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Whole Body / General

Exposure to Microwaves

Bioeffects Seen

W. W. Salisbury, John W. Clark, H. M. Hines · 1949

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1949 research showed 12-cm microwaves heat internal tissue dangerously without pain signals, revealing hidden biological effects.

Plain English Summary

Summary written for general audiences

This 1949 study by Salisbury exposed animals to high-intensity 12-centimeter microwave radiation and discovered that dangerous heat buildup occurred beneath the skin surface without triggering normal warning signals like fever or pain. The research revealed that microwave radiation could cause internal tissue heating that the body's natural protection mechanisms couldn't detect.

Why This Matters

This groundbreaking 1949 research identified one of the most concerning aspects of microwave radiation exposure: its ability to heat internal tissues without triggering the body's natural warning systems. What makes this finding particularly relevant today is that modern wireless devices operate on similar principles, though at much lower power levels. The 12-centimeter wavelength studied corresponds to frequencies around 2.5 GHz, remarkably close to today's WiFi (2.4 GHz) and some cellular frequencies. The study's core finding that microwave energy can penetrate tissue and create heat without pain sensation helps explain why current safety standards, which focus primarily on preventing tissue heating, may not adequately protect against subthermal biological effects. This early research laid the foundation for understanding how electromagnetic fields interact with living tissue in ways that bypass our evolved protective responses.

Original Figures

Diagrams extracted from the original research document.

Page 1 - A graph showing experimentally determined variation of temperature in an excised beef eye exposed to microwave radiation.
Page 2 - Figure 2C illustrates temperature curves with depth in an idealized animal, assuming no cooling due to circulation of blood.

Exposure Information

Specific exposure levels were not quantified in this study.

Cite This Study
W. W. Salisbury, John W. Clark, H. M. Hines (1949). Exposure to Microwaves.
Show BibTeX
@article{exposure_to_microwaves_g6960,
  author = {W. W. Salisbury and John W. Clark and H. M. Hines},
  title = {Exposure to Microwaves},
  year = {1949},
  
  
}

Quick Questions About This Study

The 1949 Salisbury study used 12-centimeter wavelength microwave radiation, which corresponds to approximately 2.5 GHz frequency. This wavelength is remarkably similar to modern WiFi and cellular frequencies used today.
The microwave radiation heated tissue beneath the surface without activating pain receptors or fever responses. This means the body's natural warning systems failed to detect the dangerous heat buildup occurring inside.
Unlike surface heating that triggers immediate pain, 12-centimeter microwaves penetrated deep into tissue and generated heat internally. This subsurface heating bypassed the body's protective pain and temperature regulation mechanisms completely.
This was among the first studies to demonstrate that microwave radiation could cause biological effects without obvious symptoms. It revealed that electromagnetic energy could harm living tissue through mechanisms the body couldn't naturally detect.
Yes, the 12-centimeter wavelength studied in 1949 translates to about 2.5 GHz, which is very close to today's WiFi (2.4 GHz) and cellular frequencies, though modern devices use much lower power levels.