6,486 Studies Reviewed. 85.2% of Original Studies Found Biological Effects. The Evidence is Clear.
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SAR (Specific Absorption Rate)

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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

Evaluation of selected biochemical parameters in the saliva of young males using mobile phones

Abu Khadra KM, Khalil AM, Abu Samak M, Aljaberi A. · 2014

Researchers evaluated biochemical parameters in the saliva of 12 young males before and after using a mobile phone. The phone emitted radio frequency signals of 1800 MHz with a 1.09 w/kg specific absorption rate, and participants used it for 15 and 30 minutes. SOD levels followed a quadratic trend, rising after 15 minutes of talking but then dropping as talking time increased. The researchers suggested that exposure to electromagnetic radiation may exert an oxidative stress on human cells, as evidenced by the increase in the concentration of the superoxide radical anion released in the saliva of cell phone users.

Evaluation of selected biochemical parameters in the saliva of young males using mobile phones.

Abu Khadra KM, Khalil AM, Abu Samak M, Aljaberi A. · 2014

Researchers measured biochemical changes in saliva from 12 young men before and after using mobile phones at typical exposure levels (1.09 W/kg SAR). They found that just 15 minutes of phone use triggered a significant increase in superoxide dismutase (an enzyme that fights cellular damage), indicating the body was responding to oxidative stress from the radiation.

Biochemical Modifications and Neuronal Damage in Brain of Young and Adult Rats After Long-Term Exposure to Mobile Phone Radiations.

Motawi TK, Darwish HA, Moustafa YM, Labib MM. · 2014

Researchers exposed young and adult rats to cell phone radiation (SAR 1.13 W/kg) for 2 hours daily over 60 days and found significant brain damage. The radiation caused oxidative stress (cellular damage from harmful molecules), triggered programmed cell death, and led to visible neuronal damage, with young rats showing particularly affected brain development. This suggests that chronic cell phone exposure may harm brain tissue through multiple biological pathways.

Effects of chronic exposure to 950 MHz ultra-high-frequency electromagnetic radiation on reactive oxygen species metabolism in the right and left cerebral cortex of young rats of different ages.

Furtado-Filho OV et al. · 2015

Researchers exposed young rats to 950 MHz ultra-high-frequency electromagnetic radiation to measure oxidative damage to DNA, proteins, and lipids in the left and right cerebral cortex. Radiation exposure lasted 30 minutes per day for up to 27 days, with a specific absorption rate ranging from 1.32 to 1.14 W/kg. In neonates, no modification of the biomarkers tested was detected, while 6-day-old exposed rats showed increased carbonylated proteins in the right cerebral cortex and decreased blood glucose. The researchers concluded that the elevated carbonylated proteins in the right cerebral cortex did not appear to be a consequence of oxidative stress.

Possible cause for altered spatial cognition of prepubescent rats exposed to chronic radiofrequency electromagnetic radiation.

Narayanan SN, Kumar RS, Karun KM, Nayak SB, Bhat PG. · 2015

Researchers exposed young rats to 900 MHz radiofrequency radiation (similar to cell phone frequencies) for one hour daily over four weeks and tested their learning and memory abilities. The exposed rats showed decreased learning abilities and poorer memory retention, especially when tested 48 hours after training. Brain tissue examination revealed structural damage to the hippocampus, the brain region critical for memory and spatial navigation.

[Effect of 900 MHz electromagnetic fields on the expression of GABA receptor of cerebral cortical neurons in postnatal rats]

Wang Q, Cao ZJ, Bai XT. · 2005

Researchers exposed cerebral cortical neurons from postnatal rats to 900 MHz continuous microwave EMF with a SAR of 1.15 to 3.22 mW/g for 2 hours per day over 6 consecutive days and for 12 hours at one time. GABA receptor was selected as the biological endpoint. Significant changes in GABA receptor expression were observed in exposed neurons (P < 0.01), and the expression was significantly regulated by the microwave with a power window effect.

Oxidative Stress102 citations

900 MHz pulse-modulated radiofrequency radiation induces oxidative stress on heart, lung, testis and liver tissues

Esmekaya MA, Ozer C, Seyhan N · 2011

Researchers exposed male Wistar albino rats to 900 MHz pulse-modulated RF radiation at a SAR of 1.20 W/kg for 20 minutes per day over three weeks to investigate oxidative damage in multiple tissues. MDA and NOx levels were significantly increased in liver, lung, testis, and heart tissues of the exposed group compared to sham and control groups, while GSH levels were significantly lower in exposed rat tissues. No significant difference was observed between the sham and control groups.

Oxidative Stress129 citations

Effects of mobile phones on oxidant/antioxidant balance in cornea and lens of rats

Balci M, Devrim E, Durak I · 2007

Researchers assigned forty female albino Wistar rats to one of four groups to study the effects of mobile phone radiation on oxidant/antioxidant balance in corneal and lens tissues. One group received mobile phone radiation for 4 weeks, a second group received radiation plus a daily oral dose of vitamin C (250 mg/kg), a third group received vitamin C alone, and a fourth group served as a control. In corneal tissue, MDA level and CAT activity significantly increased and SOD activity was significantly decreased in the mobile phone group compared with the control group. In lens tissue, only the MDA level significantly increased in the mobile phone group relative to the control group, while SOD, GSH-Px, and CAT did not differ significantly between groups.

Non-thermal DNA breakage by mobile-phone radiation (1800MHz) in human fibroblasts and in transformed GFSH-R17 rat granulosa cells in vitro.

Diem E, Schwarz C, Adlkofer F, Jahn O, Rudiger H. · 2005

Researchers exposed cultured human diploid fibroblasts and transformed GFSH-R17 rat granulosa cells to 1800 MHz RF-EMF at SAR levels of 1.2 or 2 W/kg, using both intermittent and continuous exposures. DNA strand breaks were determined by means of the alkaline and neutral comet assay. Effects occurred after 16 h exposure in both cell types, and intermittent exposure showed a stronger effect in the comet assay than continuous exposure. The researchers concluded that the induced DNA damage cannot be based on thermal effects.

DNA & Genetic DamageNo Effects Found

Measurement of DNA damage after acute exposure to pulsed-wave 2450 MHz microwaves in rat brain cells by two alkaline comet assay methods.

Lagroye I et al. · 2004

The study aimed to investigate the effect of 2450 MHz pulsed-wave microwaves on DNA damage in rat brain cells and whether proteinase K is needed to detect such damage. Rats exposed to γ-rays showed significant DNA damage using both comet assay versions independent of proteinase K. Neither assay version detected any difference in comet length or normalized comet moment between sham-exposed and microwave-exposed rats regardless of proteinase K inclusion. No DNA damage was detected in brain cells after exposure to 2450 MHz pulsed-wave microwaves at 1.2 W kg−1 regardless of proteinase K inclusion. The results support the conclusion that low-level 2450 MHz pulsed-wave microwave exposures do not induce DNA damage detectable by the alkaline comet assay.

Interaction of microwaves and a temporally incoherent magnetic field on spatial learning in the rat.

Lai H. · 2004

Microwave-exposed rats had a significant deficit in learning the platform location compared with sham-exposed rats. Noise exposure alone did not affect performance, but simultaneous noise exposure significantly reduced the microwave-induced learning deficit. In the probe trial, microwave-exposed rats spent less time in the target quadrant, whereas microwave-plus-noise rats performed like sham rats.

Acute exposure to pulsed 2450-MHz microwaves affects water maze learning in the rat.

Wang, BM, Lai, H · 2000

Rats were trained in six sessions to locate a submerged platform in a circular water maze. They were exposed to pulsed 2450-MHz microwaves for 1 hour before each training session. Microwave-exposed rats were slower than sham-exposed and cage control rats in learning to locate the platform. During the probe trial, microwave-exposed animals spent significantly less time in the quadrant that had contained the platform. There was no significant difference in swim speed among the three groups.

DNA & Genetic DamageNo Effects Found141 citations

DNA damage in rat brain cells after in vivo exposure to 2450 MHz electromagnetic radiation and various methods of euthanasia.

Malyapa RS et al. · 1998

Researchers exposed rats to 2450 MHz microwave radiation (the same frequency used in microwave ovens and some WiFi devices) for 2 hours to see if it would damage DNA in brain cells, as a previous study had suggested. They found no DNA damage in either the brain's cortex or hippocampus regions, contradicting the earlier research. This study suggests that short-term exposure to this type of radiation at moderate levels may not cause immediate genetic damage to brain cells.

DNA & Genetic DamageNo Effects Found

DNA damage in rat brain cells after in vivo exposure to 2450 MHz electromagnetic radiation and various methods of euthanasia.

Malyapa RS et al. · 1998

Researchers exposed male Sprague-Dawley rats to 2450 MHz continuous-wave microwaves for two hours at 1.2 W/kg specific absorption rate. No significant differences in DNA damage were found between sham-exposed and irradiated rats in either the cerebral cortex or hippocampus, regardless of euthanasia method. Rats euthanized by CO2 asphyxia showed more intrinsic DNA damage and greater experiment-to-experiment variation than those euthanized by guillotine. The authors concluded that guillotine euthanasia is the most appropriate method for DNA damage studies. The study did not confirm previous reports of DNA damage from 2450 MHz microwave exposure.

Melatonin and a spin-trap compound block radiofrequency electromagnetic radiation-induced DNA strand breaks in rat brain cells.

Lai, H, Singh, NP, · 1997

Researchers investigated the effects of microwave exposure on DNA strand breaks in rat brain cells. They found that treating rats with either melatonin or the spin-trap compound PBN immediately before and after radiofrequency electromagnetic radiation exposure blocked the DNA strand breaks. Because both substances are free radical scavengers, the researchers hypothesized that free radicals are involved in the radiofrequency electromagnetic radiation-induced DNA damage.

Naltrexone blocks RFR-induced DNA double strand breaks in rat brain cells

Lai H, Carino MA, Singh NP · 1997

Researchers exposed rats to 2450 MHz pulsed radiofrequency radiation at a power density of 2 mW/cm2 for 2 hours and then measured DNA double strand breaks in brain cells. The RFR exposure significantly increased DNA double strand breaks in rat brain cells, and the effect was partially blocked by naltrexone treatment. The researchers concluded that endogenous opioids play a mediating role in RFR-induced DNA strand breaks in brain cells of the rat.

Naltrexone blocks RFR-induced DNA double strand breaks in rat brain cells.

Lai, H, Carino, MA, Singh, NP, · 1997

Researchers exposed rats to 2.45 GHz microwave radiation (the same frequency used in WiFi and microwave ovens) for 2 hours and found it caused DNA double strand breaks in brain cells. When they gave the rats naltrexone, a drug that blocks the body's natural opioids, it partially prevented this DNA damage. This suggests the body's own opioid system plays a role in how microwave radiation damages DNA in brain cells.

Naltrexone blocks RFR-induced DNA double strand breaks in rat brain cells.

Lai, H, Carino, MA, Singh, NP · 1997

Researchers exposed rats to microwave radiation at 2450 MHz (similar to WiFi frequencies) for 2 hours and found significant DNA damage in brain cells. When they gave the rats naltrexone, a drug that blocks the body's natural opioids, the DNA damage was partially prevented. This suggests that microwave radiation triggers the release of natural opioids in the brain, which then contributes to genetic damage.

Single- and double-strand DNA breaks in rat brain cells after acute exposure to radiofrequency electromagnetic radiation

Lai H, Singh NP · 1996

Researchers investigated single- and double-strand DNA breaks in rat brain cells after acute exposure to radiofrequency electromagnetic radiation. Rats received acute 2-hour exposure to pulsed or continuous-wave 2450-MHz radiofrequency electromagnetic radiation, producing a whole-body average-specific absorption rate of 1.2 W/kg. An increase in both types of DNA strand breaks was observed after exposure to either the pulsed or continuous-wave radiation, with no significant difference between the two forms.

Inter-beat intervals of cardiac-cell aggregates during exposure to 2.45 GHz CW, pulsed, and square-wave-modulated microwaves.

Seaman RL, DeHaan RL · 1993

Researchers studied inter-beat intervals of aggregated cardiac cells from chicken embryos during 190-second exposures to 2.45 GHz microwaves. The inter-beat interval decreased during exposures at 42.0 W/kg and higher with continuous-wave or square-wave modulation, consistent with thermal effects. Increases occurred during continuous-wave exposures at 1.2-12.2 W/kg and decreases after pulse-modulated exposures at 8.4-12.2 W/kg, which were not consistent with simple thermal effects.