Effects of microwaves on the adrenal cortex

Area of Science:

• Electromagnetic fields
• Endocrinology
• Physiology

Background:

• Microwave exposure is increasingly prevalent.
• Understanding its physiological effects, particularly on the endocrine system, is crucial.
• Adrenocortical secretion is a key stress response indicator.

Purpose of the Study:

• To investigate the impact of varying microwave power densities on adrenocortical secretion in rats.
• To identify factors influencing the adrenal cortex's sensitivity to microwave exposure.
• To establish thresholds for microwave-induced adrenocortical stimulation.

Main Methods:

• Male Long-Evans rats exposed to 2.45 GHz microwaves (0.1–55 mW/cm², 0.02–11 W/kg SAR).
• Serum corticosterone (CS) measured as an index of adrenocortical function.
• Ten exposure protocols used to assess confounding factors like temperature, acclimation, ethanol, and ether.

Main Results:

• Increased CS concentration correlated with power density and colonic temperature, inversely with baseline CS.
• Adrenal stimulation required a minimum of 20 mW/cm² (4 W/kg) or 0.7°C colonic temperature increase.
• Hyperthermia was necessary for CS increase; effects were transient, with acclimation after ten exposures.

Conclusions:

• Microwave exposure, primarily through hyperthermia, stimulates adrenocortical secretion in rats.
• Factors like facilitated heat loss, ethanol, and ether modulate this response.
• Specific power density and temperature thresholds exist for microwave-induced adrenal stimulation.