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
Ammari M et al. · 2010
French researchers exposed rats to cell phone radiation for 8 weeks and found increased brain inflammation markers that lasted at least 10 days after exposure ended. This suggests chronic mobile phone use may trigger inflammatory brain responses similar to those seen in neurodegenerative diseases.
Yang X, He G, Hao Y, Chen C, Li M, Wang Y, Zhang G, Yu Z · 2010
Researchers exposed brain immune cells called microglia to 2.45 GHz radiofrequency radiation (the same frequency used in WiFi and microwave ovens) for 20 minutes at high intensity. They found that this EMF exposure triggered inflammation in the brain cells by activating a specific molecular pathway called JAK2-STAT3, which led to increased production of inflammatory chemicals. This suggests that EMF exposure may contribute to brain inflammation through well-defined biological mechanisms.
Ammari M, Lecomte A, Sakly M, Abdelmelek H, de-Seze R. · 2008
French researchers exposed rats to cell phone radiation and measured brain enzyme activity. High-intensity exposure (6 W/kg) for 15 minutes daily reduced brain activity in memory and decision-making regions after one week. Lower exposures showed no effects, suggesting intensity matters for brain function.
Ammari M et al. · 2008
French researchers exposed rats to cell phone radiation (900 MHz) for 24 weeks and found that high-level exposure caused persistent brain inflammation. The study measured GFAP, a protein that increases when brain support cells called astrocytes become activated in response to injury or stress. This suggests that chronic cell phone radiation exposure may trigger ongoing inflammatory responses in brain tissue.
Ammari M et al. · 2008
French researchers exposed rats to 900-MHz cell phone radiation for up to 24 weeks to test whether it would impair their spatial memory and navigation abilities. The rats showed no memory deficits even when exposed to radiation levels 3-12 times higher than typical cell phone use. This suggests that chronic exposure to GSM cell phone signals may not directly damage the brain's memory systems.
Brillaud E, Piotrowski A, de Seze R. · 2007
French researchers exposed rats to cell phone radiation (900MHz GSM signal) for just 15 minutes and then examined their brains over the following 10 days. They found significant increases in glial cell activity (brain cells that support and protect neurons) in multiple brain regions, peaking 2-3 days after exposure. This glial response indicates the brain was reacting to the radiation exposure as if responding to injury or stress.
Brillaud E, Piotrowski A, de Seze R · 2007
French researchers exposed rats to 15 minutes of cell phone radiation and found brain inflammation that peaked after 2 days and lasted up to 10 days. The study measured stress proteins in brain tissue, suggesting brief phone exposure can trigger inflammatory responses in the brain.
Mausset-Bonnefont AL et al. · 2004
French researchers exposed rats to cell phone radiation (900 MHz GSM) for just 15 minutes and found immediate brain damage. The exposure triggered a strong inflammatory response from brain support cells (glial reaction) and disrupted key brain chemical systems involved in movement, memory, and mood. Despite these cellular changes, the rats showed no obvious behavioral problems in the short term.
Adair ER, Cobb BL, Mylacraine KS, Kelleher SA, · 1999
Researchers exposed 14 volunteers to radio frequency radiation at 450 and 2450 MHz (similar to cell phone frequencies) for 45 minutes at power levels exceeding current safety guidelines. The exposure caused measurable increases in skin temperature, with the body responding through increased sweating and blood flow to maintain normal core body temperature within 0.1 degrees Celsius.
Behari J, Kunjilwar KK, and Pyne S · 1998
Researchers exposed developing rats to radiofrequency radiation similar to what cell phones emit and found it significantly increased activity of a critical brain enzyme called Na+-K+-ATPase by 15-20%. This enzyme is essential for nerve cell function and brain development. The findings suggest that RF radiation can alter fundamental brain chemistry in developing animals, raising concerns about potential effects on brain development in children.
Hao Y, Yang X, Chen C, Yuan-Wang, Wang X, Li M, Yu Z · 2010
Researchers exposed brain immune cells called microglia to 2.45 GHz radiation (the same frequency used in WiFi and microwave ovens) for 20 minutes and found it activated these cells through a specific cellular pathway called STAT3. The activated microglia began producing inflammatory molecules including nitric oxide and tumor necrosis factor-alpha. This matters because microglial activation is linked to brain inflammation and neurological problems.
Maes A, Collier M, Verschaeve L · 2000
Belgian researchers exposed human immune cells (lymphocytes) to radiation from a 455.7 MHz car phone at high intensity levels (6.5 W/kg SAR) to see if it would cause genetic damage or make the cells more vulnerable to other cancer-causing agents. They found no evidence that the phone radiation caused chromosome damage on its own, nor did it increase the harmful effects when combined with known mutagens like chemicals or X-rays.
Harvey C, French PW · 2000
Researchers exposed human immune cells to microwave radiation at 864.3 MHz for 20 minutes daily over seven days. The exposure altered key cellular proteins and changed gene expression related to cell growth and death, even at temperatures too low to cause heating effects.
Harvey C, French PW. · 2000
Researchers exposed human immune cells (mast cells) to microwave radiation at 864.3 MHz for 20 minutes daily over a week, using power levels that kept the cells cooler than body temperature. They found that this non-thermal exposure altered the activity of protein kinase C (a key cellular signaling molecule) and changed the expression of three genes, including one linked to cancer development and another associated with cell death.
Natarajan M, Vijayalaxmi , Szilagyi M, Roldan FN, Meltz ML · 2002
Researchers exposed human immune cells called monocytes to high-powered pulsed microwave radiation at 8.2 GHz for 90 minutes and measured changes in their cellular activity. They found that the radiation triggered a 3.6-fold increase in the activity of NF-κB, a crucial protein that controls genes involved in inflammation, immune responses, and cell survival. This demonstrates that microwave radiation can activate important cellular signaling pathways that regulate long-term cellular functions.
Kim TH et al. · 2008
Researchers exposed mice to cell phone radiation at 849 MHz and 1763 MHz frequencies for up to 12 months, delivering radiation directly to their heads at levels much higher than typical phone use. They found no evidence of brain cell death, abnormal cell growth, or other cellular changes in the exposed animals compared to unexposed controls.
Kim TH et al. · 2008
Researchers exposed mice to cell phone radiation at 849 MHz and 1763 MHz frequencies for up to 12 months, using radiation levels about 4 times higher than current safety limits. They found no changes in brain cell death, cell growth, or tissue damage compared to unexposed mice. This suggests that chronic exposure to these specific frequencies at high levels may not cause detectable brain tissue changes in mice.
Sauter C et al. · 2011
German researchers exposed 30 young men to mobile phone radiation (900 MHz and 1,966 MHz) for over 7 hours daily for three days, then tested their cognitive abilities including attention, memory, and vigilance. After accounting for natural daily variations in mental performance, they found no significant effects from either type of phone radiation on any cognitive function tested.
Ruigrok HJ et al. · 2018
Researchers tested whether 1800 MHz radiofrequency radiation from wireless devices could activate heat-sensitive cell channels through non-thermal effects. They found RF radiation only activated these channels when it produced actual heating, providing no evidence for non-thermal biological effects at the cellular level.
Pashovkina MS, Akoev IG · 2000
Russian researchers exposed guinea pig blood samples to 2375 MHz microwave radiation (similar to WiFi frequencies) for just 1-3 minutes and measured changes in alkaline phosphatase, an important enzyme involved in cellular metabolism. They found that specific pulse frequencies, particularly at 70 Hz, nearly doubled the enzyme's activity levels. This suggests that even brief exposures to common wireless frequencies can trigger measurable biological responses at the cellular level.
Pakhomov AG, Dubovick BV, Degtyariov IG, Pronkevich AN · 1995
Russian researchers exposed isolated frog heart tissue to 915 MHz microwave radiation (similar to cell phone frequencies) for 40 minutes to see how it affected heart function, both alone and combined with various drugs. They found that microwaves alone had no effect on heart rhythm or strength, but when combined with caffeine, the microwaves amplified caffeine's stimulating effects by about 15% - even at power levels too low to cause heating. This suggests that non-thermal microwave exposure might interact with certain substances to affect heart function in ways we don't fully understand.
David G. Cogan et al. · 1958
This 1958 research by Cogan investigated the relationship between ultra-high-frequency (microwave) radiation and cataract formation in laboratory animals. The study examined whether microwave radiation exposure could cause eye damage, specifically the clouding of the lens that characterizes cataracts. This represents early scientific recognition that microwave radiation could affect sensitive tissues like the eyes.
Mickley GA, Cobb BL · 1998
Researchers exposed rats to microwave radiation at levels that caused significant body heating and found it disrupted their ability to distinguish between familiar and new objects - a key indicator of working memory function. However, rats that had been previously exposed to the heating developed a tolerance that protected them from both the temperature increase and memory problems. The study suggests that microwave-induced heating can impair cognitive function, but the brain may adapt to protect itself from repeated exposures.
Unknown authors
This study examined how microwave radiation affects nerve function in frog sciatic nerves, specifically testing whether blocking active transport (the Na-K pump) would eliminate microwave effects on nerve vitality. The research used ouabain to block the sodium-potassium pump that maintains nerve function, then measured how microwave exposure affected nerve activity under these conditions.
Akbarnejad Z et al. · 2017
Researchers exposed rats with Alzheimer's-like brain damage to 50 Hz electromagnetic fields (the same frequency as power lines) for 14 days and tested their memory using a water maze. The electromagnetic field exposure significantly improved the rats' learning and memory abilities, even reversing some of the cognitive damage. This suggests that certain electromagnetic frequencies might have therapeutic potential for neurodegenerative conditions.