HEATING OF HUMAN AND ANIMAL TISSUES BY MEANS OF HIGH FREQUENCY CURRENT WITH WAVELENGTH OF TWELVE CENTIMETERS
OSBORNE, SL, FREDERICK, MS · 1948
1948 research on 12-centimeter microwave tissue heating laid groundwork for today's thermal-only EMF safety standards.
Plain English Summary
This 1948 study investigated how 12-centimeter wavelength microwave radiation heats human and animal tissues, likely for medical diathermy applications. The research examined tissue heating effects from high-frequency electromagnetic fields, providing early scientific documentation of how microwave energy interacts with biological tissues. This work represents foundational research into microwave heating mechanisms that would later inform both medical applications and safety standards.
Why This Matters
This 1948 research represents a crucial early investigation into how microwave radiation affects biological tissues - work that laid the groundwork for understanding EMF bioeffects we're still grappling with today. The 12-centimeter wavelength studied corresponds to approximately 2.5 GHz, remarkably close to the 2.4 GHz frequency used by WiFi routers, Bluetooth devices, and microwave ovens in your home. What makes this particularly relevant is that it documented heating effects in tissues, the very mechanism the FCC still relies on today for setting EMF exposure limits.
The reality is that this thermal-only approach to EMF safety, established decades ago based on heating research like this, ignores the mounting evidence of non-thermal biological effects from modern wireless technologies. While this study focused on intentional medical heating applications, today's devices expose us to similar frequencies at lower powers but for vastly longer durations. The science demonstrates that chronic exposure to these frequencies can trigger biological responses well below heating thresholds - effects that weren't even considered when our current safety standards were established.
Figures from the Original Paper
Diagrams extracted from the original research document.
Exposure Information
Specific exposure levels were not quantified in this study. Duration: twenty minutes
Study Details
To determine whether high frequency current of this magnitude would heat living tissues to a temperature of 104 F. at a depth of 2 inches (5.08 cm.) and to learn whether the heat gradient as the result of treatment was normal, that is, a decreasing temperature from superficial to the deeper underlying tissues, or whether there was a reversal of this normal heat gradient.
All temperatures were measured with thermocouples made of constantan and copper wires (28- gage Leed...
1. Leg Muscles of the Dog.—The average thigh temperature for ten experiments using a 6 inch (15.24 c...
The heat produced in living animal tissues by exposure to high frequency radiations of 12cm. wavelength has been studied. The heat decreases from the superficial to the deeper tissues, but this temperature gradient is not as steep as in the short wave diathermy. The temperature difference between the subcutaneous and 1 inch (2.54 cm.) level showed more variation among individual experiments than did the difference between the 1 inch (2.54 cm.) and 2 inch (5.08 cm.) levels. In one experiment the animal was exposed to a strong breeze during treatment. The final temperatures showed an increase from the subcutaneous level to a depth of 1 1/2 inches (3.81 cm.). The microtherm unit used in our experiments has a maximum output of 125 watts. The output of the SCR-517 used by Fallis is three hundred and sixty times the maximum output of the microtherm. In contrast to the foregoing experiments we exposed local areas for twenty minute periods. In view of the evidence produced by these investigators it would seem improbable that any ill effects should result from the limited exposure used in clinical practice. The heating of the human thigh with the microtherm generator produced temperatures of 104.2 F. (40.1 C.) at a depth of 2 inches (5.08 cm.), which meets the heating requirements of the Council on Physical Medicine of the American Medical Association.
Show BibTeX
@article{heating_of_human_and_animal_tissues_by_means_of_high_frequency_current_with_wave_g3729,
author = {OSBORNE and SL and FREDERICK and MS},
title = {HEATING OF HUMAN AND ANIMAL TISSUES BY MEANS OF HIGH FREQUENCY CURRENT WITH WAVELENGTH OF TWELVE CENTIMETERS},
year = {1948},
}