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Human detection thresholds of DC, AC, and hybrid electric fields: a double-blind study

2021 · Mixed · Moderate evidence

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MixedModerate evidencePaper 1064

In 203 participants exposed in a double-blind whole-body laboratory setting, detection thresholds for hybrid electric fields were lower than for DC-only or AC-only fields. Ion current exposure enhanced electric field perception. High relative humidity facilit…

Study snapshot

Publicationmanual · 2021
Study typerandomized_trial
Reported directionMixed
Evidence ratingModerate

Abstract

Human detection thresholds of DC, AC, and hybrid electric fields: a double-blind study Michael Kursawe, Dominik Stunder, Thomas Krampert, Andrea Kaifie, Sarah Drießen, Thomas Kraus, Kathrin Jankowiak. Human detection thresholds of DC, AC, and hybrid electric fields: a double-blind study. Environ Health. 2021 Aug 21;20(1):92. doi: 10.1186/s12940-021-00781-4. Abstract Background: In the course of the ongoing transition of electric energy systems, transmission corridors are often upgraded to higher voltages and other technologies leading to another quality of human exposure. The study aims to determine human detection thresholds for direct current (DC), alternating current (AC), and hybrid electric fields (various DC; constant AC). Methods: A total of 203 participants were exposed to DC, AC, and hybrid electric fields (EFs) in a highly specialized whole-body exposure laboratory using a double-blind experimental setting. Additionally, the participants were exposed to ion currents in part of the DC and hybrid sessions. To investigate environmental influences, relative humidity was changed in two subgroups during EF perception. Methods derived from the signal detection theory and the adaptive staircase procedure based on the single interval adjustment matrix were used to assess individual sensitivity and detection thresholds, respectively. Results: The results indicated that detection thresholds of hybrid EF were lower compared to single EF presentation of DC or AC. Ion current exposure enhanced EF perception. High relative humidity facilitated DC EF perception, whereas low relative humidity reinforced the perception of AC EFs. Conclusions: With this systematic investigation of human perception of DC, AC, and hybrid EFs, detection thresholds were provided, which can help improve the construction processes of energy transmission systems and the prevention of unwanted sensory perception by contributing to the determination of limit values. Conclusion This study is the first systematic investigation of hybrid EF perception in humans using a double-blind experimental setup. While detection thresholds of DC and AC EF were lower compared to previous studies, the synergistic effect of both field types on human perception was shown. Especially, in the minimal hybrid EF combination (2 kV/m DC and 4 kV/m AC), 40% of the participants were able to successfully detect the EF. In terms of unwanted sensory perception, this should be considered in the discussion on reference levels and recommendations for hybrid EFs, which current remain non-existent. Furthermore, we suggest a further investigation on low hybrid EFs in detail to obtain a fine-grained picture of the lower bound of human EF perception. Although the average detection thresholds do not undercut the existing reference levels for DC and AC EFs, the study found evidence for successful EF perception around these reference levels in a small subset of participants. As the reference levels were mainly designed to prevent adverse health effects during EF exposure [14, 16], the current results do not question these values. Furthermore, the findings can be utilized in the discussion on whether sensory perception, as a byproduct of EF exposure, is acceptable. We enhanced the external validity of the results by investigating subgroups across different levels of relative humidity. Hints for an enhanced perception of DC EF in a high-humidity environment and a facilitated AC perception under low-humidity conditions were confirmed. These results may further contribute to the understanding of the underlying mechanisms and should be considered as well in the discussion on recommendations for EF exposure. Thus, this study provided reliable EF detection thresholds that add quantitative information on sensory perception to the discourse on the impact of EF exposure. In this manner, it can help to improve the construction processes of planned HVDC and hybrid overhead power lines. Open access paper: ehjournal.biomedcentral.com

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typerandomized_trial
Effect directionmixed
PopulationHuman participants
Sample size203
ExposureELF
Evidence strengthModerateConfidence: 74% · Peer reviewed: yes

Main findings

In 203 participants exposed in a double-blind whole-body laboratory setting, detection thresholds for hybrid electric fields were lower than for DC-only or AC-only fields. Ion current exposure enhanced electric field perception. High relative humidity facilitated DC electric field perception, while low relative humidity reinforced perception of AC electric fields.

Outcomes measured

  • Detection thresholds for DC electric fields
  • Detection thresholds for AC electric fields
  • Detection thresholds for hybrid (DC+AC) electric fields
  • Effect of ion current exposure on electric field perception
  • Effect of relative humidity on electric field perception
View raw extracted JSON
{
  "study_type": "randomized_trial",
  "exposure": {
    "band": "ELF",
    "source": "power transmission / overhead power lines (HVDC, AC, hybrid)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Human participants",
  "sample_size": 203,
  "outcomes": [
    "Detection thresholds for DC electric fields",
    "Detection thresholds for AC electric fields",
    "Detection thresholds for hybrid (DC+AC) electric fields",
    "Effect of ion current exposure on electric field perception",
    "Effect of relative humidity on electric field perception"
  ],
  "main_findings": "In 203 participants exposed in a double-blind whole-body laboratory setting, detection thresholds for hybrid electric fields were lower than for DC-only or AC-only fields. Ion current exposure enhanced electric field perception. High relative humidity facilitated DC electric field perception, while low relative humidity reinforced perception of AC electric fields.",
  "effect_direction": "mixed",
  "limitations": [],
  "evidence_strength": "moderate",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "electric fields",
    "DC electric field",
    "AC electric field",
    "hybrid electric field",
    "human perception",
    "detection threshold",
    "double-blind",
    "ion currents",
    "relative humidity",
    "HVDC",
    "overhead power lines"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.32,
      "reason": "Study concerns human exposure and perception thresholds relevant to high-voltage transmission environments (HVDC/AC/hybrid), which can overlap with occupational settings."
    }
  ]
}
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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1186/s12940-021-00781-4
PubMed: Not supplied

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