Among the many biological effects caused by low intensity extremely high frequency electromagnetic fields (EHF-EMF) reported in the literature, those on the nervous system are a promising area for further research. The mechanisms by which these fields alter neural activity are still unclear and thus far there appears to be no frequency dependence regarding neuronal responses. Therefore, proper in vitro models for preliminary screening studies of the interaction between neural cells with EMF are needed. We designed an artificial axon model consisting of a series of parallel RC networks. Each RC network contained an aqueous solution of lipid vesicles with a gradient of potassium (K+) concentration as the functional element. We investigated the effects of EHF-EMF (53.37 GHz–39 mW) on the propagation of the electric impulse. We report that exposure to the EHF-EMF increases the amplitude of electrical signal by inducing a potassium efflux from lipid vesicles. Further, exposure to the EHF-EMF potentiates the action of valinomycin – a K+ carrier – increasing the extent of K+ transport across the lipid membrane. We conclude that exposure to the EHF-EMF facilitates the electrical signal propagation by increasing transmembrane potassium efflux, and that the model presented is promising for future screening studies of different EMF frequency spectrum bands.

In 2016 the Directive 2013/35/EU regarding the protection of health and safety of workers exposed to electromagnetic fields was transposed in Italy. Since then, the authors of this paper have been faced with several issues related to the implementation of the provisions of the Directive, which pose some interpretative and operative concerns. A primary critical feature of the Directive is that, in some circumstances, conditions of “overexposure”, i.e., of exceeding the exposure limits, are allowed. In the case of transient effects, the “flexibility” concerning the compliance with exposure limits is based on the approach introduced by ICNIRP in its guidelines on static magnetic fields and on time-varying electric and magnetic fields. On the contrary, the possibility of exceeding the exposure limits for health effects, formally recognized in the article of the Directive dealing with derogations, is not included in the ICNIRP guidelines. This paper analyzes the main concerns in interpreting and managing some provisions of the Directive with particular reference to the issue of how the employer can manage the situations of overexposure.

Purpose This study aims to perform a classification and rigorous numerical evaluation of the risks of occupational exposure in the health environment related to the administration of transcranial magnetic stimulation (TMS) treatment. The study investigates the numerically estimated induced electric field that occurs in the human tissues of an operator caused by exposure to the variable magnetic field produced by TMS during treatments. This could be a useful starting point for future risk assessment studies and safety indications in this context. Methods We performed a review of the actual positions assumed by clinicians during TMS treatments. Three different TMS coils (two circular and one figure‐of‐eight) were modeled and characterized numerically. Different orientations and positions of each coil with respect to the body of the operator were investigated to evaluate the induced electric (‐E) field in the body tissues. The collected data were processed to allow comparison with the safety standards for occupational exposure, as suggested by the International Commission on Non‐Ionizing Radiation Protection (ICNIRP) 2010 guidelines. Results Under the investigated conditions, exposure to TMS shows some criticalities for the operator performing the treatment. Depending on the model of the TMS coil and its relative position with respect to the operator's body, the numerically estimated E‐field could exceed the limits suggested by the ICNIRP 2010 guidelines. We established that the worst‐case scenario for the three coils occurs when they are placed in correspondence of the abdomen, with the handle oriented parallel to the body (II orientation). Working at a maximum TMS stimulator output (MSO), the induced E‐field is up to 7.32 V/m (circular coil) and up to 1.34 V/m (figure‐of‐eight coil). The induced E‐field can be modulated by the TMS percentage of MSO (%MSO) and by the distance between the source and the operator. At %MSO equal to or below 80%, the figure‐of‐eight coil was compliant with the ICNIRP limit (1.13 V/m). Conversely, the circular coil causes an induced E‐field above the limits, even when powered at a %MSO of 30%. Thus, in the investigated worst‐case conditions, an operator working with a circular coil should keep a distance from its edge to be compliant with the guidelines limit, which depends on the selected %MSO: 38 cm at 100%, 32 cm at 80%, 26.8 cm at 50%, and 19.8 cm at 30%. Furthermore, attention should be paid to the induced E‐field reached in the operator's hand as the operator typically holds the coil by hand. In fact in the hand, we estimated an induced E‐field up to 10 times higher than the limits. Conclusions Our numerical results indicate that coil positions, orientations, and distances with respect to the operator's body can determine the levels of induced E‐field that exceed the ICNIRP limits. The induced E‐field is also modulated by the choice of %MSO, which is related to the TMS application. Even under the best exposure conditions, attention should be paid to the exposure of the ha...

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