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No Changes in Cerebral Microcirculatory Parameters in Rat During Local Cortex Exposure to Microwaves

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Masuda H, Hirota S, Ushiyama A, Hirata A, Arima T, Watanabe H, Wake K, Watanabe S, Taki M, Nagai A, Ohkubo C · 2015

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Rats showed no immediate brain blood flow changes during 50-minute exposure to cell phone-level RF radiation at 2.0 W/kg.

Plain English Summary

Summary written for general audiences

Researchers exposed rat brain tissue to cell phone-level radiofrequency radiation (1439 MHz) for 50 minutes. They found no changes in blood vessel size, blood flow speed, or brain inflammation during exposure, suggesting this radiation level doesn't immediately disrupt brain circulation.

Why This Matters

This study provides important data on whether RF radiation at levels comparable to heavy cell phone use can immediately affect brain blood circulation. The 2.0 W/kg exposure level is at the upper limit of what current safety standards allow for localized exposure, making these findings directly relevant to real-world device use. However, the research has significant limitations that readers should understand. The study only measured immediate effects during the 50-minute exposure period and didn't examine longer-term impacts or cumulative effects from repeated exposures. The reality is that most people use wireless devices for hours daily over years or decades. While this research suggests no acute circulatory disruption, it doesn't address whether chronic, low-level exposures might gradually affect brain blood flow or whether other biological processes might be impacted at these exposure levels.

Exposure Details

SAR
2 W/kg
Source/Device
1439 MHz
Exposure Duration
50 min

Exposure Context

This study used 2 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 ContextA logarithmic scale showing exposure levels relative to Building Biology concern thresholds and regulatory limits.Study Exposure Level in ContextThis study: 2 W/kgExtreme Concern0.1 W/kgFCC Limit1.6 W/kgEffects observed in the Extreme Concern range (Building Biology)FCC limit is 1x higher than this exposure level

Study Details

The aim of this study was to determine whether cerebral microcirculatory parameters in rats were modified during local cortex exposure to a radiofrequency electromagnetic field (RF) under non-thermal conditions.

The cortex tissue targeted was locally exposed to 1439 MHz RF using a figure-8 loop antenna at an av...

No extravasation of intravenously injected fluorescent dye was observed during RF exposure. There wa...

These findings suggest that no dynamic changes occurred in cerebral microcirculation even during local cortex exposure under these conditions.

Cite This Study
Masuda H, Hirota S, Ushiyama A, Hirata A, Arima T, Watanabe H, Wake K, Watanabe S, Taki M, Nagai A, Ohkubo C (2015). No Changes in Cerebral Microcirculatory Parameters in Rat During Local Cortex Exposure to Microwaves In Vivo. 29(2):207-215, 2015.
Show BibTeX
@article{h_2015_no_changes_in_cerebral_1185,
  author = {Masuda H and Hirota S and Ushiyama A and Hirata A and Arima T and Watanabe H and Wake K and Watanabe S and Taki M and Nagai A and Ohkubo C},
  title = {No Changes in Cerebral Microcirculatory Parameters in Rat During Local Cortex Exposure to Microwaves},
  year = {2015},
  
  url = {https://iv.iiarjournals.org/content/29/2/207},
}

Quick Questions About This Study

Researchers exposed rat brain tissue to cell phone-level radiofrequency radiation (1439 MHz) for 50 minutes. They found no changes in blood vessel size, blood flow speed, or brain inflammation during exposure, suggesting this radiation level doesn't immediately disrupt brain circulation.