The effect of pulsed and sinusoidal magnetic fields on the morphology of developing chick embryos

Bioelectromagnetics · 1997 · Harm · Low evidence

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HarmLow evidencePaper 2709

Study snapshot

PublicationBioelectromagnetics · 1997

Study typeanimal

Reported directionHarm

Evidence ratingLow

Abstract

Several investigators have reported robust, statistically significant results that indicate that weak (approximately 1 microT) magnetic fields (MFs) increase the rate of morphological abnormalities in chick embryos. However, other investigators have reported that weak MFs do not appear to affect embryo morphology at all. We present the results of experiments conducted over five years in five distinct campaigns spanning several months each. In four of the campaigns, exposure was to a pulsed magnetic field (PMF); and in the final campaign, exposure was to a 60 Hz sinusoidal magnetic field (MF). A total of over 2500 White Leghorn chick embryos were examined. When the results of the campaigns were analyzed separately, a range of responses was observed. Four campaigns (three PMF campaigns and one 60 Hz campaign) exhibited statistically significant increases (P > or = 0.01), ranging from 2-fold to 7-fold, in the abnormality rate in MF-exposed embryos. In the remaining PMF campaign, there was only a slight (roughly 50%), statistically insignificant (P = 0.2) increase in the abnormality rate due to MF exposure. When the morphological abnormality rate of all of the PMF-exposed embryos was compared to that of all of the corresponding control embryos, a statistically significant (P > or = .001) result was obtained, indicating that PMF exposure approximately doubled the abnormality rate. Like-wise, when the abnormality rate of the sinusoid-exposed embryos was compared to the corresponding control embryos, the abnormality rate was increased (approximately tripled). This robust result indicates that weak EMFs can induce morphological abnormalities in developing chick embryos. We have attempted to analyze some of the confounding factors that may have contributed to the lack of response in one of the campaigns. The genetic composition of the breeding stock was altered by the breeder before the start of the nonresponding campaign. We hypothesize that the genetic composition of the breeding stock determines the susceptibility of any given flock to EMF-induced abnormalities and therefore could represent a confounding factor in studies of EMF-induced bioeffects in chick embryos. Editor Note: The increase in NTDs seen in this study was the smoking gun for why rfsafe.com was founded a year later in 1998

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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 typeanimal

Effect directionharm

PopulationWhite Leghorn chick embryos

Sample sizeNot supplied

ExposureELF · 6e-05 MHz · Five distinct campaigns spanning several months each over five years

Evidence strengthLowConfidence: 88% · Peer reviewed: yes

Main findings

Across over 2500 chick embryos examined in five campaigns, four campaigns showed statistically significant increases in morphological abnormality rates after weak magnetic field exposure, ranging from 2-fold to 7-fold. Pooled pulsed magnetic field exposure approximately doubled the abnormality rate, and 60 Hz sinusoidal magnetic field exposure approximately tripled it. One pulsed-field campaign showed only a statistically insignificant roughly 50% increase.

Outcomes measured

morphological abnormalities in developing chick embryos

Limitations

One pulsed magnetic field campaign did not show a statistically significant response.
The authors identify altered genetic composition of the breeding stock as a possible confounding factor affecting susceptibility.
Animal embryo study; applicability to other species is not addressed in the abstract.
Detailed pulsed-field exposure parameters are not provided in the abstract.

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 6e-05,
    "sar_wkg": null,
    "duration": "Five distinct campaigns spanning several months each over five years"
  },
  "population": "White Leghorn chick embryos",
  "sample_size": null,
  "outcomes": [
    "morphological abnormalities in developing chick embryos"
  ],
  "main_findings": "Across over 2500 chick embryos examined in five campaigns, four campaigns showed statistically significant increases in morphological abnormality rates after weak magnetic field exposure, ranging from 2-fold to 7-fold. Pooled pulsed magnetic field exposure approximately doubled the abnormality rate, and 60 Hz sinusoidal magnetic field exposure approximately tripled it. One pulsed-field campaign showed only a statistically insignificant roughly 50% increase.",
  "effect_direction": "harm",
  "limitations": [
    "One pulsed magnetic field campaign did not show a statistically significant response.",
    "The authors identify altered genetic composition of the breeding stock as a possible confounding factor affecting susceptibility.",
    "Animal embryo study; applicability to other species is not addressed in the abstract.",
    "Detailed pulsed-field exposure parameters are not provided in the abstract."
  ],
  "evidence_strength": "low",
  "confidence": 0.88,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "chick embryos",
    "magnetic fields",
    "pulsed magnetic field",
    "60 Hz",
    "ELF",
    "morphological abnormalities",
    "developmental effects",
    "bioelectromagnetics"
  ],
  "suggested_hubs": []
}

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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: 10.1002/(sici)1521-186x(1997)18:6<431::aid-bem5>3.0.co;2-3
PubMed: 9261540

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