Characterization of the Core Temperature Response of Free-Moving Rats to 1.95 GHz Electromagnetic Fields

Authors: Bala N, Croft RJ, McIntosh RL, Iskra S, Frankland JV, McKenzie RJ, Deng C

Year: 2025 Jul

Category: Bioelectromagnetics, Physiology

Journal: Bioelectromagnetics

DOI: 10.1002/bem.70013

URL: https://onlinelibrary.wiley.com/doi/10.1002/bem.70013

Abstract

Overview

This study examined how free-moving adult male and female Sprague Dawley rats responded in core body temperature (CBT) to exposure at 1.95 GHz radiofrequency electromagnetic fields (RF-EMFs). Using temperature capsules implanted in the rats' intraperitoneal cavities and radiotelemetry, researchers measured CBT changes during and after a 3-hour RF-EMF exposure inside specially designed reverberation chambers.

Findings

  • Rats were exposed to RF-EMFs at whole-body average specific absorption rate (WBA-SAR) levels of 0.1, 0.4, and 4 W/kg, compared with a sham (no exposure) control.
  • Significant peak increase in CBT (+0.49°C) was detected after 26 minutes of exposure at 4 W/kg, with no significant increase at 0.1 or 0.4 W/kg at that same time.
  • In the last 30 minutes of RF-EMF exposure:
    • 4 W/kg: temperature increase of 0.62°C
    • 0.4 W/kg: temperature increase of 0.14°C
    • 0.1 W/kg: no significant temperature increase
  • Twenty minutes after exposure ended, only the 4 W/kg group retained a significantly higher temperature compared to sham (+0.37°C).
  • The maximum CBT increase remained less than 1°C, suggesting effective thermoregulatory compensation up to these RF-EMF exposures.
  • Temperature elevation at 4 W/kg significantly decreased immediately upon the end of exposure, highlighting that post-exposure measurement may underestimate maximum temperature effects of RF-EMF.

Conclusion

The study demonstrates that RF-EMF exposures at higher SAR values (notably 4 W/kg) can cause measurable thermal effects in animal models. While the rats compensated well for thermal load, these findings confirm a physiological response to electromagnetic fields, which supports the importance of safety limits when considering health risks from electromagnetic field exposures.

RF-EMF rat study core body temperature specific absorption rate electromagnetic field exposure thermal response animal model
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