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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:

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

Showing 871 studies with measured sar (specific absorption rate) exposure

Brain & Nervous SystemNo Effects Found

No effects of mobile phone use on cortical auditory change-detection in children: an ERP study

Kwon MS et al. · 2010

Researchers tested whether cell phone radiation affects children's ability to process sounds by measuring brain activity in 17 children aged 11-12 while they were exposed to 902 MHz signals from a GSM phone. The study found no significant changes in the brain's auditory processing or sound memory functions during short exposures (12 minutes total). However, the researchers noted their study could only detect large effects, meaning smaller impacts might have gone unnoticed.

Brain & Nervous SystemNo Effects Found

Preattentive auditory information processing under exposure to the 902 MHz GSM mobile phone electromagnetic field: A mismatch negativity (MMN) study.

Kwon MS et al. · 2009

Researchers tested whether cell phone radiation affects the brain's ability to automatically detect changes in sounds by measuring brain waves in 17 healthy adults while a GSM phone was placed next to their ear. They found no differences in brain responses whether the phone was on or off, suggesting that acute exposure to cell phone radiation doesn't impair this basic auditory processing function. This study adds to research examining how electromagnetic fields might affect brain function during everyday phone use.

Brain & Nervous SystemNo Effects Found

Preattentive auditory information processing under exposure to the 902 MHz GSM mobile phone electromagnetic field: A mismatch negativity (MMN) study

Kwon MS et al. · 2009

Finnish researchers tested whether GSM mobile phone radiation affects the brain's ability to automatically detect changes in sounds, a key function for processing speech and music. They measured brain responses in 17 healthy adults while exposing them to 902 MHz radiation at levels typical of cell phone use (SAR up to 1.21 W/kg). The study found no changes in the brain's automatic sound processing abilities during EMF exposure.

The effect of pulsed electromagnetic radiation from mobile phone on the levels of monoamine neurotransmitters in four different areas of rat brain

Aboul Ezz HS, Khadrawy YA, Ahmed NA, Radwan NM, El Bakry MM · 2013

Researchers exposed rats to cell phone radiation (1800 MHz) for 24 hours daily over 1-4 months and measured key brain chemicals called neurotransmitters in four brain regions. The radiation significantly altered levels of dopamine, norepinephrine, and serotonin - chemicals that control mood, memory, learning, and stress responses. These changes persisted even after radiation exposure stopped, suggesting that chronic cell phone use may disrupt normal brain chemistry.

The effect of pulsed electromagnetic radiation from mobile phone on the levels of monoamine neurotransmitters in four different areas of rat brain.

Aboul Ezz HS, Khadrawy YA, Ahmed NA, Radwan NM, El Bakry MM. · 2013

Researchers exposed rats to cell phone radiation (1800 MHz, similar to 2G networks) for up to 4 months and measured key brain chemicals called neurotransmitters that control mood, memory, and learning. The radiation significantly altered levels of dopamine, serotonin, and norepinephrine across four different brain regions. These chemical changes could explain why some people report memory problems, learning difficulties, and increased stress after heavy cell phone use.

Cell Phone Generated Radio Frequency Electromagnetic Field Effects on the Locomotor Behaviors of the Fishes Poecilia reticulata and Danio rerio.

Lee D, Lee J, Lee I. · 2015

Researchers exposed guppies and zebrafish to cell phone radiation (1800 MHz) for 3 minutes and tracked their swimming behavior. They found that fed fish showed significant changes in their movement patterns and swimming speed when exposed to the RF EMF, while hungry fish showed no changes. The study ruled out temperature effects, confirming the behavioral changes were due to the electromagnetic field itself.

Reproductive Health164 citations

Effects of Radiofrequency Electromagnetic Wave Exposure from Cellular Phones on the Reproductive Pattern in Male Wistar Rats.

Kesari KK, Kumar S, Behari J. · 2011

Researchers exposed male rats to cell phone radiation for 2 hours daily over 35 days at levels similar to what humans experience during phone calls (SAR 0.9 W/kg). The radiation significantly damaged sperm cells by creating harmful free radicals and disrupting the body's natural antioxidant defenses. These changes indicate potential fertility problems, suggesting that regular cell phone use might affect male reproductive health.

900-MHz microwave radiation promotes oxidation in rat brain

Kesari KK, Kumar S, Behari J. · 2011

Researchers exposed young rats to 900 MHz mobile phone radiation (the same frequency used by many cell phones) for 2 hours daily over 45 days. They found significant brain changes including increased oxidative stress (cellular damage from unstable molecules), decreased antioxidant protection, and elevated markers associated with cell death. The study suggests that prolonged mobile phone radiation exposure may harm brain tissue through oxidative damage.

Mobile phone usage and male infertility in Wistar rats.

Kesari KK, Kumar S, Behari J. · 2010

Researchers exposed male rats to mobile phone radiation for 2 hours daily over 35 days at levels similar to phone use (0.9 W/kg SAR). They found significant decreases in sperm count and protein activity, along with increased cell death in reproductive tissues. The study suggests mobile phone radiation may contribute to male fertility problems through cellular damage.

Upregulation of Specific mRNA Levels in Rat Brain After Cell Phone Exposure

Yan JG, Agresti M, Zhang LL, Yan Y, Matloub HS. · 2008

Researchers exposed rats to cell phone radiation (1.9 GHz) for 6 hours daily over 18 weeks and examined changes in brain tissue at the molecular level. They found statistically significant increases in mRNA (genetic instructions for making proteins) associated with brain injury and repair processes. The study suggests that chronic cell phone exposure may cause cumulative brain damage that could eventually become clinically significant.

Cancer & TumorsNo Effects Found

TP53 tumor suppressor protein in normal human fibroblasts does not respond to 837 MHz microwave exposure.

Li et al. · 1999

Researchers exposed human cells to 837 MHz microwave radiation (the frequency used by early cell phones) for 2 hours at power levels ranging from 0.9 to 9.0 W/kg. They measured levels of TP53, a critical protein that normally increases when cells are damaged and helps prevent cancer formation. The study found no changes in TP53 levels up to 48 hours after exposure, suggesting these microwave frequencies did not trigger the cellular damage response.

Effects of cell phone radiofrequency signal exposure on brain glucose metabolism

Volkow ND et al. · 2011

Researchers measured brain activity in 47 healthy people while they held cell phones to their ears for 50 minutes. They found that brain glucose metabolism (a measure of brain activity) increased by 7% in the area closest to the phone's antenna. While the study authors called the health significance 'unknown,' this demonstrates that cell phone radiation does measurably affect brain function at typical usage levels.

CardiovascularNo Effects Found

Effects of 900 MHz electromagnetic field emitted by cellular phones on electrocardiograms of guinea pigs

Meral I, Tekintangac Y, Demir H · 2014

Researchers exposed guinea pigs to cell phone radiation for 12 hours daily over 30 days and monitored their heart function using electrocardiograms (ECGs). The study found no significant changes in heart rhythm or electrical activity compared to unexposed animals. However, the researchers noted that longer exposure periods might be needed to detect potential cardiovascular effects from mobile phone radiation.

The effect of mobile phone on the number of Purkinje cells: a stereological study

Rağbetli MC et al. · 2010

Researchers exposed pregnant mice to cell phone radiation at levels similar to what phones emit during calls (0.95 W/kg SAR) and examined brain development in their offspring. They found a significant decrease in Purkinje cells, which are crucial neurons in the cerebellum that control movement and coordination. This suggests that prenatal exposure to mobile phone radiation may affect normal brain development.

Effects of mobile phone use on brain tissue from the rat and a possible protective role of vitamin C - a preliminary study.

Imge EB, Kiliçoğlu B, Devrim E, Cetin R, Durak I · 2010

Researchers exposed rats to cell phone radiation (900 MHz) for four weeks and measured changes in brain tissue chemistry. They found that phone radiation reduced the activity of key protective enzymes in the brain, but vitamin C supplementation helped restore these protective mechanisms. This suggests that cell phone radiation may stress brain cells through oxidative damage, but antioxidants might offer some protection.

Induction of oxidative stress in male rats subchronically exposed to electromagnetic fields at non-thermal intensities.

Achudume A, Onibere B, Aina F, Tchokossa P. · 2010

Researchers exposed rats to cell phone radiation (900 MHz and 1800 MHz) for 40 or 60 days. While 40 days showed no effects, 60 days significantly weakened the animals' antioxidant defenses and altered cellular chemistry, suggesting prolonged exposure may overwhelm natural protection against cellular damage.

Induction of oxidative stress in male rats subchronically exposed to electromagnetic fields at non-thermal intensities

Achudume A, Onibere B, Aina F, Tchokossa P · 2010

Researchers exposed rats to cell phone tower frequencies for 40-60 days. After 60 days, the rats' natural antioxidant defenses significantly weakened, making cells more vulnerable to damage. This suggests prolonged exposure to non-thermal radiation levels may compromise the body's ability to protect against cellular harm.

The effect of mobile phone on the number of Purkinje cells: A stereological study.

Rağbetlı MC et al. · 2010

Researchers exposed pregnant mice to mobile phone radiation at levels similar to what humans experience (0.95 W/kg SAR) and found a significant decrease in Purkinje cells in the developing cerebellum of offspring. Purkinje cells are critical neurons that control movement, balance, and coordination. This study suggests that prenatal exposure to mobile phone radiation may affect brain development in areas responsible for motor function.

Oxidative Stress215 citations

Effects of 900-MHz electromagnetic field emitted from cellular phone on brain oxidative stress and some vitamin levels of guinea pigs.

Meral I et al. · 2007

Researchers exposed guinea pigs to cell phone radiation (900 MHz) for 12 hours daily over 30 days and found significant oxidative stress in brain tissue. The radiation increased harmful compounds called free radicals while depleting the brain's natural antioxidant defenses. This suggests that prolonged cell phone exposure may damage brain cells through oxidative stress, the same process linked to aging and neurodegenerative diseases.

Effects of 900-MHz electromagnetic field emitted from cellular phone on brain oxidative stress and some vitamin levels of guinea pigs.

Meral I et al. · 2007

Researchers exposed guinea pigs to cell phone radiation for 12 hours daily over 30 days and measured brain tissue damage. They found increased oxidative stress (cellular damage from free radicals) in the brain, with higher levels of harmful compounds and lower levels of protective antioxidants. This suggests that prolonged cell phone radiation exposure may damage brain cells through oxidative stress mechanisms.

Histopathological, immunohistochemical, and stereological analysis of the effect of Gingko biloba (Egb761) on the hippocampus of rats exposed to long-term cellphone radiation.

Gevrek F. · 2017

Researchers exposed rats to cellphone radiation levels similar to human phone calls for one month. The radiation damaged the hippocampus brain region responsible for memory by killing brain cells. Ginkgo biloba extract significantly reduced this damage, suggesting potential protection against EMF harm.

Evaluation of the potential of mobile phone specific electromagnetic fields (UMTS) to produce micronuclei in human glioblastoma cell lines.

Al-Serori H et al. · 2017

Austrian researchers exposed human brain tumor cells to UMTS cell phone radiation for 16 hours at levels reflecting real-world phone use (SAR levels of 0.25 to 1.0 W/kg). They found no evidence of DNA damage or chromosomal abnormalities, though the highest exposure level triggered programmed cell death in one type of brain cancer cell. This study suggests UMTS phone signals may not directly damage genetic material in brain cells.

Effects of GSM-like radiofrequency irradiation during the oogenesis and spermiogenesis of Xenopus laevis.

Boga A, Emre M, Sertdemir Y, Uncu İ, Binokay S, Demirhan O. · 2016

Researchers exposed adult frogs to cell phone radiation (900 MHz) for 8 hours daily over 5 weeks, then examined their offspring. Exposed parents produced 3-5 times more abnormal and dead embryos than unexposed pairs, demonstrating that radiofrequency radiation can damage reproductive cells and harm the next generation.