Related Experiment Videos
Foot currents and ankle SARs induced by dielectric heaters
D L Conover1, C E Moss, W E Murray
1Physical Agents Effects Branch, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998.
Bioelectromagnetics
|January 1, 1992
Summary
Radio-frequency electromagnetic fields from dielectric heaters can induce high foot currents in operators. Some currents exceeded proposed safety limits, leading to significant specific absorption rates (SARs) in ankles.
Area of Science:
- Electromagnetics
- Occupational Health
- Biophysics
Background:
- Workers operating dielectric heaters are exposed to radio-frequency electromagnetic fields.
- Near-field exposures, dominated by reactive coupling, can lead to substantial specific absorption rates (SARs).
Purpose of the Study:
- To present data on ankle-specific SARs and foot currents in relation to radio-frequency electromagnetic field strengths.
- To assess the risk posed by foot currents exceeding proposed safety standards.
Main Methods:
- Measurements of foot currents to ground were taken from operators working near dielectric heaters (6.5-65 MHz).
- Electric and magnetic field strengths were quantified at typical operator distances.
- Ankle-specific SARs were calculated based on measured foot currents.
Main Results:
- Maximal foot currents ranged from 3 to 617 mA rms.
- Nearly 27% of dielectric heaters induced foot currents exceeding the proposed 200-mA safety limit.
- Calculated ankle SARs reached up to approximately 176 W/kg at 617 mA.
Conclusions:
- Foot currents induced by dielectric heaters can exceed established safety guidelines.
- High foot currents correlate with significant specific absorption rates in the ankle, posing a potential health risk to operators.