Specific Absorption Rate (SAR) measures the rate at which RF energy is absorbed by body tissue, expressed in watts per kilogram (W/kg). SAR is used to rate cell phones and other devices held against the body. The FCC limit for cell phones is 1.6 W/kg averaged over 1 gram of tissue.
Based on Building Biology Institute guidelines (W/kg (watts per kilogram)):
See where common exposures fall on the scale:
Showing 871 studies with measured sar (specific absorption rate) exposure
Sunohara T, Hirata A, Laakso I, Onishi T · 2014
Scientists tested how much electromagnetic energy people absorb from wireless phone charging pads at 140 kHz frequency. They found extremely low absorption levels - 72 nanowatts per kilogram at 1 watt power. This confirms wireless charging systems operate far below safety limits for human exposure.
Joseph W, Vermeeren G, Verloock L, Heredia MM, Martens L · 2008
Scientists measured radiofrequency radiation from phones, WiFi, and other devices in 28 real-world situations. They found office environments often had higher exposure than outdoors, with the highest levels on trains and buses where phones work harder to maintain connections, affecting actual body absorption rates.
Joseph W et al. · 2012
Researchers measured how much radiofrequency energy people absorb from TV and radio signals in five European countries. One-year-old children absorbed nearly twice as much energy as adults from the same environmental exposures, revealing important age-related differences in electromagnetic energy absorption.
Tsybulin O et al. · 2013
Researchers exposed developing quail embryos to cell phone radiation at extremely low power levels (1000 times weaker than typical phone exposure) and found dramatically different effects depending on exposure duration. Short exposure (38 hours) actually stimulated development and reduced DNA damage, while longer exposure (158 hours) stunted development and increased DNA damage. This reveals that EMF effects aren't simply dose-dependent but follow complex biological patterns.
Schwartz JL, Mealing GA · 1993
Researchers exposed frog heart tissue to 1 GHz radiofrequency radiation (similar to cell phone frequencies) for 32 minutes at various power levels to see if it affected calcium movement and heart muscle contractions. They found no changes in either calcium flow or the heart muscle's ability to contract, even at the highest exposure levels tested. This suggests that short-term RF exposure at these frequencies may not directly disrupt basic heart muscle function.
Joseph W, Vermeeren G, Verloock L, Martens L. · 2010
Researchers measured how much wireless radiation the body absorbs from cell phones and WiFi. They found that 1-year-old children absorb nearly three times more energy than adults from the same signal strength, revealing children face disproportionately higher exposure from everyday wireless devices.
Verma M, Dutta SK. · 1993
Researchers exposed cells containing neuron-specific enolase genes to low-level microwave radiation (915 MHz) and found it increased production of neuron-specific enolase, a protein that serves as a diagnostic marker for brain and lung cancers. The exposure level was extremely low at 0.05 milliwatts per kilogram, far below current safety limits. This suggests that even minimal microwave exposure can alter the expression of genes linked to cancer markers.
Deshmukh PS et al. · 2013
Researchers exposed rats to extremely low-level cell phone radiation (900 MHz) for 2 hours daily over 30 days and found significant damage to memory and learning abilities. The study also detected increased oxidative stress in the blood, indicating cellular damage from free radicals. This matters because the radiation level used was far below current safety limits, yet still produced measurable biological effects.
Deshmukh PS et al. · 2013
Researchers exposed rats to extremely low-level 900 MHz microwave radiation (similar to cell phone frequencies) for 2 hours daily over 30 days. The exposed rats showed significant cognitive impairment and increased oxidative stress (cellular damage from harmful molecules called free radicals) compared to unexposed control rats. This suggests that even very weak microwave radiation can affect brain function and cause cellular damage.
Deshmukh PS et al. · 2013
Researchers exposed rats to extremely low-level 900 MHz microwave radiation (similar to cell phone frequencies) for 2 hours daily over 30 days. The exposed rats showed significant memory and learning problems, plus increased oxidative stress (cellular damage) in their blood. This matters because the radiation level was about 1,000 times lower than current safety limits, yet still caused measurable brain and cellular effects.
Lahham A, Sharabati A, ALMasri H. · 2017
Researchers measured WiFi radiation exposure from wireless networks at 69 locations across homes, hospitals, schools, and universities in Palestine. They found power density levels averaging 0.12 μW/cm², with the highest exposures near university access points and the lowest in schools. All measured levels were well below international safety guidelines, staying at least 221 times below recommended limits even in worst-case scenarios.
Pelletier A et al. · 2013
French researchers exposed young rats to cell phone-frequency radiation for five weeks and found disrupted sleep patterns, reduced blood flow to extremities, and increased daytime eating. These changes suggest that chronic radiofrequency exposure can interfere with the body's natural energy regulation systems.
Lee W, Yang KL. · 2014
Researchers exposed fish embryos to extremely low frequency electromagnetic fields (3.2 kHz) at various intensities to study developmental effects. They found that EMF exposure accelerated embryonic development across multiple measures including eye formation, brain development, and hatching time. Fish exposed to the highest EMF levels also showed increased anxiety-like behavior after hatching.
Nittby H et al. · 2009
Researchers exposed rats to cell phone radiation at various power levels for 2 hours, then examined their brains 7 days later. They found that the blood-brain barrier (the protective shield that normally keeps toxins out of the brain) became more permeable, allowing proteins to leak into brain tissue. This suggests that even a single exposure to cell phone radiation can compromise the brain's protective barrier for at least a week.
Eberhardt JL, Persson BR, Brun AE, Salford LG, Malmgren LO · 2008
Swedish researchers exposed rats to cell phone radiation at levels similar to what users experience and found it damaged the blood-brain barrier (the protective shield around the brain) and harmed brain cells. The damage appeared at very low exposure levels and persisted for weeks after exposure ended. This suggests that regular cell phone use could potentially compromise brain protection and cause neurological damage over time.
Eberhardt JL, Persson BR, Brun AE, Salford LG, Malmgren LO. · 2008
Swedish researchers exposed rats to cell phone radiation at 900 MHz for 2 hours and examined their brains 14 and 28 days later. They found that the radiation compromised the blood-brain barrier (the protective shield around the brain) and caused nerve cell damage. The blood-brain barrier leaked proteins into brain tissue within 14 days, while actual nerve cell death appeared after 28 days.
Bourdineaud JP et al. · 2017
Scientists exposed earthworms to cell phone radiation (900 MHz) for two hours at levels far below safety limits. The worms showed DNA damage and stress responses that lasted over 24 hours after exposure ended, suggesting even brief, low-level mobile phone frequencies cause lasting biological harm.
Bourdineaud JP et al. · 2017
Earthworms exposed to cell phone radiation (900 MHz) for two hours showed DNA damage and stress responses lasting 24+ hours. The radiation levels were 100 times weaker than safety limits, yet still caused genetic changes, suggesting brief low-level EMF exposure creates lasting biological effects.
Cain CD, Thomas DL, Adey WR · 1997
Researchers exposed mouse cells to cell phone-like radiation (836.55 MHz TDMA signals) for 28 days to see if it would enhance cancer cell formation when combined with a known tumor-promoting chemical. The radiation exposure at levels similar to cell phone use did not increase cancer cell formation compared to unexposed cells. This suggests that this type of radiofrequency exposure does not act as a tumor promoter in laboratory cell cultures.
Stagg RB, Thomas WJ, Jones RA, Adey WR · 1997
Researchers exposed brain cells (both normal and cancerous glioma cells) to cell phone-like radiofrequency radiation at 836.55 MHz for 24 hours to see if it would promote tumor growth by affecting DNA synthesis. While they found small increases in DNA activity in some cancer cell experiments, this didn't translate to actual increased cell growth or proliferation in either normal or cancerous cells.
Schwartz JL, House DE, Mealing GA · 1990
Researchers exposed isolated frog hearts to 240-MHz radio frequency fields (similar to some wireless communication frequencies) for 30 minutes to study calcium movement in heart tissue. They found that when the RF field was pulsed at 16 Hz, calcium ions moved out of the heart cells at rates 18-21% higher than normal, but only at very low power levels. This suggests that even weak RF fields can disrupt normal cellular processes in heart tissue when delivered at specific frequencies.
Pérez-Castejón C et al. · 2009
Spanish researchers exposed human brain cancer cells (astrocytoma) to pulsed microwave radiation at 9.6 GHz for various time periods up to 24 hours. They found that after 24 hours of exposure, the cancer cells showed significantly increased proliferation (growth and division) compared to unexposed cells, even at extremely low power levels. This suggests that microwave radiation may accelerate the growth of existing brain tumors.
Ghazizadeh V, Nazıroğlu M · 2014
Researchers exposed brain and nerve cells from epileptic rats to Wi-Fi radiation (2.45 GHz) for one hour and found it triggered additional calcium influx and cell death beyond what epilepsy alone caused. The Wi-Fi exposure activated specific calcium channels (TRPV1) that allowed harmful calcium to flood into neurons, leading to oxidative stress and programmed cell death. This suggests Wi-Fi radiation may worsen neurological conditions by overwhelming brain cells with calcium.
Deshmukh PS et al. · 2016
Researchers exposed rats to cell phone radiation (900-2450 MHz) for 2 hours daily over 90 days at levels 1000 times below safety limits. The low-level radiation still impaired learning and memory while damaging brain DNA, suggesting current safety standards may be inadequate.
Megha K et al. · 2015
Researchers exposed rats to low-level cell phone radiation (900 MHz and 1800 MHz) for 30 days and measured brain chemicals called neurotransmitters, which help brain cells communicate. The exposed rats showed significant decreases in four key neurotransmitters (dopamine, norepinephrine, epinephrine, and serotonin) in the brain region responsible for memory and learning. These changes could explain why some people report memory and concentration problems after heavy cell phone use.