8,700 Studies Reviewed. 87.0% Found Biological Effects. The Evidence is Clear.
Shield Your Body
Cancer & Tumors119 citations

Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields.

Bioeffects Seen

Adey WR, Byus CV, Cain CD, Higgins RJ, Jones RA, Kean CJ, Kuster N, MacMurray A, Stagg RB, Zimmerman G. · 2000

View Original Abstract
Share:

FM radiofrequency signals showed no brain tumor effects in rats, but digital phone signals may behave differently.

Plain English Summary

Summary written for general audiences

Researchers exposed 540 laboratory rats to radiofrequency signals mimicking cell phone use throughout their entire lives to test whether this exposure increases brain tumor risk. The study found no increased rates of brain tumors from the RF exposure, even when combined with a cancer-causing chemical. Interestingly, this contrasts with the same research team's previous study using digital phone signals, which showed a protective effect against brain tumors.

Why This Matters

This comprehensive 2-year study provides important evidence about RF exposure and brain cancer risk, but with a crucial caveat about signal type. The researchers used frequency-modulated (FM) signals rather than the pulsed digital signals that dominate modern wireless communication. The exposure levels (1.0-1.2 W/kg) closely matched real-world cell phone use in the brain. What makes this study particularly significant is that it directly contrasts with the same team's earlier work showing digital phone signals actually reduced tumor rates. This suggests that the specific characteristics of RF signals matter tremendously for biological effects. The science demonstrates that continuous wave or frequency-modulated fields may behave very differently in biological systems compared to pulsed or amplitude-modulated signals. What this means for you is that studies showing 'no effect' from older analog-type signals may not apply to today's digital wireless technologies that pulse on and off rapidly.

Exposure Details

SAR
1.0 and 1.2 W/kg
Source/Device
836.55 MHz +/- 12.5 KHz deviation
Exposure Duration
Intermittent field exposures began on gestation day 19 and continued until weaning at 21 days, resuming thereafter at 31 days and continuing until experiment termination at 731-734 days

Exposure Context

This study used 1.0 and 1.2 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 ContextStudy Exposure Level in ContextThis study: 1.0 and 1.2 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern rangeFCC limit is 2x higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 12.5 kHz - 836.5 MHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 12.5 kHz - 836.5 MHzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Study Details

The aim of this study is to observe Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields.

In a 2-year bioassay, we exposed Fischer 344 rats to a frequency-modulated (FM) signal (836.55 MHz +...

Of the original 540 rats, 168 died before the termination of the experiment. In these rats, ENU sign...

These negative findings with FM fields contrast with our study using standard digital phone fields pulsed on and off at 50/se, where a trend was noted toward reduced incidence of both spontaneous and ENU-induced CNS tumors (W. R. Adey et al., Radiat. Res., 152: 293-302, 1999). Although consistent but not attaining significance in the experiment overall (spontaneous CNS tumors, P < 0.08 one-tailed; P < 0.16 two-tailed; ENU-induced CNS tumors, P < 0.08 one-tailed, P < 0.16 two-tailed), the trend was significant (P < 0.015 one-tailed, P < 0.03, two-tailed) in rats that received ENU and died prior to experiment termination, with a primary brain tumor as the cause of death. We discuss differences in the signaling structure of digital and FM fields. Certain bioeffects induced by either amplitude-modulated or pulsed radiofrequency fields at athermal levels have not been seen with fields of similar average power but unvarying in intensity (continuous wave or frequency-modulated fields).

Cite This Study
Adey WR, Byus CV, Cain CD, Higgins RJ, Jones RA, Kean CJ, Kuster N, MacMurray A, Stagg RB, Zimmerman G. (2000). Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields. Cancer Res 60(7):1857-1863, 2000.
Show BibTeX
@article{wr_2000_spontaneous_and_nitrosoureainduced_primary_795,
  author = {Adey WR and Byus CV and Cain CD and Higgins RJ and Jones RA and Kean CJ and Kuster N and MacMurray A and Stagg RB and Zimmerman G.},
  title = {Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields.},
  year = {2000},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/10766172/},
}
PubMed: 10766172

Cited By (119 papers)

View all 119 citing papers on Semantic Scholar

Quick Questions About This Study

A comprehensive study exposing 540 rats to cell phone-like radiofrequency signals throughout their entire lives found no increased brain tumor rates. The research used frequency-modulated signals similar to analog phones and detected no changes in tumor incidence, even when combined with cancer-causing chemicals.
Research on radiofrequency exposure and brain cancer shows mixed results depending on signal type. A 2000 study found frequency-modulated RF fields caused no tumor increases, while the same team's previous research with digital phone signals suggested a protective effect against brain tumors.
Studies suggest different RF signal types may have varying biological effects. Research found frequency-modulated signals (like analog phones) showed no tumor protection, while pulsed digital phone signals demonstrated a trend toward reduced brain tumor incidence in laboratory animals exposed throughout their lifetimes.
Laboratory research indicates brain tumor risk from phone radiation depends on signal characteristics. Frequency-modulated RF exposure showed no increased tumor rates in a lifetime animal study, contrasting with digital signals that appeared to reduce tumor incidence in previous research by the same team.
RF field exposure effects on tumor development vary by signal type and modulation. Continuous frequency-modulated fields showed no impact on brain tumor rates in laboratory studies, while amplitude-modulated or pulsed fields at similar power levels have demonstrated different biological effects in research.