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

Immune System

Antibody responses of mice exposed to low-power microwaves under combined, pulse-and-amplitude modulation.

No Effects Found

Veyret B, Bouthet C, Deschaux P, de Seze R, Geffard M, Joussot-Dubien J, le Diraison M, Moreau JM, Caristan A, · 1991

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Modulated microwave signals altered mouse immune responses at power levels 1,000 times lower than cell phones, while unmodulated signals showed no effect.

Plain English Summary

Summary written for general audiences

French researchers exposed mice to low-power pulsed microwaves (similar to radar frequencies) for 10 hours daily over five days to test effects on immune system function. They found that simple pulsed signals had little effect, but when the signals included additional amplitude modulation, the mice showed significant changes in antibody production - some frequencies strengthened immune responses while others weakened them.

Why This Matters

This 1991 study reveals a crucial insight often overlooked in EMF research: modulation matters enormously. The science demonstrates that it's not just the power level that determines biological effects, but how the signal is structured. At extremely low power levels - about 1,000 times weaker than what your cell phone produces - these researchers found measurable immune system changes, but only when the microwave signal carried specific modulation patterns. What this means for you is significant, because virtually all modern wireless devices use complex modulation schemes to carry data. The reality is that current safety standards focus primarily on heating effects from average power, largely ignoring these modulation-dependent biological responses that can occur at much lower exposure levels.

Exposure Details

SAR
0.015 W/kg
Power Density
0.03 mW/cm²
Source/Device
9.4 GHz modulation (AM) by a sinusoid at discrete frequencies between 14 and 41 MHz
Exposure Duration
10 h/day

Exposure Context

This study used 0.03 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: 0.03 mW/cm²Extreme Concern - 1,000 µW/m²FCC Limit - 10M µW/m²Effects observed in the Extreme Concern range (Building Biology)FCC limit is 33 times higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 41 MHz - 9.40 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 41 MHz - 9.40 GHzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Study Details

Irradiation by pulsed microwaves (9.4 GHz, 1 microsecond pulses at 1,000/s), both with and without concurrent amplitude modulation (AM) by a sinusoid at discrete frequencies between 14 and 41 MHz, was assessed for effects on the immune system of Balb/C mice.

The mice were immunized either by sheep red blood cells (SRBC) or by glutaric-anhydride conjugated b...

In the absence of AM, the pulsed field did not greatly alter immune responsiveness. In contrast, exp...

Cite This Study
Veyret B, Bouthet C, Deschaux P, de Seze R, Geffard M, Joussot-Dubien J, le Diraison M, Moreau JM, Caristan A, (1991). Antibody responses of mice exposed to low-power microwaves under combined, pulse-and-amplitude modulation. Bioelectromagnetics 12(1):47-56, 1991.
Show BibTeX
@article{b_1991_antibody_responses_of_mice_3465,
  author = {Veyret B and Bouthet C and Deschaux P and de Seze R and Geffard M and Joussot-Dubien J and le Diraison M and Moreau JM and Caristan A and},
  title = {Antibody responses of mice exposed to low-power microwaves under combined, pulse-and-amplitude modulation.},
  year = {1991},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/2012621/},
}
PubMed: 2012621

Cited By (67 papers)

View all 67 citing papers on Semantic Scholar

Quick Questions About This Study

Research shows radar-like microwaves can alter immune function, but the effects depend on signal characteristics. A 1991 French study found that simple pulsed radar signals had minimal impact, but when combined with amplitude modulation, the same frequencies significantly strengthened or weakened antibody production in mice.
Microwave radiation's impact on immunity depends on the specific signal type. French researchers found that basic pulsed microwaves caused little immune change, but adding amplitude modulation created frequency-dependent effects - some frequencies actually boosted immune responses while others suppressed antibody production in laboratory mice.
Simple pulsed microwave signals showed minimal health effects in controlled studies, but complex modulated signals can impact biological systems. Research demonstrates that when pulsed microwaves include additional amplitude modulation, they can significantly alter immune system function, creating both strengthening and weakening effects.
Radar exposure risks to immunity depend on signal complexity rather than just power levels. Studies show basic radar-like pulses cause minimal immune changes, but signals with combined modulation patterns can significantly alter antibody production, creating unpredictable strengthening or suppression of immune responses.
Microwave frequency effects on antibodies depend on modulation patterns, not just the base frequency. Research found that 9.4 GHz microwaves with amplitude modulation between 14-41 MHz created frequency-specific changes in antibody production, while the same base frequency without modulation showed little immune impact.