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Athermic and Thermic Absorption Processes with Microwaves from 1 mm to 30 cm

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D. A. Copson · 1967

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1967 research recognized both heating and non-heating biological effects from microwaves, establishing early safety concerns for wireless technology.

Plain English Summary

Summary written for general audiences

This 1967 review examined microwave absorption in biological systems across frequencies from 1mm to 30cm wavelengths. The study noted that maximum safe exposure was set at 0.01 watts per square centimeter and explored both thermal heating effects (like medical diathermy) and non-thermal biological mechanisms. The research highlighted early concerns about microwave hazards as communication technologies expanded.

Why This Matters

This historical review is significant because it documents early recognition of microwave biological effects just as wireless communication was emerging. The 0.01 watts per square centimeter exposure limit mentioned here translates to 10 milliwatts per square centimeter - notably higher than today's FCC limit of 1-5 mW/cm² for cell phones, showing how safety standards have evolved. What's particularly important is the study's acknowledgment of both thermal and 'athermic' (non-thermal) effects, challenging the industry narrative that only heating matters. The research recognized that microwaves could affect biological systems through mechanisms beyond simple tissue heating - a concept that remains contentious today despite decades of supporting evidence.

Exposure Information

Specific exposure levels were not quantified in this study.

Cite This Study
D. A. Copson (1967). Athermic and Thermic Absorption Processes with Microwaves from 1 mm to 30 cm.
Show BibTeX
@article{athermic_and_thermic_absorption_processes_with_microwaves_from_1_mm_to_30_cm_g7255,
  author = {D. A. Copson},
  title = {Athermic and Thermic Absorption Processes with Microwaves from 1 mm to 30 cm},
  year = {1967},
  
  
}

Quick Questions About This Study

The study referenced a maximum exposure limit of 0.01 watts per square centimeter of body surface. This equals 10 milliwatts per square centimeter, which is actually higher than current FCC limits of 1-5 mW/cm² for cell phones.
The research examined microwaves from 1mm to 30cm wavelengths. This broad spectrum covers frequencies used in modern communications, medical diathermy, and various industrial applications including masers and early wireless technologies.
Yes, the study specifically distinguished between 'thermic' (heating) and 'athermic' (non-heating) absorption processes. This early recognition challenges claims that microwaves only affect biology through tissue heating mechanisms.
The study examined medical diathermy, communications systems, masers, and freeze-drying applications. Researchers noted the 'vastly broadened use' of microwave energy in communications was creating new demands for biological hazard knowledge.
The study noted engineering problems including microwave generation, transmission, distribution, impedance matching, and vacuum transitions at high power levels. Researchers also identified glow discharge from residual gases as a particular concern.