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Note: This study found no significant biological effects under its experimental conditions. We include all studies for scientific completeness.

Brain & Nervous System

Effects of subchronic exposure to a 1439 MHz electromagnetic field on the microcirculatory parameters in rat brain.

No Effects Found

Masuda H, Ushiyama A, Hirota S, Wake K, Watanabe S, Yamanaka Y, Taki M, Ohkubo C · 2007

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Four weeks of cell phone-level RF exposure showed no effects on brain blood vessels in rats.

Plain English Summary

Summary written for general audiences

Researchers exposed rats' heads to cell phone-level radiation (1439 MHz) for one hour daily over four weeks to study effects on brain blood vessels. They found no changes in blood-brain barrier function, immune cell behavior, or blood flow in the brain. This suggests that this level of radiofrequency exposure may not disrupt the brain's delicate blood vessel system.

Why This Matters

This study provides reassuring data about one specific aspect of brain health under radiofrequency exposure. The researchers used a SAR level of 2.4 W/kg, which is close to current safety limits for cell phone use (2.0 W/kg in the US). The blood-brain barrier is a critical protective system that prevents harmful substances from entering brain tissue, so finding no disruption is significant. However, this represents just one study examining one specific endpoint. The reality is that brain effects from EMF exposure remain an active area of research, with other studies showing different results for different biological markers. What this means for you is that while this particular study found no vascular effects in the brain, it doesn't address other potential neurological impacts that research continues to investigate.

Exposure Details

SAR
2.4 W/kg
Source/Device
1439 MHz
Exposure Duration
60 min/day, 5 days/week, for 4 weeks

Exposure Context

This study used 2.4 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: 2.4 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern range (Building Biology)This level is 1 times the FCC limit
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 1.44 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 1.44 GHzPower lines50/60 Hz5G mm28 GHzLogarithmic scale

Study Details

The aim of this study was to investigate whether repeated exposure to radio frequency electromagnetic field (RF-EMF) of 1439 MHz affects the cerebral microcirculation, including blood-brain barrier function, in a rat brain.

The head of the rat was exposed for four weeks (60 min/day, 5 days/week) to RF-EMF at 2.4 W/kg of br...

No extravasation of intravenously injected dyes from pial venules was found at any BASAR level. No s...

These findings suggest that there were no effects on the cerebral microcirculation under the given RF-EMF exposure conditions.

Cite This Study
Masuda H, Ushiyama A, Hirota S, Wake K, Watanabe S, Yamanaka Y, Taki M, Ohkubo C (2007). Effects of subchronic exposure to a 1439 MHz electromagnetic field on the microcirculatory parameters in rat brain. In Vivo. 21(4):563-570, 2007.
Show BibTeX
@article{h_2007_effects_of_subchronic_exposure_3235,
  author = {Masuda H and Ushiyama A and Hirota S and Wake K and Watanabe S and Yamanaka Y and Taki M and Ohkubo C},
  title = {Effects of subchronic exposure to a 1439 MHz electromagnetic field on the microcirculatory parameters in rat brain.},
  year = {2007},
  
  url = {https://iv.iiarjournals.org/content/21/4/563.short},
}

Quick Questions About This Study

A 2007 study found no damage to brain blood vessels from cell phone-level radiation. Researchers exposed rats to 1439 MHz signals for four weeks and detected no changes in blood-brain barrier function or blood flow patterns.
Research shows cell phone radiation at 1439 MHz does not affect brain blood flow. A four-week study found plasma velocity in brain blood vessels remained normal throughout exposure to cell phone-level electromagnetic fields.
Studies indicate 1439 MHz radiation does not harm brain circulation. Researchers found no effects on cerebral blood vessels, blood-brain barrier function, or immune cell behavior after daily one-hour exposures for four weeks.
Current research suggests RF radiation at cell phone frequencies may not cause brain blood vessel problems. A 2007 study found no disruption to the brain's delicate blood vessel system from 1439 MHz exposure.
Studies show cell phone EMF at 1439 MHz does not affect the blood-brain barrier. Researchers found no leakage of injected dyes from brain blood vessels after four weeks of daily electromagnetic field exposure.