Calculation Of Induced Currents In A HumanBody Represented By A Spheroidal Model

Abstract

There has been much discussion about possible health risks from exposure to power system electric and magnetic fields. The induced current densities in a human body located in these extremely low frequency fields can be determined by calculation. The basic restriction of the ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines for 50 Hz fields is 10 mA/nf (to workers). The aim of this study is to examine the induced current densities due to power system fields in the working environment by using the spheroidal calculation model. The study includes 27 workers exposed to electric and magnetic fields from power systems in different work environments. The fields in the workplaces were measured for calculation. The internal field and current density induced in a human body by the electric and magnetic fields was calculated using the spheroidal model, which is suitable for evaluating the current density in the whole body. Tissue conductivity of 0.2 S/m was used in this calculation. The highest measured values in different workplaces were 0.14 kV/m ... 11.2 kV/m for electric fields and 0.57 uT ... 16.2 uT for magnetic fields. The calculated internal fields caused by the electric fields were 0.097 mV/m ... 7.79 mV/m. The induced internal currents were 0.019 mA/nf ... 1.56 rnA/m^ by electric fields and 0.0050 mA/nf ... 0.14 mA/nf by magnetic fields. When the current densities were roughly summed the values were 0.024 mA/nf ... 1.70 mA/nf. The internal current densities are clearly below the ICNIRP guidelines, 10 mA/m For the general public the exposure limits are lower because of safety margins. The calculated values are far from these values as well. The calculated internal currents caused by electric fields are about ten times higher than the currents caused by magnetic fields.