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Magnetic Fields (ELF)

Personal digital assistant (PDA) cell phone units produce elevated extremely-low frequency electromagnetic field emissions.

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Sage C, Johansson O, Sage SA · 2007

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PDAs produced electromagnetic field spikes up to 90 microTesla during normal use, far exceeding typical household exposure levels.

Plain English Summary

Summary written for general audiences

Researchers measured electromagnetic fields from early smartphone-like devices during normal use. They found these devices produced surprisingly high electromagnetic pulses - up to 90 microTesla when powering on and 60 microTesla during email activities - potentially exposing users throughout day and night.

Why This Matters

This 2007 study was ahead of its time in documenting how wireless devices create unexpected electromagnetic field exposures beyond their intended radio frequency emissions. The ELF-EMF levels measured here - particularly the 60-90 microTesla spikes - are remarkably high compared to typical household exposures, which usually range from 0.1-1 microTesla. What makes this research particularly relevant today is that modern smartphones and tablets operate with far more complex processors and wireless functions than these early PDAs, potentially creating even more varied electromagnetic field patterns. The reality is that we carry these devices against our bodies for hours each day, yet most people have no idea they're being exposed to these electromagnetic field bursts every time an email downloads or the device switches on. This study highlights a critical gap in how we assess device safety - focusing only on intended radio frequency emissions while ignoring the unintended electromagnetic fields generated by internal electronics.

Exposure Details

Magnetic Field
0.01 and 0.002, 0.01 and 0.03-0.06 and 0.000 5 ,0.001 and 0.09 mG
Exposure Duration
24h

Exposure Context

This study used 0.01 and 0.002, 0.01 and 0.03-0.06 and 0.000 5 ,0.001 and 0.09 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 ContextA logarithmic scale showing exposure levels relative to Building Biology concern thresholds and regulatory limits.Study Exposure Level in ContextThis study: 0.01 and 0.002, 0.01 and 0.03-0.06 and 0.000 5 ,0.001 and 0.09 mGExtreme Concern5 mGFCC Limit2,000 mGEffects observed in the No Concern range (Building Biology)FCC limit is 2,000,000x higher than this exposure level

Study Details

Initial tests indicate that personal and occupational use of personal digital assistants (PDAs or palm-held wireless units) produce high intensity bursts of extremely-low frequency electromagnetic fields (ELF-EMF). These emissions could result in comparatively high ELF-EMF exposure in persons that carry a PDA close to the body (i.e., in a pocket or on a belt); or held to the head for cell phone conversations. ELF-EMF emissions of 10 microT were recorded on PDAs during normal office use over a 24 h test period. ``

Results of ELF-EMF measurements show that email transmit and receive functions produce rapid, short-...

Cite This Study
Sage C, Johansson O, Sage SA (2007). Personal digital assistant (PDA) cell phone units produce elevated extremely-low frequency electromagnetic field emissions. Bioelectromagnetics.28(5):386-92,2007.
Show BibTeX
@article{c_2007_personal_digital_assistant_pda_1303,
  author = {Sage C and Johansson O and Sage SA},
  title = {Personal digital assistant (PDA) cell phone units produce elevated extremely-low frequency electromagnetic field emissions.},
  year = {2007},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/17357117/},
}
PubMed: 17357117

Quick Questions About This Study

Researchers measured electromagnetic fields from early smartphone-like devices during normal use. They found these devices produced surprisingly high electromagnetic pulses - up to 90 microTesla when powering on and 60 microTesla during email activities - potentially exposing users throughout day and night.