Biological Model in Electromagnetic Exposure Safety

摘要

At present time, there are two very different criteria for setting electromagnetic field (EMF) exposure safety (hygienic) standards. These regulations are based on different sciencebased approaches using different metrics, such as specific absorption rate (SAR-ICNIRP) and power exposure (PE-Russia) [1,2]. The exposure metrics of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) require the measurement of electric, magnetic field strength and power density (PD). In the frequency band 100 kHz-10GHz, the ICNIRP basic restrictions hinge on the concept of specific absorption rate (SAR) which is denned as where E is the RMS value of the electric field in tissue, σ and ρ are the tissue conductivity and mass density. In (1) also, C_i and dT/dt are the specific heat of tissue and the time derivative of the temperature at the onset of the RF exposure. SAR measures the rate of EMF energy absorption in the unit of weight of an exposed object. SAR is used to quantify tissue exposure from EMF in the far and the near field of RF sources, where PD might not be defined or even definable. The SAR basic restrictions of ICNIRP are time independent because the rate of energy absorption is limited, not its total amount.