6,486 Studies Reviewed. 85.2% of Original Studies Found Biological Effects. The Evidence is Clear.
All Exposure Types

SAR (Specific Absorption Rate)

Share:

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.

Concern Level Thresholds

Based on Building Biology Institute guidelines (W/kg (watts per kilogram)):

No Concern
< 0.4 W/kg
Slight Concern
0.4 – 1.0 W/kg
Severe Concern
1.0 – 1.6 W/kg
Extreme Concern
> 1.6 W/kg (FCC limit)

See where common exposures fall on the scale:

A logarithmic scale showing your reading relative to Building Biology concern thresholds and FCC regulatory limits.Your SAR Exposure in ContextNo ConcernSlightSevereExtreme0.0010.010.1FCC Limit →0.00110 W/kg

Showing 898 studies with measured sar (specific absorption rate) exposure

Cognitive Impairment and Neurogenotoxic Effects in Rats Exposed to Low-Intensity Microwave Radiation

Deshmukh PS et al. · 2015

Researchers exposed male Fischer rats to microwave radiation for 180 days at 3 different frequencies, namely, 900, 1800 MHz, and 2450 MHz. The study investigated effects on cognitive function, heat shock protein 70 (HSP70), and DNA damage in rat brain. The results showed declined cognitive function, elevated HSP70 level, and DNA damage in the brains of microwave-exposed animals. The researchers concluded that chronic low-intensity microwave exposure in the frequency range of 900 to 2450 MHz may cause hazardous effects on the brain.

Detection of Low Level Microwave Radiation Induced Deoxyribonucleic Acid Damage Vis-à-vis Genotoxicity in Brain of Fischer Rats

Deshmukh PS et al. · 2013

The study investigated possible DNA-damaging effects of low-level microwave radiation in the brains of male Fischer rats. Rats were exposed for 30 days at three frequencies: 900, 1800, and 2450 MHz, at specific absorption rates on the order of 10−4 W/kg. DNA damage in brain tissue was assessed using alkaline comet assay after the exposure period. The researchers concluded that low SAR microwave radiation at these frequencies may induce DNA strand breaks in brain tissue.

Cognitive Impairment and Neurogenotoxic Effects in Rats Exposed to Low-Intensity Microwave Radiation.

Deshmukh PS et al. · 2015

Researchers exposed rats to extremely low-intensity microwave radiation at cell phone frequencies (900, 1800, and 2450 MHz) for 180 days and found significant cognitive impairment and DNA damage in brain tissue. The exposure levels were thousands of times lower than current safety limits, yet still caused measurable harm including memory problems and genetic damage. This challenges the assumption that only high-intensity radiation poses health risks.

Microwave radiation induced oxidative stress, cognitive impairment and inflammation in brain of Fischer rats.

Megha K et al. · 2012

Researchers exposed rats to cell phone-level microwave radiation (900 MHz and 1800 MHz) for 2 hours daily over 30 days and measured brain effects. The exposed rats showed significant cognitive impairment, increased brain inflammation, and oxidative stress (cellular damage from unstable molecules) compared to unexposed rats. This suggests that chronic microwave exposure at levels similar to cell phone use may harm brain function and memory.

Microwave radiation induced oxidative stress, cognitive impairment and inflammation in brain of Fischer rats

Megha K et al. · 2012

Researchers exposed rats to cell phone-level microwave radiation (900 MHz) for 2 hours daily over 30 days and found significant brain damage including memory problems, cellular stress, and inflammation. The exposure level was extremely low - about 1,000 times weaker than current safety limits - yet still caused measurable harm to brain tissue. This challenges the assumption that only high-intensity radiation poses health risks.

Microwave radiation induced oxidative stress, cognitive impairment and inflammation in brain of Fischer rats.

Megha K et al. · 2012

Researchers exposed male Fischer-344 rats to 900 MHz and 1800 MHz microwave radiation for 30 days at 2 hours per day to evaluate oxidative stress, cognitive impairment, and inflammation in the brain. Compared with sham-exposed animals, microwave-exposed rats showed significant impairment in cognitive function and oxidative stress in brain tissues. A significant increase in the cytokines IL-6 and TNF-alpha was also observed following microwave exposure.

Brain & Nervous SystemNo Effects Found

Histopathological examinations of rat brains after long-term exposure to GSM-900 mobile phone radiation.

Grafström G et al. · 2008

Researchers exposed 32 rats to GSM-900 radiation once weekly for two hours over 55 weeks at average whole-body SAR values of 0.6 and 60 mW/kg. Sixteen rats were sham exposed and eight served as cage controls. After behavioral tests conducted 5–7 weeks after the last exposure, the brains were examined for albumin extravasation, dark neurons, lipofuscin aggregation, and neuronal cytoskeletal changes, but no significant alterations were detected.

Cognitive impairment in rats after long-term exposure to GSM-900 mobile phone radiation.

Nittby H et al. · 2008

Researchers exposed rats to GSM-900 mobile phone radiation for 2 hours each week for 55 weeks at SAR levels of 0.6 and 60 mW/kg, then compared them to sham-exposed controls. GSM-exposed rats had impaired memory for objects and their temporal order of presentation compared to sham-exposed controls (P = 0.02). Detecting the place in which an object was presented was not affected by GSM exposure, and no difference in exploratory behaviour was seen in the open-field test.

Brain & Nervous SystemNo Effects Found

Histopathological examinations of rat brains after long-term exposure to GSM-900 mobile phone radiation.

Grafström G et al. · 2008

Swedish researchers exposed rats to GSM-900 cell phone radiation once weekly for over a year at power levels similar to what humans experience during phone calls. When they examined the rats' brains afterward, they found no signs of damage including blood-brain barrier leakage, cell death, or aging-related changes. This suggests that intermittent cell phone radiation exposure at typical usage levels may not cause detectable brain tissue damage.

Cellular EffectsNo Effects Found

Comparison of dose dependences for bioeffects of continuous-wave and high-peak power microwave emissions using gel-suspended cell cultures.

Pakhomov AG, Gaj ek P, Allen L, Stuck BE, Murphy MR · 2002

Researchers compared bioeffects of continuous wave and extremely high power pulse microwaves at 9.3 GHz and 1.25 W average power using yeast cell density in agarose gel. Cell density was strongly affected by irradiation and correlated with local temperature rise, but no statistically significant difference between CW and EHPP was found across the SAR range. A trend (P<0.1) for a difference appeared at average SAR of 100 W/kg and higher, corresponding to peak SAR above 20 MW/kg for EHPP.

Low-amplitude, high-frequency electromagnetic field exposure causes delayed and reduced growth in Rosa hybrida.

Grémiaux A et al. · 2015

Researchers exposed small rose bush plants to high-frequency electromagnetic fields and followed shoot growth for over a one-month period after exposure. Shoots that arose from post-formed secondary buds showed delayed and significantly reduced growth of 45%, while shoots from pre-formed buds and plants exposed at the 5-leaf stage showed no growth modification. The measured plant energy uptake suggested this biological response was likely not due to a thermal effect.

Microwave exposure affecting reproductive system in male rats.

Kesari KK, Behari J. · 2010

Sperm GPx and SOD activity showed a significant decrease in exposed rats, while catalase showed a significant increase compared with the control group. The percentage of apoptosis was higher in the exposed group, and significant decreases were found in the S phase and G2/M transition phase of the cell cycle. The researchers concluded that these radiations may have a significant effect on the reproductive system of male rats, which may be an indication of male infertility.

Fifty-gigahertz Microwave exposure effect of radiations on rat brain.

Kesari KK, Behari J. · 2009

Researchers investigated the effects of 50-GHz microwave radiation on the brain of Wistar rats. The animals were exposed for 2 hours a day for 45 days continuously at a power level of 0.86 μW/cm2. Exposed rats showed DNA double-strand breaks and a significant decrease in GPx and SOD activity in brain cells, while catalase activity showed a significant increase compared with control. PKC decreased significantly in the whole brain and hippocampus of the exposed group.

Liver antioxidant stores protect the brain from electromagnetic radiation (900 and 1800 MHz)-induced oxidative stress in rats during pregnancy and the development of offspring.

Cetin H et al. · 2014

Researchers divided thirty-two rats and their offspring into three groups: a control group, a 900 MHz group, and an 1800 MHz group, with the two exposed groups receiving electromagnetic radiation for 60 minutes per day during pregnancy and neonatal development. Brain and liver glutathione peroxidase activities, as well as liver vitamin A and beta-carotene concentrations, decreased in the exposed groups. Brain iron, vitamin A, and beta-carotene concentrations increased in the exposed groups, and by the sixth week, selenium concentrations in the brain decreased in the exposed groups. There were no statistically significant differences in glutathione, vitamin E, chromium, copper, magnesium, manganese, and zinc concentrations between the three groups.

Mobile phone 'talk-mode' signal delays EEG-determined sleep onset.

Hung CS, Anderson C, Horne JA, McEvoy P · 2007

Researchers exposed 10 healthy young adults to talk, listen, standby, or sham signal modes for 30 minutes, then gave them a 90-minute sleep opportunity. Sleep latency after talk mode was markedly and significantly delayed beyond listen and sham modes. This condition effect was also evident in 1–4 Hz EEG frontal power, a frequency range described as particularly sensitive to sleep onset. There was no condition effect for subjective sleepiness.

Non-thermal heat-shock response to microwaves

de Pomerai D et al. · 2000

Researchers exposed nematode worms (C. elegans) overnight to 750-MHz microwaves at a SAR of 0.001 W/kg and measured levels of heat-shock proteins (HSPs). The worms showed an increase in HSPs following that exposure. The authors argued that the effect on HSPs was non-thermal and suggested that 'current exposure limits for microwave equipment may need to be reconsidered.'

Cellular Effects107 citations

Changes in cellular proteins due to environmental non-ionizing radiation. i. Heat-shock proteins.

Kwee S, Raskmark P, Velizarov P. · 2001

Researchers exposed human cells to extremely weak radiofrequency radiation (similar to cell phones) at levels 400 times below safety standards. They found that even this minimal exposure triggered the production of heat-shock proteins - cellular stress indicators that normally appear when cells are damaged or under threat. This demonstrates that biological effects can occur at radiation levels far below what regulators consider safe.