Temperature rise for the human head for cellular telephones and for peak SARs prescribed in safety guidelines

The bioheat equation is solved for an anatomically based model of the human head with a resolution of 3 X 3 X 3 mm to study the thermal implications o f exposure to electromagnetic (EM) fields typical of cellular telephones bo th at 835 and 1900 MHz. It is shown that similar to the measured data, up t o 4.5 degreesC temperature elevation may be caused for locations of the pin na by a cellular telephone warmed by electronic circuitry to temperatures a s high as 39 degreesC, with temperature increases for the internal tissues such as the brain and eye that are no more than 0.1 degreesC-0.2 degreesC h igher than the basal values. Similar to previous studies by other authors, additional temperature increases due to EM fields of cellular telephones ar e fairly small and typically less than 0.1 degreesC. Another objective was to study the thermal implications of the SAR limits for the occupational ex posures of 8 W/kg for any 1 g, or 10 W/kg for any 10 g of tissue suggested in the commonly used safety guidelines. Such specific absorption rates (SAR s) would lead to temperature elevations for the electromagnetically exposed parts of the brain up to 0.5 degreesC with 10 W/kg for any 10 g of tissue resulting in somewhat higher temperatures and for larger volumes. Similar t emperature increases are also calculated by increasing the arterial blood t emperature, except that the temperature increases due to the SAR are for th e more limited volume rather than the entire brain.