To determine if a near field radiofrequency exposure could induce a stress response.
The aims of this study were 1) if the loose-tube restraints (some movement allowed) necessary for accurate near field radiofrequency exposures could cause a stress response in animals, 2) if near field radiofrequency exposures to the head could induce a stress response in animals above that observed in sham-exposed immobilized animals, and 3) if a threshold level for brain near field radiofrequency exposure could be identified using a series of molecular stress markers.
|Exposure duration||continuous for 2 h|
|Distance between exposed object and exposure source||5 cm|
|Chamber||Carousel containing 10 cylindrical PVC tubes arranged radially around a central antenna (see reference article).|
|Setup||Animals were loosely restrained in the PVC cylindrical tubes. Clear acrylic pins were placed vertically behind the animal to prevent backward mobility. Only five animals at a time were placed in every other tube for symmetry. The field-exposure and the sham-exposure carousels were located in the same rack.|
The data revealed that Iridium-modulated microwave fields at brain SAR levels up to 5 W/kg did not induce a stress response in terms of elevated core body temperature, plasma ACTH and corticosteroids, or brain ODC, Fos and Jun mRNA levels in rats immobilized in loose-tube restraints (compared to sham-exposed loose-tube immobilized animals).
However, the non-tube-trained rats did experience a significant stress response when placed into the tube restraint apparatus. This stress response was seen clearly as short-term (less than 2 h) increases in plasma ACTH and corticosterone levels and a transient, small increase in core body temperature. Adaptation by prior conditioning (tube training) lessened the extent and duration of the stress-related marker elevations.
In conclusion, the pulse modulated digital Iridium radiofrequency field at SAR-values up to 5 W/kg is incapable of altering these stress-related responses. This conclusion is further supported by the use of a radiofrequency field exposure apparatus that minimized immobilization stress.