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Naltrexone-sensitive analgesia following exposure of mice to 2450-MHz radiofrequency radiation

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Maillefer RH, Quock RM · 1992

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Microwave radiation triggered stress-response mechanisms in mice at high heating levels, showing RF effects extend beyond simple tissue warming.

Plain English Summary

Summary written for general audiences

Researchers exposed mice to microwave radiation at 2450 MHz (the same frequency used in microwave ovens) for 10 minutes and measured their pain response. They found that higher radiation levels caused the mice's bodies to heat up and triggered natural pain-killing mechanisms in the brain, similar to how the body responds to other forms of thermal stress. This suggests that microwave radiation can cause biological effects beyond just heating tissue.

Why This Matters

This 1992 study provides important evidence that radiofrequency radiation produces measurable biological responses through thermal mechanisms at relatively high exposure levels. The SAR values used (23.7 to 45.5 W/kg) are substantially higher than current safety limits for cell phones (2 W/kg), but they demonstrate that RF radiation can trigger the body's stress response systems when heating occurs. What makes this research significant is that it shows RF exposure doesn't just heat tissue passively - it activates complex biological pathways, including the brain's opioid system that normally responds to pain and stress. While these exposure levels exceed typical daily RF encounters, the study illustrates how electromagnetic fields can influence neurological processes when thermal thresholds are reached, supporting the need for continued research into RF bioeffects.

Exposure Details

SAR
23.7, 34.6, and 45.5 W/kg
Power Density
10, 15, and 20 µW/m²
Source/Device
2450-MHz
Exposure Duration
10 min

Exposure Context

This study used 10, 15, and 20 µW/m² for radio frequency:

This study used 23.7, 34.6, and 45.5 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: 10, 15, and 20 µW/m²Extreme Concern - 1,000 uW/m2FCC Limit - 10M uW/m2Effects observed in the Severe Concern rangeFCC limit is 1,000,000x higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 2.45 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 2.45 GHzPower lines50/60 Hz5G mm28 GHzLogarithmic scale

Study Details

To determine whether exposure to radiofrequency radiation (RFR) would induce sufficient thermal stress to activate endogenous opioid mechanisms.

For the present study,male Swiss Webster mice were exposed to 10, 15, and 20 mW/cm2 RFR in a 2450-MH...

Confinement in the RFR exposure chamber alone did not appreciably alter body temperature but did app...

These findings suggest that 1) RFR produces SAR-dependent hyperthermia and analgesia, and 2) RFR-induced analgesia is mediated by opioid mechanisms while confinement-induced analgesia involves nonopioid mechanisms.

Cite This Study
Maillefer RH, Quock RM (1992). Naltrexone-sensitive analgesia following exposure of mice to 2450-MHz radiofrequency radiation Physiol Behav 52(3):511-514, 1992.
Show BibTeX
@article{rh_1992_naltrexonesensitive_analgesia_following_exposure_1172,
  author = {Maillefer RH and Quock RM},
  title = {Naltrexone-sensitive analgesia following exposure of mice to 2450-MHz radiofrequency radiation},
  year = {1992},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/1409913/},
}
PubMed: 1409913

Cited By (4 papers)

Quick Questions About This Study

Yes, microwave radiation at 2450 MHz can affect pain sensitivity by triggering natural pain-killing mechanisms in the brain. A 1992 study found that mice exposed to this frequency experienced reduced pain response through opioid pathways, similar to how the body responds to thermal stress.
Yes, 2450 MHz radiation causes biological effects beyond simple tissue heating. Research shows this frequency triggers the brain's natural pain-relief systems and raises body temperature in a dose-dependent manner, indicating that microwave radiation produces measurable physiological responses in living organisms.
Microwave oven frequency (2450 MHz) can affect brain chemistry by activating opioid pain-relief pathways. While this study found these effects occurred alongside tissue heating, it demonstrates that this common frequency produces measurable changes in nervous system function beyond thermal effects.
Radiofrequency exposure at 2450 MHz impacts the nervous system by activating natural pain-killing mechanisms in the brain. The study found this occurs through opioid pathways and increases with higher radiation levels, showing the nervous system responds to RF energy exposure.
Microwave radiation at 2450 MHz reduces pain sensitivity by triggering the brain's natural opioid system. This analgesic effect increases with higher radiation levels and was blocked when researchers used naltrexone, a drug that prevents opioid activity in the brain.