Setup and dosimetry for exposure of human skin in vivo to RF-EMF at 900 MHz.

The aim of this study was a dosimetrical analysis of an experimental setup used in the exposure of 10 female volunteers to GSM 900 radiation. The exposure was carried out by irradiating a small region of the right forearms of the volunteers for 1 h, after which biopsies were taken from the exposed skin for protein analysis. The source of irradiation was a half-wave dipole fed with a computer controlled GSM phone. The specific absorption rate (SAR) induced in the skin biopsy was assessed by computer simulations. The numerical model of the arm consisted of a muscle tissue simulating cylinder covered with thin skin (1 mm) and fat (3 mm) layers. The simulation models were validated by measurements with a homogeneous cylindrical liquid phantom. The average SAR value in the biopsy was 1.3 W/kg and the estimated uncertainty +/-20% (K = 2). The main source of error was found to be variations in the distance of the forearm from the dipole (10 +/- 1 mm). Other significant sources of uncertainty are individual variations of the fat layer and arm thicknesses, and the uncertainty of radio frequency (RF) power measurement.