The authors demonstrated in previous studies that combined exposure to radiofrequency irradiation (10 MHz) and the industrial solvent, 2-methoxyethanol, produces enhanced teratogenicity in rats (see publication 3522 and publication 3519).
The purpose of the present study was to determine the effects of varying the degree and duration of hyperthermia induced by radiofrequency irradiation (sufficient to maintain colonic temperatures at control [38.5], 39.0, 40.0, or 41.0°C for up to 6 h) and 2-methoxyethanol administered on gestation day 13 of rats.
Focusing on characterizing the dose-response pattern of interactions, this investigation seeks to determine the lowest interactive effect level.
Exposure duration: continuous for 2, 4 or 6 h
Target colonic temperature was set to 39°C
Exposure duration: continuous for 1, 2, 3 or 4 h
Target colonic temperature was set to 40°C
Exposure duration: continuous for 1 h
Target colonic temperature was set to 41°C
|Chamber||Near field synthesizers enclosed within copper wire chambers housed in Forma 7010 or 74668 environmental chambers|
|Setup||Rats placed in cylindrical Plexiglas holders with 12 mm holes which was placed on a Plexiglas table. The holders were designed to prevent the rat from changing its orientation. Each rat was oriented in its long axis for induced electric field to be parallel.|
|SAR||7.9 W/kg||mean||measured and calculated||whole body||applied initially to raise the temperature from 38.5°C to 39°C, 40°C or 41°C (20 min approximately)|
|SAR||0.8 W/kg||mean||measured and calculated||whole body||to 7.9 W/kg; SAR was adjusted to maintain the target temperature|
The findings are consistent with previous observations. Significant interactions were observed between 2-methoxyethanol and radiofrequency irradiation sufficient to maintain colonic temperatures at 41°C for 1 h, but no consistent interactions were revealed at lower temperatures even with longer durations. These findings indicate that combined exposure effects should be considered when developing both radiofrequency irradiation and chemical exposure guidelines.