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EFFECTS OF FREQUENCY, IRRADIATION GEOMETRY AND POLARISATION ON COMPUTATION OF SAR IN HUMAN BRAIN.

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Zhou H, Su Z, Ning J, Wang C, Xie X, Qu D, Wu K, Zhang X, Pan J, Yang G. · 2014

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Human brains show peak RF energy absorption at cell phone frequencies due to head resonance effects.

Plain English Summary

Summary written for general audiences

Researchers used computer modeling to calculate how much radiofrequency energy (SAR) gets absorbed by different parts of the human brain at various frequencies. They found that the brain absorbs particularly high levels of energy at around 250 MHz and 900-1200 MHz frequencies, likely because the head acts like an antenna that resonates at these specific frequencies. This matters because these frequency ranges overlap with common wireless technologies like cell phones and radio broadcasts.

Why This Matters

This study reveals a critical vulnerability in how our brains interact with radiofrequency radiation. The finding that human heads exhibit resonance effects at specific frequencies - particularly around 250 MHz and in the 900-1200 MHz range used by many cell phones - means our brains may absorb far more energy than previously assumed at these frequencies. Put simply, your head can act like an antenna, concentrating RF energy in your brain tissue at certain frequencies. What makes this research particularly significant is that it challenges the one-size-fits-all approach to SAR limits. The reality is that RF absorption varies dramatically based on frequency, polarization, and exposure geometry. This suggests that current safety standards, which rely on averaged SAR values, may not adequately protect against peak absorption in critical brain regions at resonant frequencies.

Exposure Information

A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 250 MHz - 1.20 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 250 MHz - 1.20 GHzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Specific exposure levels were not quantified in this study. The study examined exposure from: ∼250 MHz and 900-1200 MHz

Study Details

In order to determine the specific absorption rate (SAR) of radio frequency (RF) waves in the human brain, and to investigate the effects of geometry and polarisation on SAR value

the finite-difference time-domain method was applied for the SAR computation. An anatomically realis...

. The results suggested that high SAR values were found in the brain, i.e. ∼250 MHz for vertical pol...

Cite This Study
Zhou H, Su Z, Ning J, Wang C, Xie X, Qu D, Wu K, Zhang X, Pan J, Yang G. (2014). EFFECTS OF FREQUENCY, IRRADIATION GEOMETRY AND POLARISATION ON COMPUTATION OF SAR IN HUMAN BRAIN. Radiat Prot Dosimetry. 2014 Jan 6.
Show BibTeX
@article{h_2014_effects_of_frequency_irradiation_2710,
  author = {Zhou H and Su Z and Ning J and Wang C and Xie X and Qu D and Wu K and Zhang X and Pan J and Yang G.},
  title = {EFFECTS OF FREQUENCY, IRRADIATION GEOMETRY AND POLARISATION ON COMPUTATION OF SAR IN HUMAN BRAIN.},
  year = {2014},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/24399107/},
}
PubMed: 24399107

Cited By (2 papers)

Quick Questions About This Study

The brain absorbs particularly high levels of radiofrequency energy at 250 MHz because the human head acts like an antenna that resonates at this specific frequency. Computer modeling shows this creates peak absorption rates, especially with vertical polarization signals from radio broadcasts and communication systems.
Computer modeling reveals that vertical polarization creates high brain absorption at 250 MHz, while both vertical and horizontal polarization cause elevated absorption at 900-1200 MHz frequencies. The polarization direction significantly influences how much radiofrequency energy your brain tissue absorbs.
Research shows the brain absorbs exceptionally high levels of radiofrequency energy at 900-1200 MHz frequencies due to head resonance effects. This frequency range overlaps with common cell phone and wireless technologies, creating peak specific absorption rates in brain tissue.
Computer modeling demonstrates that the human head acts as a resonating antenna at specific frequencies like 250 MHz and 900-1200 MHz, creating peak absorption zones. The head's dimensions determine these resonance frequencies, affecting how much radiofrequency energy different brain regions absorb.
Researchers use sophisticated computer modeling to calculate specific absorption rates (SAR) in different brain regions across various frequencies, polarizations, and exposure geometries. These models revealed peak brain energy absorption at 250 MHz and 900-1200 MHz due to head resonance effects.