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Physiologic aspects of microwave irradiation of mammals

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Sol M. Michaelson, Roderick A. E. Thomson, Joe W. Howland · 1961

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This pioneering 1961 study established early scientific foundation for understanding microwave radiation's thermal effects on mammals.

Plain English Summary

Summary written for general audiences

This 1961 research by SM Michaelson examined how microwave radiation affects the physiology of mammals including dogs, rabbits, and rats. The study focused on thermal effects and biological responses to microwave irradiation. This represents some of the earliest systematic research into how microwave energy impacts living systems.

Why This Matters

This study stands as a landmark in EMF research, conducted at a time when microwave technology was rapidly expanding but safety concerns were just emerging. Michaelson's work on thermal effects laid crucial groundwork for understanding how microwave radiation interacts with biological systems. What makes this research particularly relevant today is that it examined multiple mammalian species, providing broader insights into how microwave exposure affects warm-blooded animals generally. The reality is that in 1961, microwave ovens were just becoming commercially available, and cellular technology was decades away. Yet researchers like Michaelson were already investigating the biological impacts of microwave frequencies that would later become ubiquitous in our daily lives through WiFi, cell phones, and countless wireless devices operating in similar frequency ranges.

Figures from the Original Paper

Diagrams extracted from the original research document.

graphPage 3 - Figure 1. Response of dog to microwave exposure.
p. 3 of the original PDF
graphPage 4 - AI-described figure: Figure 4 illustrates the thermal response to microwave exposure over time.
p. 4 of the original PDF
chartPage 5 - AI-described figure: Figure 5 illustrates physiologic response in normal dogs exposed to microwaves, showing changes in hematocrit and weight over time.
p. 5 of the original PDF

Exposure Information

A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 2.8 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 2.8 GHzPower lines50/60 Hz5G mm28 GHzLogarithmic scale

Specific exposure levels were not quantified in this study. Duration: 2 hours/day for 30 days

Study Details

To investigate the physiologic effects of microwave irradiation on mammals, particularly focusing on thermal responses, leukocyte changes, and the influence of environmental factors and anesthetics.

Adult mongrels of either sex, 1-5 yr of age, were exposed to 2,800 Mcycle/sec pulsed microwaves usin...

The dog pants as soon as irradiation starts, with the rate of panting increasing and stabilizing onl...

The study demonstrates that microwave irradiation of mammals produces characteristic physiologic responses, with some related to heating of superficial tissues. Specific changes in leukocyte levels occur independently of hematocrit or temperature increase. Postexposure lymphocytopenia and eosinopenia appear related to duration of exposure. Anesthetization of the dog results in increased thermal susceptibility which is not evident in the rabbit or rat. Consumption of water during exposure depresses the thermal response. Exposure at increased ambient temperature results in synergism of thermal effect reducing tolerance to microwaves. Vasomotor integrity appears to be a critical factor in regulating the thermal response. No specific long-term effects such as cataracts have been observed in animals held for more than 1 year post-exposure.

Cite This Study
Sol M. Michaelson, Roderick A. E. Thomson, Joe W. Howland (1961). Physiologic aspects of microwave irradiation of mammals.
Show BibTeX
@article{physiologic_aspects_of_microwave_irradiation_of_mammals_g3743,
  author = {Sol M. Michaelson and Roderick A. E. Thomson and Joe W. Howland},
  title = {Physiologic aspects of microwave irradiation of mammals},
  year = {1961},
  
  
}
No DOI on file for this study.

Quick Questions About This Study

The research examined dogs, rabbits, and rats to understand how microwave irradiation affects mammalian physiology. Using multiple species provided broader insights into biological responses across different warm-blooded animals.
This study established foundational understanding of microwave-biological interactions before widespread consumer adoption. It provided early scientific framework for evaluating safety as microwave technology expanded into ovens, communications, and wireless devices.
The study concentrated on thermal effects and physiologic responses to microwave irradiation. This thermal focus became the basis for later safety standards, though non-thermal effects weren't well understood at the time.
Many modern wireless technologies including WiFi and cell phones operate in microwave frequency ranges similar to what Michaelson studied. This early research provided baseline understanding for evaluating biological effects of these technologies.
Using multiple mammalian species allowed broader conclusions about microwave effects on warm-blooded animals generally. This systematic approach established important precedents for rigorous EMF biological research methodology.