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
Sharma A, Sisodia R, Bhatnagar D, Saxena VK · 2013
Researchers exposed mice to 10 GHz microwave radiation for two hours daily over 30 days, then tested their memory using a water maze. Exposed mice took significantly longer to learn and remember locations, with reduced brain protein levels, suggesting microwave exposure may impair learning and memory.
Spichtig S, Scholkmann F, Chin L, Lehmann H, Wolf M · 2012
Swiss researchers measured brain blood flow in 16 people exposed to 3G cell phone radiation. Even low-level exposure increased blood oxygen levels within 80 seconds, while higher levels also raised heart rate. The changes were small but measurable, showing cell phones can alter brain circulation.
Spichtig S, Scholkmann F, Chin L, Lehmann H, Wolf M · 2012
Swiss researchers measured brain blood flow in 16 people exposed to 3G cell phone radiation. They found that even low-level exposure (0.18 W/kg) changed brain circulation patterns, while higher levels increased heart rate. These effects occurred at radiation levels considered safe by current standards.
Dabrowski MP et al. · 2003
Researchers exposed immune cells from healthy volunteers to pulse-modulated 1300 MHz microwave radiation at levels similar to cell phone emissions. The radiation significantly altered immune cell function, increasing production of inflammatory molecules and changing how immune cells communicate with each other. This suggests that even low-level microwave exposure can disrupt normal immune system operations.
Dabrowski MP et al. · 2003
Researchers exposed immune cells from 16 healthy people to low-level cell phone radiation (1300 MHz) and found significant changes in immune system function. The radiation increased production of inflammatory molecules (IL-1β and IL-10) while decreasing protective factors, essentially pushing the immune system toward a more inflammatory state. These changes occurred at radiation levels similar to what you might experience from cell phone use.
McNamee JP et al. · 2016
Canadian researchers exposed mice to 1.9 GHz radiofrequency radiation (similar to cell phone signals) for 4 hours daily over 5 days and examined gene activity in seven different brain regions. They found no consistent changes in gene expression at exposure levels of 0.2 or 1.4 W/kg, though they acknowledge their study may have missed very small changes below 1.5-fold. This suggests that short-term RF exposure at these levels doesn't significantly alter how genes function in the brain.
Söderqvist F, Carlberg M, Hardell L · 2015
Swedish researchers tested whether cell phone radiation affects the blood-brain barrier (the brain's protective shield) by measuring specific proteins in blood samples from 24 volunteers before and after exposure to phone-like signals. The study found no significant differences in these barrier-protecting proteins between real exposure and fake exposure sessions. However, the researchers noted that all participants were regular cell phone users, which may have influenced the results.
Waldmann P et al. · 2013
Researchers exposed human blood cells from 40 volunteers to cell phone radiation (1,800 MHz) for 28 hours at three different intensities and tested for DNA damage using multiple methods. The study found no evidence that the radiation caused genetic damage to the cells at any exposure level. This collaborative study across six independent laboratories used rigorous controls and blinded analysis to ensure reliable results.
Lu Y et al. · 2012
Researchers exposed rats to 2.45 GHz microwave radiation (the same frequency used by WiFi and microwave ovens) for 3 hours daily over 30 days at very low power levels. The radiation caused significant memory and learning problems, and the rats' brain cells had trouble absorbing glucose, which is essential for brain function. However, when researchers gave the rats extra glucose, it reversed the memory problems.
Hirose H et al. · 2010
Japanese researchers exposed rat brain immune cells called microglia to 1950 MHz cell phone radiation for 2 hours at various power levels, then monitored the cells for signs of activation or inflammation. They found no significant differences between exposed and unexposed cells in terms of immune markers or inflammatory proteins. This suggests that short-term exposure to 3G cell phone frequencies at typical power levels does not trigger immune responses in brain cells.
Hirose H et al. · 2010
Researchers exposed brain immune cells called microglia to cell phone radiation at levels up to 2.0 W/kg for two hours to see if it would activate an inflammatory response. They found no signs of activation or increased production of inflammatory molecules compared to unexposed cells. This suggests that moderate levels of cell phone radiation don't trigger brain inflammation in laboratory conditions.
Regel SJ et al. · 2007
Swiss researchers exposed 15 men to cell phone radiation at varying intensities before sleep. Stronger radiation caused measurable changes in brain waves during sleep and slowed reaction times. This study provides evidence that EMF exposure affects brain function proportionally to radiation intensity.
Regel SJ et al. · 2007
Swiss researchers exposed 15 men to cell phone-like radiation at different intensities for 30 minutes before sleep, then monitored their brain activity and cognitive performance. They found that stronger radiation caused measurable changes in brain wave patterns during sleep and slowed reaction times on memory tasks. This demonstrates a dose-response relationship, meaning higher radiation exposure produces more pronounced effects on brain function.
Klug S, Hetscher M, Giles S, Kohlsmann S, Kramer K, · 1997
German researchers exposed developing rat embryos to radio frequency electromagnetic fields at various power levels for up to 36 hours to test whether EMF exposure during critical development stages causes birth defects or growth problems. The study found no significant effects on embryo development, growth, or cellular structure across all tested exposure levels, including levels far exceeding typical telecommunication device emissions. This suggests that RF fields at these intensities may not pose developmental risks during embryonic growth.
Phelan AM, Lange DG, Kues HA, Lutty GA · 1992
Researchers exposed melanoma cells to low-level microwave radiation at 2.45 GHz (the same frequency as microwave ovens) and found it altered cell membrane structure, making them more rigid. The effect only occurred in cells containing melanin (the pigment that gives skin its color) and was caused by oxygen radicals - harmful molecules that can damage cells. This suggests people with darker skin may be more vulnerable to microwave radiation effects.
Esmekaya MA et al. · 2011
Researchers exposed human immune cells to 1.8GHz cell phone radiation for up to 48 hours and found significant DNA damage and cellular destruction that worsened over time. Ginkgo biloba extract provided some protection, suggesting certain antioxidants might help reduce radiation-induced genetic damage in immune cells.
Faraone et al. · 2006
Scientists tested how much cell phone radiation mice absorbed in a specialized exposure system. The 900 MHz radiation (older cell phone frequency) was precisely delivered at doses up to 3.4 watts per kilogram, concentrating mainly in the head, neck, and abdomen areas.
Ntzouni MP, Stamatakis A, Stylianopoulou F, Margaritis LH. · 2011
Researchers exposed mice to cell phone radiation at human-level intensities and tested their memory recognition abilities. Mice showed significant memory problems, especially when exposed during the 17-day period when memories form. This suggests mobile phone radiation may interfere with the brain's memory formation processes.
Ntzouni MP, Stamatakis A, Stylianopoulou F, Margaritis LH · 2011
Greek researchers exposed mice to mobile phone radiation at levels similar to what humans experience during phone calls (SAR 0.22 W/kg) and tested their ability to recognize objects they had seen before. The study found that chronic exposure for 17 days significantly impaired the mice's short-term memory, particularly during the critical period when memories are being consolidated and stored in the brain. This suggests that mobile phone radiation may interfere with the brain's ability to form and retain new memories.
Chen L, Qin F, Chen Y, Sun J, Tong J. · 2014
Researchers exposed male mice to cell phone-level radiation (1800 MHz) for two hours daily over 32 days. The radiation reduced sperm count and testosterone while increasing estradiol and disrupting natural daily hormone rhythms, suggesting potential male fertility risks from cell phone use.
Kwon MS et al. · 2011
Finnish researchers exposed 13 young men to typical cell phone radiation for 33 minutes and used brain scans to measure energy use. They found glucose metabolism (brain fuel) significantly decreased in specific regions near the phone, showing even brief exposure measurably changes brain function.
Gurbuz N, Sirav B, Kuzay D, Ozer C, Seyhan N. · 2015
Researchers exposed diabetic rats to cell phone radiation (2100 MHz) to see if it caused genetic damage in bladder cells by looking for micronuclei - small fragments of broken DNA that indicate cellular damage. They found no increase in genetic damage in either healthy or diabetic rats exposed to the radiation compared to unexposed animals. The study suggests that this level of RF radiation may not cause DNA damage in bladder cells, even in animals with diabetes who might be more vulnerable.
Akar A et al. · 2012
Researchers exposed rats to WiFi-level radiation (2.45 GHz) for 2 hours daily over 21 days. They found the front layer of the cornea became significantly thicker in exposed rats compared to unexposed ones, suggesting everyday wireless device radiation may cause structural eye changes.
Bourthoumieu S et al. · 2012
Researchers exposed human embryonic cells to cell phone radiation (GSM-900 MHz) for 24 hours at various intensities to see if it would activate p53, a crucial protein that helps protect cells from DNA damage and cancer. The study found no significant changes in p53 expression or activation at any exposure level tested, including levels up to 4 W/kg. This suggests that GSM cell phone radiation may not trigger this particular cellular stress response in embryonic cells.
Terro F et al. · 2012
French researchers exposed brain cells to cell phone radiation for 24 hours and found it reduced alpha-synuclein protein levels by 24%. This protein is linked to Parkinson's disease. The changes occurred due to slight heating rather than direct cellular damage, showing radiation affects brain proteins even at typical phone exposure levels.