Hyperthermia in radiofrequency-exposed rhesus monkeys: a comparison of frequency and orientation effects med./bio.

To determine the effect on body temperature and plasma cortisol levels of whole body exposure of rhesus monkeys to a near-resonant frequency. Monkeys were exposed for 4 hr to 225 MHz, electric field oriented parallel to the long axis of the body (225 MHz-E), and to 225 MHz, magnetic field orientation (225 MHz-H), or to 1290 MHz, electric field orientation. On a separate occasion, the monkeys were irradiated at night to 225 MHz-E.

• animal
• rhesus monkey (Macaca mulatta)
• whole body

Average rectal temperature increases for day exposure to 225 MHz-E were 0.4 and 1.7°C for 4-hr exposures to 2.5 and 5.0 mW/cm². No alterations in cortisol contents occurred during any exposures to 5 mW/cm² or less. Night exposures to 5 mW/cm² at 225 MHz-E raised mean rectal temperature 2.1°C. Exposure to 5 mW/cm² at 225 MHz-H for 4 hr resulted in a 0.2°C rise in mean rectal temperature. For 4 hr of 1290-MHz exposure to 20, 28, or 38 mW/cm², the mean body temperature increases were 0.4, 0.7, and 1.3°C, respectively.
The degree of hyperthermia caused by radiofrequency exposure was shown to be frequency and orientation dependent for equivalent power densities.