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 899 studies with measured sar (specific absorption rate) exposure
Lai H, Carino MA, Horita A, Guy AW, · 1992
Researchers exposed rats to 2450 MHz microwave radiation (similar to WiFi frequencies) for 45 minutes and found it reduced brain chemicals needed for memory and learning in the hippocampus. This shows microwave radiation can disrupt normal brain function through the body's natural opioid pathways.
Lai H, Carino MA, Horita A, Guy AW · 1992
Researchers exposed rats to microwave radiation (2450 MHz) for 45 minutes and measured changes in brain receptors that respond to anxiety and stress. A single exposure increased these stress-related receptors in the brain's cortex, but repeated exposures over 10 days showed the brain adapted to the radiation. The findings suggest that microwave radiation at levels similar to some wireless devices can trigger a stress response in the brain.
Lai H, Carino MA, Wen YF, Horita A, Guy AW · 1991
Researchers exposed rats to microwave radiation at 2450 MHz (the same frequency as WiFi and microwave ovens) and found it altered brain receptors involved in memory and learning. When they gave the rats naltrexone (a drug that blocks opioid receptors) before exposure, it prevented these brain changes. This suggests microwave radiation affects the brain through the body's natural opioid system.
Partsvania B, Sulaberidze T, Shoshiashvili L, Modebadze Z · 2011
Scientists exposed mollusk neurons to 900-MHz cell phone radiation at low levels. While the neurons' basic function remained normal, they responded to signals significantly faster during exposure. This suggests cell phone radiation can alter how quickly nerve cells process information, even temporarily.
Partsvania B, Sulaberidze T, Shoshiashvili L, Modebadze Z · 2011
Scientists exposed mollusk nerve cells to 900 MHz cell phone radiation for one hour. While the neurons still fired normally, they responded faster to stimulation after exposure. This shows cell phone radiation can alter how quickly individual nerve cells process information, even temporarily.
Spiers DE, Baummer SC · 1991
Scientists exposed developing quail eggs to microwave radiation for 8 hours daily and found it accelerated embryo growth by 9-61% through heating effects. The faster development occurred without apparent abnormalities, demonstrating that microwave exposure can alter biological processes even when organisms seem normal.
Shirai T et al. · 2007
Researchers exposed young rats to cell phone-like radiation (1.95 GHz W-CDMA signals) for 2 years to see if it would promote brain tumor development in animals already given a cancer-causing chemical. The study found no significant increase in brain tumors from the radiation exposure at levels of 0.67 and 2.0 W/kg SAR. This suggests that chronic exposure to this type of cell phone radiation does not accelerate brain tumor formation in this animal model.
Roggeveen S, van Os J, Lousberg R · 2015
Dutch researchers measured brain activity in 31 women exposed to 3G phone radiation. Brain scans showed measurable electrical responses within milliseconds of exposure, even though participants couldn't consciously detect when phones were transmitting, proving brains unconsciously respond to mobile phone radiation.
Roggeveen S, van Os J, Viechtbauer W, Lousberg R · 2015
Researchers exposed 31 healthy women to 3G cell phone radiation for 15 minutes and measured brain activity using EEG (electroencephalogram, which records electrical activity in the brain). They found significant changes in multiple brain wave patterns when the phone was held to the ear, but not when placed on the chest. This demonstrates that cell phone radiation can directly alter brain activity in just 15 minutes of exposure.
Roggeveen S, van Os J, Lousberg R. · 2015
Researchers used EEG brain scans to monitor 31 women while they held active versus inactive 3G phones near their ears for 15 minutes. When the phone was actively transmitting radiation near the ear, their brains showed measurable electrical responses that occurred unconsciously within milliseconds of each radiation pulse. This demonstrates that human brains can detect and respond to cell phone radiation even when people aren't aware of the exposure.
Roggeveen S, van Os J, Viechtbauer W, Lousberg R. · 2015
Researchers exposed 31 healthy women to 3G cell phone radiation for 15 minutes and measured their brain wave activity using EEG. They found significant changes in multiple brain wave patterns (alpha, beta, and gamma waves) when the phone was held at the ear, but no changes when placed on the chest. This demonstrates that cell phone radiation can directly alter brain electrical activity in a location-specific way.
Shahbazi-Gahrouei D et al. · 2012
Researchers tested whether cell phone radiation interferes with laboratory blood tests that measure pregnancy hormones (chorionic gonadotropin). They exposed blood samples to 900MHz radiation from two phones with different power levels and found that the radiation significantly altered the test results, especially at higher concentrations and stronger radiation levels. This suggests that cell phones could interfere with important medical tests in hospital laboratories.
Klose M et al. · 2014
German researchers exposed young rats to cell phone radiation (900 MHz) for nearly their entire lives, testing their learning and memory abilities at different ages. Despite using radiation levels up to 10 W/kg (much higher than typical phone exposure), they found no significant effects on behavior, memory, or brain development. This long-term study suggests that chronic cell phone radiation exposure starting in early development may not impair cognitive function.
Leung S et al. · 2011
Researchers tested how 2G and 3G cell phone signals affect brain function in teenagers and adults during 55-minute exposures. They found 3G signals reduced memory accuracy in teenagers, while both signal types altered brain wave patterns in all age groups, showing measurable impacts on brain processing.
Vorobyov V, Janać B, Pesić V, Prolić Z. · 2010
Researchers monitored brain activity in rats exposed to low-level microwave radiation (similar to cell phone signals) for 10 minutes daily over five days. They found that repeated exposures disrupted the normal communication patterns between two key brain regions - the cortex (responsible for thinking) and hypothalamus (which controls hormones and basic body functions). The effects got stronger with each day of exposure, suggesting the brain changes accumulate over time.
Croft RJ et al. · 2010
Scientists tested how 2G and 3G cell phone signals affect brain waves in 103 people of different ages during 55-minute exposures. Only young adults showed brain wave changes from 2G signals, while teenagers and elderly showed no effects, suggesting age influences brain sensitivity to phone radiation.
Malyapa RS et al. · 1997
Researchers exposed lab-grown cells to microwave radiation at 2450 MHz (the same frequency used in microwave ovens and older WiFi) for up to 24 hours to see if it would damage DNA. Using a highly sensitive test called the comet assay, they found no DNA damage at either exposure level tested. This contradicted earlier studies that suggested microwave radiation could break DNA strands in brain cells.
Ono T et al. · 2004
Researchers exposed pregnant mice to 2.45 GHz radiofrequency radiation (the same frequency used in microwave ovens and WiFi) for 16 hours daily throughout pregnancy, then examined their offspring for DNA mutations in brain, liver, spleen, and reproductive organs. They found no increase in genetic damage compared to unexposed mice, even at radiation levels significantly higher than typical human exposure. This suggests that prenatal RF exposure at these levels does not cause detectable DNA mutations in developing mammals.
Karaca E et al. · 2012
Researchers exposed mouse brain cells to radiofrequency radiation at 10.7 GHz (similar to cell phone frequencies) and found dramatic genetic damage. The radiation caused an 11-fold increase in micronuclei formation, which indicates DNA breaks and chromosomal damage, while also altering genes involved in cell death and survival. This laboratory study demonstrates that RF radiation at levels comparable to cell phone exposure can directly damage brain cell DNA.
Cogulu O. · 2012
Researchers exposed mouse brain cells to radiofrequency waves at levels similar to cell phone radiation for 18 hours total over three days. They found an 11-fold increase in DNA damage markers and significant changes in genes that control cell death. This suggests that RF radiation at everyday exposure levels may harm brain cells and damage DNA.
Karaca E et al. · 2012
Turkish researchers exposed mouse brain cells to radiofrequency radiation at 10.715 GHz (similar to cell phone frequencies) for 6 hours daily over 3 days. They found an 11-fold increase in DNA damage markers and significant changes in gene expression related to cell death. This suggests that RF radiation at levels comparable to wireless devices can directly damage brain cell DNA and disrupt normal cellular functions.
Haarala C et al. · 2007
Finnish researchers tested whether mobile phone radiation affects thinking skills by having 36 men perform cognitive tasks while exposed to different types of phone signals on either the left or right side of their heads. They found no measurable differences in mental performance between real phone radiation exposure and fake exposure, regardless of which side of the head was exposed. The study suggests that typical mobile phone use doesn't impair basic cognitive functions like memory or attention in healthy adults.
Krause CM, Pesonen M, Haarala Björnberg C, Hämäläinen H. · 2007
Finnish researchers exposed 72 men to 902 MHz mobile phone radiation while they performed memory tasks, measuring brain wave patterns through EEG. The study found only modest, inconsistent effects on brain oscillations in the alpha frequency range, with no impact on actual memory performance. The researchers concluded that any brain wave changes from phone radiation appear to be subtle, variable, and difficult to replicate consistently.
Paul Raj R, Behari J, Rao AR · 1999
Researchers exposed young rats to radiofrequency radiation at cell phone-like levels for 35 days and found significant changes in brain chemistry, including increased calcium movement and enzyme activity. These cellular changes in developing brains suggest RF exposure during growth may disrupt normal brain function.
Ning W, Xu SJ, Chiang H, Xu ZP, Zhou SY, Yang W, Luo JH · 2007
Researchers exposed developing rat brain cells (hippocampal neurons) to cell phone radiation at 1800 MHz for 15 minutes daily over 8 days. At the higher exposure level (2.4 W/kg), the radiation significantly disrupted normal brain cell development, reducing the formation of dendrites (the branch-like structures neurons use to communicate) and synapses (connection points between neurons). This suggests cell phone radiation during critical developmental periods could interfere with normal brain formation.