Measurement of Intermediate Frequency Magnetic Fields Generated by Household Induction Cookers for Epidemiological Studies and Development of an Exposure Estimation Model

2022 · Unclear · Low evidence

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UnclearLow evidencePaper 686

Study snapshot

Publicationmanual · 2022

Study typeexposure_assessment

Reported directionUnclear

Evidence ratingLow

Abstract

Measurement of Intermediate Frequency Magnetic Fields Generated by Household Induction Cookers for Epidemiological Studies and Development of an Exposure Estimation Model Kitajima T, Schüz J, Morita A, Ikeda W, Tanaka H, Togawa K, Gabazza EC, Taki M, Toriyabe K, Ikeda T, Sokejima S. Measurement of Intermediate Frequency Magnetic Fields Generated by Household Induction Cookers for Epidemiological Studies and Development of an Exposure Estimation Model. Int J Environ Res Public Health. 2022 Sep 21;19(19):11912. doi: 10.3390/ijerph191911912. Abstract Introduction: Exposure assessment of intermediate frequency (IF) electromagnetic fields (EMFs) is difficult and epidemiological studies are limited. In the present study, we aimed to estimate the exposure of pregnant women to IF-EMFs generated by induction cookers in the household using a questionnaire and discussed its applicability to epidemiological studies. Method: Two main home-visit surveys were conducted: a Phase 1 survey to develop an estimation model and a Phase 2 survey to validate the model. The estimation model included the following variables: wattage, cookware diameter, and distance from the hob center (center of the stove). Four models were constructed to determine the importance of each variable and the general applicability for epidemiological studies. In addition, estimated exposure values were calculated based on the Phase 2 survey questionnaire responses and compared with the actual measured values using the Spearman rank correlation coefficient. Result: The average value of the magnetic field measured in the Phase 1 survey was 0.23 μT (variance: 0.13) at a horizontal distance of 30 cm at the height of the cooking table. The highest validity model was inputted distance from the hob center to the body surface that is variable (correlation coefficient = 0.54, 95% confidence interval: 0.22–0.75). No clear differences were identified in the correlation coefficients for each model (z-value: 0.09– 0.18, p-value: 0.86–0.93). Discussion and Conclusions: No differences were found in the validity of the four models. This could be due to the biased wattage of the validation population, and for versatility it would be preferable to use three variables (distance, wattage, and estimation using the diameter of the cookware) whenever possible. To our knowledge, this is the first systematic measurement of magnetic fields generated by more than 70 induction cookers in a real household environment. This study will contribute to finding dose–response relationships in epidemiological studies of intermediate-frequency exposure without the use of instrumentation. One of the limitations of this study is it estimates instantaneous exposure in place during cooking only. Open access paper: mdpi.com

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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 typeexposure_assessment

Effect directionunclear

PopulationPregnant women (exposure estimation target); household setting (home-visit surveys)

Sample sizeNot supplied

ExposureIF · instantaneous exposure during cooking (in place)

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

In Phase 1, the average measured magnetic field was 0.23 μT (variance 0.13) at 30 cm horizontal distance at the height of the cooking table. In Phase 2 validation, the highest-validity model (using distance from hob center to body surface as a variable) showed a correlation coefficient of 0.54 (95% CI 0.22–0.75) between estimated and measured exposure; no clear differences in correlation coefficients were found across the four models (z 0.09–0.18; p 0.86–0.93).

Outcomes measured

Intermediate frequency magnetic field measurements (μT) from household induction cookers
Questionnaire-based exposure estimation model performance/validity (Spearman rank correlation between estimated and measured values)

Limitations

Exposure assessment limited to instantaneous exposure during cooking only
Potential bias in wattage distribution of the validation population (noted as affecting model validity/versatility)
Sample size not reported in abstract

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "IF",
    "source": "household induction cookers",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "instantaneous exposure during cooking (in place)"
  },
  "population": "Pregnant women (exposure estimation target); household setting (home-visit surveys)",
  "sample_size": null,
  "outcomes": [
    "Intermediate frequency magnetic field measurements (μT) from household induction cookers",
    "Questionnaire-based exposure estimation model performance/validity (Spearman rank correlation between estimated and measured values)"
  ],
  "main_findings": "In Phase 1, the average measured magnetic field was 0.23 μT (variance 0.13) at 30 cm horizontal distance at the height of the cooking table. In Phase 2 validation, the highest-validity model (using distance from hob center to body surface as a variable) showed a correlation coefficient of 0.54 (95% CI 0.22–0.75) between estimated and measured exposure; no clear differences in correlation coefficients were found across the four models (z 0.09–0.18; p 0.86–0.93).",
  "effect_direction": "unclear",
  "limitations": [
    "Exposure assessment limited to instantaneous exposure during cooking only",
    "Potential bias in wattage distribution of the validation population (noted as affecting model validity/versatility)",
    "Sample size not reported in abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "intermediate frequency",
    "magnetic fields",
    "EMF",
    "induction cooker",
    "household exposure",
    "pregnant women",
    "questionnaire",
    "exposure estimation model",
    "home-visit survey",
    "validation",
    "Spearman correlation"
  ],
  "suggested_hubs": [
    {
      "slug": "exposure-assessment",
      "weight": 0.9,
      "reason": "Study focuses on measuring IF magnetic fields from induction cookers and developing/validating a questionnaire-based exposure estimation model for epidemiological studies."
    }
  ]
}

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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: 10.3390/ijerph191911912
PubMed: Not supplied

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