Progress in Dosimetric Studies for Cellular Mobile System Exposure Part 1: Exposure to Mobile Terminals

For many years, dosimetric studies of the interaction between a mobile terminal and the human body have concentrated on the effect on the head of the user. The studies have been conducted on two parallel paths: computational and experimental, and, for both paths, the past decade has seen a steady trend towards increasing realism in the representation of the components of the complete interaction system. This was achieved by use of detailed three-dimensional images of the human head, later complemented by realistic representations of the human hand, as holding the terminal. Recently, techniques to represent the terminal itself with a high degree of detail have been perfected. The high degree of realism gives confidence, especially for lay persons, that no subtlety in the electromagnetic field distributions has been overlooked. The target parameter has traditionally been the specific absorption rate (SAR), but recently several groups have shown some success in simulating the actual temperature rise in the human tissue. For the future, it is probable that many new usage scenarios will have to be considered. It is possible that temperature rise instead of SAR may become the preferred target parameter, although this would require agreement at the international standardisation level. It is also possible that microscopic bioelectromagnetic phenomena may become the basis for the target parameters in the longer term. If this were to happen, the modulation of the signal would certainly have to be taken into account. Even in the short-to-medium term, the use of wide band signals may mean that preferred practice would have to migrate to use of realistic waveforms, rather than monochromatic carrier signals as at present.