxiety by calming overactive brain areas.