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Microwaves: Effect on Thermoregulatory Behavior in Rats

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James P. Dilger, Stuart G. A. McLaughlin, Thomas J. McIntosh, Sidney A. Simon · 1979

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Rats detected internal heating from 2450 MHz microwaves even when core temperature measurements showed no change.

Plain English Summary

Summary written for general audiences

Researchers exposed rats to 2450 MHz microwave radiation (the same frequency used in microwave ovens) and found the animals changed their heat-seeking behavior even when their core body temperature didn't change. The rats pressed a lever less frequently to turn on a warming lamp when exposed to microwaves, suggesting they were detecting internal heating that standard temperature measurements couldn't detect.

Why This Matters

This 1979 study reveals something crucial that the wireless industry would prefer you not think about: animals can detect biological effects from microwave radiation at levels that don't register on conventional measuring tools. The rats' behavioral changes occurred at power densities between 5-20 milliwatts per square centimeter - levels that are actually higher than typical cell phone exposure but within range of what you might experience near a microwave oven or WiFi router. What makes this research particularly significant is that it challenges the fundamental assumption underlying current safety standards: that if there's no measurable temperature increase, there's no biological effect. The rats knew something was happening to their bodies even when thermometers said otherwise. This suggests our current approach to measuring EMF effects may be missing important biological responses that living organisms can detect but our instruments cannot.

Exposure Information

Specific exposure levels were not quantified in this study.

Cite This Study
James P. Dilger, Stuart G. A. McLaughlin, Thomas J. McIntosh, Sidney A. Simon (1979). Microwaves: Effect on Thermoregulatory Behavior in Rats.
Show BibTeX
@article{microwaves_effect_on_thermoregulatory_behavior_in_rats_g5002,
  author = {James P. Dilger and Stuart G. A. McLaughlin and Thomas J. McIntosh and Sidney A. Simon},
  title = {Microwaves: Effect on Thermoregulatory Behavior in Rats},
  year = {1979},
  
  
}

Quick Questions About This Study

Yes, the rats changed their heat-seeking behavior when exposed to 2450 MHz microwaves even though their core body temperature showed no measurable increase, suggesting they detected internal heating that instruments couldn't measure.
The rats showed behavioral responses to 2450 MHz microwave exposure at power densities between 5-20 milliwatts per square centimeter during 15-minute exposure periods in this controlled laboratory study.
Rats pressed the lever to turn on an infrared warming lamp less frequently when exposed to 2450 MHz microwaves, indicating they sensed internal heating and reduced their heat-seeking behavior accordingly.
Researchers clipped the rats' fur to ensure more uniform microwave penetration and heating patterns, eliminating the insulating effect of fur that could interfere with consistent exposure levels across the animals.
The researchers suggested their findings might help explain reported 'nonthermal' microwave effects, since the rats detected biological changes that didn't show up as measurable core temperature increases using standard methods.