Neurovegetative disturbances in workers exposed to 50 Hz electromagnetic fields.

Abstract

OBJECTIVES: Since the circulatory and nervous systems are composed of electrically excitable tissues, it is plausible that they can be stimulated by electromagnetic fields (EMF). No clinical studies have as yet been carried out to explain whether and how occupational exposure to 50 Hz EMF can influence the neurovegetative regulation of the cardiovascular function. The present project was undertaken to assess the autonomic function in workers occupationally exposed to 50 Hz EMF, by analyzing the heart rate variability. MATERIALS AND METHODS: The study group comprised 63 workers of switchyard substations, aged 22-67 years (39.2 +/- 10.0 years), and the control group 42 workers of radio link stations, aged 20-68 years (40.7 +/- 9.2 years), employed at workposts free from EMF exposure. The age range and employment duration in both groups did not differ significantly. To assess the neurovegetative regulation of the cardiac function, heart rate variability (HRV) analysis was made based on 512 normal heart beats recorded at rest. The analysis, performed using fast Fourier transformation, concerned the time- and frequency-domain HRV parameters. Power spectrum in the very low (VLF), low (LF) and high (HF) frequency bands was determined. RESULTS: The relative risk of decreased HRV (STD R-R < 27 ms), calculated with use of a logistic regression model, was significantly higher in the exposed group than in controls (OR = 2.8). The VLF power spectrum was significantly higher in the exposed group and correlated with the exposure level. The percentage of subjects with dominant sympathetic function (LF/HF > 1) was significantly higher in the study group than in controls (65% vs. 47%). CONCLUSIONS: It was concluded that occupational exposure to 50 Hz EMF could influence the neurovegetative regulation of the cardiovascular system.

AI evidence extraction

Main findings

Compared with controls, the exposed group had a significantly higher relative risk of decreased HRV (STD R-R < 27 ms; OR = 2.8). VLF power spectrum was significantly higher in the exposed group and correlated with exposure level. The proportion with dominant sympathetic function (LF/HF > 1) was higher in exposed workers than controls (65% vs. 47%).

Outcomes measured

• Heart rate variability (HRV) parameters (time- and frequency-domain)
• Decreased HRV (STD R-R < 27 ms)
• VLF power spectrum
• LF/HF ratio (dominant sympathetic function)

Limitations

• No exposure metrics or measurement methods are described in the abstract (only that VLF correlated with exposure level).
• Cross-sectional assessment at rest; temporality/causality cannot be established from the abstract.
• Potential confounding factors are not described beyond age range and employment duration being similar.

Suggested hubs

• occupational-exposure (0.95)
  Study evaluates autonomic/cardiovascular outcomes in workers occupationally exposed to 50 Hz EMF.

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    "study_type": "cohort",
    "exposure": {
        "band": "ELF",
        "source": "occupational",
        "frequency_mhz": 0.05000000000000000277555756156289135105907917022705078125,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Workers of switchyard substations (exposed) and workers of radio link stations (controls)",
    "sample_size": 105,
    "outcomes": [
        "Heart rate variability (HRV) parameters (time- and frequency-domain)",
        "Decreased HRV (STD R-R < 27 ms)",
        "VLF power spectrum",
        "LF/HF ratio (dominant sympathetic function)"
    ],
    "main_findings": "Compared with controls, the exposed group had a significantly higher relative risk of decreased HRV (STD R-R < 27 ms; OR = 2.8). VLF power spectrum was significantly higher in the exposed group and correlated with exposure level. The proportion with dominant sympathetic function (LF/HF > 1) was higher in exposed workers than controls (65% vs. 47%).",
    "effect_direction": "harm",
    "limitations": [
        "No exposure metrics or measurement methods are described in the abstract (only that VLF correlated with exposure level).",
        "Cross-sectional assessment at rest; temporality/causality cannot be established from the abstract.",
        "Potential confounding factors are not described beyond age range and employment duration being similar."
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "50 Hz",
        "ELF EMF",
        "occupational exposure",
        "switchyard substations",
        "autonomic function",
        "neurovegetative regulation",
        "cardiovascular",
        "heart rate variability",
        "VLF",
        "LF/HF",
        "sympathetic function"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.9499999999999999555910790149937383830547332763671875,
            "reason": "Study evaluates autonomic/cardiovascular outcomes in workers occupationally exposed to 50 Hz EMF."
        }
    ]
}

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