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1439 MHz pulsed TDMA fields affect performance of rats in a T-maze task only when body temperature is elevated.

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Yamaguchi H, Tsurita G, Ueno S, Watanabe S, Wake K, Taki M, Nagawa H. · 2003

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Cell phone radiation impaired rat learning only when exposure was high enough to cause tissue heating, not at levels four times above phone limits.

Plain English Summary

Summary written for general audiences

Researchers exposed rats to cell phone-type radiation (1439 MHz) while testing their ability to learn and remember food locations in a maze. They found that only the highest exposure levels - which caused body temperature to rise - impaired the rats' learning performance. At exposure levels about four times stronger than typical cell phones (but without heating effects), no learning problems occurred.

Why This Matters

This study provides important context for understanding when EMF exposure might affect cognitive function. The key finding is that learning impairment occurred only when radiation exposure was intense enough to heat body tissue - a threshold effect that suggests thermal mechanisms rather than non-thermal biological impacts. However, we should note the exposure levels tested here. The 'safe' level that showed no effects (7.5 W/kg to the brain) was still nearly four times higher than current cell phone limits. What this means for you is that while this particular study didn't find cognitive effects at moderately elevated exposure levels, it doesn't rule out subtler impacts from chronic, lower-level exposures that characterize real-world cell phone use. The research also focused on acute learning tasks rather than long-term cognitive development or more complex brain functions.

Exposure Details

SAR
1.7, 7.5 W/kg
Source/Device
1439 MHz
Exposure Duration
1 h daily for 4 days or for 4 weeks t

Exposure Context

This study used 1.7, 7.5 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: 1.7, 7.5 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern rangeFCC limit is 1x higher than this level
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

This study sought to clarify the effects of exposure to electromagnetic waves (EMW) used in cellular phones on learning and memory processes.

Sprague-Dawley rats were exposed for either 1 h daily for 4 days or for 4 weeks to a pulsed 1439 MHz...

The animals exposed to EMW with the brain average SAR of 25 W/kg for 4 days showed statistically sig...

These results suggest that the exposure to a TDMA field at levels about four times stronger than emitted by cellular phones does not affect the learning and memory processes when there are no thermal effects.

Cite This Study
Yamaguchi H, Tsurita G, Ueno S, Watanabe S, Wake K, Taki M, Nagawa H. (2003). 1439 MHz pulsed TDMA fields affect performance of rats in a T-maze task only when body temperature is elevated. Bioelectromagnetics 24(4):223-230, 2003.
Show BibTeX
@article{h_2003_1439_mhz_pulsed_tdma_1442,
  author = {Yamaguchi H and Tsurita G and Ueno S and Watanabe S and Wake K and Taki M and Nagawa H.},
  title = {1439 MHz pulsed TDMA fields affect performance of rats in a T-maze task only when body temperature is elevated.},
  year = {2003},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/12696082/},
}
PubMed: 12696082

Cited By (40 papers)

Quick Questions About This Study

No, 1439 MHz TDMA radiation at levels four times stronger than cell phones (7.5 W/kg) did not impair rat learning or memory in maze tests. Only extremely high exposures (25 W/kg) that caused body temperature increases affected performance, suggesting thermal effects rather than radiation itself caused the problems.
A brain SAR of 25 W/kg from 1439 MHz radiation significantly impaired rats' T-maze reversal learning performance. However, exposure at 7.5 W/kg showed no learning problems. For comparison, cell phones are limited to maximum 2 W/kg, making these findings less relevant to typical phone use.
No, this 2003 study found that 1439 MHz pulsed TDMA fields only affected rat learning when they caused body temperature increases. At exposure levels without thermal effects, even those four times stronger than cell phone emissions, no learning or memory impairments occurred in the animals.
Four days of 1439 MHz radiation exposure at 25 W/kg impaired rat memory performance in maze tests. However, both 4-day and 4-week exposures at the lower 7.5 W/kg level showed no memory problems, indicating duration alone doesn't cause effects without sufficient intensity.
Yes, the study specifically found that 1439 MHz radiation at 25 W/kg significantly decreased correct choices in the reversal learning task, where rats had to adapt to changed food locations. This suggests the radiation may particularly affect cognitive flexibility when thermal effects occur.