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Local exposure of the rat cortex to radiofrequency electromagnetic fields increases local cerebral blood flow along with temperature

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Masuda H, Hirata A, Kawai H, Wake K, Watanabe S, Arima T, Poulletier de Gannes F, Lagroye I, Veyret B. · 2011

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RF radiation increases brain blood flow and temperature in a dose-dependent manner, even at levels just above current safety limits.

Plain English Summary

Summary written for general audiences

Researchers exposed rat brains to cell phone-frequency radiation and found it increased both brain temperature and blood flow. Higher radiation levels caused greater effects. This shows radiofrequency radiation triggers measurable biological changes in brain tissue, including the brain's natural response to heating.

Why This Matters

This study provides clear evidence that radiofrequency radiation causes measurable physiological changes in brain tissue, specifically increased blood flow and temperature. The researchers used SAR levels ranging from 10.5 to 263 W/kg - with even the lowest level showing effects. To put this in perspective, current SAR limits for cell phones are 1.6 W/kg in the US and 2 W/kg in Europe, yet this study found biological responses at levels just 5-6 times higher than these regulatory limits. The dose-response relationship is particularly significant, showing that the brain's vascular system responds proportionally to RF intensity. What this means for you is that your brain tissue demonstrably reacts to RF exposure by increasing blood flow, likely as a protective mechanism against heating. While this study used laboratory conditions and higher exposures than typical phone use, it contradicts claims that RF radiation below heating thresholds is biologically inert.

Exposure Details

SAR
10.5, 40.3, 130, and 263 W/kg
Source/Device
1,950 MHz
Exposure Duration
continuous for 18 min

Exposure Context

This study used 10.5, 40.3, 130, and 263 W/kg for SAR (device absorption):

Building Biology guidelines are practitioner-based limits from real-world assessments. BioInitiative Report recommendations are based on peer-reviewed science. Check Your Exposure to compare your own measurements.

Where This Falls on the Concern Scale

Study Exposure Level in ContextStudy Exposure Level in ContextThis study: 10.5, 40.3, 130, and 263 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern rangeFCC limit is 0x higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 1.95 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 1.95 GHzPower lines50/60 Hz5G mm28 GHzLogarithmic scale

Study Details

The aim of the present study was to detect reproducible responses to local RF exposure in the parietal cortex of anesthetized rats and to determine their dependence on RF intensity.

The target cortex tissue was locally exposed to 2-GHz RF using a figure-eight loop antenna within a ...

All parameters except for the calf hypodermis temperature increased significantly in exposed animals...

These findings suggest that local RF exposure of the rat cortex drives a regulation of CBF accompanied by a local temperature rise, and our findings may be helpful for discussing physiological changes in the local cortex region, which is locally exposed to RF.

Cite This Study
Masuda H, Hirata A, Kawai H, Wake K, Watanabe S, Arima T, Poulletier de Gannes F, Lagroye I, Veyret B. (2011). Local exposure of the rat cortex to radiofrequency electromagnetic fields increases local cerebral blood flow along with temperature J Appl Physiol. 110(1):142-148, 2011.
Show BibTeX
@article{h_2011_local_exposure_of_the_141,
  author = {Masuda H and Hirata A and Kawai H and Wake K and Watanabe S and Arima T and Poulletier de Gannes F and Lagroye I and Veyret B.},
  title = {Local exposure of the rat cortex to radiofrequency electromagnetic fields increases local cerebral blood flow along with temperature},
  year = {2011},
  doi = {10.1152/japplphysiol.01035.2010},
  url = {https://journals.physiology.org/doi/full/10.1152/japplphysiol.01035.2010},
}
DOI: 10.1152/japplphysiol.01035.2010

Cited By (31 papers)

View all 31 citing papers on Semantic Scholar

Quick Questions About This Study

Yes, 1950 MHz radiation significantly increased cerebral blood flow in rat brains during 18-minute exposures. The 2011 study found this blood flow increase correlated with brain temperature rises, suggesting the brain responds to radiofrequency heating by increasing circulation to cool itself.
Yes, 1950 MHz radiation (similar to cell phone frequencies) caused measurable brain temperature increases in rats. Higher radiation intensity produced greater heating effects. The study showed radiofrequency exposure triggers both temperature rises and the brain's natural cooling response through increased blood flow.
Brain blood flow changes occurred within 18 minutes of 1950 MHz radiation exposure in rats. The study found blood flow elevation correlated with temperature rises, with effects appearing in the early part of exposure, especially at higher radiation intensities.
Yes, the study found radiation intensity directly correlated with brain effects. Higher 1950 MHz exposure levels caused greater increases in both brain temperature and blood flow. This dose-response relationship suggests stronger radiofrequency signals produce more pronounced biological changes in brain tissue.
RF exposure increases brain blood flow as a natural cooling mechanism. When 1950 MHz radiation heats brain tissue, increased blood circulation helps dissipate the excess heat. This represents the brain's physiological attempt to regulate temperature during radiofrequency exposure.