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SAR / Device Absorption

Foot currents and ankle SARs induced by dielectric heaters.

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Conover DL, Moss CE, Murray WE, Edwards RM, Cox C, Grajewski B, Werren DM, Smith JM · 1992

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Industrial workers near dielectric heaters experienced ankle energy absorption rates up to 176 W/kg, vastly exceeding typical EMF safety limits.

Plain English Summary

Summary written for general audiences

Workers operating industrial dielectric heaters showed dangerously high electromagnetic energy absorption in their ankles. Twenty-seven percent of these heating machines created electrical currents through workers' feet exceeding safety limits, with maximum energy absorption reaching 176 watts per kilogram in ankle tissue.

Why This Matters

This occupational health study reveals a critical gap in how we assess EMF safety. While most research focuses on whole-body or brain exposure, this work demonstrates that specific body parts can experience extremely high energy absorption rates even when overall exposure seems manageable. The ankle SAR of 176 W/kg found in some workers is extraordinarily high - for context, cell phone SAR limits are typically around 1.6-2 W/kg. What makes this particularly concerning is that these workers were simply doing their jobs, standing where they normally worked near industrial heating equipment. The reality is that occupational EMF exposures often involve near-field conditions where traditional safety calculations break down, creating localized absorption hot spots that current safety standards don't adequately address.

Exposure Details

SAR
5, 29,57, and 176 W/kg
Electric Field
10000, 2400000 V/m
Source/Device
6.5 to 65 MHz

Exposure Context

This study used 10000, 2400000 V/m for electric fields:

This study used 5, 29,57, and 176 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: 5, 29,57, and 176 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern rangeFCC limit is 0x higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 65 MHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 65 MHzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Study Details

The aim of this study is to investigate Foot currents and ankle SARs induced by dielectric heaters.

The determination of foot currents was based on near-field exposures in which reactive coupling domi...

Nearly 27 percent of the dielectric heaters induced foot currents that exceeded the 200-mA limit tha...

Cite This Study
Conover DL, Moss CE, Murray WE, Edwards RM, Cox C, Grajewski B, Werren DM, Smith JM (1992). Foot currents and ankle SARs induced by dielectric heaters. Bioelectromagnetics 13(2):103-110, 1992.
Show BibTeX
@article{dl_1992_foot_currents_and_ankle_910,
  author = {Conover DL and Moss CE and Murray WE and Edwards RM and Cox C and Grajewski B and Werren DM and Smith JM},
  title = {Foot currents and ankle SARs induced by dielectric heaters.},
  year = {1992},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/1590810/},
}
PubMed: 1590810

Cited By (16 papers)

Quick Questions About This Study

Yes, industrial dielectric heaters can cause dangerous electromagnetic energy absorption in workers' ankles. A 1992 study found these machines created electrical currents through workers' feet, with maximum energy absorption reaching 176 watts per kilogram in ankle tissue.
Working near industrial RF heaters poses significant risks to your feet and ankles. Research shows 27% of these heating machines create electrical currents through workers' feet that exceed proposed safety limits, potentially causing tissue heating.
Industrial dielectric heating equipment creates measurable radiation effects in workers, particularly in their lower extremities. Studies document dangerous levels of electromagnetic energy absorption in ankle tissue, with some readings exceeding safety recommendations by substantial margins.
RF heaters pose serious ankle injury risks through excessive electromagnetic energy absorption. Research found these industrial machines can generate up to 176 watts per kilogram of energy absorption in ankle tissue, far exceeding levels considered safe.
Dielectric heaters significantly impact worker safety by creating dangerous electrical currents through employees' bodies. Nearly 30% of these industrial heating machines generate foot currents exceeding proposed safety standards, potentially causing tissue damage in ankles and feet.