The Impact of Thermal Modeling on Limiting RF-EMF*

Copyright © 2013 Norbert Leitgeb. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The paper quantitatively assesses the relationship between specific energy absorption rates (SAR) of radio frequency (RF) electromagnetic fields (EMF) and resulting intracorporal tissue temperature changes (∆T) at whole body exposure of a small person to resonant RF EMF. Applied thermal modeling allowed accounting also for dynamic thermoregula-tory responses. As expected from physical laws the correlation of all local SAR values and ∆T data was fairly good. However, at local level SAR proved to be only weakly associated with ∆T. Even if averaged, over any 10 g tissue the ratio ∆T10g/SAR10g still varied by almost two orders of magnitudes. Blood perfusion was found to play a major role in affecting local temperature changes and caused even net cooling. The results demonstrate that local SAR is a poor sur-rogate for local temperature change, and that conventional static thermal modeling underestimates body core tempera-ture. Results demonstrated that recommended reference levels of RF EMF fail to reliably prevent from exceeding yet legally binding basic restrictions not only with regard to whole-body SAR but also with regard to whole-body tempera-ture rise (ΔT). Consequently, from a legal point of view general presumption of conformity is no longer justified. While thermal basic restrictions were exceeded if related to the whole-body averaged value, compliance could not be exclude