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

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.

DNA damage in Molt-4 T- lymphoblastoid cells exposed to cellular telephone radiofrequency fields in vitro.

Phillips et al. · 1998

Researchers exposed immune system cells to radiofrequency radiation from cell phone signals at extremely low power levels for 2 to 21 hours. They found that very low exposures actually reduced DNA damage, while slightly higher exposures increased DNA breaks in the cellular genetic material. This suggests that even minimal RF radiation can alter DNA integrity in immune cells, though the effects varied depending on the specific exposure level.

DNA damage in Molt-4 T- lymphoblastoid cells exposed to cellular telephone radiofrequency fields in vitro

Phillips et al. · 1998

Researchers exposed Molt-4 T-lymphoblastoid cells in vitro to pulsed radiofrequency signals at cellular telephone frequencies of 813.5625 MHz (iDEN® signal) and 836.55 MHz (TDMA signal) to detect DNA damage. The alkaline comet assay was used to measure DNA single-strand breaks in exposed cell cultures compared to sham-exposed cultures. At an SAR of 24 μW g−1, exposure to the iDEN® signal for 2 h and 21 h significantly increased DNA damage, while at 2.4 μW g−1 the same signal significantly decreased DNA damage. The researchers concluded that the data indicate a need to study the effects of exposure to RF signals on direct DNA damage and on the rate at which DNA damage is repaired.

Effects of modulated and continuous microwave irradiation on the morphology and cell surface negative charge of 3T3 fibroblasts.

Somosy Z, Thuroczy G, Kubasova T, Kovacs J, Szabo LD · 1991

Researchers exposed mouse embryo 3T3 cells to 2450 MHz continuous and 16 Hz square-modulated microwaves at absorbed energies from 0.0024 to 2.4 mW/g. Modulated waves caused more morphological changes than continuous waves at the same intensity. Cell surface negative charge decreased after modulated-wave exposure but was unchanged after continuous-wave exposure at the same dose. Modulated waves at 0.024 mW/g increased cell ruffling and caused cytoplasmic ultrastructural alterations, while continuous waves required higher doses of 0.24 and 2.4 mW/g for similar effects.

Effect of long-term exposure of 2.4 GHz radiofrequency radiation emitted from Wi-Fi equipment on testes functions.

Dasdag S, Taş M, Akdag MZ, Yegin K. · 2014

The study used Wistar Albino adult male rats divided into a sham group and an exposure group, with rats in the exposure group exposed to 2.4 GHz radiofrequency radiation for 24 hours a day during 12 months. Sperm head defects increased in the exposed group, and weight of the epididymis and seminal vesicles, seminiferous tubule diameter, and tunica albuginea thickness all decreased. Other measured parameters did not show statistically significant differences between the groups.

Brain & Nervous SystemNo Effects Found

Influence of a 902.4 MHz GSM signal on the human visual system: Investigation of the discrimination threshold

Irlenbusch L et al. · 2007

Researchers measured the visual discrimination threshold in 33 subjects during both RF and sham exposures. Each experiment consisted of two 30-minute periods with a 5-minute break, and the threshold was recorded every 10 seconds. The RF exposure used a 902.4 MHz GSM signal pulsed at 217 Hz with a power flux density of 1 W/m². No statistically significant difference in the threshold was found between RF and sham exposures.

Brain & Nervous SystemNo Effects Found

Influence of a 902.4 MHz GSM signal on the human visual system: investigation of the discrimination threshold.

Irlenbusch L et al. · 2007

Researchers exposed 33 people to GSM mobile phone signals near their eyes to test whether radiofrequency radiation affects visual sensitivity (the ability to detect light differences). Using exposure levels similar to holding a phone close to your face, they found no measurable changes in visual discrimination abilities during 30-minute exposure sessions. This suggests that typical mobile phone use doesn't immediately impair basic visual function.

CardiovascularNo Effects Found

Character of the effect of microwave on conduction velocity of frog ventricular muscle.

Yee KC, Chou CK, Guy AW · 1994

Researchers investigated the effect of microwave exposure on conduction velocity of frog ventricular muscle. Thirty-two frog hearts were divided into four groups and placed in temperature-controlled waveguides with Ringer's solution. One group served as control while three groups were exposed for 2 hours to pulsed 2,450 MHz microwave fields at SARs of 0.003, 2, and 6 W/kg. No significant difference in conduction velocity was found between control and exposed groups.

SAR in a child voxel phantom from exposure to wireless computer networks (Wi-Fi).

Findlay RP, Dimbylow PJ. · 2010

Researchers calculated specific energy absorption rate (SAR) values in a 10-year-old sitting voxel model from exposure to electromagnetic fields at 2.4 and 5 GHz, frequencies commonly used by Wi-Fi devices. Both plane-wave exposure and irradiation from antennas in the near field were investigated for a variety of exposure conditions. In all situations studied, the calculated SAR values were considerably below basic restrictions.

The effects of mobile phones on apoptosis in cerebral tissue: an experimental study on rats.

Yilmaz A et al. · 2014

Researchers exposed rats to mobile phone radiation at typical usage levels for four weeks, then examined brain tissue for signs of cell death (apoptosis). They found significantly increased levels of proteins that control cell death in the exposed rats compared to unexposed controls. This suggests that mobile phone radiation may trigger cellular stress responses in brain tissue at exposure levels similar to everyday phone use.

The effects of mobile phones on apoptosis in cerebral tissue: an experimental study on rats

Yilmaz A et al. · 2014

Researchers exposed rats to electromagnetic waves from mobile phones at frequencies between 1900 and 2100 MHz for a four-week period to study effects on apoptosis-related proteins in brain tissue. Immunohistopathological examinations showed that the study group had more p53 and Bcl-2 positive stained cells, and they were stained denser, with statistically significant differences between the study and control groups (p < 0.003). The researchers concluded that electromagnetic waves from mobile phones may have an effect on apoptosis.

Effects of radiofrequency radiation exposure on blood-brain barrier permeability in male and female rats

Sirav B, Seyhan N · 2011

Researchers exposed male and female Wistar albino rats to 0.9 and 1.8 GHz continuous-wave radiofrequency radiation for 20 minutes to investigate effects on blood-brain barrier permeability. A significant increase in albumin was found in the brains of the RF-exposed male rats when compared to sham-exposed male brains. In female rats, no albumin extravasation was found in the brain after RFR exposure. The researchers noted that these results suggest that exposure at levels below the international limits can affect vascular permeability in the brain of male rats.

Cellular EffectsNo Effects Found

An investigation of the effects of TETRA RF fields on intracellular calcium in neurones and cardiac myocytes.

Green AC et al. · 2005

Intracellular calcium concentration ([Ca(2 +) ](i)) was measured in cultured rat cerebellar granule cells and cardiac myocytes during exposure to TETRA fields (380.8875 MHz pulse modulated at 17.6 Hz, 25% duty cycle). Granule cells exposed at specific absorption rates (SARs) of 5, 10, 20, 50 or 400 mW x kg(-1) showed no significant changes in resting [Ca(2 +) ](i). Exposure to TETRA (50 or 400 mW x kg(-1)) had no significant effect on either the rate or amplitude of spontaneous Ca(2 +) transients in cardiac myocytes. Overall, these results showed no evidence of any consistent or biologically relevant effect of TETRA fields on [Ca(2 + )](i) in granule cells and cardiac myocytes at any of the SAR tested.

Nonthermal GSM microwaves affect chromatin conformation in human lymphocytes similar to heat shock.

Sarimov R et al. · 2004

Researchers exposed lymphocytes from seven healthy persons to GSM microwaves at different frequencies in the range of 895-915 MHz and measured changes in chromatin conformation. A 30-min exposure at 900 and 905 MHz produced statistically significant condensation of chromatin in lymphocytes from 1 of 3 tested donors. Stronger effects were found following 1-h exposure, with chromatin condensation in 3 donors and decondensation in 1 donor. The observed chromatin changes were similar to effects of heat shock within the temperature window of 40/spl deg/C-44/spl deg/C.

Specific absorption rate levels measured in a phantom head exposed to radio frequency transmissions from analog hand-held mobile phones.

Anderson V, Joyner KH · 1995

Researchers measured electric fields induced within a phantom head from exposure to three different advanced mobile phone system (AMPS) hand-held telephones using an implantable E-field probe. The phones were positioned alongside the phantom head as in typical use and were configured to transmit at maximum power (600 mW nominal). The SARs induced in the eye ranged from 0.007 to 0.21 W/kg, and maximum levels in the brain ranged from 0.12 to 0.83 W/kg, all below recommended safety limits.

Sleep & Circadian RhythmNo Effects Found

1800 MHz electromagnetic field effects on melatonin release from isolated pineal glands.

Sukhotina I, Streckert JR, Bitz AK, Hansen VW, Lerchl A · 2006

Researchers exposed isolated pineal glands from Djungarian hamsters to 1800 MHz continuous wave or GSM-modulated signals at SAR levels of 8, 80, 800, and 2700 mW/kg for 7 hours. At 800 mW/kg SAR both signal types significantly enhanced melatonin release, but at 2700 mW/kg SAR continuous wave elevated melatonin while GSM-modulated exposure suppressed it. The authors concluded that the data do not support the melatonin hypothesis that nonthermal radiofrequency exposure suppresses melatonin synthesis.

Reactive oxygen species elevation and recovery in Drosophila bodies and ovaries following short-term and long-term exposure to DECT base EMF

Manta AK, Stravopodis DJ, Papassideri IS, Margaritis LH. · 2014

Researchers measured reactive oxygen species (ROS) levels in the bodies and ovaries of 4-day-old Drosophila melanogaster flies after exposing them to DECT base radiation at 1.88–1.90 GHz. Male and female bodies showed a twofold increase in ROS levels after 6 hours of exposure, with ROS levels returning to normal 24 hours after that exposure ended. Ovaries responded more quickly, reaching a 2.5-fold ROS increase after 1 hour of exposure, with levels returning to normal 4 hours after that exposure ended.

Reactive oxygen species elevation and recovery in Drosophila bodies and ovaries following short-term and long-term exposure to DECT base EMF.

Manta AK, Stravopodis DJ, Papassideri IS, Margaritis LH · 2013

Researchers exposed fruit flies to radiation from cordless phone base stations. The flies showed doubled levels of cell-damaging molecules within hours, even at very low radiation levels. This suggests common household wireless devices may cause cellular stress below current safety standards.

Effects of long-term exposure to 900 megahertz electromagnetic field on heart morphology and biochemistry of male adolescent rats.

Kerimoğlu G et al. · 2016

Male rats were divided into control, sham, and EMF-exposed groups, with the EMF group exposed to 900 MHz EMF for 1 hour per day between postnatal days 21 and 59. Biochemical analysis showed increased malondialdehyde and superoxide dismutase levels, and reduced glutathione and catalase levels in the EMF-exposed group compared to controls. The percentage of apoptotic myocardial cells in the EMF-exposed group was higher than in either the sham or control groups, and electron microscopy revealed altered Z band structure, decreased myofilaments, and pronounced vacuolization.

Electromagnetic radiation at 900 MHz induces sperm apoptosis through bcl-2, bax and caspase-3 signaling pathways in rats.

Liu Q, Si T, Xu X, Liang F, Wang L, Pan S. · 2015

Rats were exposed to 900 MHz electromagnetic radiation at a specific absorption rate of 0.66 ± 0.01 W/kg for 2 h/d, and sperm were examined after 50 days. The percentage of apoptotic sperm cells in the exposure group was significantly increased by 91.42% compared with the control group. Reactive oxygen species concentration in the exposure group was increased by 46.21%, while total antioxidant capacity was decreased by 28.01%. Radiation also decreased the protein and mRNA expression of bcl-2 and increased that of bax, cytochrome c, and caspase-3.

Oxidative Stress104 citations

GSM Base Station Electromagnetic Radiation and Oxidative Stress in Rats.

Yurekli AI et al. · 2006

Researchers used a gigahertz transverse electromagnetic (GTEM) cell to expose rats to electromagnetic fields at the GSM base transceiver station frequency of 945 MHz. The power density applied was 3.67 W/m2 (specific absorption rate = 11.3 mW/kg), which the researchers described as well below current exposure limits. MDA levels increased and GSH concentrations decreased significantly (p < 0.0001) under this exposure. There was also a less significant (p = 0.0190) increase in SOD (superoxide dismutase) activity under EM exposure.

Long-term electromagnetic exposure of developing neuronal networks: A flexible experimental setup.

Oster S et al. · 2016

Researchers developed and characterized a flexible experimental setup based on a transverse electromagnetic waveguide for controlled, reproducible exposure of developing neuronal networks in vitro. The Stripline showed very good performance in the 800-1000 MHz band, with simulations indicating uniform specific absorption rate values of 361.7 ± 11.4 mW/kg at 1 W, 900 MHz across a large exposure area. Thermal drift during exposure did not exceed 0.1 K in the cellular medium. Embryonic rat cortical neurons were cultured on microelectrode array chips for non-invasive electrophysiological assessment over several weeks, demonstrating the system's reliability for long-term studies.