On the importance of body posture and skin modelling with respect toin situelectric field strengths in magnetic field exposure scenarios

Abstract

The reference levels and maximum permissible exposure values for magnetic fields that are currently used have been derived from basic restrictions under the assumption of upright standing body models in a standard posture, i.e. with arms laterally down and without contact with metallic objects. Moreover, if anatomical modelling of the body was used at all, the skin was represented as a single homogeneous tissue layer. In the present paper we addressed the possible impacts of posture and skin modelling in scenarios of exposure to a 50 Hz uniform magnetic field on the in situ electric field strength in peripheral tissues, which must be limited in order to avoid peripheral nerve stimulation. We considered different body postures including situations where body parts form large induction loops (e.g. clasped hands) with skin-to-skin and skin-to-metal contact spots and compared the results obtained with a homogeneous single-layer skin model to results obtained with a more realistic two-layer skin representation consisting of a low-conductivity stratum corneum layer on top of a combined layer for the cellular epidermis and dermis. Our results clearly indicated that postures with loops formed of body parts may lead to substantially higher maximum values of induced in situ electric field strengths than in the case of standard postures due to a highly concentrated current density and in situ electric field strength in the skin-to-skin and skin-to-metal contact regions. With a homogeneous single-layer skin, as is used for even the most recent anatomical body models in exposure assessment, the in situ electric field strength may exceed the basic restrictions in such situations, even when the reference levels and maximum permissible exposure values are not exceeded. However, when using the more realistic two-layer skin model the obtained in situ electric field strengths were substantially lower and no violations of the basic restrictions occurred, which can be explained by the current-limiting effect of the low-conductivity stratum corneum layer.

Assessment of the Induced Electric Fields in a Carbon-Fiber Electrical Vehicle Equipped with a Wireless Power Transfer System

“…The electric field is then averaged over a 2 × 2 × 2 mm 3 cube according to the ICNIRP guidelines [3]. The 99th percentile is instead not used after considerations from several research groups [26][27][28][29][30].…”

Arc Welding Processes: An Electrical Safety Analysis

“…The modeling of the skin is nowadays an open problem for the scientific community [27], [28], [29], [30]. …”

Effect of Electrical Conductivity Uncertainty in the Assessment of the Electric Fields Induced in the Brain by Exposure to Uniform Magnetic Fields at 50 Hz

“…Please note that the conductivity ratios of the head tissues do not vary significantly up to frequencies of 100 kHz [28]. Therefore, the results obtained in the present study could be scaled within this frequency range [29]. Numerical calculations were performed with the purpose of estimating the variability of the calculated electric field strengths due to the uncertainty in the electrical conductivity of the tissues.…”

“…We selected the frequency of 50 Hz as it corresponds to the European power line frequency, and therefore it represents a common real-life exposure scenario. For this reason, most of the investigations in this field of research considered a frequency of 50 Hz [5], [6], [8], [16], [23], [29]. Please note that the conductivity ratios of the head tissues do not vary significantly up to frequencies of 100 kHz [28].…”