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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

Millimeter-wave effects on electric activity of crayfish stretch receptors.

No Effects Found

Khramov RN, Sosunov EA, Koltun SV, Ilyasova EN, Lednev VV · 1991

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Millimeter waves temporarily altered nerve activity in crayfish through heating effects at power levels 25-250 times higher than typical 5G exposure.

Plain English Summary

Summary written for general audiences

Researchers exposed crayfish nerve cells to millimeter-wave radiation (similar to what 5G uses) at power levels up to 250 mW/cm2 and measured changes in nerve firing patterns. They found temporary decreases in nerve activity during exposure that returned to normal afterward, with the effects appearing to be caused by slight heating (about 1.5°C) rather than the electromagnetic fields themselves. This suggests that millimeter waves affect nerve function primarily through thermal heating rather than direct electromagnetic interference.

Why This Matters

This 1991 study provides important baseline data on how millimeter-wave radiation affects nerve function, using frequencies that overlap with today's 5G networks (24-100 GHz). The power density of 250 mW/cm2 used here is significantly higher than typical 5G exposures, which generally range from 1-10 mW/cm2. What's particularly noteworthy is that the researchers found the effects were temperature-dependent rather than frequency-specific, suggesting thermal rather than non-thermal mechanisms. While crayfish neurons aren't identical to human neurons, this research adds to our understanding of how millimeter waves interact with nervous system tissue. The temporary nature of the effects and their correlation with heating provides context for evaluating potential biological impacts of 5G technology.

Exposure Details

Power Density
250 mW/cm²
Source/Device
34-78 GHz

Exposure Context

This study used 250 mW/cm² for radio frequency:

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: 250 mW/cm²Extreme Concern - 1,000 µW/m²FCC Limit - 10M µW/m²Effects observed in the Extreme Concern range (Building Biology)This level is 250 times the FCC limit
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 78 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 78 GHzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHzLogarithmic scale

Study Details

The effects of super high frequency (SHF) microwaves (34-78 GHz) on rates of spontaneous firing of the slowly adapting, stretch-receptor neurons of crayfish were studied.

Initially, irradiation of continuously perfused, fluid-cooled preparations at power densities to 250...

Cite This Study
Khramov RN, Sosunov EA, Koltun SV, Ilyasova EN, Lednev VV (1991). Millimeter-wave effects on electric activity of crayfish stretch receptors. Bioelectromagnetics 12(4):203-214, 1991.
Show BibTeX
@article{rn_1991_millimeterwave_effects_on_electric_3135,
  author = {Khramov RN and Sosunov EA and Koltun SV and Ilyasova EN and Lednev VV},
  title = {Millimeter-wave effects on electric activity of crayfish stretch receptors.},
  year = {1991},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/1930305/},
}
PubMed: 1930305

Cited By (18 papers)

Quick Questions About This Study

Research on crayfish nerve cells exposed to millimeter waves (34-78 GHz) found only temporary changes in nerve activity that returned to normal after exposure ended. The effects appeared caused by slight heating rather than direct electromagnetic damage to the nerves themselves.
A 1991 study found millimeter waves caused temporary decreases in nerve cell firing rates, but these changes reversed completely when exposure stopped. The effects were attributed to mild heating (1.5°C increase) rather than direct electromagnetic interference with neural function.
Testing on nerve cells using 5G-similar frequencies (34-78 GHz) showed only reversible effects during exposure. The temporary changes in nerve activity appeared to result from thermal heating rather than permanent electromagnetic damage to nervous system function.
Studies using high-power millimeter wave exposure found no permanent nerve damage. While nerve firing rates temporarily decreased during exposure, they returned to normal levels afterward, suggesting the effects were thermal rather than causing lasting neurological harm.
Millimeter wave exposure temporarily reduces nerve cell firing rates through mild heating effects. Research shows these changes are reversible and frequency-independent, with nerve activity returning to baseline levels once the electromagnetic field exposure ends completely.