Study type: Medical/biological study (experimental study)

Identification of Environmental and Experimental Factors Influencing Human Perception of DC and AC Electric Fields. med./bio.

Published in: Bioelectromagnetics 2021 [in press]

Aim of study (acc. to author)

In this preliminary study, the human perception of static electric fields, alternating electric fields and their co-exposure should be investigated and factors that influence the perception should be determined.

Background/further details

As part of the energy transition in Germany, high-voltage direct current (HVDC) lines producing static electric fields are in planning. However, the human perception of static electric fields was rarely investigated in the past. In the present preliminary study, the essential settings for a future comprehensive main study should be identified.
Eleven healthy participants (9 males and 2 females) aged 23 to 33 years were included in the randomized cross-over study. Two participants dropped out during the period of the experiments. Overall, 5 test days per participant were carried out. To investigate the influence of experimental and environmental factors on human electric field perception, the ramp slope of electric field buildup, exposure duration, ion current density, polarity, and relative humidity were modified on different test days.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 0 Hz
Exposure duration: up to 25 s with full field strength per trial
Exposure 2: 50 Hz
Exposure duration: up to 25 s with full field strength per trial
Exposure 3: 0–50 Hz
Exposure duration: up to 25 s with full field strength per trial

Exposure 1

Main characteristics
Frequency 0 Hz
Type
Exposure duration up to 25 s with full field strength per trial
Additional info static electric field
Exposure setup
Exposure source
Chamber the exposure lab was 4 m long and wide and 3 m high, and contained a central height‐adjustable chair; the room and the chair were built of laminated densified wood to prevent conductive processes and charge accumulation; relative humidity could be set to 30%, 50%, or 70%, whereas temperature was constantly kept at 22 °C (±0.2 °C); several measures were taken to guarantee real sham exposure conditions and the double‐blind study design; security measures were taken to prevent arc discharge and to ensure participant's safety
Setup the electric field and ion current generating systems were located in the ceiling of the exposure lab and consisted of four high‐voltage electrodes; the electrodes were 4 m in diameter and mounted on top of each other; electrodes 1, 2, and 4 consisted of 2 mm‐thick perforated aluminum sheets, while electrode 3 was constructed of single high‐grade steel wires with a diameter of 200 μm and a distance of 0.1 m to each other.; whereas electrodes 2, 3, and 4 were used to generate a uniform ion current flow, electrode 1 was primarily used for electric field generation; fourteen grading electrodes positioned on top of each other on the exposure lab walls ensured a homogeneous electric field between electrode 1 and the floor, which was used as the base plate
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 10 kV/m minimum calibration - -
electric field strength 44 kV/m maximum calibration - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration up to 25 s with full field strength per trial
Additional info electric alternating field
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 10 kV/m minimum calibration - -
electric field strength 30 kV/m maximum calibration - -

Exposure 3

Main characteristics
Frequency 0–50 Hz
Type
Exposure duration up to 25 s with full field strength per trial
Additional info co-exposure
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 4 kV/m - calibration - electric alternating field
electric field strength 6 kV/m minimum calibration - static electric field
electric field strength 30 kV/m maximum calibration - static electric field

Reference articles

  • Blondin JP et al. (1996): Human perception of electric fields and ion currents associated with high-voltage DC transmission lines.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

Overall perception threshold was 23.4 kV/m for static electric fields, 16.9 kV/m for alternating electric fields and 11.4 kV/m for co-exposure, indicating that the averaged perception threshold for co-exposure to 4 kV/m alternating electric field and 6–30 kV/m static electric field was lower than that for the respective exposures alone. Relative humidity was identified as an environmental factor influencing the perception of static electric fields and alternating electric fields. An appropriate ramp slope and an exposure duration for future studies was elaborated. Subjective sensations evoked under exposure were individually different and attributed to various parts of the body; however, no participant reported painful sensations.
The authors concluded that several environmental and experimental factors influencing the human perception of electric fields and preliminary perception tresholds could be identified, which provide an essential basis for a large‐scale main study.

Study character:

Study funded by

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