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

Cellular EffectsNo Effects Found

Exposure to GSM RF fields does not affect calcium homeostasis in human endothelial cells, rat pheocromocytoma cells or rat hippocampal neurons.

O'Connor RP, Madison SD, Leveque P, Roderick HL, Bootman MD · 2010

Researchers used a high-throughput imaging platform to monitor calcium changes in cells exposed to 900 MHz GSM fields at specific absorption rates of 0.012–2 W/kg. The study examined resting calcium, agonist-evoked calcium signals, calcium store emptying, and store-operated calcium entry. GSM field data were compared with continuous wave fields and no-field controls. No changes in calcium signals were detected even at the highest field strengths, which exceeded typical phone exposure levels. The researchers concluded they could not detect any consequence of RF exposure under their experimental conditions.

Exposure to radiation from global system for mobile communications at 1,800 MHz significantly changes gene expression in rat hippocampus and cortex.

Nittby H et al. · 2008

Swedish researchers exposed rats to cell phone radiation at 1,800 MHz for six hours and found significant changes in brain gene expression. The radiation altered genes controlling cell membranes and signal transmission in memory-critical brain regions, occurring at levels similar to extended human cell phone use.

Exposure to radiation from global system for mobile communications at 1,800 MHz significantly changes gene expression in rat hippocampus and cortex.

Nittby H et al. · 2008

Researchers exposed rats to cell phone radiation at 1,800 MHz for 6 hours and found significant changes in brain gene activity. The genetic alterations affected genes controlling cell membranes and cellular communication in the cortex and hippocampus, the same brain regions where previous studies documented blood-brain barrier damage.

Exposure to radiation from global system for mobile communications at 1,800 MHz significantly changes gene expression in rat hippocampus and cortex.

Nittby H et al. · 2008

Researchers exposed Fischer 344 rats to radiation from a GSM mobile test phone at 1,800 MHz for 6 hours and then analyzed gene expression in the cortex and hippocampus. Four rats were exposed in an anechoic chamber one at a time, and four control rats were kept in the same chamber for the same duration without exposure. Gene ontology analysis found highly significant changes in gene categories related to membrane functions in both brain regions.

Influence of electromagnetic Fields on reproductive system of male rats.

Kumar S, Behari J, Sisodia R. · 2012

Researchers exposed 70-day-old male Wistar rats to 10 GHz microwave radiation for 2 h per day for 45 days at power density 0.21 mW/cm(2) and SAR of 0.014 W/kg, with a sham-exposed control group. Scanning electron microscopy revealed shrinkage of the seminiferous tubule lumen, and apoptotic bodies were present in the exposed group. Flow cytometry showed micronuclei formation in lymphocytes, comet assay confirmed DNA strand breaks, and testosterone levels were significantly decreased alongside testicular shrinkage.

Evaluation of genotoxic effects in male Wistar rats following microwave exposure.

Kumar S, Kesari KK, Behari J. · 2010

Wistar rats were exposed to microwaves for 2 hours a day for 45 days at either 10 GHz or 50 GHz, and blood cells and serum were then analyzed. The exposed rats showed micronuclei formation and a significant increase in ROS production, along with significant changes in glutathione peroxidase, superoxide dismutase, and catalase levels. The researchers concluded that microwave exposure may be effective at the genetic level and suggested this may indicate tumor promotion through overproduction of reactive oxygen species.

Cellular Effects212 citations

Microwave radiation can alter protein conformation without bulk heating.

de Pomerai DI et al. · 2003

Researchers investigated whether microwave radiation could alter protein conformation without bulk heating. Microwave radiation enhanced the aggregation of bovine serum albumin in vitro in a time- and temperature-dependent manner. Microwave radiation also promoted amyloid fibril formation by bovine insulin at 60 degrees C. These changes in protein conformation were not accompanied by measurable temperature changes, consistent with estimates of specific absorbed radiation of 15-20 mW kg(-1).

Antibody responses of mice exposed to low-power microwaves under combined, pulse-and-amplitude modulation.

Veyret B et al. · 1991

Researchers exposed Balb/C mice to pulsed microwaves at 9.4 GHz, both with and without amplitude modulation at frequencies between 14 and 41 MHz, to assess effects on the immune system. Exposure took place for five consecutive days at 10 hours per day, at a whole-body-averaged SAR of approximately 0.015 W/kg. When the pulsed field was combined with amplitude modulation, immune responses were significantly augmented or weakened depending on the AM frequency used, while the pulsed field alone did not greatly alter immune responsiveness.

Immune SystemNo Effects Found

Antibody responses of mice exposed to low-power microwaves under combined, pulse-and-amplitude modulation.

Veyret B et al. · 1991

French researchers exposed mice to low-power pulsed microwaves (similar to radar frequencies) for 10 hours daily over five days to test effects on immune system function. They found that simple pulsed signals had little effect, but when the signals included additional amplitude modulation, the mice showed significant changes in antibody production - some frequencies strengthened immune responses while others weakened them.

Exposure to 900 MHz electromagnetic fields activates the mkp-1/ERK pathway and causes blood-brain barrier damage and cognitive impairment in rats.

Tang J et al. · 2015

Researchers exposed 108 male Sprague-Dawley rats to a 900 MHz, 1 mW/cm2 electromagnetic field for 14 or 28 days at 3 hours per day, with some rats left unexposed as a sham group. Rats exposed for 28 days crossed platforms less often and spent less time in the target quadrant than rats exposed for 14 days and unexposed rats. Twenty-eight days of exposure was also associated with cellular edema, neuronal cell organelle degeneration, and albumin and HO-1 extravasation in the hippocampus and cortex. The researchers found that 28 days of EMF exposure induced the expression of mkp-1, resulting in ERK dephosphorylation.

Purkinje cell number decreases in the adult female rat cerebellum following exposure to 900 MHz electromagnetic field

Sonmez OF, Odaci E, Bas O, Kaplan S · 2010

Researchers exposed 16-week-old adult female rats to 900 MHz EMF for 1 hour per day for 28 days and then counted Purkinje cells in the cerebellum using a stereological technique. The total number of Purkinje cells in the exposed group was significantly lower than in both the control group (p < 0.004) and the sham-exposed group (p < 0.002). Body and brain weights did not differ significantly between the exposed and unexposed groups.

900 MHz electromagnetic field exposure affects qualitative and quantitative features of hippocampal pyramidal cells in the adult female rat

Bas O, Odaci E, Kaplan S, Acer N, Ucok K, Colakoglu S · 2009

Researchers investigated the number of pyramidal cells in the hippocampus of 16-week-old female rats following postnatal exposure to 900 MHz EMF. Rats in the EMF group were exposed to 900 MHz EMF for 1 hour per day for 28 days, with a SAR ranging from 0.016 (whole body) to 2 W/kg (locally in the head). Postnatal EMF exposure caused a significant decrease of the pyramidal cell number in the CA, and cell loss was also visible at qualitative observation.

900 MHz electromagnetic field exposure affects qualitative and quantitative features of hippocampal pyramidal cells in the adult female rat.

Bas O, Odaci E, Kaplan S, Acer N, Ucok K, Colakoglu S. · 2009

Researchers exposed young female rats to cell phone radiation (900 MHz) for one hour daily over 28 days and found significant loss of brain cells in the hippocampus, a region critical for memory and learning. The radiation levels used (0.016-2 W/kg SAR) overlap with what people experience during cell phone use. This cellular damage was visible both through precise cell counting and direct microscopic observation.

Oxidative Stress147 citations

Protective effects of melatonin and caffeic acid phenethyl ester against retinal oxidative stress in long-term use of mobile phone: A comparative study.

Ozguner F, Bardak Y, Comlekci S. · 2006

Researchers compared how well melatonin and caffeic acid phenethyl ester (CAPE) protected rat retinas from oxidative stress caused by exposure to 900 MHz mobile-phone radiation. Melatonin and CAPE were administered daily for 60 days to the rats prior to their EMR exposure. Retinal levels of the oxidative stress markers NO and MDA increased in EMR-exposed rats, while both melatonin and CAPE caused a significant reduction in those levels. Antioxidant enzyme activities (SOD, GSH-Px, and CAT) decreased in EMR-exposed animals, but both treatments significantly increased those activities.

Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz.

Salford LG, Brun A, Sturesson K, Eberhardt JL, Persson BRq · 1994

Researchers exposed male and female Fischer 344 rats to 915 MHz microwaves as continuous wave and pulse-modulated at 8, 16, 50, and 200 Hz in a transverse electromagnetic transmission line chamber. Albumin leakage occurred in 56 of 184 exposed rats versus 5 of 62 controls, and continuous wave exposure yielded 14 positive findings out of 35 that were significantly different from controls (P = 0.002). The specific energy absorption rate varied between 0.016 and 5 W/kg, and rats were exposed for 2 hours without anesthesia.

Chronic Exposure to a GSM-like Signal (Mobile Phone) Does Not Stimulate the Development of DMBA-Induced Mammary Tumors in Rats: Results of Three Consecutive Studies.

Bartsch H et al. · 2002

Researchers tested a GSM-like RF signal on mammary tumors induced by DMBA in female Sprague-Dawley rats as a model for human breast cancer. Three experiments were carried out under strictly standardized conditions using a GSM-like signal at 900 MHz pulsed at 217 Hz. The overall results showed no statistically significant effect of RF-field exposure on tumor latency, and cumulative tumor incidence was unaffected as well. The researchers concluded that low-level RF radiation does not appear to possess carcinogenic or cancer-promoting effects on DMBA-induced mammary tumors.

2.45-GHz microwave irradiation adversely affects reproductive function in male mouse, Mus musculus by inducing oxidative and nitrosative stress.

Shahin S, Mishra V, Singh SP, Chaturvedi CM. · 2014

Researchers exposed twelve-week-old male Swiss strain mice to 2.45-GHz microwave radiation for 2 hours per day for 30 days at a power density of 0.029812 mW/cm2 and SAR of 0.018 W/Kg. Microwave irradiation induced a significant decrease in sperm count and sperm viability, along with a decrease in seminiferous tubule diameter and degeneration of seminiferous tubules. Reduced testicular 3β HSD activity and plasma testosterone levels were also observed in the exposed mice. The researchers suggested that chronic exposure to nonionizing microwave radiation may lead to infertility via a free radical species-mediated pathway.

2.45-GHz microwave irradiation adversely affects reproductive function in male mouse, Mus musculus by inducing oxidative and nitrosative stress.

Shahin S, Mishra V, Singh SP, Chaturvedi CM · 2014

Researchers exposed male mice to 2.45-GHz microwave radiation (the same frequency used by Wi-Fi and microwaves) for 2 hours daily over 30 days at very low power levels. The exposed mice showed significant decreases in sperm count and viability, reduced testosterone levels, and damaged reproductive tissue. The study suggests these effects occur through oxidative stress, where radiation generates harmful free radicals that damage cells.

Reproductive Health100 citations

Effect of whole-body 1800MHz GSM-like microwave exposure on testicular steroidogenesis and histology in mice.

Forgacs Z et al. · 2006

Researchers studied the possible effects of whole-body 1800 MHz GSM-like microwave exposure on male reproduction in mice. After repeated exposure at 0.018-0.023 W/kg SAR, an elevated serum testosterone level was measured, but no histopathological alteration could be detected in the reproductive organs. Leydig cell cultures from exposed animals did not differ from controls in their steroidogenic response.

Effects of GSM modulated radio-frequency electromagnetic radiation on permeability of blood–brain barrier in male & female rats

Sırav B, Seyhan N · 2016

Researchers used young adult male and female Wistar albino rats to investigate whether pulse modulated 900 MHz and 1800 MHz radio-frequency radiation affects the permeability of the blood-brain barrier. Permeability was measured by quantifying Evans blue dye that passed into the brain after intravenous injection. In both male radio-frequency radiation exposed groups, blood-brain barrier permeability was found to be increased compared with controls, with 1800 MHz found more effective in males. For female rats, 900 MHz exposure was associated with increased permeability, but no statistical difference was found between the 1800 MHz exposed and control groups.

Selenium Reduces Mobile Phone (900 MHz)-Induced Oxidative Stress, Mitochondrial Function, and Apoptosis in Breast Cancer Cells.

Kahya MC, Nazıroğlu M, Ciğ B. · 2014

Researchers studied the effects of 900 MHz radiation on oxidative stress, apoptosis, and mitochondrial depolarization in a breast cancer cell line. Cells were exposed to 900 MHz radiation for 1 hour at a SAR value of 0.36 ± 0.02 W/kg, and some groups were also incubated with sodium selenite before exposure.