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
Misa Agustiño MJ et al. · 2012
Researchers exposed rats to WiFi-frequency radiation (2.45 GHz) for 30 minutes and found it triggered cellular stress responses in thyroid tissue. Heat shock proteins dropped significantly within 90 minutes, though recovered by 24 hours, demonstrating that brief microwave exposure can disrupt normal thyroid cell function.
Nittby H et al. · 2012
Swedish researchers exposed land snails to cell phone radiation at 1900 MHz (the same frequency used by many mobile phones) for one hour, then tested their response to painful heat. The radiation-exposed snails showed significantly reduced sensitivity to pain compared to unexposed snails, suggesting the electromagnetic fields had an anesthetic-like effect on their nervous systems.
Nittby H et al. · 2012
Researchers exposed land snails to cell phone radiation at 1900 MHz for one hour and tested their response to heat-induced pain. The exposed snails showed reduced sensitivity to thermal pain compared to unexposed controls, suggesting the radiofrequency radiation acted as a pain reliever. This finding indicates that non-thermal levels of cell phone radiation can alter nervous system responses in living organisms.
Schwarz C et al. · 2008
German researchers exposed human cells to cell phone radiation (UMTS, 1,950 MHz) at levels well below safety limits to test for DNA damage. They found that skin cells (fibroblasts) showed significant genetic damage at extremely low exposure levels - as little as 0.05 W/kg, which is 40 times lower than the current safety limit. However, immune cells (lymphocytes) showed no damage, suggesting different cell types respond differently to radiofrequency radiation.
Schwarz C et al. · 2008
Researchers exposed human cells to 3G mobile phone radiation (UMTS at 1,950 MHz) at levels well below safety limits to test for DNA damage. They found that certain cells called fibroblasts showed significant genetic damage after exposure, while immune cells called lymphocytes were unaffected. This suggests that 3G radiation can cause DNA damage in some human cell types even at supposedly safe exposure levels.
Takashima Y et al. · 2006
Japanese researchers exposed cells to 2.45 GHz radiation (WiFi frequency) at different power levels. Cell growth remained normal up to 100 W/kg, but died at 200 W/kg when temperatures exceeded 104°F, showing cellular damage occurs only from significant heating effects.
Dutta SK, Verma M, Blackman CF · 1994
Researchers exposed bacteria containing a mammalian enzyme gene to radiofrequency radiation and electric/magnetic fields at very low power levels. They found that 16 Hz modulation increased enzyme activity by 59-62%, while 60 Hz modulation decreased it by 24-28%. This demonstrates that biological systems can respond to extremely weak electromagnetic fields in frequency-specific ways.
Kues HA et al. · 1992
Researchers exposed monkeys to 2.45 GHz microwave radiation after applying common eye drops. The medications dramatically increased eye damage sensitivity, lowering the injury threshold from 10 mW/cm² to just 1 mW/cm². People using certain eye medications may face higher risks from everyday microwave exposure.
Terao Y et al. · 2007
Researchers tested whether 30 minutes of mobile phone exposure affects eye movement control (saccades) in 10 healthy adults. They measured various types of rapid eye movements before and after exposure to 800 MHz radiation at 0.054 W/kg SAR. The study found no significant changes in eye movement performance, suggesting short-term mobile phone use doesn't impair this aspect of brain function.
Cao H, Qin F, Liu X, Wang J, Cao Y, Tong J, Zhao H. · 2015
Researchers exposed rats to cell phone-level radiation for 2 hours daily over 32 days. The radiation disrupted natural 24-hour cycles of antioxidant production, with nighttime exposures causing the biggest drops in protective compounds like melatonin. This suggests RF radiation may interfere with the body's internal clock.
Cao H, Qin F, Liu X, Wang J, Cao Y, Tong J, Zhao H · 2015
Researchers exposed rats to cell phone radiation (1.8 GHz) for two hours daily over 32 days. The radiation disrupted natural daily rhythms of protective antioxidants in blood, with the largest decreases occurring during nighttime exposure, suggesting interference with the body's 24-hour protective cycles.
Jech R et al. · 2001
Researchers exposed 22 patients with narcolepsy (a sleep disorder causing excessive daytime sleepiness) to cell phone radiation for 45 minutes and measured their brain activity during cognitive tasks. They found that the electromagnetic fields improved the patients' reaction times by 20 milliseconds and enhanced brain responses to visual stimuli, suggesting the radiation temporarily reduced their sleepiness and improved mental performance.
Vollrath L, Spessert R, Kratzsch T, Keiner M, Hollmann H · 1997
German researchers exposed rats and hamsters to 900 MHz radio frequency fields (similar to early cell phones) for up to 6 hours to see if it would affect their pineal glands, which produce the sleep hormone melatonin. They found no changes in melatonin production or pineal gland structure at any exposure level tested. This suggests that short-term RF exposure at these levels doesn't disrupt the body's natural sleep-wake cycle regulation.
Takahashi S et al. · 2010
Researchers exposed pregnant rats to 2.14 GHz radiofrequency radiation (similar to cell tower signals) for 20 hours daily throughout pregnancy and nursing. They found no harmful effects on the mothers, their offspring, or the next generation, examining everything from growth and development to memory and reproductive function. This suggests that exposure levels similar to those from cell towers may not cause developmental problems in mammals.
Parazzini M et al. · 2009
Researchers exposed 134 healthy young adults to 20 minutes of radiofrequency radiation from UMTS mobile phones at maximum power while testing their hearing function before and after exposure. The study found no consistent changes in hearing ability, ear function, or auditory processing after the RF exposure. This suggests that short-term exposure to cell phone radiation at typical usage levels does not cause immediate measurable damage to human hearing.
Parazzini M et al. · 2009
European researchers exposed 134 healthy young adults to radiofrequency radiation from UMTS mobile phones for 20 minutes and tested their hearing immediately before and after exposure. The study found no measurable effects on hearing function, including hearing thresholds, inner ear responses, or brain processing of sound. This suggests that short-term exposure to cell phone radiation at typical usage levels doesn't immediately impact the auditory system.
Capri M et al. · 2004
Researchers exposed human immune cells to cell phone radiation for three days. GSM signals (used by mobile phones) slightly reduced immune cell growth and altered cell membranes, while steady radiation showed no effects. This suggests pulsed phone signals may uniquely affect immune function.
Lu ST, Mathur SP, Akyel Y, Lee JC · 1999
Researchers exposed rats to ultrawide-band electromagnetic pulses (a type of radar technology) for just 6 minutes and measured their blood pressure for up to 4 weeks afterward. The exposed rats developed persistent low blood pressure (hypotension) that lasted for weeks, while their heart rate remained normal. This suggests that brief exposure to these high-intensity electromagnetic pulses can cause lasting cardiovascular effects.
Raslear TG, Akyel Y, Bates F, Belt M, Lu ST · 1993
Researchers exposed rats to extremely high-power pulsed microwaves while the animals performed time discrimination tasks to test cognitive function. The microwave exposure impaired the rats' ability to distinguish between different time durations and increased their failure to respond during trials, even at power levels well below safety guidelines. This suggests that pulsed microwave radiation can affect decision-making and cognitive processing in the brain.
Chagnaud, JL, Moreau, JM, Veyret, B · 1999
Researchers exposed rats with chemically-induced tumors to GSM cell phone radiation (900 MHz) for 2 hours daily over 2 weeks to see if the radiation would accelerate cancer development. The study found no effect - the microwave exposure neither sped up nor delayed tumor growth, and didn't affect animal survival rates. The exposure levels used were within current safety limits for human whole-body exposure.
Taberski K et al. · 2014
Researchers exposed hamsters to 900 MHz electromagnetic fields (similar to 2G cell phone signals) at different power levels for one week each to study metabolic changes. At the highest exposure level (4 W/kg), hamsters showed reduced daytime metabolism, lower food consumption, and slightly elevated skin temperature, even though their core body temperature remained stable. This suggests that high-level radiofrequency exposure can alter basic metabolic processes in mammals.
Shirai T et al. · 2014
Japanese researchers exposed three generations of rats to cell phone signals (2.14 GHz W-CDMA) for 20 hours daily, testing brain function and development across multiple generations. They found no adverse effects on brain function, behavior, or development in any of the three generations studied. This comprehensive multigenerational study suggests that chronic exposure to these specific cell phone frequencies at the tested levels did not cause detectable brain or developmental problems in rats.
Shirai T et al. · 2014
Japanese researchers exposed rats to cell phone radiation (2.14 GHz W-CDMA signals) for 20 hours daily across three generations to see if it affected brain development and behavior. They found no abnormalities in brain function, behavior, or general health in any generation of rats, even with continuous exposure from pregnancy through adulthood. The study suggests that this type of cell phone radiation at these exposure levels does not cause harmful effects that pass from parents to offspring.
Poulletier de Gannes F et al. · 2012
French researchers exposed pregnant rats to Wi-Fi signals (2.45 GHz) for 2 hours daily during pregnancy to test whether this radiation could harm developing babies. They found no birth defects, developmental problems, or other harmful effects in the rat pups, even at the highest exposure level tested (4 W/kg). This study suggests that Wi-Fi exposure during pregnancy may not cause developmental harm at levels tested.
Sambucci M et al. · 2011
Italian researchers exposed newborn mice to WiFi-like signals (2.45 GHz) for 5 weeks during early development to see if young immune systems are more vulnerable to wireless radiation. They found essentially no effects on immune system development at either low (0.08 W/kg) or high (4 W/kg) exposure levels, with only one minor change in male mice at the higher level. The study suggests that developing immune systems may not be as sensitive to WiFi radiation as some have theorized.