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Changes in human EEG alpha activity following exposure to two different pulsed magnetic field sequences.

Bioeffects Seen

Cook CM, Saucier DM, Thomas AW, Prato FS. · 2009

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Everyday magnetic field exposure altered human brain waves within 5 minutes, showing our brains actively respond to EMF levels considered safe.

Plain English Summary

Summary written for general audiences

Researchers exposed 32 people to weak pulsed magnetic fields (the type generated by power lines and electrical devices) for 15 minutes while measuring their brain waves. They found that different pulse patterns altered alpha brain wave activity in the back regions of the brain within just 5 minutes of exposure. The changes persisted even after exposure ended, suggesting that these everyday magnetic fields can measurably affect brain function.

Why This Matters

This study provides clear evidence that extremely low frequency magnetic fields at everyday exposure levels can alter human brain activity. The magnetic field strength used (200 microTesla) is well within the range you encounter from common household appliances and power lines. What makes this research particularly significant is that brain wave changes occurred within just 5 minutes of exposure and persisted afterward. The study also found that previous exposures influenced how the brain responded to subsequent magnetic field exposure, suggesting potential cumulative effects. This adds to a growing body of evidence showing that the brain is sensitive to EMF exposure at levels regulatory agencies currently consider safe. While we don't yet know the long-term health implications of these brain wave changes, the research demonstrates that our nervous systems are clearly responding to the electromagnetic environment we've created around ourselves.

Exposure Details

Magnetic Field
0.2 mG
Source/Device
0–500 Hz
Exposure Duration
15 min

Exposure Context

This study used 0.2 mG for magnetic fields:

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: 0.2 mGExtreme Concern - 5 mGFCC Limit - 2,000 mGEffects observed in the Slight Concern rangeFCC limit is 10,000x higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 500 Hz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 500 HzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Study Details

The present study investigates the effects of a weak (+/-200 microT(pk)), pulsed, extremely low frequency magnetic field (ELF MF) upon the human electroencephalogram (EEG).

In the present study, subjects (n = 32) were exposed to two different pulsed MF sequences (1 and 2, ...

Results suggest that compared to sham exposure, alpha activity was lowered over the occipital–pariet...

This study supports our previous observation of EEG changes after 5 min pulsed ELF MF exposure. The results of this study are also consistent with existing EEG experiments of ELF MF and mobile phone effects upon the brain.

Cite This Study
Cook CM, Saucier DM, Thomas AW, Prato FS. (2009). Changes in human EEG alpha activity following exposure to two different pulsed magnetic field sequences. Bioelectromagnetics. 30(1):9-20, 2009.
Show BibTeX
@article{cm_2009_changes_in_human_eeg_233,
  author = {Cook CM and Saucier DM and Thomas AW and Prato FS.},
  title = {Changes in human EEG alpha activity following exposure to two different pulsed magnetic field sequences.},
  year = {2009},
  doi = {10.1002/bem.20434},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/bem.20434},
}
DOI: 10.1002/bem.20434

Cited By (51 papers)

View all 51 citing papers on Semantic Scholar

Quick Questions About This Study

Yes, research shows that weak pulsed magnetic fields from power lines can alter alpha brain wave activity in just 5 minutes. A 2009 study found that different pulse patterns changed brain wave activity in the back regions of the brain, with effects persisting even after exposure ended.
Yes, different pulse sequences of low-frequency magnetic fields (0-500 Hz) produce opposite effects on brain waves. One sequence lowered alpha activity in brain regions, while another sequence increased it, showing that specific patterns matter for how these fields affect neural function.
Brain wave changes from pulsed magnetic field exposure persist beyond the actual exposure period. The 2009 Cook study found that alpha brain wave alterations continued even after the 15-minute magnetic field exposure ended, indicating lasting effects on brain function.
Yes, prior exposure to pulsed magnetic fields appears to influence how your brain responds to subsequent exposures. Research found that previous magnetic field exposure determined participants' brain wave responses in follow-up experiments, suggesting cumulative or conditioning effects on neural activity.
The occipital-parietal regions at the back of the brain show the strongest responses to power line frequency magnetic fields. These areas, involved in visual processing and spatial awareness, demonstrated significant alpha wave changes within 5 minutes of exposure to pulsed magnetic fields.