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THE ABSORPTION OF ELECTROMAGNETIC ENERGY IN BODY TISSUES

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Herman P. Schwan, Geo Morris Piersol · 1955

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This 1955 research established foundational principles for understanding how electromagnetic energy heats body tissues.

Plain English Summary

Summary written for general audiences

This pioneering 1955 study by Herman Schwan examined how electromagnetic energy from microwave sources gets absorbed by human body tissues, focusing on the heating effects and temperature changes. The research explored how microwaves interact with different tissues and how blood flow affects heat distribution, laying crucial groundwork for understanding electromagnetic absorption in biological systems.

Why This Matters

This landmark research represents one of the earliest systematic investigations into how electromagnetic energy interacts with human tissue. Schwan's work established fundamental principles that remain relevant today as we grapple with exponentially higher EMF exposures from wireless devices. The study's focus on tissue heating and electromagnetic absorption patterns helped establish the foundation for modern specific absorption rate (SAR) measurements used in cell phone safety testing. What makes this research particularly significant is its timing - conducted in 1955, it anticipated many of the biological interaction mechanisms we're still studying today. The reality is that while this early research focused primarily on thermal effects from high-power microwave sources, we now know that biological effects can occur at much lower power levels through non-thermal mechanisms that weren't well understood at the time.

Exposure Information

A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 2.5-4 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 2.5-4 GHzPower lines50/60 Hz5G mm28 GHzLogarithmic scale

Specific exposure levels were not quantified in this study. Duration: 20 minutes average duration of treatment

Study Details

To review and critically analyze the absorption of electromagnetic energy in body tissues, particularly focusing on physiological and clinical aspects of microwave diathermy.

The study is a review and critical analysis of existing literature on electromagnetic energy absorpt...

The review found that effective tissue heating can be brought about by microwave diathermy. Temperat...

Microwave radiation can be applied more conveniently than other forms of diathermy. The degree of heating and depth of penetration depend upon the type of director used, power output, distance from skin surface, and treatment duration. The physiological effects include increased temperature, accelerated blood flow, vasodilatation, and increased metabolic activities. However, accurate determination of dosage and energy absorbed by tissues cannot be determined accurately, relying instead on subjective patient sensation.

Cite This Study
Herman P. Schwan, Geo Morris Piersol (1955). THE ABSORPTION OF ELECTROMAGNETIC ENERGY IN BODY TISSUES.
Show BibTeX
@article{the_absorption_of_electromagnetic_energy_in_body_tissues_g69,
  author = {Herman P. Schwan and Geo Morris Piersol},
  title = {THE ABSORPTION OF ELECTROMAGNETIC ENERGY IN BODY TISSUES},
  year = {1955},
  
  
}
No DOI on file for this study.

Quick Questions About This Study

The study investigated how electromagnetic energy from microwave sources gets absorbed by human body tissues, examining heating effects, temperature changes, and how blood flow influences heat distribution throughout different tissue types.
Schwan's work established fundamental principles of electromagnetic absorption in biological tissues that became the foundation for modern SAR measurements and safety standards used in wireless device testing today.
Microwave diathermy uses controlled electromagnetic heating for medical therapy. This 1955 research helped establish how tissues absorb electromagnetic energy, principles that apply to understanding modern wireless device interactions with the body.
The research examined how electromagnetic energy converts to heat in body tissues and how blood circulation affects temperature distribution, establishing key concepts for understanding thermal effects of electromagnetic exposure.
This foundational work on electromagnetic absorption in tissues helped establish the scientific basis for specific absorption rate (SAR) limits that regulate how much electromagnetic energy wireless devices can deposit in human tissue.