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

## TL;DR

The study found that exposing rats to 1.95 GHz electromagnetic fields at high power increases their body temperature, but they can regulate it effectively at lower power levels.

## Contribution

This study is the first to measure core body temperature changes in free-moving rats during and after 1.95 GHz RF-EMF exposure using implanted telemetry.

## Key findings

- Exposure to 4 W/kg RF-EMF increased core body temperature by 0.62°C during the last 30 minutes of exposure.
- Rats exposed to 0.1 and 0.4 W/kg RF-EMF showed minimal temperature increases, indicating effective thermoregulation.
- Post-exposure temperature measurements may not capture the maximum temperature changes caused by RF-EMF.

## Abstract

The present study investigated the core body temperature (CBT) response of free‐moving adult male and female Sprague Dawley rats, during and following a 3‐h exposure to 1.95 GHz radiofrequency electromagnetic fields (RF‐EMFs) within custom‐built reverberation chambers, using temperature capsules implanted within the intraperitoneal cavity and data transmitted via radiotelemetry. Comparing RF‐EMF exposures (at Whole‐Body Average‐Specific Absorption Rate [WBA‐SAR] levels of 0.1, 0.4, and 4 W/kg) to the sham exposed condition, we identified a statistically significant peak increase in CBT after 26 min of RF‐EMF exposure at 4 W/kg (+0.49°C), but not in the 0.1 or 0.4 W/kg conditions at the same timepoint. In the last 30 min of the RF‐EMF exposure, temperature was significantly increased in both the 4 W/kg (0.62°C) and 0.4 W/kg (0.14°C) conditions, but not 0.1 W/kg, when compared to sham. After 20 min following cessation of exposure, post temperature was still significantly higher in the 4 W/kg condition when compared to the sham (0.37°C), but not in either 0.1 or 0.4 W/kg. Based on our findings, it is apparent that rats can effectively compensate for increased thermal loads of up to 4 W/kg as the maximum temperature rise was substantially lower than 1°C. In addition, the elevated CBT during exposure in the 4 W/kg condition was significantly reduced immediately after exposure cessation, indicating that measures of CBT following RF‐EMF exposure cessation may not reflect maximum RF‐EMF‐mediated changes in the CBT of rats. Bioelectromagnetics. 00:00–00, 2025. © 2025 Bioelectromagnetics Society.

Exposure of 1.95 GHz electromagnetic fields at 4 W/kg WBA‐SAR increases core body temperature by 0.62°C.Rat thermoregulation can effectively compensate for thermal load due to exposure to RF‐EMF at 0.1 and 0.4 W/kg WBA‐SAR (maximum increase = 0.14°C).Post cessation measures of CBT in rats may not reflect maximum RF‐EMF‐mediated changes.

Exposure of 1.95 GHz electromagnetic fields at 4 W/kg WBA‐SAR increases core body temperature by 0.62°C.

Rat thermoregulation can effectively compensate for thermal load due to exposure to RF‐EMF at 0.1 and 0.4 W/kg WBA‐SAR (maximum increase = 0.14°C).

Post cessation measures of CBT in rats may not reflect maximum RF‐EMF‐mediated changes.