Computational Assessment of Pregnant Woman Models Exposed to Uniform ELF- Magnetic Fields: Compliance with the European Current Exposure Regulations for the General Public and Occupational Exposures at 50 Hz

Ilaria Liorni, Marta Parazzini, Serena Fiocchi, Mark Douglas, Myles Capstick, Niels Kuster, and Paolo Ravazzani, Radiation Protection Dosimetry, online ahead of print November 30, 2015

The compliance of pregnant women with the current regulations regarding exposure to electric (EF) and magnetic fields (MF) at the low-frequency range of the electromagnetic spectrum as defined in the EU Council Recommendation 1999/529/EU and European Parliament and EU Directive 2013/35/EU was studied. These regulatory documents suggest limits for exposure to extremely low frequency magnetic fields for both the general public and workers, respectively, but without defining special limits for pregnant women. Exposure to low-frequency magnetic fields induces stimulation of the central (CNS) and peripheral (PNS) nervous system tissues. Computational modeling in SEMCAD X was used to evaluate exposures of a pregnant woman, based on the model Ella of the Virtual Population, with fetus at gestational ages (GA) 3, 7 and 9 months. Compliance with the 2010 Guidelines For Limiting Exposure To Time-Varying Electric And Magnetic Fields (1 Hz TO 100 kHz) published in 2010 by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) was also evaluated.

For the pregnant woman at all GAs and for all orientations of an incident 50 Hz, 100 µT magnetic field, the peak induced current density is in compliance with EU Recommendation 1999/529/EU for exposure of the general public. The whole body exposure of the fetus is also within compliance limits at 3 and 7 months GA; at 9 months GA, exposure exceeds limits in many non-nervous-system tissues.

For occupational exposures to incident 50 Hz fields of 1 mT or 6 mT, corresponding to low or high "action levels" (AL), the electric fields induced in pregnant women and fetuses are in compliance with EU Directive 2013/35/EU. However, a more stringent comparison to the basic restriction of the ICNIRP Guidelines 2010 for the general public shows that peak current densities induced in the fetal CNS tissues of the head by exposure to 1 mT at 7 and 9 months GA and to 6 mT at all GAs are higher than the limits and, thus, not intrinsically compliant with the safety recommendations.

The scientific and technical impact of the study can be summarized as:

• Compliance with EU exposure recommendations has been assessed specifically for a pregnant woman with fetus at three gestational ages
• The exposure level of the pregnant woman is always in compliance with guidelines for both the general public and workers
• Non-compliance with guidelines for the general public for exposure of some non-nervous-system fetal tissues was identified
• Occupational exposure of the fetus is apparently in compliance according to the EU Directive 2013/35/EU, but comparison to the ICNIRP guidelines reveals non-compliant exposures in the CNS tissues of the head  

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