Effect of Occupational Extremely Low-Frequency Electromagnetic Field Exposure on the Thyroid Gland of Workers: A Prospective Study

Current medical science · 2022 · Mixed · Low evidence

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MixedLow evidencePaper 735

Study snapshot

PublicationCurrent medical science · 2022

Study typecohort

Reported directionMixed

Evidence ratingLow

Abstract

Effect of Occupational Extremely Low-Frequency Electromagnetic Field Exposure on the Thyroid Gland of Workers: A Prospective Study Fang YY, Tu Q, Zhang YT, Liu J, Liu HG, Zhao ZH, Wu H, Yin TJ. Effect of Occupational Extremely Low-Frequency Electromagnetic Field Exposure on the Thyroid Gland of Workers: A Prospective Study. Curr Med Sci. 2022 Aug;42(4):817-823. doi: 10.1007/s11596-022-2610-8. Abstract Objective: The aim of this study was to investigate the biological effects of occupational extremely low- frequency electromagnetic field (ELF-EMF) exposure on the thyroid gland. Methods: We conducted a prospective analysis of 85 workers (exposure group) exposed to an ELF-EMF (100 μT, 10-100 Hz) produced by the electromagnetic aircraft launch system and followed up on thyroid function indices, immunological indices, and color Doppler images for 3 years. Additionally, 116 healthy volunteers were randomly selected as controls (control group), the thyroid function of whom was compared to the exposure group. Results: No significant difference was observed in thyroid function between the exposure and control groups. During the follow-up of the exposure group, the serum free triiodothyronine (FT3) level was found to slowly decrease and free thyroxine (FT4) level slowly increase with increasing exposure time. However, no significant difference was found in thyroid-stimulating hormone (TSH) over the three years, and no significant difference was observed in the FT3, FT4 and TSH levels between different exposure subgroups. Furthermore, no significant changes were observed in thyroid autoantibody levels and ultrasound images between subgroups or over time. Conclusion: Long-term exposure to ELF-EMF may promote thyroid secretion of T4 and inhibit deiodination of T4 to T3. ELF-EMF has no significant effect on thyroid immune function and morphology. pubmed.ncbi.nlm.nih.gov Excerpt One of the currently popular research topics is whether thyroid cancer can be induced by long-term ELF-EMF exposure. As we know, cancer is caused by DNA damage, but it is generally believed that ELF-EMF is too weak to directly damage DNA. Nevertheless, a recent study shows that long-term occupational exposure to ELF-EMF may cause a genetically toxic effect. The researchers believe that DNA damage is caused by the magnetic field due to the oxidative stress that the magnetic field induced [32]. Another meta-analysis on the relation between ELF- EMF and the risk of cancer suggests that ELF-EMF increases the risk of cancer [33]. 32 Bagheri Hosseinabadi M, Khanjani N, Mirzaii M, et al. DNA damage from long-term occupational exposure to extremely low frequency electromagnetic fields among power plant workers. Mutat Res, 2019,846:403079 33 Zhang Y, Lai J, Ruan G, et al. Meta-analysis of extremely low frequency electromagnetic fields and cancer risk: a pooled analysis of epidemiologic studies. Environ Int, 2016,88:36-43

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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 typecohort

Effect directionmixed

PopulationWorkers exposed to ELF-EMF produced by an electromagnetic aircraft launch system; controls were healthy volunteers

Sample size201

ExposureELF · 3 years follow-up; exposure described as 100 μT, 10–100 Hz

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

There was no significant difference in thyroid function between the exposure group and controls. Over 3 years within the exposure group, FT3 slowly decreased and FT4 slowly increased with increasing exposure time, while TSH did not significantly change; no significant differences in FT3/FT4/TSH were observed between exposure subgroups. Thyroid autoantibody levels and ultrasound images showed no significant changes between subgroups or over time.

Outcomes measured

Thyroid function indices (FT3, FT4, TSH)
Immunological indices (thyroid autoantibodies)
Thyroid color Doppler ultrasound images (morphology)

Limitations

Exposure metric details beyond 100 μT and 10–100 Hz not described in the abstract
Control group comparison described only for thyroid function (not clearly for immune indices or imaging)
No quantitative effect sizes or statistical details provided in the abstract

View raw extracted JSON

{
  "study_type": "cohort",
  "exposure": {
    "band": "ELF",
    "source": "occupational (electromagnetic aircraft launch system)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "3 years follow-up; exposure described as 100 μT, 10–100 Hz"
  },
  "population": "Workers exposed to ELF-EMF produced by an electromagnetic aircraft launch system; controls were healthy volunteers",
  "sample_size": 201,
  "outcomes": [
    "Thyroid function indices (FT3, FT4, TSH)",
    "Immunological indices (thyroid autoantibodies)",
    "Thyroid color Doppler ultrasound images (morphology)"
  ],
  "main_findings": "There was no significant difference in thyroid function between the exposure group and controls. Over 3 years within the exposure group, FT3 slowly decreased and FT4 slowly increased with increasing exposure time, while TSH did not significantly change; no significant differences in FT3/FT4/TSH were observed between exposure subgroups. Thyroid autoantibody levels and ultrasound images showed no significant changes between subgroups or over time.",
  "effect_direction": "mixed",
  "limitations": [
    "Exposure metric details beyond 100 μT and 10–100 Hz not described in the abstract",
    "Control group comparison described only for thyroid function (not clearly for immune indices or imaging)",
    "No quantitative effect sizes or statistical details provided in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low-frequency electromagnetic field",
    "ELF-EMF",
    "occupational exposure",
    "thyroid gland",
    "FT3",
    "FT4",
    "TSH",
    "thyroid autoantibodies",
    "ultrasound",
    "prospective study",
    "electromagnetic aircraft launch system"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.9,
      "reason": "Study evaluates long-term occupational ELF-EMF exposure in workers."
    }
  ]
}

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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: 10.1007/s11596-022-2610-8
PubMed: 35963949

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